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jashkenas--coffeescript/lib/coffeescript/rewriter.js

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// Generated by CoffeeScript 2.0.0-alpha1
2010-07-25 03:15:12 -04:00
(function() {
var BALANCED_PAIRS, CALL_CLOSERS, EXPRESSION_CLOSE, EXPRESSION_END, EXPRESSION_START, IMPLICIT_CALL, IMPLICIT_END, IMPLICIT_FUNC, IMPLICIT_UNSPACED_CALL, INVERSES, LINEBREAKS, SINGLE_CLOSERS, SINGLE_LINERS, generate, k, left, len, ref, rite,
indexOf = [].indexOf || function(item) { for (var i = 0, l = this.length; i < l; i++) { if (i in this && this[i] === item) return i; } return -1; };
generate = function(tag, value, origin) {
var tok;
tok = [tag, value];
tok.generated = true;
if (origin) {
tok.origin = origin;
}
return tok;
};
2010-12-23 13:50:52 -05:00
exports.Rewriter = (function() {
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
class Rewriter {
rewrite(tokens1) {
this.tokens = tokens1;
this.removeLeadingNewlines();
this.closeOpenCalls();
this.closeOpenIndexes();
this.normalizeLines();
this.tagPostfixConditionals();
this.addImplicitBracesAndParens();
this.addLocationDataToGeneratedTokens();
this.fixOutdentLocationData();
return this.tokens;
2010-10-02 05:57:16 -04:00
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
scanTokens(block) {
var i, token, tokens;
tokens = this.tokens;
i = 0;
while (token = tokens[i]) {
i += block.call(this, token, i, tokens);
2012-04-10 14:57:45 -04:00
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
return true;
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
detectEnd(i, condition, action) {
var levels, ref, ref1, token, tokens;
tokens = this.tokens;
levels = 0;
while (token = tokens[i]) {
if (levels === 0 && condition.call(this, token, i)) {
return action.call(this, token, i);
}
if (!token || levels < 0) {
return action.call(this, token, i - 1);
}
if (ref = token[0], indexOf.call(EXPRESSION_START, ref) >= 0) {
levels += 1;
} else if (ref1 = token[0], indexOf.call(EXPRESSION_END, ref1) >= 0) {
levels -= 1;
}
i += 1;
2012-04-10 14:57:45 -04:00
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
return i - 1;
2012-04-10 14:57:45 -04:00
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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var i, k, len, ref, tag;
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
if (i) {
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
closeOpenCalls() {
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var ref;
return ((ref = token[0]) === ')' || ref === 'CALL_END') || token[0] === 'OUTDENT' && this.tag(i - 1) === ')';
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2015-02-07 14:16:59 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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2015-02-07 14:16:59 -05:00
var ref;
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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2015-02-07 14:16:59 -05:00
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
return i + j + fuzz - 1;
2015-02-07 14:16:59 -05:00
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
looksObjectish(j) {
var end, index;
if (this.indexOfTag(j, '@', null, ':') > -1 || this.indexOfTag(j, null, ':') > -1) {
return true;
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
index = this.indexOfTag(j, EXPRESSION_START);
if (index > -1) {
end = null;
this.detectEnd(index + 1, (function(token) {
var ref;
return ref = token[0], indexOf.call(EXPRESSION_END, ref) >= 0;
}), (function(token, i) {
return end = i;
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if (this.tag(end + 1) === ':') {
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
return false;
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
findTagsBackwards(i, tags) {
var backStack, ref, ref1, ref2, ref3, ref4, ref5;
backStack = [];
while (i >= 0 && (backStack.length || (ref2 = this.tag(i), indexOf.call(tags, ref2) < 0) && ((ref3 = this.tag(i), indexOf.call(EXPRESSION_START, ref3) < 0) || this.tokens[i].generated) && (ref4 = this.tag(i), indexOf.call(LINEBREAKS, ref4) < 0))) {
if (ref = this.tag(i), indexOf.call(EXPRESSION_END, ref) >= 0) {
backStack.push(this.tag(i));
}
if ((ref1 = this.tag(i), indexOf.call(EXPRESSION_START, ref1) >= 0) && backStack.length) {
backStack.pop();
}
i -= 1;
}
return ref5 = this.tag(i), indexOf.call(tags, ref5) >= 0;
}
addImplicitBracesAndParens() {
var stack, start;
stack = [];
start = null;
return this.scanTokens(function(token, i, tokens) {
var endImplicitCall, endImplicitObject, forward, inImplicit, inImplicitCall, inImplicitControl, inImplicitObject, newLine, nextTag, offset, prevTag, prevToken, ref, ref1, ref2, ref3, ref4, ref5, s, sameLine, stackIdx, stackTag, stackTop, startIdx, startImplicitCall, startImplicitObject, startsLine, tag;
tag = token[0];
prevTag = (prevToken = i > 0 ? tokens[i - 1] : [])[0];
nextTag = (i < tokens.length - 1 ? tokens[i + 1] : [])[0];
stackTop = function() {
return stack[stack.length - 1];
};
startIdx = i;
forward = function(n) {
return i - startIdx + n;
};
inImplicit = function() {
var ref, ref1;
return (ref = stackTop()) != null ? (ref1 = ref[2]) != null ? ref1.ours : void 0 : void 0;
};
inImplicitCall = function() {
var ref;
return inImplicit() && ((ref = stackTop()) != null ? ref[0] : void 0) === '(';
};
inImplicitObject = function() {
var ref;
return inImplicit() && ((ref = stackTop()) != null ? ref[0] : void 0) === '{';
};
inImplicitControl = function() {
var ref;
return inImplicit && ((ref = stackTop()) != null ? ref[0] : void 0) === 'CONTROL';
};
startImplicitCall = function(j) {
var idx;
idx = j != null ? j : i;
stack.push([
'(', idx, {
ours: true
}
]);
tokens.splice(idx, 0, generate('CALL_START', '('));
if (j == null) {
return i += 1;
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
};
endImplicitCall = function() {
stack.pop();
tokens.splice(i, 0, generate('CALL_END', ')', ['', 'end of input', token[2]]));
return i += 1;
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
if (inImplicitControl()) {
stack.pop();
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
stack.push([tag, i]);
return forward(1);
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
if (indexOf.call(EXPRESSION_START, tag) >= 0) {
stack.push([tag, i]);
return forward(1);
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
start = stack.pop();
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
if ((indexOf.call(IMPLICIT_FUNC, tag) >= 0 && token.spaced || tag === '?' && i > 0 && !tokens[i - 1].spaced) && (indexOf.call(IMPLICIT_CALL, nextTag) >= 0 || indexOf.call(IMPLICIT_UNSPACED_CALL, nextTag) >= 0 && !((ref = tokens[i + 1]) != null ? ref.spaced : void 0) && !((ref1 = tokens[i + 1]) != null ? ref1.newLine : void 0))) {
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
if (indexOf.call(IMPLICIT_FUNC, tag) >= 0 && this.indexOfTag(i + 1, 'INDENT') > -1 && this.looksObjectish(i + 2) && !this.findTagsBackwards(i, ['CLASS', 'EXTENDS', 'IF', 'CATCH', 'SWITCH', 'LEADING_WHEN', 'FOR', 'WHILE', 'UNTIL'])) {
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2015-02-07 14:16:59 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
return forward(1);
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
});
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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Change OUTDENT tokens to be positioned at the end of the previous token This commit adds another post-processing step after normal lexing that sets the locationData on all OUTDENT tokens to be at the last character of the previous token. This does feel like a little bit of a hack. Ideally the location data would be set correctly in the first place and not in a post-processing step, but I tried that and some temporary intermediate tokens were causing problems, so I decided to set the location data once those intermediate tokens were removed. Also, having this as a separate processing step makes it more robust and isolated. This fixes the problem in https://github.com/decaffeinate/decaffeinate/issues/371 . In that issue, the CoffeeScript tokens had three OUTDENT tokens in a row, and the last two overlapped with the `]`. Since at least one of those OUTDENT tokens was considered part of the function body, the function expression had an ending position just after the end of the `]`. OUTDENT tokens are sort of a weird case in the lexer anyway, since they often don't correspond to an actual location in the source code. It seems like the code in `lexer.coffee` makes an attempt at finding a good place for them, but in some cases, it has a bad result. This seems hard to avoid in the general case. For example, in this code: ```coffee [-> a] ``` There must be an OUTDENT between the `a` and the `]`, but CoffeeScript tokens have an inclusive start and end, so they must always be at least one character wide (I think). In this case, the lexer was choosing the `]` as the location, and the parser ended up generating correct location data, I believe because it ignores the outermost INDENT and OUTDENT tokens. However, with multiple OUTDENT tokens in a row, the parser ends up producing location data that is wrong. It seems to me like there isn't a solid answer to "what location do OUTDENT tokens have", since it hasn't mattered much, but for this commit, I'm defining it: they always have the location of the last character of the previous token. This should hopefully be fairly safe because tokens are still in the same order relative to each other. Also, it's worth noting that this makes the start location for OUTDENT tokens awkward. However, OUTDENT tokens are always used to mark the end of something, so their `last_line` and `last_column` values are always what matter when determining AST node bounds, so it is most important for those to be correct.
2016-08-11 09:28:17 -04:00
return 1;
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
});
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Change OUTDENT tokens to be positioned at the end of the previous token This commit adds another post-processing step after normal lexing that sets the locationData on all OUTDENT tokens to be at the last character of the previous token. This does feel like a little bit of a hack. Ideally the location data would be set correctly in the first place and not in a post-processing step, but I tried that and some temporary intermediate tokens were causing problems, so I decided to set the location data once those intermediate tokens were removed. Also, having this as a separate processing step makes it more robust and isolated. This fixes the problem in https://github.com/decaffeinate/decaffeinate/issues/371 . In that issue, the CoffeeScript tokens had three OUTDENT tokens in a row, and the last two overlapped with the `]`. Since at least one of those OUTDENT tokens was considered part of the function body, the function expression had an ending position just after the end of the `]`. OUTDENT tokens are sort of a weird case in the lexer anyway, since they often don't correspond to an actual location in the source code. It seems like the code in `lexer.coffee` makes an attempt at finding a good place for them, but in some cases, it has a bad result. This seems hard to avoid in the general case. For example, in this code: ```coffee [-> a] ``` There must be an OUTDENT between the `a` and the `]`, but CoffeeScript tokens have an inclusive start and end, so they must always be at least one character wide (I think). In this case, the lexer was choosing the `]` as the location, and the parser ended up generating correct location data, I believe because it ignores the outermost INDENT and OUTDENT tokens. However, with multiple OUTDENT tokens in a row, the parser ends up producing location data that is wrong. It seems to me like there isn't a solid answer to "what location do OUTDENT tokens have", since it hasn't mattered much, but for this commit, I'm defining it: they always have the location of the last character of the previous token. This should hopefully be fairly safe because tokens are still in the same order relative to each other. Also, it's worth noting that this makes the start location for OUTDENT tokens awkward. However, OUTDENT tokens are always used to mark the end of something, so their `last_line` and `last_column` values are always what matter when determining AST node bounds, so it is most important for those to be correct.
2016-08-11 09:28:17 -04:00
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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2012-04-10 14:57:45 -04:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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2012-04-10 14:57:45 -04:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
});
}
[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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2012-04-10 14:57:45 -04:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
2017-01-13 00:55:30 -05:00
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[CS2] Compile class constructors to ES2015 classes (#4354) * Compile classes to ES2015 classes Rather than compiling classes to named functions with prototype and class assignments, they are now compiled to ES2015 class declarations. Backwards compatibility has been maintained by compiling ES2015- incompatible properties as prototype or class assignments. `super` continues to be compiled as before. Where possible, classes will be compiled "bare", without an enclosing IIFE. This is possible when the class contains only ES2015 compatible expressions (methods and static methods), and has no parent (this last constraint is a result of the legacy `super` compilation, and could be removed once ES2015 `super` is being used). Classes are still assigned to variables to maintain compatibility for assigned class expressions. There are a few changes to existing functionality that could break backwards compatibility: - Derived constructors that deliberately don't call `super` are no longer possible. ES2015 derived classes can't use `this` unless the parent constructor has been called, so it's now called implicitly when not present. - As a consequence of the above, derived constructors with @ parameters or bound methods and explicit `super` calls are not allowed. The implicit `super` must be used in these cases. * Add tests to verify class interoperability with ES * Refactor class nodes to separate executable body logic Logic has been redistributed amongst the class nodes so that: - `Class` contains the logic necessary to compile an ES class declaration. - `ExecutableClassBody` contains the logic necessary to compile CS' class extensions that require an executable class body. `Class` still necessarily contains logic to determine whether an expression is valid in an ES class initializer or not. If any invalid expressions are found then `Class` will wrap itself in an `ExecutableClassBody` when compiling. * Rename `Code#static` to `Code#isStatic` This naming is more consistent with other `Code` flags. * Output anonymous classes when possible Anonymous classes can be output when: - The class has no parent. The current super compilation needs a class variable to reference. This condition will go away when ES2015 super is in use. - The class contains no bound static methods. Bound static methods have their context set to the class name. * Throw errors at compile time for async or generator constructors * Improve handling of anonymous classes Anonymous classes are now always anonymous. If a name is required (e.g. for bound static methods or derived classes) then the class is compiled in an `ExecutableClassBody` which will give the anonymous class a stable reference. * Add a `replaceInContext` method to `Node` `replaceInContext` will traverse children looking for a node for which `match` returns true. Once found, the matching node will be replaced by the result of calling `replacement`. * Separate `this` assignments from function parameters This change has been made to simplify two future changes: 1. Outputting `@`-param assignments after a `super` call. In this case it is necessary that non-`@` parameters are available before `super` is called, so destructuring has to happen before `this` assignment. 2. Compiling destructured assignment to ES6 In this case also destructuring has to happen before `this`, as destructuring can happen in the arguments list, but `this` assignment can not. A bonus side-effect is that default values for `@` params are now output as ES6 default parameters, e.g. (@a = 1) -> becomes function a (a = 1) { this.a = a; } * Change `super` handling in class constructors Inside an ES derived constructor (a constructor for a class that extends another class), it is impossible to access `this` until `super` has been called. This conflicts with CoffeeScript's `@`-param and bound method features, which compile to `this` references at the top of a function body. For example: class B extends A constructor: (@param) -> super method: => This would compile to something like: class B extends A { constructor (param) { this.param = param; this.method = bind(this.method, this); super(...arguments); } } This would break in an ES-compliant runtime as there are `this` references before the call to `super`. Before this commit we were dealing with this by injecting an implicit `super` call into derived constructors that do not already have an explicit `super` call. Furthermore, we would disallow explicit `super` calls in derived constructors that used bound methods or `@`-params, meaning the above example would need to be rewritten as: class B extends A constructor: (@param) -> method: => This would result in a call to `super(...arguments)` being generated as the first expression in `B#constructor`. Whilst this approach seems to work pretty well, and is arguably more convenient than having to manually call `super` when you don't particularly care about the arguments, it does introduce some 'magic' and separation from ES, and would likely be a pain point in a project that made use of significant constructor overriding. This commit introduces a mechanism through which `super` in constructors is 'expanded' to include any generated `this` assignments, whilst retaining the same semantics of a super call. The first example above now compiles to something like: class B extends A { constructor (param) { var ref ref = super(...arguments), this.param = param, this.method = bind(this.method, this), ref; } } * Improve `super` handling in constructors Rather than functions expanding their `super` calls, the `SuperCall` node can now be given a list of `thisAssignments` to apply when it is compiled. This allows us to use the normal compiler machinery to determine whether the `super` result needs to be cached, whether it appears inline or not, etc. * Fix anonymous classes at the top level Anonymous classes in ES are only valid within expressions. If an anonymous class is at the top level it will now be wrapped in parenthses to force it into an expression. * Re-add Parens wrapper around executable class bodies This was lost in the refactoring, but it necessary to ensure `new class ...` works as expected when there's an executable body. * Throw compiler errors for badly configured derived constructors Rather than letting them become runtime errors, the following checks are now performed when compiling a derived constructor: - The constructor **must** include a call to `super`. - The constructor **must not** reference `this` in the function body before `super` has been called. * Add some tests exercising new class behaviour - async methods in classes - `this` access after `super` in extended classes - constructor super in arrow functions - constructor functions can't be async - constructor functions can't be generators - derived constructors must call super - derived constructors can't reference `this` before calling super - generator methods in classes - 'new' target * Improve constructor `super` errors Add a check for `super` in non-extended class constructors, and explicitly mention derived constructors in the "can't reference this before super" error. * Fix compilation of multiple `super` paths in derived constructors `super` can only be called once, but it can be called conditionally from multiple locations. The chosen fix is to add the `this` assignments to every super call. * Additional class tests, added as a separate file to simplify testing and merging. Some methods are commented out because they currently throw and I'm not sure how to test for compilation errors like those. There is also one test which I deliberately left without passing, `super` in an external prototype override. This test should 'pass' but is really a variation on the failing `super only allowed in an instance method` tests above it. * Changes to the tests. Found bug in super in prototype method. fixed. * Added failing test back in, dealing with bound functions in external prototype overrides. * Located a bug in the compiler relating to assertions and escaped ES6 classes. * Move tests from classes-additional.coffee into classes.coffee; comment out console.log * Cleaned up tests and made changes based on feedback. Test at the end still has issues, but it's commented out for now. * Make HoistTarget.expand recursive It's possible that a hoisted node may itself contain hoisted nodes (e.g. a class method inside a class method). For this to work the hoisted fragments need to be expanded recursively. * Uncomment final test in classes.coffee The test case now compiles, however another issue is affecting the test due to the error for `this` before `super` triggering based on source order rather than execution order. These have been commented out for now. * Fixed last test TODOs in test/classes.coffee Turns out an expression like `this.foo = super()` won't run in JS as it attempts to lookup `this` before evaluating `super` (i.e. throws "this is not defined"). * Added more tests for compatability checks, statics, prototypes and ES6 expectations. Cleaned test "nested classes with super". * Changes to reflect feedback and to comment out issues that will be addressed seperately. * Clean up test/classes.coffee - Trim trailing whitespace. - Rephrase a condition to be more idiomatic. * Remove check for `super` in derived constructors In order to be usable at runtime, an extended ES class must call `super` OR return an alternative object. This check prevented the latter case, and checking for an alternative return can't be completed statically without control flow analysis. * Disallow 'super' in constructor parameter defaults There are many edge cases when combining 'super' in parameter defaults with @-parameters and bound functions (and potentially property initializers in the future). Rather than attempting to resolve these edge cases, 'super' is now explicitly disallowed in constructor parameter defaults. * Disallow @-params in derived constructors without 'super' @-parameters can't be assigned unless 'super' is called.
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};
Rewriter.prototype.generate = generate;
return Rewriter;
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})();
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BALANCED_PAIRS = [['(', ')'], ['[', ']'], ['{', '}'], ['INDENT', 'OUTDENT'], ['CALL_START', 'CALL_END'], ['PARAM_START', 'PARAM_END'], ['INDEX_START', 'INDEX_END'], ['STRING_START', 'STRING_END'], ['REGEX_START', 'REGEX_END']];
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exports.INVERSES = INVERSES = {};
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EXPRESSION_START = [];
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EXPRESSION_END = [];
for (k = 0, len = BALANCED_PAIRS.length; k < len; k++) {
ref = BALANCED_PAIRS[k], left = ref[0], rite = ref[1];
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EXPRESSION_START.push(INVERSES[rite] = left);
EXPRESSION_END.push(INVERSES[left] = rite);
}
EXPRESSION_CLOSE = ['CATCH', 'THEN', 'ELSE', 'FINALLY'].concat(EXPRESSION_END);
IMPLICIT_FUNC = ['IDENTIFIER', 'PROPERTY', 'SUPER', ')', 'CALL_END', ']', 'INDEX_END', '@', 'THIS'];
IMPLICIT_CALL = ['IDENTIFIER', 'PROPERTY', 'NUMBER', 'INFINITY', 'NAN', 'STRING', 'STRING_START', 'REGEX', 'REGEX_START', 'JS', 'NEW', 'PARAM_START', 'CLASS', 'IF', 'TRY', 'SWITCH', 'THIS', 'UNDEFINED', 'NULL', 'BOOL', 'UNARY', 'YIELD', 'AWAIT', 'UNARY_MATH', 'SUPER', 'THROW', '@', '->', '=>', '[', '(', '{', '--', '++'];
IMPLICIT_UNSPACED_CALL = ['+', '-'];
IMPLICIT_END = ['POST_IF', 'FOR', 'WHILE', 'UNTIL', 'WHEN', 'BY', 'LOOP', 'TERMINATOR'];
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SINGLE_LINERS = ['ELSE', '->', '=>', 'TRY', 'FINALLY', 'THEN'];
SINGLE_CLOSERS = ['TERMINATOR', 'CATCH', 'FINALLY', 'ELSE', 'OUTDENT', 'LEADING_WHEN'];
LINEBREAKS = ['TERMINATOR', 'INDENT', 'OUTDENT'];
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CALL_CLOSERS = ['.', '?.', '::', '?::'];
}).call(this);