Error.stackTraceLimit = Infinity
{Scope} = require './scope'
{isUnassignable, JS_FORBIDDEN} = require './lexer'nodes.coffee contains all of the node classes for the syntax tree. Most
nodes are created as the result of actions in the grammar,
but some are created by other nodes as a method of code generation. To convert
the syntax tree into a string of JavaScript code, call compile() on the root.
Error.stackTraceLimit = Infinity
{Scope} = require './scope'
{isUnassignable, JS_FORBIDDEN} = require './lexer'Import the helpers we plan to use.
{compact, flatten, extend, merge, del, starts, ends, some,
addDataToNode, attachCommentsToNode, locationDataToString,
throwSyntaxError} = require './helpers'Functions required by parser.
exports.extend = extend
exports.addDataToNode = addDataToNodeConstant functions for nodes that don’t need customization.
YES = -> yes
NO = -> no
THIS = -> this
NEGATE = -> @negated = not @negated; thisThe various nodes defined below all compile to a collection of CodeFragment objects.
A CodeFragments is a block of generated code, and the location in the source file where the code
came from. CodeFragments can be assembled together into working code just by catting together
all the CodeFragments’ code snippets, in order.
exports.CodeFragment = class CodeFragment
constructor: (parent, code) ->
@code = "#{code}"
@type = parent?.constructor?.name or 'unknown'
@locationData = parent?.locationData
@comments = parent?.comments
toString: ->This is only intended for debugging.
"#{@code}#{if @locationData then ": " + locationDataToString(@locationData) else ''}"Convert an array of CodeFragments into a string.
fragmentsToText = (fragments) ->
(fragment.code for fragment in fragments).join('')The Base is the abstract base class for all nodes in the syntax tree.
Each subclass implements the compileNode method, which performs the
code generation for that node. To compile a node to JavaScript,
call compile on it, which wraps compileNode in some generic extra smarts,
to know when the generated code needs to be wrapped up in a closure.
An options hash is passed and cloned throughout, containing information about
the environment from higher in the tree (such as if a returned value is
being requested by the surrounding function), information about the current
scope, and indentation level.
exports.Base = class Base
compile: (o, lvl) ->
fragmentsToText @compileToFragments o, lvlOccasionally a node is compiled multiple times, for example to get the name
of a variable to add to scope tracking. When we know that a “premature”
compilation won’t result in comments being output, set those comments aside
so that they’re preserved for a later compile call that will result in
the comments being included in the output.
compileWithoutComments: (o, lvl, method = 'compile') ->
if @comments
@ignoreTheseCommentsTemporarily = @comments
delete @comments
unwrapped = @unwrapAll()
if unwrapped.comments
unwrapped.ignoreTheseCommentsTemporarily = unwrapped.comments
delete unwrapped.comments
fragments = @[method] o, lvl
if @ignoreTheseCommentsTemporarily
@comments = @ignoreTheseCommentsTemporarily
delete @ignoreTheseCommentsTemporarily
if unwrapped.ignoreTheseCommentsTemporarily
unwrapped.comments = unwrapped.ignoreTheseCommentsTemporarily
delete unwrapped.ignoreTheseCommentsTemporarily
fragments
compileNodeWithoutComments: (o, lvl) ->
@compileWithoutComments o, lvl, 'compileNode'Common logic for determining whether to wrap this node in a closure before compiling it, or to compile directly. We need to wrap if this node is a statement, and it’s not a pureStatement, and we’re not at the top level of a block (which would be unnecessary), and we haven’t already been asked to return the result (because statements know how to return results).
compileToFragments: (o, lvl) ->
o = extend {}, o
o.level = lvl if lvl
node = @unfoldSoak(o) or this
node.tab = o.indent
fragments = if o.level is LEVEL_TOP or not node.isStatement(o)
node.compileNode o
else
node.compileClosure o
@compileCommentFragments o, node, fragments
fragments
compileToFragmentsWithoutComments: (o, lvl) ->
@compileWithoutComments o, lvl, 'compileToFragments'Statements converted into expressions via closure-wrapping share a scope object with their parent closure, to preserve the expected lexical scope.
compileClosure: (o) ->
if jumpNode = @jumps()
jumpNode.error 'cannot use a pure statement in an expression'
o.sharedScope = yes
func = new Code [], Block.wrap [this]
args = []
if @contains ((node) -> node instanceof SuperCall)
func.bound = yes
else if (argumentsNode = @contains isLiteralArguments) or @contains isLiteralThis
args = [new ThisLiteral]
if argumentsNode
meth = 'apply'
args.push new IdentifierLiteral 'arguments'
else
meth = 'call'
func = new Value func, [new Access new PropertyName meth]
parts = (new Call func, args).compileNode o
switch
when func.isGenerator or func.base?.isGenerator
parts.unshift @makeCode "(yield* "
parts.push @makeCode ")"
when func.isAsync or func.base?.isAsync
parts.unshift @makeCode "(await "
parts.push @makeCode ")"
parts
compileCommentFragments: (o, node, fragments) ->
return fragments unless node.commentsThis is where comments, that are attached to nodes as a comments
property, become CodeFragments. “Inline block comments,” e.g.
/* */-delimited comments that are interspersed within code on a line,
are added to the current fragments stream. All other fragments are
attached as properties to the nearest preceding or following fragment,
to remain stowaways until they get properly output in compileComments
later on.
unshiftCommentFragment = (commentFragment) ->
if commentFragment.unshiftFind the first non-comment fragment and insert commentFragment
before it.
unshiftAfterComments fragments, commentFragment
else
if fragments.length isnt 0
precedingFragment = fragments[fragments.length - 1]
if commentFragment.newLine and precedingFragment.code isnt '' and
not /\n\s*$/.test precedingFragment.code
commentFragment.code = "\n#{commentFragment.code}"
fragments.push commentFragment
for comment in node.comments when comment not in @compiledComments
@compiledComments.push comment # Don’t output this comment twice.For block/here comments, denoted by ###, that are inline comments
like 1 + ### comment ### 2, create fragments and insert them into
the fragments array.
Otherwise attach comment fragments to their closest fragment for now,
so they can be inserted into the output later after all the newlines
have been added.
if comment.here # Block comment, delimited by `###`.
commentFragment = new HereComment(comment).compileNode o
else # Line comment, delimited by `#`.
commentFragment = new LineComment(comment).compileNode o
if (commentFragment.isHereComment and not commentFragment.newLine) or
node.includeCommentFragments()Inline block comments, like 1 + /* comment */ 2, or a node whose
compileToFragments method has logic for outputting comments.
unshiftCommentFragment commentFragment
else
fragments.push @makeCode '' if fragments.length is 0
if commentFragment.unshift
fragments[0].precedingComments ?= []
fragments[0].precedingComments.push commentFragment
else
fragments[fragments.length - 1].followingComments ?= []
fragments[fragments.length - 1].followingComments.push commentFragment
fragmentsIf the code generation wishes to use the result of a complex expression in multiple places, ensure that the expression is only ever evaluated once, by assigning it to a temporary variable. Pass a level to precompile.
If level is passed, then returns [val, ref], where val is the compiled value, and ref
is the compiled reference. If level is not passed, this returns [val, ref] where
the two values are raw nodes which have not been compiled.
cache: (o, level, shouldCache) ->
complex = if shouldCache? then shouldCache this else @shouldCache()
if complex
ref = new IdentifierLiteral o.scope.freeVariable 'ref'
sub = new Assign ref, this
if level then [sub.compileToFragments(o, level), [@makeCode(ref.value)]] else [sub, ref]
else
ref = if level then @compileToFragments o, level else this
[ref, ref]Occasionally it may be useful to make an expression behave as if it was ‘hoisted’, whereby the result of the expression is available before its location in the source, but the expression’s variable scope corresponds the source position. This is used extensively to deal with executable class bodies in classes.
Calling this method mutates the node, proxying the compileNode and compileToFragments
methods to store their result for later replacing the target node, which is returned by the
call.
hoist: ->
@hoisted = yes
target = new HoistTarget @
compileNode = @compileNode
compileToFragments = @compileToFragments
@compileNode = (o) ->
target.update compileNode, o
@compileToFragments = (o) ->
target.update compileToFragments, o
target
cacheToCodeFragments: (cacheValues) ->
[fragmentsToText(cacheValues[0]), fragmentsToText(cacheValues[1])]Construct a node that returns the current node’s result. Note that this is overridden for smarter behavior for many statement nodes (e.g. If, For)…
makeReturn: (res) ->
me = @unwrapAll()
if res
new Call new Literal("#{res}.push"), [me]
else
new Return meDoes this node, or any of its children, contain a node of a certain kind?
Recursively traverses down the children nodes and returns the first one
that verifies pred. Otherwise return undefined. contains does not cross
scope boundaries.
contains: (pred) ->
node = undefined
@traverseChildren no, (n) ->
if pred n
node = n
return no
nodePull out the last node of a node list.
lastNode: (list) ->
if list.length is 0 then null else list[list.length - 1]toString representation of the node, for inspecting the parse tree.
This is what coffee --nodes prints out.
toString: (idt = '', name = @constructor.name) ->
tree = '\n' + idt + name
tree += '?' if @soak
@eachChild (node) -> tree += node.toString idt + TAB
treePasses each child to a function, breaking when the function returns false.
eachChild: (func) ->
return this unless @children
for attr in @children when @[attr]
for child in flatten [@[attr]]
return this if func(child) is false
this
traverseChildren: (crossScope, func) ->
@eachChild (child) ->
recur = func(child)
child.traverseChildren(crossScope, func) unless recur is noreplaceInContext 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.
replaceInContext: (match, replacement) ->
return false unless @children
for attr in @children when children = @[attr]
if Array.isArray children
for child, i in children
if match child
children[i..i] = replacement child, @
return true
else
return true if child.replaceInContext match, replacement
else if match children
@[attr] = replacement children, @
return true
else
return true if children.replaceInContext match, replacement
invert: ->
new Op '!', this
unwrapAll: ->
node = this
continue until node is node = node.unwrap()
nodeDefault implementations of the common node properties and methods. Nodes will override these with custom logic, if needed.
children are the properties to recurse into when tree walking. The
children list is the structure of the AST. The parent pointer, and
the pointer to the children are how you can traverse the tree.
children: []isStatement has to do with “everything is an expression”. A few things
can’t be expressions, such as break. Things that isStatement returns
true for are things that can’t be used as expressions. There are some
error messages that come from nodes.coffee due to statements ending up
in expression position.
isStatement: NOTrack comments that have been compiled into fragments, to avoid outputting them twice.
compiledComments: []includeCommentFragments lets compileCommentFragments know whether this node
has special awareness of how to handle comments within its output.
includeCommentFragments: NOjumps tells you if an expression, or an internal part of an expression
has a flow control construct (like break, or continue, or return,
or throw) that jumps out of the normal flow of control and can’t be
used as a value. This is important because things like this make no sense;
we have to disallow them.
jumps: NOIf node.shouldCache() is false, it is safe to use node more than once.
Otherwise you need to store the value of node in a variable and output
that variable several times instead. Kind of like this: 5 need not be
cached. returnFive(), however, could have side effects as a result of
evaluating it more than once, and therefore we need to cache it. The
parameter is named shouldCache rather than mustCache because there are
also cases where we might not need to cache but where we want to, for
example a long expression that may well be idempotent but we want to cache
for brevity.
shouldCache: YES
isChainable: NO
isAssignable: NO
isNumber: NO
unwrap: THIS
unfoldSoak: NOIs this node used to assign a certain variable?
assigns: NOFor this node and all descendents, set the location data to locationData
if the location data is not already set.
updateLocationDataIfMissing: (locationData) ->
return this if @locationData and not @forceUpdateLocation
delete @forceUpdateLocation
@locationData = locationData
@eachChild (child) ->
child.updateLocationDataIfMissing locationDataThrow a SyntaxError associated with this node’s location.
error: (message) ->
throwSyntaxError message, @locationData
makeCode: (code) ->
new CodeFragment this, code
wrapInParentheses: (fragments) ->
[@makeCode('('), fragments..., @makeCode(')')]
wrapInBraces: (fragments) ->
[@makeCode('{'), fragments..., @makeCode('}')]fragmentsList is an array of arrays of fragments. Each array in fragmentsList will be
concatenated together, with joinStr added in between each, to produce a final flat array
of fragments.
joinFragmentArrays: (fragmentsList, joinStr) ->
answer = []
for fragments, i in fragmentsList
if i then answer.push @makeCode joinStr
answer = answer.concat fragments
answerA HoistTargetNode represents the output location in the node tree for a hoisted node. See Base#hoist.
exports.HoistTarget = class HoistTarget extends BaseExpands hoisted fragments in the given array
@expand = (fragments) ->
for fragment, i in fragments by -1 when fragment.fragments
fragments[i..i] = @expand fragment.fragments
fragments
constructor: (@source) ->
super()Holds presentational options to apply when the source node is compiled.
@options = {}Placeholder fragments to be replaced by the source node’s compilation.
@targetFragments = { fragments: [] }
isStatement: (o) ->
@source.isStatement oUpdate the target fragments with the result of compiling the source. Calls the given compile function with the node and options (overriden with the target presentational options).
update: (compile, o) ->
@targetFragments.fragments = compile.call @source, merge o, @optionsCopies the target indent and level, and returns the placeholder fragments
compileToFragments: (o, level) ->
@options.indent = o.indent
@options.level = level ? o.level
[ @targetFragments ]
compileNode: (o) ->
@compileToFragments o
compileClosure: (o) ->
@compileToFragments oThe block is the list of expressions that forms the body of an
indented block of code – the implementation of a function, a clause in an
if, switch, or try, and so on…
exports.Block = class Block extends Base
constructor: (nodes) ->
super()
@expressions = compact flatten nodes or []
children: ['expressions']Tack an expression on to the end of this expression list.
push: (node) ->
@expressions.push node
thisRemove and return the last expression of this expression list.
pop: ->
@expressions.pop()Add an expression at the beginning of this expression list.
unshift: (node) ->
@expressions.unshift node
thisIf this Block consists of just a single node, unwrap it by pulling it back out.
unwrap: ->
if @expressions.length is 1 then @expressions[0] else thisIs this an empty block of code?
isEmpty: ->
not @expressions.length
isStatement: (o) ->
for exp in @expressions when exp.isStatement o
return yes
no
jumps: (o) ->
for exp in @expressions
return jumpNode if jumpNode = exp.jumps oA Block node does not return its entire body, rather it ensures that the final expression is returned.
makeReturn: (res) ->
len = @expressions.length
while len--
expr = @expressions[len]
@expressions[len] = expr.makeReturn res
@expressions.splice(len, 1) if expr instanceof Return and not expr.expression
break
thisA Block is the only node that can serve as the root.
compileToFragments: (o = {}, level) ->
if o.scope then super o, level else @compileRoot oCompile all expressions within the Block body. If we need to return the result, and it’s an expression, simply return it. If it’s a statement, ask the statement to do so.
compileNode: (o) ->
@tab = o.indent
top = o.level is LEVEL_TOP
compiledNodes = []
for node, index in @expressions
if node.hoistedThis is a hoisted expression. We want to compile this and ignore the result.
node.compileToFragments o
continue
node = (node.unfoldSoak(o) or node)
if node instanceof BlockThis is a nested block. We don’t do anything special here like enclose it in a new scope; we just compile the statements in this block along with our own.
compiledNodes.push node.compileNode o
else if top
node.front = yes
fragments = node.compileToFragments o
unless node.isStatement o
fragments = indentInitial fragments, @
[..., lastFragment] = fragments
unless lastFragment.code is '' or lastFragment.isComment
fragments.push @makeCode ';'
compiledNodes.push fragments
else
compiledNodes.push node.compileToFragments o, LEVEL_LIST
if top
if @spaced
return [].concat @joinFragmentArrays(compiledNodes, '\n\n'), @makeCode('\n')
else
return @joinFragmentArrays(compiledNodes, '\n')
if compiledNodes.length
answer = @joinFragmentArrays(compiledNodes, ', ')
else
answer = [@makeCode 'void 0']
if compiledNodes.length > 1 and o.level >= LEVEL_LIST then @wrapInParentheses answer else answerIf we happen to be the top-level Block, wrap everything in a safety closure, unless requested not to. It would be better not to generate them in the first place, but for now, clean up obvious double-parentheses.
compileRoot: (o) ->
o.indent = if o.bare then '' else TAB
o.level = LEVEL_TOP
@spaced = yes
o.scope = new Scope null, this, null, o.referencedVars ? []Mark given local variables in the root scope as parameters so they don’t end up being declared on this block.
o.scope.parameter name for name in o.locals or []
fragments = @compileWithDeclarations o
HoistTarget.expand fragments
fragments = @compileComments fragments
return fragments if o.bare
[].concat @makeCode("(function() {\n"), fragments, @makeCode("\n}).call(this);\n")Compile the expressions body for the contents of a function, with declarations of all inner variables pushed up to the top.
compileWithDeclarations: (o) ->
fragments = []
post = []
for exp, i in @expressions
exp = exp.unwrap()
break unless exp instanceof Literal
o = merge(o, level: LEVEL_TOP)
if i
rest = @expressions.splice i, 9e9
[spaced, @spaced] = [@spaced, no]
[fragments, @spaced] = [@compileNode(o), spaced]
@expressions = rest
post = @compileNode o
{scope} = o
if scope.expressions is this
declars = o.scope.hasDeclarations()
assigns = scope.hasAssignments
if declars or assigns
fragments.push @makeCode '\n' if i
fragments.push @makeCode "#{@tab}var "
if declars
declaredVariables = scope.declaredVariables()
for declaredVariable, declaredVariablesIndex in declaredVariables
fragments.push @makeCode declaredVariable
if Object::hasOwnProperty.call o.scope.comments, declaredVariable
fragments.push o.scope.comments[declaredVariable]...
if declaredVariablesIndex isnt declaredVariables.length - 1
fragments.push @makeCode ', '
if assigns
fragments.push @makeCode ",\n#{@tab + TAB}" if declars
fragments.push @makeCode scope.assignedVariables().join(",\n#{@tab + TAB}")
fragments.push @makeCode ";\n#{if @spaced then '\n' else ''}"
else if fragments.length and post.length
fragments.push @makeCode "\n"
fragments.concat post
compileComments: (fragments) ->
for fragment, fragmentIndex in fragmentsInsert comments into the output at the next or previous newline. If there are no newlines at which to place comments, create them.
if fragment.precedingCommentsDetermine the indentation level of the fragment that we are about
to insert comments before, and use that indentation level for our
inserted comments. At this point, the fragments’ code property
is the generated output JavaScript, and CoffeeScript always
generates output indented by two spaces; so all we need to do is
search for a code property that begins with at least two spaces.
fragmentIndent = ''
for pastFragment in fragments[0...(fragmentIndex + 1)] by -1
indent = /^ {2,}/m.exec pastFragment.code
if indent
fragmentIndent = indent[0]
break
else if '\n' in pastFragment.code
break
code = "\n#{fragmentIndent}" + (
for commentFragment in fragment.precedingComments
if commentFragment.isHereComment and commentFragment.multiline
multident commentFragment.code, fragmentIndent, no
else
commentFragment.code
).join("\n#{fragmentIndent}").replace /^(\s*)$/gm, ''
for pastFragment, pastFragmentIndex in fragments[0...(fragmentIndex + 1)] by -1
newLineIndex = pastFragment.code.lastIndexOf '\n'
if newLineIndex is -1Keep searching previous fragments until we can’t go back any further, either because there are no fragments left or we’ve discovered that we’re in a code block that is interpolated inside a string.
if pastFragmentIndex is 0
pastFragment.code = '\n' + pastFragment.code
newLineIndex = 0
else if pastFragment.isStringWithInterpolations and pastFragment.code is '{'
code = code[1..] + '\n' # Move newline to end.
newLineIndex = 1
else
continue
delete fragment.precedingComments
pastFragment.code = pastFragment.code[0...newLineIndex] +
code + pastFragment.code[newLineIndex..]
breakYes, this is awfully similar to the previous if block, but if you
look closely you’ll find lots of tiny differences that make this
confusing if it were abstracted into a function that both blocks share.
if fragment.followingCommentsDoes the first trailing comment follow at the end of a line of code,
like ; // Comment, or does it start a new line after a line of code?
trail = fragment.followingComments[0].trail
fragmentIndent = ''Find the indent of the next line of code, if we have any non-trailing comments to output. We need to first find the next newline, as these comments will be output after that; and then the indent of the line that follows the next newline.
unless trail and fragment.followingComments.length is 1
onNextLine = no
for upcomingFragment in fragments[fragmentIndex...]
unless onNextLine
if '\n' in upcomingFragment.code
onNextLine = yes
else
continue
else
indent = /^ {2,}/m.exec upcomingFragment.code
if indent
fragmentIndent = indent[0]
break
else if '\n' in upcomingFragment.code
breakIs this comment following the indent inserted by bare mode? If so, there’s no need to indent this further.
code = if fragmentIndex is 1 and /^\s+$/.test fragments[0].code
''
else if trail
' '
else
"\n#{fragmentIndent}"Assemble properly indented comments.
code += (
for commentFragment in fragment.followingComments
if commentFragment.isHereComment and commentFragment.multiline
multident commentFragment.code, fragmentIndent, no
else
commentFragment.code
).join("\n#{fragmentIndent}").replace /^(\s*)$/gm, ''
for upcomingFragment, upcomingFragmentIndex in fragments[fragmentIndex...]
newLineIndex = upcomingFragment.code.indexOf '\n'
if newLineIndex is -1Keep searching upcoming fragments until we can’t go any further, either because there are no fragments left or we’ve discovered that we’re in a code block that is interpolated inside a string.
if upcomingFragmentIndex is fragments.length - 1
upcomingFragment.code = upcomingFragment.code + '\n'
newLineIndex = upcomingFragment.code.length
else if upcomingFragment.isStringWithInterpolations and upcomingFragment.code is '}'
code = "#{code}\n"
newLineIndex = 0
else
continue
delete fragment.followingCommentsAvoid inserting extra blank lines.
code = code.replace /^\n/, '' if upcomingFragment.code is '\n'
upcomingFragment.code = upcomingFragment.code[0...newLineIndex] +
code + upcomingFragment.code[newLineIndex..]
break
fragmentsWrap up the given nodes as a Block, unless it already happens to be one.
@wrap: (nodes) ->
return nodes[0] if nodes.length is 1 and nodes[0] instanceof Block
new Block nodesLiteral is a base class for static values that can be passed through
directly into JavaScript without translation, such as: strings, numbers,
true, false, null…
exports.Literal = class Literal extends Base
constructor: (@value) ->
super()
shouldCache: NO
assigns: (name) ->
name is @value
compileNode: (o) ->
[@makeCode @value]
toString: ->This is only intended for debugging.
" #{if @isStatement() then super() else @constructor.name}: #{@value}"
exports.NumberLiteral = class NumberLiteral extends Literal
exports.InfinityLiteral = class InfinityLiteral extends NumberLiteral
compileNode: ->
[@makeCode '2e308']
exports.NaNLiteral = class NaNLiteral extends NumberLiteral
constructor: ->
super 'NaN'
compileNode: (o) ->
code = [@makeCode '0/0']
if o.level >= LEVEL_OP then @wrapInParentheses code else code
exports.StringLiteral = class StringLiteral extends Literal
compileNode: (o) ->
res = if @csx then [@makeCode @unquote(yes, yes)] else super()
unquote: (doubleQuote = no, newLine = no) ->
unquoted = @value[1...-1]
unquoted = unquoted.replace /\\"/g, '"' if doubleQuote
unquoted = unquoted.replace /\\n/g, '\n' if newLine
unquoted
exports.RegexLiteral = class RegexLiteral extends Literal
exports.PassthroughLiteral = class PassthroughLiteral extends Literal
exports.IdentifierLiteral = class IdentifierLiteral extends Literal
isAssignable: YES
eachName: (iterator) ->
iterator @
exports.CSXTag = class CSXTag extends IdentifierLiteral
exports.PropertyName = class PropertyName extends Literal
isAssignable: YES
exports.ComputedPropertyName = class ComputedPropertyName extends PropertyName
compileNode: (o) ->
[@makeCode('['), @value.compileToFragments(o, LEVEL_LIST)..., @makeCode(']')]
exports.StatementLiteral = class StatementLiteral extends Literal
isStatement: YES
makeReturn: THIS
jumps: (o) ->
return this if @value is 'break' and not (o?.loop or o?.block)
return this if @value is 'continue' and not o?.loop
compileNode: (o) ->
[@makeCode "#{@tab}#{@value};"]
exports.ThisLiteral = class ThisLiteral extends Literal
constructor: ->
super 'this'
compileNode: (o) ->
code = if o.scope.method?.bound then o.scope.method.context else @value
[@makeCode code]
exports.UndefinedLiteral = class UndefinedLiteral extends Literal
constructor: ->
super 'undefined'
compileNode: (o) ->
[@makeCode if o.level >= LEVEL_ACCESS then '(void 0)' else 'void 0']
exports.NullLiteral = class NullLiteral extends Literal
constructor: ->
super 'null'
exports.BooleanLiteral = class BooleanLiteral extends LiteralA return is a pureStatement—wrapping it in a closure wouldn’t make sense.
exports.Return = class Return extends Base
constructor: (@expression) ->
super()
children: ['expression']
isStatement: YES
makeReturn: THIS
jumps: THIS
compileToFragments: (o, level) ->
expr = @expression?.makeReturn()
if expr and expr not instanceof Return then expr.compileToFragments o, level else super o, level
compileNode: (o) ->
answer = []TODO: If we call expression.compile() here twice, we’ll sometimes
get back different results!
if @expression
answer = @expression.compileToFragments o, LEVEL_PAREN
unshiftAfterComments answer, @makeCode "#{@tab}return "Since the return got indented by @tab, preceding comments that are
multiline need to be indented.
for fragment in answer
if fragment.isHereComment and '\n' in fragment.code
fragment.code = multident fragment.code, @tab
else if fragment.isLineComment
fragment.code = "#{@tab}#{fragment.code}"
else
break
else
answer.push @makeCode "#{@tab}return"
answer.push @makeCode ';'
answeryield return works exactly like return, except that it turns the function
into a generator.
exports.YieldReturn = class YieldReturn extends Return
compileNode: (o) ->
unless o.scope.parent?
@error 'yield can only occur inside functions'
super o
exports.AwaitReturn = class AwaitReturn extends Return
compileNode: (o) ->
unless o.scope.parent?
@error 'await can only occur inside functions'
super oA value, variable or literal or parenthesized, indexed or dotted into, or vanilla.
exports.Value = class Value extends Base
constructor: (base, props, tag, isDefaultValue = no) ->
super()
return base if not props and base instanceof Value
@base = base
@properties = props or []
@[tag] = yes if tag
@isDefaultValue = isDefaultValueIf this is a @foo = assignment, if there are comments on @ move them
to be on foo.
if @base?.comments and @base instanceof ThisLiteral and @properties[0]?.name?
moveComments @base, @properties[0].name
children: ['base', 'properties']Add a property (or properties ) Access to the list.
add: (props) ->
@properties = @properties.concat props
@forceUpdateLocation = yes
this
hasProperties: ->
@properties.length isnt 0
bareLiteral: (type) ->
not @properties.length and @base instanceof typeSome boolean checks for the benefit of other nodes.
isArray : -> @bareLiteral(Arr)
isRange : -> @bareLiteral(Range)
shouldCache : -> @hasProperties() or @base.shouldCache()
isAssignable : -> @hasProperties() or @base.isAssignable()
isNumber : -> @bareLiteral(NumberLiteral)
isString : -> @bareLiteral(StringLiteral)
isRegex : -> @bareLiteral(RegexLiteral)
isUndefined : -> @bareLiteral(UndefinedLiteral)
isNull : -> @bareLiteral(NullLiteral)
isBoolean : -> @bareLiteral(BooleanLiteral)
isAtomic : ->
for node in @properties.concat @base
return no if node.soak or node instanceof Call
yes
isNotCallable : -> @isNumber() or @isString() or @isRegex() or
@isArray() or @isRange() or @isSplice() or @isObject() or
@isUndefined() or @isNull() or @isBoolean()
isStatement : (o) -> not @properties.length and @base.isStatement o
assigns : (name) -> not @properties.length and @base.assigns name
jumps : (o) -> not @properties.length and @base.jumps o
isObject: (onlyGenerated) ->
return no if @properties.length
(@base instanceof Obj) and (not onlyGenerated or @base.generated)
isElision: ->
return no unless @base instanceof Arr
@base.hasElision()
isSplice: ->
[..., lastProp] = @properties
lastProp instanceof Slice
looksStatic: (className) ->
(@this or @base instanceof ThisLiteral or @base.value is className) and
@properties.length is 1 and @properties[0].name?.value isnt 'prototype'The value can be unwrapped as its inner node, if there are no attached properties.
unwrap: ->
if @properties.length then this else @baseA reference has base part (this value) and name part.
We cache them separately for compiling complex expressions.
a()[b()] ?= c -> (_base = a())[_name = b()] ? _base[_name] = c
cacheReference: (o) ->
[..., name] = @properties
if @properties.length < 2 and not @base.shouldCache() and not name?.shouldCache()
return [this, this] # `a` `a.b`
base = new Value @base, @properties[...-1]
if base.shouldCache() # `a().b`
bref = new IdentifierLiteral o.scope.freeVariable 'base'
base = new Value new Parens new Assign bref, base
return [base, bref] unless name # `a()`
if name.shouldCache() # `a[b()]`
nref = new IdentifierLiteral o.scope.freeVariable 'name'
name = new Index new Assign nref, name.index
nref = new Index nref
[base.add(name), new Value(bref or base.base, [nref or name])]We compile a value to JavaScript by compiling and joining each property.
Things get much more interesting if the chain of properties has soak
operators ?. interspersed. Then we have to take care not to accidentally
evaluate anything twice when building the soak chain.
compileNode: (o) ->
@base.front = @front
props = @properties
if props.length and @base.cached?Cached fragments enable correct order of the compilation,
and reuse of variables in the scope.
Example:
a(x = 5).b(-> x = 6) should compile in the same order as
a(x = 5); b(-> x = 6)
(see issue #4437, https://github.com/jashkenas/coffeescript/issues/4437)
fragments = @base.cached
else
fragments = @base.compileToFragments o, (if props.length then LEVEL_ACCESS else null)
if props.length and SIMPLENUM.test fragmentsToText fragments
fragments.push @makeCode '.'
for prop in props
fragments.push (prop.compileToFragments o)...
fragmentsUnfold a soak into an If: a?.b -> a.b if a?
unfoldSoak: (o) ->
@unfoldedSoak ?= do =>
ifn = @base.unfoldSoak o
if ifn
ifn.body.properties.push @properties...
return ifn
for prop, i in @properties when prop.soak
prop.soak = off
fst = new Value @base, @properties[...i]
snd = new Value @base, @properties[i..]
if fst.shouldCache()
ref = new IdentifierLiteral o.scope.freeVariable 'ref'
fst = new Parens new Assign ref, fst
snd.base = ref
return new If new Existence(fst), snd, soak: on
no
eachName: (iterator) ->
if @hasProperties()
iterator @
else if @base.isAssignable()
@base.eachName iterator
else
@error 'tried to assign to unassignable value'Comment delimited by ### (becoming /* */).
exports.HereComment = class HereComment extends Base
constructor: ({ @content, @newLine, @unshift }) ->
super()
compileNode: (o) ->
multiline = '\n' in @content
hasLeadingMarks = /\n\s*[#|\*]/.test @content
@content = @content.replace /^([ \t]*)#(?=\s)/gm, ' *' if hasLeadingMarksUnindent multiline comments. They will be reindented later.
if multiline
largestIndent = ''
for line in @content.split '\n'
leadingWhitespace = /^\s*/.exec(line)[0]
if leadingWhitespace.length > largestIndent.length
largestIndent = leadingWhitespace
@content = @content.replace ///^(#{leadingWhitespace})///gm, ''
@content = "/*#{@content}#{if hasLeadingMarks then ' ' else ''}*/"
fragment = @makeCode @content
fragment.newLine = @newLine
fragment.unshift = @unshift
fragment.multiline = multilineDon’t rely on fragment.type, which can break when the compiler is minified.
fragment.isComment = fragment.isHereComment = yes
fragmentComment running from # to the end of a line (becoming //).
exports.LineComment = class LineComment extends Base
constructor: ({ @content, @newLine, @unshift }) ->
super()
compileNode: (o) ->
fragment = @makeCode(if /^\s*$/.test @content then '' else "//#{@content}")
fragment.newLine = @newLine
fragment.unshift = @unshift
fragment.trail = not @newLine and not @unshiftDon’t rely on fragment.type, which can break when the compiler is minified.
fragment.isComment = fragment.isLineComment = yes
fragmentNode for a function invocation.
exports.Call = class Call extends Base
constructor: (@variable, @args = [], @soak, @token) ->
super()
@isNew = no
if @variable instanceof Value and @variable.isNotCallable()
@variable.error "literal is not a function"
@csx = @variable.base instanceof CSXTag@variable never gets output as a result of this node getting created as
part of RegexWithInterpolations, so for that case move any comments to
the args property that gets passed into RegexWithInterpolations via
the grammar.
if @variable.base?.value is 'RegExp' and @args.length isnt 0
moveComments @variable, @args[0]
children: ['variable', 'args']When setting the location, we sometimes need to update the start location to
account for a newly-discovered new operator to the left of us. This
expands the range on the left, but not the right.
updateLocationDataIfMissing: (locationData) ->
if @locationData and @needsUpdatedStartLocation
@locationData.first_line = locationData.first_line
@locationData.first_column = locationData.first_column
base = @variable?.base or @variable
if base.needsUpdatedStartLocation
@variable.locationData.first_line = locationData.first_line
@variable.locationData.first_column = locationData.first_column
base.updateLocationDataIfMissing locationData
delete @needsUpdatedStartLocation
super locationDataTag this invocation as creating a new instance.
newInstance: ->
base = @variable?.base or @variable
if base instanceof Call and not base.isNew
base.newInstance()
else
@isNew = true
@needsUpdatedStartLocation = true
thisSoaked chained invocations unfold into if/else ternary structures.
unfoldSoak: (o) ->
if @soak
if @variable instanceof Super
left = new Literal @variable.compile o
rite = new Value left
@variable.error "Unsupported reference to 'super'" unless @variable.accessor?
else
return ifn if ifn = unfoldSoak o, this, 'variable'
[left, rite] = new Value(@variable).cacheReference o
rite = new Call rite, @args
rite.isNew = @isNew
left = new Literal "typeof #{ left.compile o } === \"function\""
return new If left, new Value(rite), soak: yes
call = this
list = []
loop
if call.variable instanceof Call
list.push call
call = call.variable
continue
break unless call.variable instanceof Value
list.push call
break unless (call = call.variable.base) instanceof Call
for call in list.reverse()
if ifn
if call.variable instanceof Call
call.variable = ifn
else
call.variable.base = ifn
ifn = unfoldSoak o, call, 'variable'
ifnCompile a vanilla function call.
compileNode: (o) ->
return @compileCSX o if @csx
@variable?.front = @front
compiledArgs = []If variable is Accessor fragments are cached and used later
in Value::compileNode to ensure correct order of the compilation,
and reuse of variables in the scope.
Example:
a(x = 5).b(-> x = 6) should compile in the same order as
a(x = 5); b(-> x = 6)
(see issue #4437, https://github.com/jashkenas/coffeescript/issues/4437)
varAccess = @variable?.properties?[0] instanceof Access
argCode = (arg for arg in (@args || []) when arg instanceof Code)
if argCode.length > 0 and varAccess and not @variable.base.cached
[cache] = @variable.base.cache o, LEVEL_ACCESS, -> no
@variable.base.cached = cache
for arg, argIndex in @args
if argIndex then compiledArgs.push @makeCode ", "
compiledArgs.push (arg.compileToFragments o, LEVEL_LIST)...
fragments = []
if @isNew
@variable.error "Unsupported reference to 'super'" if @variable instanceof Super
fragments.push @makeCode 'new '
fragments.push @variable.compileToFragments(o, LEVEL_ACCESS)...
fragments.push @makeCode('('), compiledArgs..., @makeCode(')')
fragments
compileCSX: (o) ->
[attributes, content] = @args
attributes.base.csx = yes
content?.base.csx = yes
fragments = [@makeCode('<')]
fragments.push (tag = @variable.compileToFragments(o, LEVEL_ACCESS))...
if attributes.base instanceof Arr
for obj in attributes.base.objects
attr = obj.base
attrProps = attr?.properties or []Catch invalid CSX attributes:
if not (attr instanceof Obj or attr instanceof IdentifierLiteral) or (attr instanceof Obj and not attr.generated and (attrProps.length > 1 or not (attrProps[0] instanceof Splat)))
obj.error """
Unexpected token. Allowed CSX attributes are: id="val", src={source}, {props...} or attribute.
"""
obj.base.csx = yes if obj.base instanceof Obj
fragments.push @makeCode ' '
fragments.push obj.compileToFragments(o, LEVEL_PAREN)...
if content
fragments.push @makeCode('>')
fragments.push content.compileNode(o, LEVEL_LIST)...
fragments.push [@makeCode('</'), tag..., @makeCode('>')]...
else
fragments.push @makeCode(' />')
fragmentsTakes care of converting super() calls into calls against the prototype’s
function of the same name.
When expressions are set the call will be compiled in such a way that the
expressions are evaluated without altering the return value of the SuperCall
expression.
exports.SuperCall = class SuperCall extends Call
children: Call::children.concat ['expressions']
isStatement: (o) ->
@expressions?.length and o.level is LEVEL_TOP
compileNode: (o) ->
return super o unless @expressions?.length
superCall = new Literal fragmentsToText super o
replacement = new Block @expressions.slice()
if o.level > LEVEL_TOPIf we might be in an expression we need to cache and return the result
[superCall, ref] = superCall.cache o, null, YES
replacement.push ref
replacement.unshift superCall
replacement.compileToFragments o, if o.level is LEVEL_TOP then o.level else LEVEL_LIST
exports.Super = class Super extends Base
constructor: (@accessor) ->
super()
children: ['accessor']
compileNode: (o) ->
method = o.scope.namedMethod()
@error 'cannot use super outside of an instance method' unless method?.isMethod
unless method.ctor? or @accessor?
{name, variable} = method
if name.shouldCache() or (name instanceof Index and name.index.isAssignable())
nref = new IdentifierLiteral o.scope.parent.freeVariable 'name'
name.index = new Assign nref, name.index
@accessor = if nref? then new Index nref else name
if @accessor?.name?.commentsA super() call gets compiled to e.g. super.method(), which means
the method property name gets compiled for the first time here, and
again when the method: property of the class gets compiled. Since
this compilation happens first, comments attached to method: would
get incorrectly output near super.method(), when we want them to
get output on the second pass when method: is output. So set them
aside during this compilation pass, and put them back on the object so
that they’re there for the later compilation.
salvagedComments = @accessor.name.comments
delete @accessor.name.comments
fragments = (new Value (new Literal 'super'), if @accessor then [ @accessor ] else [])
.compileToFragments o
attachCommentsToNode salvagedComments, @accessor.name if salvagedComments
fragmentsRegexes with interpolations are in fact just a variation of a Call (a
RegExp() call to be precise) with a StringWithInterpolations inside.
exports.RegexWithInterpolations = class RegexWithInterpolations extends Call
constructor: (args = []) ->
super (new Value new IdentifierLiteral 'RegExp'), args, false
exports.TaggedTemplateCall = class TaggedTemplateCall extends Call
constructor: (variable, arg, soak) ->
arg = new StringWithInterpolations Block.wrap([ new Value arg ]) if arg instanceof StringLiteral
super variable, [ arg ], soak
compileNode: (o) ->
@variable.compileToFragments(o, LEVEL_ACCESS).concat @args[0].compileToFragments(o, LEVEL_LIST)Node to extend an object’s prototype with an ancestor object.
After goog.inherits from the
Closure Library.
exports.Extends = class Extends extends Base
constructor: (@child, @parent) ->
super()
children: ['child', 'parent']Hooks one constructor into another’s prototype chain.
compileToFragments: (o) ->
new Call(new Value(new Literal utility 'extend', o), [@child, @parent]).compileToFragments oA . access into a property of a value, or the :: shorthand for
an access into the object’s prototype.
exports.Access = class Access extends Base
constructor: (@name, tag) ->
super()
@soak = tag is 'soak'
children: ['name']
compileToFragments: (o) ->
name = @name.compileToFragments o
node = @name.unwrap()
if node instanceof PropertyName
[@makeCode('.'), name...]
else
[@makeCode('['), name..., @makeCode(']')]
shouldCache: NOA [ ... ] indexed access into an array or object.
exports.Index = class Index extends Base
constructor: (@index) ->
super()
children: ['index']
compileToFragments: (o) ->
[].concat @makeCode("["), @index.compileToFragments(o, LEVEL_PAREN), @makeCode("]")
shouldCache: ->
@index.shouldCache()A range literal. Ranges can be used to extract portions (slices) of arrays, to specify a range for comprehensions, or as a value, to be expanded into the corresponding array of integers at runtime.
exports.Range = class Range extends Base
children: ['from', 'to']
constructor: (@from, @to, tag) ->
super()
@exclusive = tag is 'exclusive'
@equals = if @exclusive then '' else '='Compiles the range’s source variables – where it starts and where it ends. But only if they need to be cached to avoid double evaluation.
compileVariables: (o) ->
o = merge o, top: true
shouldCache = del o, 'shouldCache'
[@fromC, @fromVar] = @cacheToCodeFragments @from.cache o, LEVEL_LIST, shouldCache
[@toC, @toVar] = @cacheToCodeFragments @to.cache o, LEVEL_LIST, shouldCache
[@step, @stepVar] = @cacheToCodeFragments step.cache o, LEVEL_LIST, shouldCache if step = del o, 'step'
@fromNum = if @from.isNumber() then Number @fromVar else null
@toNum = if @to.isNumber() then Number @toVar else null
@stepNum = if step?.isNumber() then Number @stepVar else nullWhen compiled normally, the range returns the contents of the for loop needed to iterate over the values in the range. Used by comprehensions.
compileNode: (o) ->
@compileVariables o unless @fromVar
return @compileArray(o) unless o.indexSet up endpoints.
known = @fromNum? and @toNum?
idx = del o, 'index'
idxName = del o, 'name'
namedIndex = idxName and idxName isnt idx
varPart =
if known and not namedIndex
"var #{idx} = #{@fromC}"
else
"#{idx} = #{@fromC}"
varPart += ", #{@toC}" if @toC isnt @toVar
varPart += ", #{@step}" if @step isnt @stepVar
[lt, gt] = ["#{idx} <#{@equals}", "#{idx} >#{@equals}"]Generate the condition.
[from, to] = [@fromNum, @toNum]Always check if the step isn’t zero to avoid the infinite loop.
stepNotZero = "#{ @stepNum ? @stepVar } !== 0"
stepCond = "#{ @stepNum ? @stepVar } > 0"
lowerBound = "#{lt} #{ if known then to else @toVar }"
upperBound = "#{gt} #{ if known then to else @toVar }"
condPart =
if @step?
if @stepNum? and @stepNum isnt 0
if @stepNum > 0 then "#{lowerBound}" else "#{upperBound}"
else
"#{stepNotZero} && (#{stepCond} ? #{lowerBound} : #{upperBound})"
else
if known
"#{ if from <= to then lt else gt } #{to}"
else
"(#{@fromVar} <= #{@toVar} ? #{lowerBound} : #{upperBound})"
cond = if @stepVar then "#{@stepVar} > 0" else "#{@fromVar} <= #{@toVar}"Generate the step.
stepPart = if @stepVar
"#{idx} += #{@stepVar}"
else if known
if namedIndex
if from <= to then "++#{idx}" else "--#{idx}"
else
if from <= to then "#{idx}++" else "#{idx}--"
else
if namedIndex
"#{cond} ? ++#{idx} : --#{idx}"
else
"#{cond} ? #{idx}++ : #{idx}--"
varPart = "#{idxName} = #{varPart}" if namedIndex
stepPart = "#{idxName} = #{stepPart}" if namedIndexThe final loop body.
[@makeCode "#{varPart}; #{condPart}; #{stepPart}"]When used as a value, expand the range into the equivalent array.
compileArray: (o) ->
known = @fromNum? and @toNum?
if known and Math.abs(@fromNum - @toNum) <= 20
range = [@fromNum..@toNum]
range.pop() if @exclusive
return [@makeCode "[#{ range.join(', ') }]"]
idt = @tab + TAB
i = o.scope.freeVariable 'i', single: true, reserve: no
result = o.scope.freeVariable 'results', reserve: no
pre = "\n#{idt}var #{result} = [];"
if known
o.index = i
body = fragmentsToText @compileNode o
else
vars = "#{i} = #{@fromC}" + if @toC isnt @toVar then ", #{@toC}" else ''
cond = "#{@fromVar} <= #{@toVar}"
body = "var #{vars}; #{cond} ? #{i} <#{@equals} #{@toVar} : #{i} >#{@equals} #{@toVar}; #{cond} ? #{i}++ : #{i}--"
post = "{ #{result}.push(#{i}); }\n#{idt}return #{result};\n#{o.indent}"
hasArgs = (node) -> node?.contains isLiteralArguments
args = ', arguments' if hasArgs(@from) or hasArgs(@to)
[@makeCode "(function() {#{pre}\n#{idt}for (#{body})#{post}}).apply(this#{args ? ''})"]An array slice literal. Unlike JavaScript’s Array#slice, the second parameter
specifies the index of the end of the slice, just as the first parameter
is the index of the beginning.
exports.Slice = class Slice extends Base
children: ['range']
constructor: (@range) ->
super()We have to be careful when trying to slice through the end of the array,
9e9 is used because not all implementations respect undefined or 1/0.
9e9 should be safe because 9e9 > 2**32, the max array length.
compileNode: (o) ->
{to, from} = @rangeHandle an expression in the property access, e.g. a[!b in c..].
if from?.shouldCache()
from = new Value new Parens from
if to?.shouldCache()
to = new Value new Parens to
fromCompiled = from?.compileToFragments(o, LEVEL_PAREN) or [@makeCode '0']
if to
compiled = to.compileToFragments o, LEVEL_PAREN
compiledText = fragmentsToText compiled
if not (not @range.exclusive and +compiledText is -1)
toStr = ', ' + if @range.exclusive
compiledText
else if to.isNumber()
"#{+compiledText + 1}"
else
compiled = to.compileToFragments o, LEVEL_ACCESS
"+#{fragmentsToText compiled} + 1 || 9e9"
[@makeCode ".slice(#{ fragmentsToText fromCompiled }#{ toStr or '' })"]An object literal, nothing fancy.
exports.Obj = class Obj extends Base
constructor: (props, @generated = no, @lhs = no) ->
super()
@objects = @properties = props or []
children: ['properties']
isAssignable: ->
for prop in @propertiesCheck for reserved words.
message = isUnassignable prop.unwrapAll().value
prop.error message if message
prop = prop.value if prop instanceof Assign and
prop.context is 'object' and
prop.value?.base not instanceof Arr
return no unless prop.isAssignable()
yes
shouldCache: ->
not @isAssignable()Check if object contains splat.
hasSplat: ->
return yes for prop in @properties when prop instanceof Splat
no
compileNode: (o) ->
props = @properties
if @generated
for node in props when node instanceof Value
node.error 'cannot have an implicit value in an implicit object'Object spread properties. https://github.com/tc39/proposal-object-rest-spread/blob/master/Spread.md
return @compileSpread o if @hasSplat() and not @csx
idt = o.indent += TAB
lastNode = @lastNode @propertiesCSX attributes
return @compileCSXAttributes o if @csxIf this object is the left-hand side of an assignment, all its children are too.
if @lhs
for prop in props when prop instanceof Assign
{value} = prop
unwrappedVal = value.unwrapAll()
if unwrappedVal instanceof Arr or unwrappedVal instanceof Obj
unwrappedVal.lhs = yes
else if unwrappedVal instanceof Assign
unwrappedVal.nestedLhs = yes
isCompact = yes
for prop in @properties
if prop instanceof Assign and prop.context is 'object'
isCompact = no
answer = []
answer.push @makeCode if isCompact then '' else '\n'
for prop, i in props
join = if i is props.length - 1
''
else if isCompact
', '
else if prop is lastNode
'\n'
else
',\n'
indent = if isCompact then '' else idt
key = if prop instanceof Assign and prop.context is 'object'
prop.variable
else if prop instanceof Assign
prop.operatorToken.error "unexpected #{prop.operatorToken.value}" unless @lhs
prop.variable
else
prop
if key instanceof Value and key.hasProperties()
key.error 'invalid object key' if prop.context is 'object' or not key.this
key = key.properties[0].name
prop = new Assign key, prop, 'object'
if key is prop
if prop.shouldCache()
[key, value] = prop.base.cache o
key = new PropertyName key.value if key instanceof IdentifierLiteral
prop = new Assign key, value, 'object'
else if key instanceof Value and key.base instanceof ComputedPropertyName{ [foo()] } output as { [ref = foo()]: ref }.
if prop.base.value.shouldCache()
[key, value] = prop.base.value.cache o
key = new ComputedPropertyName key.value if key instanceof IdentifierLiteral
prop = new Assign key, value, 'object'
else{ [expression] } output as { [expression]: expression }.
prop = new Assign key, prop.base.value, 'object'
else if not prop.bareLiteral?(IdentifierLiteral)
prop = new Assign prop, prop, 'object'
if indent then answer.push @makeCode indent
answer.push prop.compileToFragments(o, LEVEL_TOP)...
if join then answer.push @makeCode join
answer.push @makeCode if isCompact then '' else "\n#{@tab}"
answer = @wrapInBraces answer
if @front then @wrapInParentheses answer else answer
assigns: (name) ->
for prop in @properties when prop.assigns name then return yes
no
eachName: (iterator) ->
for prop in @properties
prop = prop.value if prop instanceof Assign and prop.context is 'object'
prop = prop.unwrapAll()
prop.eachName iterator if prop.eachName?Object spread properties. https://github.com/tc39/proposal-object-rest-spread/blob/master/Spread.md
obj2 = {a: 1, obj..., c: 3, d: 4} → obj2 = _extends({}, {a: 1}, obj, {c: 3, d: 4})
compileSpread: (o) ->
props = @propertiesStore object spreads.
splatSlice = []
propSlices = []
slices = []
addSlice = ->
slices.push new Obj propSlices if propSlices.length
slices.push splatSlice... if splatSlice.length
splatSlice = []
propSlices = []
for prop in props
if prop instanceof Splat
splatSlice.push new Value prop.name
addSlice()
else
propSlices.push prop
addSlice()
slices.unshift new Obj unless slices[0] instanceof Obj
_extends = new Value new Literal utility '_extends', o
(new Call _extends, slices).compileToFragments o
compileCSXAttributes: (o) ->
props = @properties
answer = []
for prop, i in props
prop.csx = yes
join = if i is props.length - 1 then '' else ' '
prop = new Literal "{#{prop.compile(o)}}" if prop instanceof Splat
answer.push prop.compileToFragments(o, LEVEL_TOP)...
answer.push @makeCode join
if @front then @wrapInParentheses answer else answerAn array literal.
exports.Arr = class Arr extends Base
constructor: (objs, @lhs = no) ->
super()
@objects = objs or []
children: ['objects']
hasElision: ->
return yes for obj in @objects when obj instanceof Elision
no
isAssignable: ->
return no unless @objects.length
for obj, i in @objects
return no if obj instanceof Splat and i + 1 isnt @objects.length
return no unless obj.isAssignable() and (not obj.isAtomic or obj.isAtomic())
yes
shouldCache: ->
not @isAssignable()
compileNode: (o) ->
return [@makeCode '[]'] unless @objects.length
o.indent += TAB
fragmentIsElision = (fragment) -> fragmentsToText(fragment).trim() is ','Detect if Elisions at the beginning of the array are processed (e.g. [, , , a]).
passedElision = no
answer = []
for obj, objIndex in @objects
unwrappedObj = obj.unwrapAll()Let compileCommentFragments know to intersperse block comments
into the fragments created when compiling this array.
if unwrappedObj.comments and
unwrappedObj.comments.filter((comment) -> not comment.here).length is 0
unwrappedObj.includeCommentFragments = YESIf this array is the left-hand side of an assignment, all its children are too.
if @lhs
unwrappedObj.lhs = yes if unwrappedObj instanceof Arr or unwrappedObj instanceof Obj
compiledObjs = (obj.compileToFragments o, LEVEL_LIST for obj in @objects)
olen = compiledObjs.lengthIf compiledObjs includes newlines, we will output this as a multiline
array (i.e. with a newline and indentation after the [). If an element
contains line comments, that should also trigger multiline output since
by definition line comments will introduce newlines into our output.
The exception is if only the first element has line comments; in that
case, output as the compact form if we otherwise would have, so that the
first element’s line comments get output before or after the array.
includesLineCommentsOnNonFirstElement = no
for fragments, index in compiledObjs
for fragment in fragments
if fragment.isHereComment
fragment.code = fragment.code.trim()
else if index isnt 0 and includesLineCommentsOnNonFirstElement is no and hasLineComments fragment
includesLineCommentsOnNonFirstElement = yesAdd ‘, ‘ if all Elisions from the beginning of the array are processed (e.g. [, , , a]) and
element isn’t Elision or last element is Elision (e.g. [a,,b,,])
if index isnt 0 and passedElision and (not fragmentIsElision(fragments) or index is olen - 1)
answer.push @makeCode ', '
passedElision = passedElision or not fragmentIsElision fragments
answer.push fragments...
if includesLineCommentsOnNonFirstElement or '\n' in fragmentsToText(answer)
for fragment, fragmentIndex in answer
if fragment.isHereComment
fragment.code = "#{multident(fragment.code, o.indent, no)}\n#{o.indent}"
else if fragment.code is ', ' and not fragment?.isElision
fragment.code = ",\n#{o.indent}"
answer.unshift @makeCode "[\n#{o.indent}"
answer.push @makeCode "\n#{@tab}]"
else
for fragment in answer when fragment.isHereComment
fragment.code = "#{fragment.code} "
answer.unshift @makeCode '['
answer.push @makeCode ']'
answer
assigns: (name) ->
for obj in @objects when obj.assigns name then return yes
no
eachName: (iterator) ->
for obj in @objects
obj = obj.unwrapAll()
obj.eachName iteratorThe CoffeeScript class definition. Initialize a Class with its name, an optional superclass, and a body.
exports.Class = class Class extends Base
children: ['variable', 'parent', 'body']
constructor: (@variable, @parent, @body = new Block) ->
super()
compileNode: (o) ->
@name = @determineName()
executableBody = @walkBody()Special handling to allow class expr.A extends A declarations
parentName = @parent.base.value if @parent instanceof Value and not @parent.hasProperties()
@hasNameClash = @name? and @name is parentName
node = @
if executableBody or @hasNameClash
node = new ExecutableClassBody node, executableBody
else if not @name? and o.level is LEVEL_TOPAnonymous classes are only valid in expressions
node = new Parens node
if @boundMethods.length and @parent
@variable ?= new IdentifierLiteral o.scope.freeVariable '_class'
[@variable, @variableRef] = @variable.cache o unless @variableRef?
if @variable
node = new Assign @variable, node, null, { @moduleDeclaration }
@compileNode = @compileClassDeclaration
try
return node.compileToFragments o
finally
delete @compileNode
compileClassDeclaration: (o) ->
@ctor ?= @makeDefaultConstructor() if @externalCtor or @boundMethods.length
@ctor?.noReturn = true
@proxyBoundMethods() if @boundMethods.length
o.indent += TAB
result = []
result.push @makeCode "class "
result.push @makeCode @name if @name
@compileCommentFragments o, @variable, result if @variable?.comments?
result.push @makeCode ' ' if @name
result.push @makeCode('extends '), @parent.compileToFragments(o)..., @makeCode ' ' if @parent
result.push @makeCode '{'
unless @body.isEmpty()
@body.spaced = true
result.push @makeCode '\n'
result.push @body.compileToFragments(o, LEVEL_TOP)...
result.push @makeCode "\n#{@tab}"
result.push @makeCode '}'
resultFigure out the appropriate name for this class
determineName: ->
return null unless @variable
[..., tail] = @variable.properties
node = if tail
tail instanceof Access and tail.name
else
@variable.base
unless node instanceof IdentifierLiteral or node instanceof PropertyName
return null
name = node.value
unless tail
message = isUnassignable name
@variable.error message if message
if name in JS_FORBIDDEN then "_#{name}" else name
walkBody: ->
@ctor = null
@boundMethods = []
executableBody = null
initializer = []
{ expressions } = @body
i = 0
for expression in expressions.slice()
if expression instanceof Value and expression.isObject true
{ properties } = expression.base
exprs = []
end = 0
start = 0
pushSlice = -> exprs.push new Value new Obj properties[start...end], true if end > start
while assign = properties[end]
if initializerExpression = @addInitializerExpression assign
pushSlice()
exprs.push initializerExpression
initializer.push initializerExpression
start = end + 1
end++
pushSlice()
expressions[i..i] = exprs
i += exprs.length
else
if initializerExpression = @addInitializerExpression expression
initializer.push initializerExpression
expressions[i] = initializerExpression
i += 1
for method in initializer when method instanceof Code
if method.ctor
method.error 'Cannot define more than one constructor in a class' if @ctor
@ctor = method
else if method.isStatic and method.bound
method.context = @name
else if method.bound
@boundMethods.push method
if initializer.length isnt expressions.length
@body.expressions = (expression.hoist() for expression in initializer)
new Block expressionsAdd an expression to the class initializer
This is the key method for determining whether an expression in a class
body should appear in the initializer or the executable body. If the given
node is valid in a class body the method will return a (new, modified,
or identical) node for inclusion in the class initializer, otherwise
nothing will be returned and the node will appear in the executable body.
At time of writing, only methods (instance and static) are valid in ES
class initializers. As new ES class features (such as class fields) reach
Stage 4, this method will need to be updated to support them. We
additionally allow PassthroughLiterals (backticked expressions) in the
initializer as an escape hatch for ES features that are not implemented
(e.g. getters and setters defined via the get and set keywords as
opposed to the Object.defineProperty method).
addInitializerExpression: (node) ->
if node.unwrapAll() instanceof PassthroughLiteral
node
else if @validInitializerMethod node
@addInitializerMethod node
else
nullChecks if the given node is a valid ES class initializer method.
validInitializerMethod: (node) ->
return no unless node instanceof Assign and node.value instanceof Code
return yes if node.context is 'object' and not node.variable.hasProperties()
return node.variable.looksStatic(@name) and (@name or not node.value.bound)Returns a configured class initializer method
addInitializerMethod: (assign) ->
{ variable, value: method } = assign
method.isMethod = yes
method.isStatic = variable.looksStatic @name
if method.isStatic
method.name = variable.properties[0]
else
methodName = variable.base
method.name = new (if methodName.shouldCache() then Index else Access) methodName
method.name.updateLocationDataIfMissing methodName.locationData
method.ctor = (if @parent then 'derived' else 'base') if methodName.value is 'constructor'
method.error 'Cannot define a constructor as a bound (fat arrow) function' if method.bound and method.ctor
method
makeDefaultConstructor: ->
ctor = @addInitializerMethod new Assign (new Value new PropertyName 'constructor'), new Code
@body.unshift ctor
if @parent
ctor.body.push new SuperCall new Super, [new Splat new IdentifierLiteral 'arguments']
if @externalCtor
applyCtor = new Value @externalCtor, [ new Access new PropertyName 'apply' ]
applyArgs = [ new ThisLiteral, new IdentifierLiteral 'arguments' ]
ctor.body.push new Call applyCtor, applyArgs
ctor.body.makeReturn()
ctor
proxyBoundMethods: ->
@ctor.thisAssignments = for method in @boundMethods
method.classVariable = @variableRef if @parent
name = new Value(new ThisLiteral, [ method.name ])
new Assign name, new Call(new Value(name, [new Access new PropertyName 'bind']), [new ThisLiteral])
null
exports.ExecutableClassBody = class ExecutableClassBody extends Base
children: [ 'class', 'body' ]
defaultClassVariableName: '_Class'
constructor: (@class, @body = new Block) ->
super()
compileNode: (o) ->
if jumpNode = @body.jumps()
jumpNode.error 'Class bodies cannot contain pure statements'
if argumentsNode = @body.contains isLiteralArguments
argumentsNode.error "Class bodies shouldn't reference arguments"
params = []
args = [new ThisLiteral]
wrapper = new Code params, @body
klass = new Parens new Call (new Value wrapper, [new Access new PropertyName 'call']), args
@body.spaced = true
o.classScope = wrapper.makeScope o.scope
@name = @class.name ? o.classScope.freeVariable @defaultClassVariableName
ident = new IdentifierLiteral @name
directives = @walkBody()
@setContext()
if @class.hasNameClash
parent = new IdentifierLiteral o.classScope.freeVariable 'superClass'
wrapper.params.push new Param parent
args.push @class.parent
@class.parent = parent
if @externalCtor
externalCtor = new IdentifierLiteral o.classScope.freeVariable 'ctor', reserve: no
@class.externalCtor = externalCtor
@externalCtor.variable.base = externalCtor
if @name isnt @class.name
@body.expressions.unshift new Assign (new IdentifierLiteral @name), @class
else
@body.expressions.unshift @class
@body.expressions.unshift directives...
@body.push ident
klass.compileToFragments oTraverse the class’s children and:
@properties@properties walkBody: ->
directives = []
index = 0
while expr = @body.expressions[index]
break unless expr instanceof Value and expr.isString()
if expr.hoisted
index++
else
directives.push @body.expressions.splice(index, 1)...
@traverseChildren false, (child) =>
return false if child instanceof Class or child instanceof HoistTarget
cont = true
if child instanceof Block
for node, i in child.expressions
if node instanceof Value and node.isObject(true)
cont = false
child.expressions[i] = @addProperties node.base.properties
else if node instanceof Assign and node.variable.looksStatic @name
node.value.isStatic = yes
child.expressions = flatten child.expressions
cont
directives
setContext: ->
@body.traverseChildren false, (node) =>
if node instanceof ThisLiteral
node.value = @name
else if node instanceof Code and node.bound and node.isStatic
node.context = @nameMake class/prototype assignments for invalid ES properties
addProperties: (assigns) ->
result = for assign in assigns
variable = assign.variable
base = variable?.base
value = assign.value
delete assign.context
if base.value is 'constructor'
if value instanceof Code
base.error 'constructors must be defined at the top level of a class body'The class scope is not available yet, so return the assignment to update later
assign = @externalCtor = new Assign new Value, value
else if not assign.variable.this
name = new (if base.shouldCache() then Index else Access) base
prototype = new Access new PropertyName 'prototype'
variable = new Value new ThisLiteral(), [ prototype, name ]
assign.variable = variable
else if assign.value instanceof Code
assign.value.isStatic = true
assign
compact result
exports.ModuleDeclaration = class ModuleDeclaration extends Base
constructor: (@clause, @source) ->
super()
@checkSource()
children: ['clause', 'source']
isStatement: YES
jumps: THIS
makeReturn: THIS
checkSource: ->
if @source? and @source instanceof StringWithInterpolations
@source.error 'the name of the module to be imported from must be an uninterpolated string'
checkScope: (o, moduleDeclarationType) ->
if o.indent.length isnt 0
@error "#{moduleDeclarationType} statements must be at top-level scope"
exports.ImportDeclaration = class ImportDeclaration extends ModuleDeclaration
compileNode: (o) ->
@checkScope o, 'import'
o.importedSymbols = []
code = []
code.push @makeCode "#{@tab}import "
code.push @clause.compileNode(o)... if @clause?
if @source?.value?
code.push @makeCode ' from ' unless @clause is null
code.push @makeCode @source.value
code.push @makeCode ';'
code
exports.ImportClause = class ImportClause extends Base
constructor: (@defaultBinding, @namedImports) ->
super()
children: ['defaultBinding', 'namedImports']
compileNode: (o) ->
code = []
if @defaultBinding?
code.push @defaultBinding.compileNode(o)...
code.push @makeCode ', ' if @namedImports?
if @namedImports?
code.push @namedImports.compileNode(o)...
code
exports.ExportDeclaration = class ExportDeclaration extends ModuleDeclaration
compileNode: (o) ->
@checkScope o, 'export'
code = []
code.push @makeCode "#{@tab}export "
code.push @makeCode 'default ' if @ instanceof ExportDefaultDeclaration
if @ not instanceof ExportDefaultDeclaration and
(@clause instanceof Assign or @clause instanceof Class)Prevent exporting an anonymous class; all exported members must be named
if @clause instanceof Class and not @clause.variable
@clause.error 'anonymous classes cannot be exported'
code.push @makeCode 'var '
@clause.moduleDeclaration = 'export'
if @clause.body? and @clause.body instanceof Block
code = code.concat @clause.compileToFragments o, LEVEL_TOP
else
code = code.concat @clause.compileNode o
code.push @makeCode " from #{@source.value}" if @source?.value?
code.push @makeCode ';'
code
exports.ExportNamedDeclaration = class ExportNamedDeclaration extends ExportDeclaration
exports.ExportDefaultDeclaration = class ExportDefaultDeclaration extends ExportDeclaration
exports.ExportAllDeclaration = class ExportAllDeclaration extends ExportDeclaration
exports.ModuleSpecifierList = class ModuleSpecifierList extends Base
constructor: (@specifiers) ->
super()
children: ['specifiers']
compileNode: (o) ->
code = []
o.indent += TAB
compiledList = (specifier.compileToFragments o, LEVEL_LIST for specifier in @specifiers)
if @specifiers.length isnt 0
code.push @makeCode "{\n#{o.indent}"
for fragments, index in compiledList
code.push @makeCode(",\n#{o.indent}") if index
code.push fragments...
code.push @makeCode "\n}"
else
code.push @makeCode '{}'
code
exports.ImportSpecifierList = class ImportSpecifierList extends ModuleSpecifierList
exports.ExportSpecifierList = class ExportSpecifierList extends ModuleSpecifierList
exports.ModuleSpecifier = class ModuleSpecifier extends Base
constructor: (@original, @alias, @moduleDeclarationType) ->
super()
if @original.comments or @alias?.comments
@comments = []
@comments.push @original.comments... if @original.comments
@comments.push @alias.comments... if @alias?.commentsThe name of the variable entering the local scope
@identifier = if @alias? then @alias.value else @original.value
children: ['original', 'alias']
compileNode: (o) ->
o.scope.find @identifier, @moduleDeclarationType
code = []
code.push @makeCode @original.value
code.push @makeCode " as #{@alias.value}" if @alias?
code
exports.ImportSpecifier = class ImportSpecifier extends ModuleSpecifier
constructor: (imported, local) ->
super imported, local, 'import'
compileNode: (o) ->Per the spec, symbols can’t be imported multiple times
(e.g. import { foo, foo } from 'lib' is invalid)
if @identifier in o.importedSymbols or o.scope.check(@identifier)
@error "'#{@identifier}' has already been declared"
else
o.importedSymbols.push @identifier
super o
exports.ImportDefaultSpecifier = class ImportDefaultSpecifier extends ImportSpecifier
exports.ImportNamespaceSpecifier = class ImportNamespaceSpecifier extends ImportSpecifier
exports.ExportSpecifier = class ExportSpecifier extends ModuleSpecifier
constructor: (local, exported) ->
super local, exported, 'export'The Assign is used to assign a local variable to value, or to set the property of an object – including within object literals.
exports.Assign = class Assign extends Base
constructor: (@variable, @value, @context, options = {}) ->
super()
{@param, @subpattern, @operatorToken, @moduleDeclaration} = options
children: ['variable', 'value']
isAssignable: YES
isStatement: (o) ->
o?.level is LEVEL_TOP and @context? and (@moduleDeclaration or "?" in @context)
checkAssignability: (o, varBase) ->
if Object::hasOwnProperty.call(o.scope.positions, varBase.value) and
o.scope.variables[o.scope.positions[varBase.value]].type is 'import'
varBase.error "'#{varBase.value}' is read-only"
assigns: (name) ->
@[if @context is 'object' then 'value' else 'variable'].assigns name
unfoldSoak: (o) ->
unfoldSoak o, this, 'variable'Compile an assignment, delegating to compileDestructuring or
compileSplice if appropriate. Keep track of the name of the base object
we’ve been assigned to, for correct internal references. If the variable
has not been seen yet within the current scope, declare it.
compileNode: (o) ->
isValue = @variable instanceof Value
if isValueWhen compiling @variable, remember if it is part of a function parameter.
@variable.param = @paramIf @variable is an array or an object, we’re destructuring;
if it’s also isAssignable(), the destructuring syntax is supported
in ES and we can output it as is; otherwise we @compileDestructuring
and convert this ES-unsupported destructuring into acceptable output.
if @variable.isArray() or @variable.isObject()This is the left-hand side of an assignment; let Arr and Obj
know that, so that those nodes know that they’re assignable as
destructured variables.
@variable.base.lhs = yesCheck if @variable contains Obj with splats.
hasSplat = @variable.contains (node) -> node instanceof Obj and node.hasSplat()
return @compileDestructuring o if not @variable.isAssignable() or @variable.isArray() and hasSplatObject destructuring. Can be removed once ES proposal hits Stage 4.
objDestructAnswer = @compileObjectDestruct(o) if @variable.isObject() and hasSplat
return objDestructAnswer if objDestructAnswer
return @compileSplice o if @variable.isSplice()
return @compileConditional o if @context in ['||=', '&&=', '?=']
return @compileSpecialMath o if @context in ['**=', '//=', '%%=']
unless @context
varBase = @variable.unwrapAll()
unless varBase.isAssignable()
@variable.error "'#{@variable.compile o}' can't be assigned"
varBase.eachName (name) =>
return if name.hasProperties?()
message = isUnassignable name.value
name.error message if messagemoduleDeclaration can be 'import' or 'export'.
@checkAssignability o, name
if @moduleDeclaration
o.scope.add name.value, @moduleDeclaration
else if @param
o.scope.add name.value,
if @param is 'alwaysDeclare'
'var'
else
'param'
else
o.scope.find name.valueIf this assignment identifier has one or more herecomments
attached, output them as part of the declarations line (unless
other herecomments are already staged there) for compatibility
with Flow typing. Don’t do this if this assignment is for a
class, e.g. ClassName = class ClassName {, as Flow requires
the comment to be between the class name and the {.
if name.comments and not o.scope.comments[name.value] and
@value not instanceof Class and
name.comments.every((comment) -> comment.here and not comment.multiline)
commentsNode = new IdentifierLiteral name.value
commentsNode.comments = name.comments
commentFragments = []
@compileCommentFragments o, commentsNode, commentFragments
o.scope.comments[name.value] = commentFragments
if @value instanceof Code
if @value.isStatic
@value.name = @variable.properties[0]
else if @variable.properties?.length >= 2
[properties..., prototype, name] = @variable.properties
@value.name = name if prototype.name?.value is 'prototype'
@value.base.csxAttribute = yes if @csx
val = @value.compileToFragments o, LEVEL_LIST
compiledName = @variable.compileToFragments o, LEVEL_LIST
if @context is 'object'
if @variable.shouldCache()
compiledName.unshift @makeCode '['
compiledName.push @makeCode ']'
return compiledName.concat @makeCode(if @csx then '=' else ': '), val
answer = compiledName.concat @makeCode(" #{ @context or '=' } "), valPer https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment#Assignment_without_declaration, if we’re destructuring without declaring, the destructuring assignment must be wrapped in parentheses. The assignment is wrapped in parentheses if ‘o.level’ has lower precedence than LEVEL_LIST (3) (i.e. LEVEL_COND (4), LEVEL_OP (5) or LEVEL_ACCESS (6)), or if we’re destructuring object, e.g. {a,b} = obj.
if o.level > LEVEL_LIST or isValue and @variable.base instanceof Obj and not @nestedLhs and not (@param is yes)
@wrapInParentheses answer
else
answerCheck object destructuring variable for rest elements; can be removed once ES proposal hits Stage 4.
compileObjectDestruct: (o) ->Returns a safe (cached) reference to the key for a given property
getPropKey = (prop) ->
if prop instanceof Assign
[prop.variable, key] = prop.variable.cache o
key
else
propReturns the name of a given property for use with excludeProps
Property names are quoted (e.g. a: b -> ‘a’), and everything else uses the key reference
(e.g. 'a': b -> 'a', "#{a}": b ->
getPropName = (prop) ->
key = getPropKey prop
cached = prop instanceof Assign and prop.variable isnt key
if cached or not key.isAssignable()
key
else
new Literal "'#{key.compileWithoutComments o}'"Recursive function for searching and storing rest elements in objects.
e.g. {[properties...]} = source.
traverseRest = (properties, source) =>
restElements = []
restIndex = undefined
source = new Value source unless source.properties?
for prop, index in properties
nestedSourceDefault = nestedSource = nestedProperties = null
if prop instanceof Assignprop is k: expr, we need to check expr for nested splats
if prop.value.isObject?()prop is k = {...}
continue unless prop.context is 'object'prop is k: {...}
nestedProperties = prop.value.base.properties
else if prop.value instanceof Assign and prop.value.variable.isObject()prop is k: {...} = default
nestedProperties = prop.value.variable.base.properties
[prop.value.value, nestedSourceDefault] = prop.value.value.cache o
if nestedProperties
nestedSource = new Value source.base, source.properties.concat [new Access getPropKey prop]
nestedSource = new Value new Op '?', nestedSource, nestedSourceDefault if nestedSourceDefault
restElements.push traverseRest(nestedProperties, nestedSource)...
else if prop instanceof Splat
prop.error "multiple rest elements are disallowed in object destructuring" if restIndex?
restIndex = index
restElements.push {
name: prop.name.unwrapAll()
source
excludeProps: new Arr (getPropName p for p in properties when p isnt prop)
}
if restIndex?Remove rest element from the properties after iteration
properties.splice restIndex, 1
restElementsCache the value for reuse with rest elements.
valueRefTemp =
if @value.shouldCache()
new IdentifierLiteral o.scope.freeVariable 'ref', reserve: false
else
@value.baseFind all rest elements.
restElements = traverseRest @variable.base.properties, valueRefTemp
return no unless restElements and restElements.length > 0
[@value, valueRef] = @value.cache o
result = new Block [@]
for restElement in restElements
value = new Call new Value(new Literal utility 'objectWithoutKeys', o), [restElement.source, restElement.excludeProps]
result.push new Assign new Value(restElement.name), value, null, param: if @param then 'alwaysDeclare' else null
fragments = result.compileToFragments o
if o.level is LEVEL_TOPRemove leading tab and trailing semicolon
fragments.shift()
fragments.pop()
fragmentsBrief implementation of recursive pattern matching, when assigning array or object literals to a value. Peeks at their properties to assign inner names.
compileDestructuring: (o) ->
top = o.level is LEVEL_TOP
{value} = this
{objects} = @variable.base
olen = objects.lengthSpecial-case for {} = a and [] = a (empty patterns).
Compile to simply a.
if olen is 0
code = value.compileToFragments o
return if o.level >= LEVEL_OP then @wrapInParentheses code else code
[obj] = objectsDisallow [...] = a for some reason. (Could be equivalent to [] = a?)
if olen is 1 and obj instanceof Expansion
obj.error 'Destructuring assignment has no target'Count all Splats: [a, b, c…, d, e]
splats = (i for obj, i in objects when obj instanceof Splat)Count all Expansions: [a, b, …, c, d]
expans = (i for obj, i in objects when obj instanceof Expansion)Combine splats and expansions.
splatsAndExpans = [splats..., expans...]Show error if there is more than one Splat, or Expansion.
Examples: [a, b, c…, d, e, f…], [a, b, …, c, d, …], [a, b, …, c, d, e…]
if splatsAndExpans.length > 1Sort ‘splatsAndExpans’ so we can show error at first disallowed token.
objects[splatsAndExpans.sort()[1]].error "multiple splats/expansions are disallowed in an assignment"
isSplat = splats?.length > 0
isExpans = expans?.length > 0
isObject = @variable.isObject()
isArray = @variable.isArray()
vvar = value.compileToFragments o, LEVEL_LIST
vvarText = fragmentsToText vvar
assigns = []At this point, there are several things to destructure. So the fn() in
{a, b} = fn() must be cached, for example. Make vvar into a simple
variable if it isn’t already.
if value.unwrap() not instanceof IdentifierLiteral or @variable.assigns(vvarText)
ref = o.scope.freeVariable 'ref'
assigns.push [@makeCode(ref + ' = '), vvar...]
vvar = [@makeCode ref]
vvarText = ref
slicer = (type) -> (vvar, start, end = no) ->
vvar = new IdentifierLiteral vvar unless vvar instanceof Value
args = [vvar, new NumberLiteral(start)]
args.push new NumberLiteral end if end
slice = new Value (new IdentifierLiteral utility type, o), [new Access new PropertyName 'call']
new Value new Call slice, argsHelper which outputs [].slice code.
compSlice = slicer "slice"Helper which outputs [].splice code.
compSplice = slicer "splice"Check if objects array contains object spread ({a, r...}), e.g. [a, b, {c, r...}].
hasObjSpreads = (objs) ->
(i for obj, i in objs when obj.base instanceof Obj and obj.base.hasSplat())Check if objects array contains any instance of Assign, e.g. {a:1}.
hasObjAssigns = (objs) ->
(i for obj, i in objs when obj instanceof Assign and obj.context is 'object')Check if objects array contains any unassignable object.
objIsUnassignable = (objs) ->
return yes for obj in objs when not obj.isAssignable()
noobjects are complex when there is object spread ({a…}), object assign ({a:1}),
unassignable object, or just a single node.
complexObjects = (objs) ->
hasObjSpreads(objs).length or hasObjAssigns(objs).length or objIsUnassignable(objs) or olen is 1“Complex” objects are processed in a loop.
Examples: [a, b, {c, r…}, d], [a, …, {b, r…}, c, d]
loopObjects = (objs, vvar, vvarTxt) =>
objSpreads = hasObjSpreads objs
for obj, i in objsElision can be skipped.
continue if obj instanceof ElisionIf obj is {a: 1}
if obj instanceof Assign and obj.context is 'object'
{variable: {base: idx}, value: vvar} = obj
{variable: vvar} = vvar if vvar instanceof Assign
idx =
if vvar.this
vvar.properties[0].name
else
new PropertyName vvar.unwrap().value
acc = idx.unwrap() instanceof PropertyName
vval = new Value value, [new (if acc then Access else Index) idx]
elseobj is [a…], {a…} or a
vvar = switch
when obj instanceof Splat then new Value obj.name
when i in objSpreads then new Value obj.base
else obj
vval = switch
when obj instanceof Splat then compSlice(vvarTxt, i)
else new Value new Literal(vvarTxt), [new Index new NumberLiteral i]
message = isUnassignable vvar.unwrap().value
vvar.error message if message
assigns.push new Assign(vvar, vval, null, param: @param, subpattern: yes).compileToFragments o, LEVEL_LIST“Simple” objects can be split and compiled to arrays, [a, b, c] = arr, [a, b, c…] = arr
assignObjects = (objs, vvar, vvarTxt) =>
vvar = new Value new Arr(objs, yes)
vval = if vvarTxt instanceof Value then vvarTxt else new Value new Literal(vvarTxt)
assigns.push new Assign(vvar, vval, null, param: @param, subpattern: yes).compileToFragments o, LEVEL_LIST
processObjects = (objs, vvar, vvarTxt) ->
if complexObjects objs
loopObjects objs, vvar, vvarTxt
else
assignObjects objs, vvar, vvarTxtIn case there is Splat or Expansion in objects,
we can split array in two simple subarrays.
Splat [a, b, c…, d, e] can be split into [a, b, c…] and [d, e].
Expansion [a, b, …, c, d] can be split into [a, b] and [c, d].
Examples:
a) Splat
CS: [a, b, c…, d, e] = arr
JS: [a, b, …c] = arr, [d, e] = splice.call(c, -2)
b) Expansion
CS: [a, b, …, d, e] = arr
JS: [a, b] = arr, [d, e] = slice.call(arr, -2)
if splatsAndExpans.length
expIdx = splatsAndExpans[0]
leftObjs = objects.slice 0, expIdx + (if isSplat then 1 else 0)
rightObjs = objects.slice expIdx + 1
processObjects leftObjs, vvar, vvarText if leftObjs.length isnt 0
if rightObjs.length isnt 0Slice or splice objects.
refExp = switch
when isSplat then compSplice new Value(objects[expIdx].name), rightObjs.length * -1
when isExpans then compSlice vvarText, rightObjs.length * -1
if complexObjects rightObjs
restVar = refExp
refExp = o.scope.freeVariable 'ref'
assigns.push [@makeCode(refExp + ' = '), restVar.compileToFragments(o, LEVEL_LIST)...]
processObjects rightObjs, vvar, refExp
elseThere is no Splat or Expansion in objects.
processObjects objects, vvar, vvarText
assigns.push vvar unless top or @subpattern
fragments = @joinFragmentArrays assigns, ', '
if o.level < LEVEL_LIST then fragments else @wrapInParentheses fragmentsWhen compiling a conditional assignment, take care to ensure that the operands are only evaluated once, even though we have to reference them more than once.
compileConditional: (o) ->
[left, right] = @variable.cacheReference oDisallow conditional assignment of undefined variables.
if not left.properties.length and left.base instanceof Literal and
left.base not instanceof ThisLiteral and not o.scope.check left.base.value
@variable.error "the variable \"#{left.base.value}\" can't be assigned with #{@context} because it has not been declared before"
if "?" in @context
o.isExistentialEquals = true
new If(new Existence(left), right, type: 'if').addElse(new Assign(right, @value, '=')).compileToFragments o
else
fragments = new Op(@context[...-1], left, new Assign(right, @value, '=')).compileToFragments o
if o.level <= LEVEL_LIST then fragments else @wrapInParentheses fragmentsConvert special math assignment operators like a **= b to the equivalent
extended form a = a ** b and then compiles that.
compileSpecialMath: (o) ->
[left, right] = @variable.cacheReference o
new Assign(left, new Op(@context[...-1], right, @value)).compileToFragments oCompile the assignment from an array splice literal, using JavaScript’s
Array#splice method.
compileSplice: (o) ->
{range: {from, to, exclusive}} = @variable.properties.pop()
unwrappedVar = @variable.unwrapAll()
if unwrappedVar.comments
moveComments unwrappedVar, @
delete @variable.comments
name = @variable.compile o
if from
[fromDecl, fromRef] = @cacheToCodeFragments from.cache o, LEVEL_OP
else
fromDecl = fromRef = '0'
if to
if from?.isNumber() and to.isNumber()
to = to.compile(o) - fromRef
to += 1 unless exclusive
else
to = to.compile(o, LEVEL_ACCESS) + ' - ' + fromRef
to += ' + 1' unless exclusive
else
to = "9e9"
[valDef, valRef] = @value.cache o, LEVEL_LIST
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) ->
@variable.unwrapAll().eachName iterator
exports.FuncGlyph = class FuncGlyph extends Base
constructor: (@glyph) ->
super()A function definition. This is the only node that creates a new Scope. When for the purposes of walking the contents of a function body, the Code has no children – they’re within the inner scope.
exports.Code = class Code extends Base
constructor: (params, body, @funcGlyph, @paramStart) ->
super()
@params = params or []
@body = body or new Block
@bound = @funcGlyph?.glyph is '=>'
@isGenerator = no
@isAsync = no
@isMethod = no
@body.traverseChildren no, (node) =>
if (node instanceof Op and node.isYield()) or node instanceof YieldReturn
@isGenerator = yes
if (node instanceof Op and node.isAwait()) or node instanceof AwaitReturn
@isAsync = yes
if @isGenerator and @isAsync
node.error "function can't contain both yield and await"
children: ['params', 'body']
isStatement: -> @isMethod
jumps: NO
makeScope: (parentScope) -> new Scope parentScope, @body, thisCompilation creates a new scope unless explicitly asked to share with the outer scope. Handles splat parameters in the parameter list by setting such parameters to be the final parameter in the function definition, as required per the ES2015 spec. If the CoffeeScript function definition had parameters after the splat, they are declared via expressions in the function body.
compileNode: (o) ->
if @ctor
@name.error 'Class constructor may not be async' if @isAsync
@name.error 'Class constructor may not be a generator' if @isGenerator
if @bound
@context = o.scope.method.context if o.scope.method?.bound
@context = 'this' unless @context
o.scope = del(o, 'classScope') or @makeScope o.scope
o.scope.shared = del(o, 'sharedScope')
o.indent += TAB
delete o.bare
delete o.isExistentialEquals
params = []
exprs = []
thisAssignments = @thisAssignments?.slice() ? []
paramsAfterSplat = []
haveSplatParam = no
haveBodyParam = noCheck for duplicate parameters and separate this assignments.
paramNames = []
@eachParamName (name, node, param, obj) ->
node.error "multiple parameters named '#{name}'" if name in paramNames
paramNames.push name
if node.this
name = node.properties[0].name.value
name = "_#{name}" if name in JS_FORBIDDEN
target = new IdentifierLiteral o.scope.freeVariable name, reserve: noParam is object destructuring with a default value: ({@prop = 1}) ->
In a case when the variable name is already reserved, we have to assign
a new variable name to the destructured variable: ({prop:prop1 = 1}) ->
replacement =
if param.name instanceof Obj and obj instanceof Assign and
obj.operatorToken.value is '='
new Assign (new IdentifierLiteral name), target, 'object' #, operatorToken: new Literal ':'
else
target
param.renameParam node, replacement
thisAssignments.push new Assign node, targetParse the parameters, adding them to the list of parameters to put in the
function definition; and dealing with splats or expansions, including
adding expressions to the function body to declare all parameter
variables that would have been after the splat/expansion parameter.
If we encounter a parameter that needs to be declared in the function
body for any reason, for example it’s destructured with this, also
declare and assign all subsequent parameters in the function body so that
any non-idempotent parameters are evaluated in the correct order.
for param, i in @paramsWas ... used with this parameter? (Only one such parameter is allowed
per function.) Splat/expansion parameters cannot have default values,
so we need not worry about that.
if param.splat or param instanceof Expansion
if haveSplatParam
param.error 'only one splat or expansion parameter is allowed per function definition'
else if param instanceof Expansion and @params.length is 1
param.error 'an expansion parameter cannot be the only parameter in a function definition'
haveSplatParam = yes
if param.splat
if param.name instanceof ArrSplat arrays are treated oddly by ES; deal with them the legacy way in the function body. TODO: Should this be handled in the function parameter list, and if so, how?
splatParamName = o.scope.freeVariable 'arg'
params.push ref = new Value new IdentifierLiteral splatParamName
exprs.push new Assign new Value(param.name), ref
else
params.push ref = param.asReference o
splatParamName = fragmentsToText ref.compileNodeWithoutComments o
if param.shouldCache()
exprs.push new Assign new Value(param.name), ref
else # `param` is an Expansion
splatParamName = o.scope.freeVariable 'args'
params.push new Value new IdentifierLiteral splatParamName
o.scope.parameter splatParamNameParse all other parameters; if a splat paramater has not yet been encountered, add these other parameters to the list to be output in the function definition.
else
if param.shouldCache() or haveBodyParam
param.assignedInBody = yes
haveBodyParam = yesThis parameter cannot be declared or assigned in the parameter
list. So put a reference in the parameter list and add a statement
to the function body assigning it, e.g.
(arg) => { var a = arg.a; }, with a default value if it has one.
if param.value?
condition = new Op '===', param, new UndefinedLiteral
ifTrue = new Assign new Value(param.name), param.value
exprs.push new If condition, ifTrue
else
exprs.push new Assign new Value(param.name), param.asReference(o), null, param: 'alwaysDeclare'If this parameter comes before the splat or expansion, it will go in the function definition parameter list.
unless haveSplatParamIf this parameter has a default value, and it hasn’t already been
set by the shouldCache() block above, define it as a statement in
the function body. This parameter comes after the splat parameter,
so we can’t define its default value in the parameter list.
if param.shouldCache()
ref = param.asReference o
else
if param.value? and not param.assignedInBody
ref = new Assign new Value(param.name), param.value, null, param: yes
else
ref = paramAdd this parameter’s reference(s) to the function scope.
if param.name instanceof Arr or param.name instanceof ObjThis parameter is destructured.
param.name.lhs = yesCompile foo({a, b...}) -> to foo(arg) -> {a, b...} = arg.
Can be removed once ES proposal hits Stage 4.
if param.name instanceof Obj and param.name.hasSplat()
splatParamName = o.scope.freeVariable 'arg'
o.scope.parameter splatParamName
ref = new Value new IdentifierLiteral splatParamName
exprs.push new Assign new Value(param.name), ref, null, param: 'alwaysDeclare'Compile foo({a, b...} = {}) -> to foo(arg = {}) -> {a, b...} = arg.
if param.value? and not param.assignedInBody
ref = new Assign ref, param.value, null, param: yes
else unless param.shouldCache()
param.name.eachName (prop) ->
o.scope.parameter prop.value
elseThis compilation of the parameter is only to get its name to add to the scope name tracking; since the compilation output here isn’t kept for eventual output, don’t include comments in this compilation, so that they get output the “real” time this param is compiled.
paramToAddToScope = if param.value? then param else ref
o.scope.parameter fragmentsToText paramToAddToScope.compileToFragmentsWithoutComments o
params.push ref
else
paramsAfterSplat.push paramIf this parameter had a default value, since it’s no longer in the function parameter list we need to assign its default value (if necessary) as an expression in the body.
if param.value? and not param.shouldCache()
condition = new Op '===', param, new UndefinedLiteral
ifTrue = new Assign new Value(param.name), param.value
exprs.push new If condition, ifTrueAdd this parameter to the scope, since it wouldn’t have been added yet since it was skipped earlier.
o.scope.add param.name.value, 'var', yes if param.name?.value?If there were parameters after the splat or expansion parameter, those parameters need to be assigned in the body of the function.
if paramsAfterSplat.length isnt 0Create a destructured assignment, e.g. [a, b, c] = [args..., b, c]
exprs.unshift new Assign new Value(
new Arr [new Splat(new IdentifierLiteral(splatParamName)), (param.asReference o for param in paramsAfterSplat)...]
), new Value new IdentifierLiteral splatParamNameAdd new expressions to the function body
wasEmpty = @body.isEmpty()
@body.expressions.unshift thisAssignments... unless @expandCtorSuper thisAssignments
@body.expressions.unshift exprs...
if @isMethod and @bound and not @isStatic and @classVariable
boundMethodCheck = new Value new Literal utility 'boundMethodCheck', o
@body.expressions.unshift new Call(boundMethodCheck, [new Value(new ThisLiteral), @classVariable])
@body.makeReturn() unless wasEmpty or @noReturnJavaScript doesn’t allow bound (=>) functions to also be generators.
This is usually caught via Op::compileContinuation, but double-check:
if @bound and @isGenerator
yieldNode = @body.contains (node) -> node instanceof Op and node.operator is 'yield'
(yieldNode or @).error 'yield cannot occur inside bound (fat arrow) functions'Assemble the output
modifiers = []
modifiers.push 'static' if @isMethod and @isStatic
modifiers.push 'async' if @isAsync
unless @isMethod or @bound
modifiers.push "function#{if @isGenerator then '*' else ''}"
else if @isGenerator
modifiers.push '*'
signature = [@makeCode '(']Block comments between a function name and ( get output between
function and (.
if @paramStart?.comments?
@compileCommentFragments o, @paramStart, signature
for param, i in params
signature.push @makeCode ', ' if i isnt 0
signature.push @makeCode '...' if haveSplatParam and i is params.length - 1Compile this parameter, but if any generated variables get created
(e.g. ref), shift those into the parent scope since we can’t put a
var line inside a function parameter list.
scopeVariablesCount = o.scope.variables.length
signature.push param.compileToFragments(o)...
if scopeVariablesCount isnt o.scope.variables.length
generatedVariables = o.scope.variables.splice scopeVariablesCount
o.scope.parent.variables.push generatedVariables...
signature.push @makeCode ')'Block comments between ) and ->/=> get output between ) and {.
if @funcGlyph?.comments?
comment.unshift = no for comment in @funcGlyph.comments
@compileCommentFragments o, @funcGlyph, signature
body = @body.compileWithDeclarations o unless @body.isEmpty()We need to compile the body before method names to ensure super
references are handled.
if @isMethod
[methodScope, o.scope] = [o.scope, o.scope.parent]
name = @name.compileToFragments o
name.shift() if name[0].code is '.'
o.scope = methodScope
answer = @joinFragmentArrays (@makeCode m for m in modifiers), ' '
answer.push @makeCode ' ' if modifiers.length and name
answer.push name... if name
answer.push signature...
answer.push @makeCode ' =>' if @bound and not @isMethod
answer.push @makeCode ' {'
answer.push @makeCode('\n'), body..., @makeCode("\n#{@tab}") if body?.length
answer.push @makeCode '}'
return indentInitial answer, @ if @isMethod
if @front or (o.level >= LEVEL_ACCESS) then @wrapInParentheses answer else answer
eachParamName: (iterator) ->
param.eachName iterator for param in @paramsShort-circuit traverseChildren method to prevent it from crossing scope
boundaries unless crossScope is true.
traverseChildren: (crossScope, func) ->
super(crossScope, func) if crossScopeShort-circuit replaceInContext method to prevent it from crossing context boundaries. Bound
functions have the same context.
replaceInContext: (child, replacement) ->
if @bound
super child, replacement
else
false
expandCtorSuper: (thisAssignments) ->
return false unless @ctor
@eachSuperCall Block.wrap(@params), (superCall) ->
superCall.error "'super' is not allowed in constructor parameter defaults"
seenSuper = @eachSuperCall @body, (superCall) =>
superCall.error "'super' is only allowed in derived class constructors" if @ctor is 'base'
superCall.expressions = thisAssignments
haveThisParam = thisAssignments.length and thisAssignments.length isnt @thisAssignments?.length
if @ctor is 'derived' and not seenSuper and haveThisParam
param = thisAssignments[0].variable
param.error "Can't use @params in derived class constructors without calling super"
seenSuperFind all super calls in the given context node;
returns true if iterator is called.
eachSuperCall: (context, iterator) ->
seenSuper = no
context.traverseChildren yes, (child) =>
if child instanceof SuperCallsuper in a constructor (the only super without an accessor)
cannot be given an argument with a reference to this, as that would
be referencing this before calling super.
unless child.variable.accessor
childArgs = child.args.filter (arg) ->
arg not instanceof Class and (arg not instanceof Code or arg.bound)
Block.wrap(childArgs).traverseChildren yes, (node) =>
node.error "Can't call super with @params in derived class constructors" if node.this
seenSuper = yes
iterator child
else if child instanceof ThisLiteral and @ctor is 'derived' and not seenSuper
child.error "Can't reference 'this' before calling super in derived class constructors"super has the same target in bound (arrow) functions, so check them too
child not instanceof SuperCall and (child not instanceof Code or child.bound)
seenSuperA parameter in a function definition. Beyond a typical JavaScript parameter, these parameters can also attach themselves to the context of the function, as well as be a splat, gathering up a group of parameters into an array.
exports.Param = class Param extends Base
constructor: (@name, @value, @splat) ->
super()
message = isUnassignable @name.unwrapAll().value
@name.error message if message
if @name instanceof Obj and @name.generated
token = @name.objects[0].operatorToken
token.error "unexpected #{token.value}"
children: ['name', 'value']
compileToFragments: (o) ->
@name.compileToFragments o, LEVEL_LIST
compileToFragmentsWithoutComments: (o) ->
@name.compileToFragmentsWithoutComments o, LEVEL_LIST
asReference: (o) ->
return @reference if @reference
node = @name
if node.this
name = node.properties[0].name.value
name = "_#{name}" if name in JS_FORBIDDEN
node = new IdentifierLiteral o.scope.freeVariable name
else if node.shouldCache()
node = new IdentifierLiteral o.scope.freeVariable 'arg'
node = new Value node
node.updateLocationDataIfMissing @locationData
@reference = node
shouldCache: ->
@name.shouldCache()Iterates the name or names of a Param.
In a sense, a destructured parameter represents multiple JS parameters. This
method allows to iterate them all.
The iterator function will be called as iterator(name, node) where
name is the name of the parameter and node is the AST node corresponding
to that name.
eachName: (iterator, name = @name) ->
atParam = (obj, originalObj = null) => iterator "@#{obj.properties[0].name.value}", obj, @, originalObjfoo return iterator name.value, name, @ if name instanceof Literal@foo return atParam name if name instanceof Value
for obj in name.objects ? []Save original obj.
nObj = obj if obj instanceof Assign and not obj.context?
obj = obj.variable{foo:bar} if obj instanceof Assign… possibly with a default value
if obj.value instanceof Assign
obj = obj.value.variable
else
obj = obj.value
@eachName iterator, obj.unwrap()[xs...] else if obj instanceof Splat
node = obj.name.unwrap()
iterator node.value, node, @
else if obj instanceof Value[{a}] if obj.isArray() or obj.isObject()
@eachName iterator, obj.base{@foo} else if obj.this
atParam obj, nObj else iterator obj.base.value, obj.base, @
else if obj instanceof Elision
obj
else if obj not instanceof Expansion
obj.error "illegal parameter #{obj.compile()}"
returnRename a param by replacing the given AST node for a name with a new node. This needs to ensure that the the source for object destructuring does not change.
renameParam: (node, newNode) ->
isNode = (candidate) -> candidate is node
replacement = (node, parent) =>
if parent instanceof Obj
key = node
key = node.properties[0].name if node.thisNo need to assign a new variable for the destructured variable if the variable isn’t reserved.
Examples:
({@foo}) -> should compile to ({foo}) { this.foo = foo}
foo = 1; ({@foo}) -> should compile to foo = 1; ({foo:foo1}) { this.foo = foo1 }
if node.this and key.value is newNode.value
new Value newNode
else
new Assign new Value(key), newNode, 'object'
else
newNode
@replaceInContext isNode, replacementA splat, either as a parameter to a function, an argument to a call, or as part of a destructuring assignment.
exports.Splat = class Splat extends Base
constructor: (name) ->
super()
@name = if name.compile then name else new Literal name
children: ['name']
isAssignable: ->
@name.isAssignable() and (not @name.isAtomic or @name.isAtomic())
assigns: (name) ->
@name.assigns name
compileNode: (o) ->
[@makeCode('...'), @name.compileToFragments(o, LEVEL_OP)...]
unwrap: -> @nameUsed to skip values inside an array destructuring (pattern matching) or parameter list.
exports.Expansion = class Expansion extends Base
shouldCache: NO
compileNode: (o) ->
@error 'Expansion must be used inside a destructuring assignment or parameter list'
asReference: (o) ->
this
eachName: (iterator) ->Array elision element (for example, [,a, , , b, , c, ,]).
exports.Elision = class Elision extends Base
isAssignable: YES
shouldCache: NO
compileToFragments: (o, level) ->
fragment = super o, level
fragment.isElision = yes
fragment
compileNode: (o) ->
[@makeCode ', ']
asReference: (o) ->
this
eachName: (iterator) ->A while loop, the only sort of low-level loop exposed by CoffeeScript. From it, all other loops can be manufactured. Useful in cases where you need more flexibility or more speed than a comprehension can provide.
exports.While = class While extends Base
constructor: (condition, options) ->
super()
@condition = if options?.invert then condition.invert() else condition
@guard = options?.guard
children: ['condition', 'guard', 'body']
isStatement: YES
makeReturn: (res) ->
if res
super res
else
@returns = not @jumps()
this
addBody: (@body) ->
this
jumps: ->
{expressions} = @body
return no unless expressions.length
for node in expressions
return jumpNode if jumpNode = node.jumps loop: yes
noThe main difference from a JavaScript while is that the CoffeeScript while can be used as a part of a larger expression – while loops may return an array containing the computed result of each iteration.
compileNode: (o) ->
o.indent += TAB
set = ''
{body} = this
if body.isEmpty()
body = @makeCode ''
else
if @returns
body.makeReturn rvar = o.scope.freeVariable 'results'
set = "#{@tab}#{rvar} = [];\n"
if @guard
if body.expressions.length > 1
body.expressions.unshift new If (new Parens @guard).invert(), new StatementLiteral "continue"
else
body = Block.wrap [new If @guard, body] if @guard
body = [].concat @makeCode("\n"), (body.compileToFragments o, LEVEL_TOP), @makeCode("\n#{@tab}")
answer = [].concat @makeCode(set + @tab + "while ("), @condition.compileToFragments(o, LEVEL_PAREN),
@makeCode(") {"), body, @makeCode("}")
if @returns
answer.push @makeCode "\n#{@tab}return #{rvar};"
answerSimple Arithmetic and logical operations. Performs some conversion from CoffeeScript operations into their JavaScript equivalents.
exports.Op = class Op extends Base
constructor: (op, first, second, flip) ->
super()
return new In first, second if op is 'in'
if op is 'do'
return Op::generateDo first
if op is 'new'
if (firstCall = first.unwrap()) instanceof Call and not firstCall.do and not firstCall.isNew
return firstCall.newInstance()
first = new Parens first if first instanceof Code and first.bound or first.do
@operator = CONVERSIONS[op] or op
@first = first
@second = second
@flip = !!flip
return thisThe map of conversions from CoffeeScript to JavaScript symbols.
CONVERSIONS =
'==': '==='
'!=': '!=='
'of': 'in'
'yieldfrom': 'yield*'The map of invertible operators.
INVERSIONS =
'!==': '==='
'===': '!=='
children: ['first', 'second']
isNumber: ->
@isUnary() and @operator in ['+', '-'] and
@first instanceof Value and @first.isNumber()
isAwait: ->
@operator is 'await'
isYield: ->
@operator in ['yield', 'yield*']
isUnary: ->
not @second
shouldCache: ->
not @isNumber()Am I capable of Python-style comparison chaining?
isChainable: ->
@operator in ['<', '>', '>=', '<=', '===', '!==']
invert: ->
if @isChainable() and @first.isChainable()
allInvertable = yes
curr = this
while curr and curr.operator
allInvertable and= (curr.operator of INVERSIONS)
curr = curr.first
return new Parens(this).invert() unless allInvertable
curr = this
while curr and curr.operator
curr.invert = !curr.invert
curr.operator = INVERSIONS[curr.operator]
curr = curr.first
this
else if op = INVERSIONS[@operator]
@operator = op
if @first.unwrap() instanceof Op
@first.invert()
this
else if @second
new Parens(this).invert()
else if @operator is '!' and (fst = @first.unwrap()) instanceof Op and
fst.operator in ['!', 'in', 'instanceof']
fst
else
new Op '!', this
unfoldSoak: (o) ->
@operator in ['++', '--', 'delete'] and unfoldSoak o, this, 'first'
generateDo: (exp) ->
passedParams = []
func = if exp instanceof Assign and (ref = exp.value.unwrap()) instanceof Code
ref
else
exp
for param in func.params or []
if param.value
passedParams.push param.value
delete param.value
else
passedParams.push param
call = new Call exp, passedParams
call.do = yes
call
compileNode: (o) ->
isChain = @isChainable() and @first.isChainable()In chains, there’s no need to wrap bare obj literals in parens, as the chained expression is wrapped.
@first.front = @front unless isChain
if @operator is 'delete' and o.scope.check(@first.unwrapAll().value)
@error 'delete operand may not be argument or var'
if @operator in ['--', '++']
message = isUnassignable @first.unwrapAll().value
@first.error message if message
return @compileContinuation o if @isYield() or @isAwait()
return @compileUnary o if @isUnary()
return @compileChain o if isChain
switch @operator
when '?' then @compileExistence o, @second.isDefaultValue
when '**' then @compilePower o
when '//' then @compileFloorDivision o
when '%%' then @compileModulo o
else
lhs = @first.compileToFragments o, LEVEL_OP
rhs = @second.compileToFragments o, LEVEL_OP
answer = [].concat lhs, @makeCode(" #{@operator} "), rhs
if o.level <= LEVEL_OP then answer else @wrapInParentheses answerMimic Python’s chained comparisons when multiple comparison operators are used sequentially. For example:
bin/coffee -e 'console.log 50 < 65 > 10'
true
compileChain: (o) ->
[@first.second, shared] = @first.second.cache o
fst = @first.compileToFragments o, LEVEL_OP
fragments = fst.concat @makeCode(" #{if @invert then '&&' else '||'} "),
(shared.compileToFragments o), @makeCode(" #{@operator} "), (@second.compileToFragments o, LEVEL_OP)
@wrapInParentheses fragmentsKeep reference to the left expression, unless this an existential assignment
compileExistence: (o, checkOnlyUndefined) ->
if @first.shouldCache()
ref = new IdentifierLiteral o.scope.freeVariable 'ref'
fst = new Parens new Assign ref, @first
else
fst = @first
ref = fst
new If(new Existence(fst, checkOnlyUndefined), ref, type: 'if').addElse(@second).compileToFragments oCompile a unary Op.
compileUnary: (o) ->
parts = []
op = @operator
parts.push [@makeCode op]
if op is '!' and @first instanceof Existence
@first.negated = not @first.negated
return @first.compileToFragments o
if o.level >= LEVEL_ACCESS
return (new Parens this).compileToFragments o
plusMinus = op in ['+', '-']
parts.push [@makeCode(' ')] if op in ['new', 'typeof', 'delete'] or
plusMinus and @first instanceof Op and @first.operator is op
if (plusMinus and @first instanceof Op) or (op is 'new' and @first.isStatement o)
@first = new Parens @first
parts.push @first.compileToFragments o, LEVEL_OP
parts.reverse() if @flip
@joinFragmentArrays parts, ''
compileContinuation: (o) ->
parts = []
op = @operator
unless o.scope.parent?
@error "#{@operator} can only occur inside functions"
if o.scope.method?.bound and o.scope.method.isGenerator
@error 'yield cannot occur inside bound (fat arrow) functions'
if 'expression' in Object.keys(@first) and not (@first instanceof Throw)
parts.push @first.expression.compileToFragments o, LEVEL_OP if @first.expression?
else
parts.push [@makeCode "("] if o.level >= LEVEL_PAREN
parts.push [@makeCode op]
parts.push [@makeCode " "] if @first.base?.value isnt ''
parts.push @first.compileToFragments o, LEVEL_OP
parts.push [@makeCode ")"] if o.level >= LEVEL_PAREN
@joinFragmentArrays parts, ''
compilePower: (o) ->Make a Math.pow call
pow = new Value new IdentifierLiteral('Math'), [new Access new PropertyName 'pow']
new Call(pow, [@first, @second]).compileToFragments o
compileFloorDivision: (o) ->
floor = new Value new IdentifierLiteral('Math'), [new Access new PropertyName 'floor']
second = if @second.shouldCache() then new Parens @second else @second
div = new Op '/', @first, second
new Call(floor, [div]).compileToFragments o
compileModulo: (o) ->
mod = new Value new Literal utility 'modulo', o
new Call(mod, [@first, @second]).compileToFragments o
toString: (idt) ->
super idt, @constructor.name + ' ' + @operatorexports.In = class In extends Base
constructor: (@object, @array) ->
super()
children: ['object', 'array']
invert: NEGATE
compileNode: (o) ->
if @array instanceof Value and @array.isArray() and @array.base.objects.length
for obj in @array.base.objects when obj instanceof Splat
hasSplat = yes
breakcompileOrTest only if we have an array literal with no splats
return @compileOrTest o unless hasSplat
@compileLoopTest o
compileOrTest: (o) ->
[sub, ref] = @object.cache o, LEVEL_OP
[cmp, cnj] = if @negated then [' !== ', ' && '] else [' === ', ' || ']
tests = []
for item, i in @array.base.objects
if i then tests.push @makeCode cnj
tests = tests.concat (if i then ref else sub), @makeCode(cmp), item.compileToFragments(o, LEVEL_ACCESS)
if o.level < LEVEL_OP then tests else @wrapInParentheses tests
compileLoopTest: (o) ->
[sub, ref] = @object.cache o, LEVEL_LIST
fragments = [].concat @makeCode(utility('indexOf', o) + ".call("), @array.compileToFragments(o, LEVEL_LIST),
@makeCode(", "), ref, @makeCode(") " + if @negated then '< 0' else '>= 0')
return fragments if fragmentsToText(sub) is fragmentsToText(ref)
fragments = sub.concat @makeCode(', '), fragments
if o.level < LEVEL_LIST then fragments else @wrapInParentheses fragments
toString: (idt) ->
super idt, @constructor.name + if @negated then '!' else ''A classic try/catch/finally block.
exports.Try = class Try extends Base
constructor: (@attempt, @errorVariable, @recovery, @ensure) ->
super()
children: ['attempt', 'recovery', 'ensure']
isStatement: YES
jumps: (o) -> @attempt.jumps(o) or @recovery?.jumps(o)
makeReturn: (res) ->
@attempt = @attempt .makeReturn res if @attempt
@recovery = @recovery.makeReturn res if @recovery
thisCompilation is more or less as you would expect – the finally clause is optional, the catch is not.
compileNode: (o) ->
o.indent += TAB
tryPart = @attempt.compileToFragments o, LEVEL_TOP
catchPart = if @recovery
generatedErrorVariableName = o.scope.freeVariable 'error', reserve: no
placeholder = new IdentifierLiteral generatedErrorVariableName
if @errorVariable
message = isUnassignable @errorVariable.unwrapAll().value
@errorVariable.error message if message
@recovery.unshift new Assign @errorVariable, placeholder
[].concat @makeCode(" catch ("), placeholder.compileToFragments(o), @makeCode(") {\n"),
@recovery.compileToFragments(o, LEVEL_TOP), @makeCode("\n#{@tab}}")
else unless @ensure or @recovery
generatedErrorVariableName = o.scope.freeVariable 'error', reserve: no
[@makeCode(" catch (#{generatedErrorVariableName}) {}")]
else
[]
ensurePart = if @ensure then ([].concat @makeCode(" finally {\n"), @ensure.compileToFragments(o, LEVEL_TOP),
@makeCode("\n#{@tab}}")) else []
[].concat @makeCode("#{@tab}try {\n"),
tryPart,
@makeCode("\n#{@tab}}"), catchPart, ensurePartSimple node to throw an exception.
exports.Throw = class Throw extends Base
constructor: (@expression) ->
super()
children: ['expression']
isStatement: YES
jumps: NOA Throw is already a return, of sorts…
makeReturn: THIS
compileNode: (o) ->
fragments = @expression.compileToFragments o, LEVEL_LIST
unshiftAfterComments fragments, @makeCode 'throw '
fragments.unshift @makeCode @tab
fragments.push @makeCode ';'
fragmentsChecks a variable for existence – not null and not undefined. This is
similar to .nil? in Ruby, and avoids having to consult a JavaScript truth
table. Optionally only check if a variable is not undefined.
exports.Existence = class Existence extends Base
constructor: (@expression, onlyNotUndefined = no) ->
super()
@comparisonTarget = if onlyNotUndefined then 'undefined' else 'null'
salvagedComments = []
@expression.traverseChildren yes, (child) ->
if child.comments
for comment in child.comments
salvagedComments.push comment unless comment in salvagedComments
delete child.comments
attachCommentsToNode salvagedComments, @
moveComments @expression, @
children: ['expression']
invert: NEGATE
compileNode: (o) ->
@expression.front = @front
code = @expression.compile o, LEVEL_OP
if @expression.unwrap() instanceof IdentifierLiteral and not o.scope.check code
[cmp, cnj] = if @negated then ['===', '||'] else ['!==', '&&']
code = "typeof #{code} #{cmp} \"undefined\"" + if @comparisonTarget isnt 'undefined' then " #{cnj} #{code} #{cmp} #{@comparisonTarget}" else ''
elseWe explicity want to use loose equality (==) when comparing against null,
so that an existence check roughly corresponds to a check for truthiness.
Do not change this to === for null, as this will break mountains of
existing code. When comparing only against undefined, however, we want to
use === because this use case is for parity with ES2015+ default values,
which only get assigned when the variable is undefined (but not null).
cmp = if @comparisonTarget is 'null'
if @negated then '==' else '!='
else # `undefined`
if @negated then '===' else '!=='
code = "#{code} #{cmp} #{@comparisonTarget}"
[@makeCode(if o.level <= LEVEL_COND then code else "(#{code})")]An extra set of parentheses, specified explicitly in the source. At one time we tried to clean up the results by detecting and removing redundant parentheses, but no longer – you can put in as many as you please.
Parentheses are a good way to force any statement to become an expression.
exports.Parens = class Parens extends Base
constructor: (@body) ->
super()
children: ['body']
unwrap: -> @body
shouldCache: -> @body.shouldCache()
compileNode: (o) ->
expr = @body.unwrap()If these parentheses are wrapping an IdentifierLiteral followed by a
block comment, output the parentheses (or put another way, don’t optimize
away these redundant parentheses). This is because Flow requires
parentheses in certain circumstances to distinguish identifiers followed
by comment-based type annotations from JavaScript labels.
shouldWrapComment = expr.comments?.some(
(comment) -> comment.here and not comment.unshift and not comment.newLine)
if expr instanceof Value and expr.isAtomic() and not @csxAttribute and not shouldWrapComment
expr.front = @front
return expr.compileToFragments o
fragments = expr.compileToFragments o, LEVEL_PAREN
bare = o.level < LEVEL_OP and not shouldWrapComment and (
expr instanceof Op or expr.unwrap() instanceof Call or
(expr instanceof For and expr.returns)
) and (o.level < LEVEL_COND or fragments.length <= 3)
return @wrapInBraces fragments if @csxAttribute
if bare then fragments else @wrapInParentheses fragments
exports.StringWithInterpolations = class StringWithInterpolations extends Base
constructor: (@body) ->
super()
children: ['body']unwrap returns this to stop ancestor nodes reaching in to grab @body,
and using @body.compileNode. StringWithInterpolations.compileNode is
the custom logic to output interpolated strings as code.
unwrap: -> this
shouldCache: -> @body.shouldCache()
compileNode: (o) ->
if @csxAttribute
wrapped = new Parens new StringWithInterpolations @body
wrapped.csxAttribute = yes
return wrapped.compileNode oAssumes that expr is Value » StringLiteral or Op
expr = @body.unwrap()
elements = []
salvagedComments = []
expr.traverseChildren no, (node) ->
if node instanceof StringLiteral
if node.comments
salvagedComments.push node.comments...
delete node.comments
elements.push node
return yes
else if node instanceof Parens
if salvagedComments.length isnt 0
for comment in salvagedComments
comment.unshift = yes
comment.newLine = yes
attachCommentsToNode salvagedComments, node
elements.push node
return no
else if node.commentsThis node is getting discarded, but salvage its comments.
if elements.length isnt 0 and elements[elements.length - 1] not instanceof StringLiteral
for comment in node.comments
comment.unshift = no
comment.newLine = yes
attachCommentsToNode node.comments, elements[elements.length - 1]
else
salvagedComments.push node.comments...
delete node.comments
return yes
fragments = []
fragments.push @makeCode '`' unless @csx
for element in elements
if element instanceof StringLiteral
element.value = element.unquote yes, @csx
unless @csxBackticks and ${ inside template literals must be escaped.
element.value = element.value.replace /(\\*)(`|\$\{)/g, (match, backslashes, toBeEscaped) ->
if backslashes.length % 2 is 0
"#{backslashes}\\#{toBeEscaped}"
else
match
fragments.push element.compileToFragments(o)...
else
fragments.push @makeCode '$' unless @csx
code = element.compileToFragments(o, LEVEL_PAREN)
if not @isNestedTag(element) or code.some((fragment) -> fragment.comments?)
code = @wrapInBraces codeFlag the { and } fragments as having been generated by this
StringWithInterpolations node, so that compileComments knows
to treat them as bounds. Don’t trust fragment.type, which can
report minified variable names when this compiler is minified.
code[0].isStringWithInterpolations = yes
code[code.length - 1].isStringWithInterpolations = yes
fragments.push code...
fragments.push @makeCode '`' unless @csx
fragments
isNestedTag: (element) ->
exprs = element.body?.expressions
call = exprs?[0].unwrap()
@csx and exprs and exprs.length is 1 and call instanceof Call and call.csxCoffeeScript’s replacement for the for loop is our array and object comprehensions, that compile into for loops here. They also act as an expression, able to return the result of each filtered iteration.
Unlike Python array comprehensions, they can be multi-line, and you can pass the current index of the loop as a second parameter. Unlike Ruby blocks, you can map and filter in a single pass.
exports.For = class For extends While
constructor: (body, source) ->
super()
{@source, @guard, @step, @name, @index} = source
@body = Block.wrap [body]
@own = source.own?
@object = source.object?
@from = source.from?
@index.error 'cannot use index with for-from' if @from and @index
source.ownTag.error "cannot use own with for-#{if @from then 'from' else 'in'}" if @own and not @object
[@name, @index] = [@index, @name] if @object
@index.error 'index cannot be a pattern matching expression' if @index?.isArray?() or @index?.isObject?()
@range = @source instanceof Value and @source.base instanceof Range and not @source.properties.length and not @from
@pattern = @name instanceof Value
@index.error 'indexes do not apply to range loops' if @range and @index
@name.error 'cannot pattern match over range loops' if @range and @pattern
@returns = noMove up any comments in the “for line”, i.e. the line of code with for,
from any child nodes of that line up to the for node itself so that these
comments get output, and get output above the for loop.
for attribute in ['source', 'guard', 'step', 'name', 'index'] when @[attribute]
@[attribute].traverseChildren yes, (node) =>
if node.commentsThese comments are buried pretty deeply, so if they happen to be
trailing comments the line they trail will be unrecognizable when
we’re done compiling this for loop; so just shift them up to
output above the for line.
comment.newLine = comment.unshift = yes for comment in node.comments
moveComments node, @[attribute]
moveComments @[attribute], @
children: ['body', 'source', 'guard', 'step']Welcome to the hairiest method in all of CoffeeScript. Handles the inner loop, filtering, stepping, and result saving for array, object, and range comprehensions. Some of the generated code can be shared in common, and some cannot.
compileNode: (o) ->
body = Block.wrap [@body]
[..., last] = body.expressions
@returns = no if last?.jumps() instanceof Return
source = if @range then @source.base else @source
scope = o.scope
name = @name and (@name.compile o, LEVEL_LIST) if not @pattern
index = @index and (@index.compile o, LEVEL_LIST)
scope.find(name) if name and not @pattern
scope.find(index) if index and @index not instanceof Value
rvar = scope.freeVariable 'results' if @returns
if @from
ivar = scope.freeVariable 'x', single: true if @pattern
else
ivar = (@object and index) or scope.freeVariable 'i', single: true
kvar = ((@range or @from) and name) or index or ivar
kvarAssign = if kvar isnt ivar then "#{kvar} = " else ""
if @step and not @range
[step, stepVar] = @cacheToCodeFragments @step.cache o, LEVEL_LIST, shouldCacheOrIsAssignable
stepNum = Number stepVar if @step.isNumber()
name = ivar if @pattern
varPart = ''
guardPart = ''
defPart = ''
idt1 = @tab + TAB
if @range
forPartFragments = source.compileToFragments merge o,
{index: ivar, name, @step, shouldCache: shouldCacheOrIsAssignable}
else
svar = @source.compile o, LEVEL_LIST
if (name or @own) and @source.unwrap() not instanceof IdentifierLiteral
defPart += "#{@tab}#{ref = scope.freeVariable 'ref'} = #{svar};\n"
svar = ref
if name and not @pattern and not @from
namePart = "#{name} = #{svar}[#{kvar}]"
if not @object and not @from
defPart += "#{@tab}#{step};\n" if step isnt stepVar
down = stepNum < 0
lvar = scope.freeVariable 'len' unless @step and stepNum? and down
declare = "#{kvarAssign}#{ivar} = 0, #{lvar} = #{svar}.length"
declareDown = "#{kvarAssign}#{ivar} = #{svar}.length - 1"
compare = "#{ivar} < #{lvar}"
compareDown = "#{ivar} >= 0"
if @step
if stepNum?
if down
compare = compareDown
declare = declareDown
else
compare = "#{stepVar} > 0 ? #{compare} : #{compareDown}"
declare = "(#{stepVar} > 0 ? (#{declare}) : #{declareDown})"
increment = "#{ivar} += #{stepVar}"
else
increment = "#{if kvar isnt ivar then "++#{ivar}" else "#{ivar}++"}"
forPartFragments = [@makeCode("#{declare}; #{compare}; #{kvarAssign}#{increment}")]
if @returns
resultPart = "#{@tab}#{rvar} = [];\n"
returnResult = "\n#{@tab}return #{rvar};"
body.makeReturn rvar
if @guard
if body.expressions.length > 1
body.expressions.unshift new If (new Parens @guard).invert(), new StatementLiteral "continue"
else
body = Block.wrap [new If @guard, body] if @guard
if @pattern
body.expressions.unshift new Assign @name, if @from then new IdentifierLiteral kvar else new Literal "#{svar}[#{kvar}]"
varPart = "\n#{idt1}#{namePart};" if namePart
if @object
forPartFragments = [@makeCode("#{kvar} in #{svar}")]
guardPart = "\n#{idt1}if (!#{utility 'hasProp', o}.call(#{svar}, #{kvar})) continue;" if @own
else if @from
forPartFragments = [@makeCode("#{kvar} of #{svar}")]
bodyFragments = body.compileToFragments merge(o, indent: idt1), LEVEL_TOP
if bodyFragments and bodyFragments.length > 0
bodyFragments = [].concat @makeCode('\n'), bodyFragments, @makeCode('\n')
fragments = [@makeCode(defPart)]
fragments.push @makeCode(resultPart) if resultPart
fragments = fragments.concat @makeCode(@tab), @makeCode( 'for ('),
forPartFragments, @makeCode(") {#{guardPart}#{varPart}"), bodyFragments,
@makeCode(@tab), @makeCode('}')
fragments.push @makeCode(returnResult) if returnResult
fragmentsA JavaScript switch statement. Converts into a returnable expression on-demand.
exports.Switch = class Switch extends Base
constructor: (@subject, @cases, @otherwise) ->
super()
children: ['subject', 'cases', 'otherwise']
isStatement: YES
jumps: (o = {block: yes}) ->
for [conds, block] in @cases
return jumpNode if jumpNode = block.jumps o
@otherwise?.jumps o
makeReturn: (res) ->
pair[1].makeReturn res for pair in @cases
@otherwise or= new Block [new Literal 'void 0'] if res
@otherwise?.makeReturn res
this
compileNode: (o) ->
idt1 = o.indent + TAB
idt2 = o.indent = idt1 + TAB
fragments = [].concat @makeCode(@tab + "switch ("),
(if @subject then @subject.compileToFragments(o, LEVEL_PAREN) else @makeCode "false"),
@makeCode(") {\n")
for [conditions, block], i in @cases
for cond in flatten [conditions]
cond = cond.invert() unless @subject
fragments = fragments.concat @makeCode(idt1 + "case "), cond.compileToFragments(o, LEVEL_PAREN), @makeCode(":\n")
fragments = fragments.concat body, @makeCode('\n') if (body = block.compileToFragments o, LEVEL_TOP).length > 0
break if i is @cases.length - 1 and not @otherwise
expr = @lastNode block.expressions
continue if expr instanceof Return or expr instanceof Throw or (expr instanceof Literal and expr.jumps() and expr.value isnt 'debugger')
fragments.push cond.makeCode(idt2 + 'break;\n')
if @otherwise and @otherwise.expressions.length
fragments.push @makeCode(idt1 + "default:\n"), (@otherwise.compileToFragments o, LEVEL_TOP)..., @makeCode("\n")
fragments.push @makeCode @tab + '}'
fragmentsIf/else statements. Acts as an expression by pushing down requested returns to the last line of each clause.
Single-expression Ifs are compiled into conditional operators if possible, because ternaries are already proper expressions, and don’t need conversion.
exports.If = class If extends Base
constructor: (condition, @body, options = {}) ->
super()
@condition = if options.type is 'unless' then condition.invert() else condition
@elseBody = null
@isChain = false
{@soak} = options
moveComments @condition, @ if @condition.comments
children: ['condition', 'body', 'elseBody']
bodyNode: -> @body?.unwrap()
elseBodyNode: -> @elseBody?.unwrap()Rewrite a chain of Ifs to add a default case as the final else.
addElse: (elseBody) ->
if @isChain
@elseBodyNode().addElse elseBody
else
@isChain = elseBody instanceof If
@elseBody = @ensureBlock elseBody
@elseBody.updateLocationDataIfMissing elseBody.locationData
thisThe If only compiles into a statement if either of its bodies needs to be a statement. Otherwise a conditional operator is safe.
isStatement: (o) ->
o?.level is LEVEL_TOP or
@bodyNode().isStatement(o) or @elseBodyNode()?.isStatement(o)
jumps: (o) -> @body.jumps(o) or @elseBody?.jumps(o)
compileNode: (o) ->
if @isStatement o then @compileStatement o else @compileExpression o
makeReturn: (res) ->
@elseBody or= new Block [new Literal 'void 0'] if res
@body and= new Block [@body.makeReturn res]
@elseBody and= new Block [@elseBody.makeReturn res]
this
ensureBlock: (node) ->
if node instanceof Block then node else new Block [node]Compile the If as a regular if-else statement. Flattened chains
force inner else bodies into statement form.
compileStatement: (o) ->
child = del o, 'chainChild'
exeq = del o, 'isExistentialEquals'
if exeq
return new If(@condition.invert(), @elseBodyNode(), type: 'if').compileToFragments o
indent = o.indent + TAB
cond = @condition.compileToFragments o, LEVEL_PAREN
body = @ensureBlock(@body).compileToFragments merge o, {indent}
ifPart = [].concat @makeCode("if ("), cond, @makeCode(") {\n"), body, @makeCode("\n#{@tab}}")
ifPart.unshift @makeCode @tab unless child
return ifPart unless @elseBody
answer = ifPart.concat @makeCode(' else ')
if @isChain
o.chainChild = yes
answer = answer.concat @elseBody.unwrap().compileToFragments o, LEVEL_TOP
else
answer = answer.concat @makeCode("{\n"), @elseBody.compileToFragments(merge(o, {indent}), LEVEL_TOP), @makeCode("\n#{@tab}}")
answerCompile the If as a conditional operator.
compileExpression: (o) ->
cond = @condition.compileToFragments o, LEVEL_COND
body = @bodyNode().compileToFragments o, LEVEL_LIST
alt = if @elseBodyNode() then @elseBodyNode().compileToFragments(o, LEVEL_LIST) else [@makeCode('void 0')]
fragments = cond.concat @makeCode(" ? "), body, @makeCode(" : "), alt
if o.level >= LEVEL_COND then @wrapInParentheses fragments else fragments
unfoldSoak: ->
@soak and this
UTILITIES =
modulo: -> 'function(a, b) { return (+a % (b = +b) + b) % b; }'
objectWithoutKeys: -> "
function(o, ks) {
var res = {};
for (var k in o) ([].indexOf.call(ks, k) < 0 && {}.hasOwnProperty.call(o, k)) && (res[k] = o[k]);
return res;
}
"
boundMethodCheck: -> "
function(instance, Constructor) {
if (!(instance instanceof Constructor)) {
throw new Error('Bound instance method accessed before binding');
}
}
"
_extends: -> "
Object.assign || function (target) {
for (var i = 1; i < arguments.length; i++) {
var source = arguments[i];
for (var key in source) {
if (Object.prototype.hasOwnProperty.call(source, key)) {
target[key] = source[key];
}
}
}
return target;
}
"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.
LEVEL_TOP = 1 # ...;
LEVEL_PAREN = 2 # (...)
LEVEL_LIST = 3 # [...]
LEVEL_COND = 4 # ... ? x : y
LEVEL_OP = 5 # !...
LEVEL_ACCESS = 6 # ...[0]Tabs are two spaces for pretty printing.
TAB = ' '
SIMPLENUM = /^[+-]?\d+$/Helper for ensuring that utility functions are assigned at the top level.
utility = (name, o) ->
{root} = o.scope
if name of root.utilities
root.utilities[name]
else
ref = root.freeVariable name
root.assign ref, UTILITIES[name] o
root.utilities[name] = ref
multident = (code, tab, includingFirstLine = yes) ->
endsWithNewLine = code[code.length - 1] is '\n'
code = (if includingFirstLine then tab else '') + code.replace /\n/g, "$&#{tab}"
code = code.replace /\s+$/, ''
code = code + '\n' if endsWithNewLine
codeWherever in CoffeeScript 1 we might’ve inserted a makeCode "#{@tab}" to
indent a line of code, now we must account for the possibility of comments
preceding that line of code. If there are such comments, indent each line of
such comments, and then indent the first following line of code.
indentInitial = (fragments, node) ->
for fragment, fragmentIndex in fragments
if fragment.isHereComment
fragment.code = multident fragment.code, node.tab
else
fragments.splice fragmentIndex, 0, node.makeCode "#{node.tab}"
break
fragments
hasLineComments = (node) ->
return no unless node.comments
for comment in node.comments
return yes if comment.here is no
return noMove the comments property from one object to another, deleting it from
the first object.
moveComments = (from, to) ->
return unless from?.comments
attachCommentsToNode from.comments, to
delete from.commentsSometimes when compiling a node, we want to insert a fragment at the start of an array of fragments; but if the start has one or more comment fragments, we want to insert this fragment after those but before any non-comments.
unshiftAfterComments = (fragments, fragmentToInsert) ->
inserted = no
for fragment, fragmentIndex in fragments when not fragment.isComment
fragments.splice fragmentIndex, 0, fragmentToInsert
inserted = yes
break
fragments.push fragmentToInsert unless inserted
fragments
isLiteralArguments = (node) ->
node instanceof IdentifierLiteral and node.value is 'arguments'
isLiteralThis = (node) ->
node instanceof ThisLiteral or (node instanceof Code and node.bound)
shouldCacheOrIsAssignable = (node) -> node.shouldCache() or node.isAssignable?()Unfold a node’s child if soak, then tuck the node under created If
unfoldSoak = (o, parent, name) ->
return unless ifn = parent[name].unfoldSoak o
parent[name] = ifn.body
ifn.body = new Value parent
ifn