[CS2] Remove unnecessary utility helper functions (#4526)

* Uncomment module test that was waiting for classes to be supported

* Rely on native indexOf

* Replace `bind` helper with native `bind` (no shortcut necessary)

* Update output

* Update modules class tests

* Remove helper for prototype extends

* Update docs to reflect removed extends operator

* Add shortcut for splice, like we have for slice

documentation/sections/prototypal_inheritance.md

@@ -1,6 +1,6 @@
 ## Prototypal Inheritance
 
-In addition to supporting ES2015 classes, CoffeeScript provides a few shortcuts for working with prototypes. The `extends` operator can be used to create an inheritance chain between any pair of constructor functions, and `::` gives you quick access to an object’s prototype:
+In addition to supporting ES2015 classes, CoffeeScript provides a shortcut for working with prototypes. The `::` operator gives you quick access to an object’s prototype:
 
 ```
 codeFor('prototypes', '"one_two".dasherize()')

lib/coffeescript/browser.js

@@ -1,7 +1,7 @@
 // Generated by CoffeeScript 2.0.0-beta1
 (function() {
   var CoffeeScript, compile, runScripts,
-    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; };
+    indexOf = [].indexOf;
 
   CoffeeScript = require('./coffeescript');
 

lib/coffeescript/command.js

@@ -1,7 +1,7 @@
 // Generated by CoffeeScript 2.0.0-beta1
 (function() {
   var BANNER, CoffeeScript, EventEmitter, SWITCHES, compileJoin, compileOptions, compilePath, compileScript, compileStdio, exec, findDirectoryIndex, forkNode, fs, helpers, hidden, joinTimeout, makePrelude, mkdirp, notSources, optionParser, optparse, opts, outputPath, parseOptions, path, printLine, printTokens, printWarn, removeSource, removeSourceDir, silentUnlink, sourceCode, sources, spawn, timeLog, usage, useWinPathSep, version, wait, watch, watchDir, watchedDirs, writeJs,
-    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; };
+    indexOf = [].indexOf;
 
   fs = require('fs');
 

lib/coffeescript/grammar.js

@@ -783,8 +783,6 @@
         return new Assign($1, $4, $2);
       }), o('SimpleAssignable COMPOUND_ASSIGN TERMINATOR Expression', function() {
         return new Assign($1, $4, $2);
-      }), o('SimpleAssignable EXTENDS Expression', function() {
-        return new Extends($1, $3);
       })
     ]
   };

lib/coffeescript/lexer.js

@@ -1,7 +1,7 @@
 // Generated by CoffeeScript 2.0.0-beta1
 (function() {
   var BOM, BOOL, CALLABLE, CODE, COFFEE_ALIASES, COFFEE_ALIAS_MAP, COFFEE_KEYWORDS, COMMENT, COMPARE, COMPOUND_ASSIGN, HERECOMMENT_ILLEGAL, HEREDOC_DOUBLE, HEREDOC_INDENT, HEREDOC_SINGLE, HEREGEX, HEREGEX_OMIT, HERE_JSTOKEN, IDENTIFIER, INDENTABLE_CLOSERS, INDEXABLE, INVERSES, JSTOKEN, JS_KEYWORDS, LEADING_BLANK_LINE, LINE_BREAK, LINE_CONTINUER, Lexer, MATH, MULTI_DENT, NOT_REGEX, NUMBER, OPERATOR, POSSIBLY_DIVISION, REGEX, REGEX_FLAGS, REGEX_ILLEGAL, REGEX_INVALID_ESCAPE, RELATION, RESERVED, Rewriter, SHIFT, SIMPLE_STRING_OMIT, STRICT_PROSCRIBED, STRING_DOUBLE, STRING_INVALID_ESCAPE, STRING_OMIT, STRING_SINGLE, STRING_START, TRAILING_BLANK_LINE, TRAILING_SPACES, UNARY, UNARY_MATH, UNICODE_CODE_POINT_ESCAPE, VALID_FLAGS, WHITESPACE, compact, count, invertLiterate, isForFrom, isUnassignable, key, locationDataToString, repeat, starts, throwSyntaxError,
-    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; };
+    indexOf = [].indexOf;
 
   ({Rewriter, INVERSES} = require('./rewriter'));
 

lib/coffeescript/nodes.js

@@ -1,7 +1,8 @@
 // Generated by CoffeeScript 2.0.0-beta1
 (function() {
   var Access, Arr, Assign, AwaitReturn, Base, Block, BooleanLiteral, Call, Class, Code, CodeFragment, Comment, ExecutableClassBody, Existence, Expansion, ExportAllDeclaration, ExportDeclaration, ExportDefaultDeclaration, ExportNamedDeclaration, ExportSpecifier, ExportSpecifierList, Extends, For, HoistTarget, IdentifierLiteral, If, ImportClause, ImportDeclaration, ImportDefaultSpecifier, ImportNamespaceSpecifier, ImportSpecifier, ImportSpecifierList, In, Index, InfinityLiteral, JS_FORBIDDEN, LEVEL_ACCESS, LEVEL_COND, LEVEL_LIST, LEVEL_OP, LEVEL_PAREN, LEVEL_TOP, Literal, ModuleDeclaration, ModuleSpecifier, ModuleSpecifierList, NEGATE, NO, NaNLiteral, NullLiteral, NumberLiteral, Obj, Op, Param, Parens, PassthroughLiteral, PropertyName, Range, RegexLiteral, RegexWithInterpolations, Return, SIMPLENUM, Scope, Slice, Splat, StatementLiteral, StringLiteral, StringWithInterpolations, Super, SuperCall, Switch, TAB, THIS, TaggedTemplateCall, ThisLiteral, Throw, Try, UTILITIES, UndefinedLiteral, Value, While, YES, YieldReturn, addLocationDataFn, compact, del, ends, extend, flatten, fragmentsToText, isLiteralArguments, isLiteralThis, isUnassignable, locationDataToString, merge, multident, shouldCacheOrIsAssignable, some, starts, throwSyntaxError, unfoldSoak, utility,
-    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; },
+    splice = [].splice,
+    indexOf = [].indexOf,
     slice = [].slice;
 
   Error.stackTraceLimit = 2e308;
@@ -241,7 +242,7 @@
               for (i = k = 0, len2 = children.length; k < len2; i = ++k) {
                 child = children[i];
                 if (match(child)) {
-                  [].splice.apply(children, [i, i - i + 1].concat(ref2 = replacement(child, this))), ref2;
+                  splice.apply(children, [i, i - i + 1].concat(ref2 = replacement(child, this))), ref2;
                   return true;
                 } else {
                   if (child.replaceInContext(match, replacement)) {
@@ -341,7 +342,7 @@
       for (i = j = fragments.length - 1; j >= 0; i = j += -1) {
         fragment = fragments[i];
         if (fragment.fragments) {
-          [].splice.apply(fragments, [i, i - i + 1].concat(ref1 = this.expand(fragment.fragments))), ref1;
+          splice.apply(fragments, [i, i - i + 1].concat(ref1 = this.expand(fragment.fragments))), ref1;
         }
       }
       return fragments;
@@ -1830,7 +1831,7 @@
               end++;
             }
             pushSlice();
-            [].splice.apply(expressions, [i, i - i + 1].concat(exprs)), exprs;
+            splice.apply(expressions, [i, i - i + 1].concat(exprs)), exprs;
             i += exprs.length;
           } else {
             if (initializerExpression = this.addInitializerExpression(expression)) {
@@ -1942,7 +1943,7 @@
           for (j = ref1.length - 1; j >= 0; j += -1) {
             name = ref1[j];
             name = new Value(new ThisLiteral, [name]).compile(o);
-            results.push(new Literal(`${name} = ${utility('bind', o)}(${name}, this)`));
+            results.push(new Literal(`${name} = ${name}.bind(this)`));
           }
           return results;
         }).call(this);
@@ -2629,7 +2630,7 @@
           to = "9e9";
         }
         [valDef, valRef] = this.value.cache(o, LEVEL_LIST);
-        answer = [].concat(this.makeCode(`[].splice.apply(${name}, [${fromDecl}, ${to}].concat(`), valDef, this.makeCode(")), "), valRef);
+        answer = [].concat(this.makeCode(`${utility('splice', o)}.apply(${name}, [${fromDecl}, ${to}].concat(`), valDef, this.makeCode(")), "), valRef);
         if (o.level > LEVEL_TOP) {
           return this.wrapInParentheses(answer);
         } else {
@@ -4180,23 +4181,20 @@
   })();
 
   UTILITIES = {
-    extend: function(o) {
-      return `function(child, parent) { for (var key in parent) { if (${utility('hasProp', o)}.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); return child; }`;
-    },
-    bind: function() {
-      return 'function(fn, me){ return function(){ return fn.apply(me, arguments); }; }';
-    },
-    indexOf: function() {
-      return "[].indexOf || function(item) { for (var i = 0, l = this.length; i < l; i++) { if (i in this && this[i] === item) return i; } return -1; }";
-    },
     modulo: function() {
-      return "function(a, b) { return (+a % (b = +b) + b) % b; }";
+      return 'function(a, b) { return (+a % (b = +b) + b) % b; }';
     },
     hasProp: function() {
       return '{}.hasOwnProperty';
     },
+    indexOf: function() {
+      return '[].indexOf';
+    },
     slice: function() {
       return '[].slice';
+    },
+    splice: function() {
+      return '[].splice';
     }
   };
 

lib/coffeescript/rewriter.js

@@ -1,7 +1,7 @@
 // Generated by CoffeeScript 2.0.0-beta1
 (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, 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; };
+    indexOf = [].indexOf;
 
   generate = function(tag, value, origin) {
     var tok;

lib/coffeescript/scope.js

@@ -1,7 +1,7 @@
 // Generated by CoffeeScript 2.0.0-beta1
 (function() {
   var Scope,
-    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; };
+    indexOf = [].indexOf;
 
   exports.Scope = Scope = class Scope {
     constructor(parent, expressions, method, referencedVars) {

src/grammar.coffee

@@ -699,7 +699,6 @@ grammar =
        INDENT Expression OUTDENT',              -> new Assign $1, $4, $2
     o 'SimpleAssignable COMPOUND_ASSIGN TERMINATOR
        Expression',                             -> new Assign $1, $4, $2
-    o 'SimpleAssignable EXTENDS Expression',    -> new Extends $1, $3
   ]
 
 

src/nodes.coffee

@@ -1427,7 +1427,7 @@ exports.Class = class Class extends Base
   proxyBoundMethods: (o) ->
     @ctor.thisAssignments = for name in @boundMethods by -1
       name = new Value(new ThisLiteral, [ name ]).compile o
-      new Literal "#{name} = #{utility 'bind', o}(#{name}, this)"
+      new Literal "#{name} = #{name}.bind(this)"
 
     null
 
@@ -1873,7 +1873,7 @@ exports.Assign = class Assign extends Base
       if not expandedIdx and obj instanceof Splat
         name = obj.name.unwrap().value
         obj = obj.unwrap()
-        val = "#{olen} <= #{vvarText}.length ? #{ utility 'slice', o }.call(#{vvarText}, #{i}"
+        val = "#{olen} <= #{vvarText}.length ? #{utility 'slice', o}.call(#{vvarText}, #{i}"
         rest = olen - i - 1
         if rest isnt 0
           ivar = o.scope.freeVariable 'i', single: true
@@ -1972,7 +1972,7 @@ exports.Assign = class Assign extends Base
     else
       to = "9e9"
     [valDef, valRef] = @value.cache o, LEVEL_LIST
-    answer = [].concat @makeCode("[].splice.apply(#{name}, [#{fromDecl}, #{to}].concat("), valDef, @makeCode(")), "), valRef
+    answer = [].concat @makeCode("#{utility 'splice', o}.apply(#{name}, [#{fromDecl}, #{to}].concat("), valDef, @makeCode(")), "), valRef
     if o.level > LEVEL_TOP then @wrapInParentheses answer else answer
 
   eachName: (iterator) ->
@@ -3109,49 +3109,13 @@ exports.If = class If extends Base
 # ---------
 
 UTILITIES =
-
-  # Correctly set up a prototype chain for inheritance, including a reference
-  # to the superclass for `super()` calls, and copies of any static properties.
-  extend: (o) -> "
-    function(child, parent) {
-      for (var key in parent) {
-        if (#{utility 'hasProp', o}.call(parent, key)) child[key] = parent[key];
-      }
-      function ctor() {
-        this.constructor = child;
-      }
-      ctor.prototype = parent.prototype;
-      child.prototype = new ctor();
-      return child;
-    }
-  "
-
-  # Create a function bound to the current value of "this".
-  bind: -> '
-    function(fn, me){
-      return function(){
-        return fn.apply(me, arguments);
-      };
-    }
-  '
-
-  # Discover if an item is in an array.
-  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;
-    }
-  "
-
-  modulo: -> """
-    function(a, b) { return (+a % (b = +b) + b) % b; }
-  """
+  modulo: -> 'function(a, b) { return (+a % (b = +b) + b) % b; }'
 
   # Shortcuts to speed up the lookup time for native functions.
   hasProp: -> '{}.hasOwnProperty'
+  indexOf: -> '[].indexOf'
   slice  : -> '[].slice'
+  splice : -> '[].splice'
 
 # Levels indicate a node's position in the AST. Useful for knowing if
 # parens are necessary or superfluous.

test/modules.coffee

@@ -433,47 +433,65 @@ test "export default predefined function", ->
     export default foo;"""
   eq toJS(input), output
 
-# Uncomment this test once ES2015+ `class` support is added
+test "export default class", ->
+  input = """
+    export default class foo extends bar
+      baz: ->
+        console.log 'hello, world!'"""
+  output = """
+    var foo;
 
-# test "export default class", ->
-#   input = """
-#     export default class foo extends bar
-#       baz: ->
-#         console.log 'hello, world!'"""
-#   output = """
-#     export default class foo extends bar {
-#       baz: function {
-#         return console.log('hello, world!');
-#       }
-#     }"""
-#   eq toJS(input), output
+    export default foo = class foo extends bar {
+      baz() {
+        return console.log('hello, world!');
+      }
+
+    };"""
+  eq toJS(input), output
 
-# Very limited tests for now, testing that `export class foo` either compiles
-# identically (ES2015+) or at least into some function, leaving the specifics
-# vague in case the CoffeeScript `class` interpretation changes
 test "export class", ->
   input = """
     export class foo
       baz: ->
         console.log 'hello, world!'"""
-  output = toJS input
-  ok /^export (var foo = class foo|var foo = \(function)/.test toJS input
+  output = """
+    export var foo = class foo {
+      baz() {
+        return console.log('hello, world!');
+      }
+
+    };"""
+  eq toJS(input), output
 
 test "export class that extends", ->
   input = """
     export class foo extends bar
       baz: ->
         console.log 'hello, world!'"""
-  output = toJS input
-  ok /export var foo = class foo/.test(output) and \
-    not /var foo(;|,)/.test output
+  output = """
+    export var foo = class foo extends bar {
+      baz() {
+        return console.log('hello, world!');
+      }
+
+    };"""
+  eq toJS(input), output
 
 test "export default class that extends", ->
   input = """
     export default class foo extends bar
       baz: ->
         console.log 'hello, world!'"""
-  ok /export default foo = class foo/.test toJS input
+  output = """
+    var foo;
+
+    export default foo = class foo extends bar {
+      baz() {
+        return console.log('hello, world!');
+      }
+
+    };"""
+  eq toJS(input), output
 
 test "export default named member, within an object", ->
   input = "export { foo as default, bar }"