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# `` contains all of the node classes for the syntax tree. Most
# nodes are created as the result of actions in the [grammar](grammar.html),
# 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.
{Scope} = require './scope'
{RESERVED, STRICT_PROSCRIBED} = require './lexer'
# Import the helpers we plan to use.
{compact, flatten, extend, merge, del, starts, ends, last} = require './helpers'
exports.extend = extend # for parser
# Constant functions for nodes that don't need customization.
YES = -> yes
NO = -> no
THIS = -> this
NEGATE = -> @negated = not @negated; this
#### Base
# 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
# 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).
compile: (o, lvl) ->
o = extend {}, o
o.level = lvl if lvl
node = @unfoldSoak(o) or this = o.indent
if o.level is LEVEL_TOP or not node.isStatement(o)
node.compileNode o
node.compileClosure o
# Statements converted into expressions via closure-wrapping share a scope
# object with their parent closure, to preserve the expected lexical scope.
compileClosure: (o) ->
if @jumps()
throw SyntaxError 'cannot use a pure statement in an expression.'
o.sharedScope = yes
Closure.wrap(this).compileNode o
# If 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.
cache: (o, level, reused) ->
unless @isComplex()
ref = if level then @compile o, level else this
[ref, ref]
ref = new Literal reused or o.scope.freeVariable 'ref'
sub = new Assign ref, this
if level then [sub.compile(o, level), ref.value] else [sub, ref]
# Compile to a source/variable pair suitable for looping.
compileLoopReference: (o, name) ->
src = tmp = @compile o, LEVEL_LIST
unless -Infinity < +src < Infinity or IDENTIFIER.test(src) and o.scope.check(src, yes)
src = "#{ tmp = o.scope.freeVariable name } = #{src}"
[src, tmp]
# 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]
new Return me
# Does this node, or any of its children, contain a node of a certain kind?
# Recursively traverses down the *children* of the nodes, yielding to a block
# and returning true when the block finds a match. `contains` does not cross
# scope boundaries.
contains: (pred) ->
contains = no
@traverseChildren no, (node) ->
if pred node
contains = yes
return no
# Is this node of a certain type, or does it contain the type?
containsType: (type) ->
this instanceof type or @contains (node) -> node instanceof type
# Pull out the last non-comment node of a node list.
lastNonComment: (list) ->
i = list.length
return list[i] while i-- when list[i] not instanceof Comment
# `toString` representation of the node, for inspecting the parse tree.
# This is what `coffee --nodes` prints out.
toString: (idt = '', name = ->
tree = '\n' + idt + name
tree += '?' if @soak
@eachChild (node) -> tree += node.toString idt + TAB
# Passes 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
traverseChildren: (crossScope, func) ->
@eachChild (child) ->
return false if func(child) is false
child.traverseChildren crossScope, func
invert: ->
new Op '!', this
unwrapAll: ->
node = this
continue until node is node = node.unwrap()
# Default implementations of the common node properties and methods. Nodes
# will override these with custom logic, if needed.
children: []
isStatement : NO
jumps : NO
isComplex : YES
isChainable : NO
isAssignable : NO
unwrap : THIS
unfoldSoak : NO
# Is this node used to assign a certain variable?
assigns: NO
#### Block
# The 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) ->
@expressions = compact flatten nodes or []
children: ['expressions']
# Tack an expression on to the end of this expression list.
push: (node) ->
@expressions.push node
# Remove and return the last expression of this expression list.
pop: ->
# Add an expression at the beginning of this expression list.
unshift: (node) ->
@expressions.unshift node
# If 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 this
# Is this an empty block of code?
isEmpty: ->
not @expressions.length
isStatement: (o) ->
for exp in @expressions when exp.isStatement o
return yes
jumps: (o) ->
for exp in @expressions
return exp if exp.jumps o
# A 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]
if expr not instanceof Comment
@expressions[len] = expr.makeReturn res
@expressions.splice(len, 1) if expr instanceof Return and not expr.expression
# A **Block** is the only node that can serve as the root.
compile: (o = {}, level) ->
if o.scope then super o, level else @compileRoot o
# Compile 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
codes = []
for node in @expressions
node = node.unwrapAll()
node = (node.unfoldSoak(o) or node)
if node instanceof Block
# This 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
codes.push node.compileNode o
else if top
node.front = true
code = node.compile o
unless node.isStatement o
code = "#{@tab}#{code};"
code = "#{code}\n" if node instanceof Literal
codes.push code
codes.push node.compile o, LEVEL_LIST
if top
if @spaced
return "\n#{codes.join '\n\n'}\n"
return codes.join '\n'
code = codes.join(', ') or 'void 0'
if codes.length > 1 and o.level >= LEVEL_LIST then "(#{code})" else code
# If 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.scope = new Scope null, this, null
o.level = LEVEL_TOP
@spaced = yes
prelude = ""
unless o.bare
preludeExps = for exp, i in @expressions
break unless exp.unwrap() instanceof Comment
rest = @expressions[preludeExps.length...]
@expressions = preludeExps
prelude = "#{@compileNode merge(o, indent: '')}\n" if preludeExps.length
@expressions = rest
code = @compileWithDeclarations o
return code if o.bare
"#{prelude}(function() {\n#{code}\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) ->
code = post = ''
for exp, i in @expressions
exp = exp.unwrap()
break unless exp instanceof Comment or exp instanceof Literal
o = merge(o, level: LEVEL_TOP)
if i
rest = @expressions.splice i, 9e9
[spaced, @spaced] = [@spaced, no]
[code , @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
code += '\n' if i
code += "#{@tab}var "
if declars
code += scope.declaredVariables().join ', '
if assigns
code += ",\n#{@tab + TAB}" if declars
code += scope.assignedVariables().join ",\n#{@tab + TAB}"
code += ';\n'
code + post
# Wrap 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 nodes
#### Literal
# Literals are 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) ->
makeReturn: ->
if @isStatement() then this else super
isAssignable: ->
IDENTIFIER.test @value
isStatement: ->
@value in ['break', 'continue', 'debugger']
isComplex: NO
assigns: (name) ->
name is @value
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) ->
code = if @isUndefined
if o.level >= LEVEL_ACCESS then '(void 0)' else 'void 0'
else if @value is 'this'
if o.scope.method?.bound then o.scope.method.context else @value
else if @value.reserved
if @isStatement() then "#{@tab}#{code};" else code
toString: ->
' "' + @value + '"'
#### Return
# A `return` is a *pureStatement* -- wrapping it in a closure wouldn't
# make sense.
exports.Return = class Return extends Base
constructor: (expr) ->
@expression = expr if expr and not expr.unwrap().isUndefined
children: ['expression']
isStatement: YES
makeReturn: THIS
jumps: THIS
compile: (o, level) ->
expr = @expression?.makeReturn()
if expr and expr not instanceof Return then expr.compile o, level else super o, level
compileNode: (o) ->
@tab + "return#{[" #{@expression.compile o, LEVEL_PAREN}" if @expression]};"
#### Value
# A value, variable or literal or parenthesized, indexed or dotted into,
# or vanilla.
exports.Value = class Value extends Base
constructor: (base, props, tag) ->
return base if not props and base instanceof Value
@base = base
@properties = props or []
@[tag] = true if tag
return this
children: ['base', 'properties']
# Add a property (or *properties* ) `Access` to the list.
add: (props) ->
@properties = @properties.concat props
hasProperties: ->
# Some boolean checks for the benefit of other nodes.
isArray : -> not @properties.length and @base instanceof Arr
isComplex : -> @hasProperties() or @base.isComplex()
isAssignable : -> @hasProperties() or @base.isAssignable()
isSimpleNumber : -> @base instanceof Literal and SIMPLENUM.test @base.value
isString : -> @base instanceof Literal and IS_STRING.test @base.value
isAtomic : ->
for node in @properties.concat @base
return no if node.soak or node instanceof Call
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)
isSplice: ->
last(@properties) instanceof Slice
# The value can be unwrapped as its inner node, if there are no attached
# properties.
unwrap: ->
if @properties.length then this else @base
# A 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 = last @properties
if @properties.length < 2 and not @base.isComplex() and not name?.isComplex()
return [this, this] # `a` `a.b`
base = new Value @base, @properties[...-1]
if base.isComplex() # `a().b`
bref = new Literal o.scope.freeVariable 'base'
base = new Value new Parens new Assign bref, base
return [base, bref] unless name # `a()`
if name.isComplex() # `a[b()]`
nref = new Literal 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
code = @base.compile o, if props.length then LEVEL_ACCESS else null
code = "#{code}." if (@base instanceof Parens or props.length) and SIMPLENUM.test code
code += prop.compile o for prop in props
# Unfold a soak into an `If`: `a?.b` -> `a.b if a?`
unfoldSoak: (o) ->
return @unfoldedSoak if @unfoldedSoak?
result = do =>
if ifn = @base.unfoldSoak o
Array::push.apply, @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.isComplex()
ref = new Literal o.scope.freeVariable 'ref'
fst = new Parens new Assign ref, fst
snd.base = ref
return new If new Existence(fst), snd, soak: on
@unfoldedSoak = result or no
#### Comment
# CoffeeScript passes through block comments as JavaScript block comments
# at the same position.
exports.Comment = class Comment extends Base
constructor: (@comment) ->
isStatement: YES
makeReturn: THIS
compileNode: (o, level) ->
code = '/*' + multident(@comment, @tab) + "\n#{@tab}*/\n"
code = o.indent + code if (level or o.level) is LEVEL_TOP
#### Call
# Node for a function invocation. Takes care of converting `super()` calls into
# calls against the prototype's function of the same name.
exports.Call = class Call extends Base
constructor: (variable, @args = [], @soak) ->
@isNew = false
@isSuper = variable is 'super'
@variable = if @isSuper then null else variable
children: ['variable', 'args']
# Tag this invocation as creating a new instance.
newInstance: ->
base = @variable?.base or @variable
if base instanceof Call and not base.isNew
@isNew = true
# Grab the reference to the superclass's implementation of the current
# method.
superReference: (o) ->
method = o.scope.namedMethod()
throw SyntaxError 'cannot call super outside of a function.' unless method
{name} = method
throw SyntaxError 'cannot call super on an anonymous function.' unless name?
if method.klass
accesses = [new Access(new Literal '__super__')]
accesses.push new Access new Literal 'constructor' if method.static
accesses.push new Access new Literal name
(new Value (new Literal method.klass), accesses).compile o
# The appropriate `this` value for a `super` call.
superThis : (o) ->
o.scope.method?.context or "this"
# Soaked chained invocations unfold into if/else ternary structures.
unfoldSoak: (o) ->
if @soak
if @variable
return ifn if ifn = unfoldSoak o, this, 'variable'
[left, rite] = new Value(@variable).cacheReference o
left = new Literal @superReference o
rite = new Value left
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 = []
if call.variable instanceof Call
list.push call
call = call.variable
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
call.variable.base = ifn
ifn = unfoldSoak o, call, 'variable'
# Walk through the objects in the arguments, moving over simple values.
# This allows syntax like `call a: b, c` into `call({a: b}, c);`
filterImplicitObjects: (list) ->
nodes = []
for node in list
unless node.isObject?() and node.base.generated
nodes.push node
obj = null
for prop in
if prop instanceof Assign or prop instanceof Comment
nodes.push obj = new Obj properties = [], true if not obj
properties.push prop
nodes.push prop
obj = null
# Compile a vanilla function call.
compileNode: (o) ->
@variable?.front = @front
if code = Splat.compileSplattedArray o, @args, true
return @compileSplat o, code
args = @filterImplicitObjects @args
args = (arg.compile o, LEVEL_LIST for arg in args).join ', '
if @isSuper
@superReference(o) + ".call(#{@superThis(o)}#{ args and ', ' + args })"
(if @isNew then 'new ' else '') + @variable.compile(o, LEVEL_ACCESS) + "(#{args})"
# `super()` is converted into a call against the superclass's implementation
# of the current function.
compileSuper: (args, o) ->
"#{@superReference(o)}.call(#{@superThis(o)}#{ if args.length then ', ' else '' }#{args})"
# If you call a function with a splat, it's converted into a JavaScript
# `.apply()` call to allow an array of arguments to be passed.
# If it's a constructor, then things get real tricky. We have to inject an
# inner constructor in order to be able to pass the varargs.
compileSplat: (o, splatArgs) ->
return "#{ @superReference o }.apply(#{@superThis(o)}, #{splatArgs})" if @isSuper
if @isNew
idt = @tab + TAB
return """
(function(func, args, ctor) {
#{idt}ctor.prototype = func.prototype;
#{idt}var child = new ctor, result = func.apply(child, args), t = typeof result;
#{idt}return t == "object" || t == "function" ? result || child : child;
#{@tab}})(#{ @variable.compile o, LEVEL_LIST }, #{splatArgs}, function(){})
base = new Value @variable
if (name = and base.isComplex()
ref = o.scope.freeVariable 'ref'
fun = "(#{ref} = #{ base.compile o, LEVEL_LIST })#{ name.compile o }"
fun = base.compile o, LEVEL_ACCESS
fun = "(#{fun})" if SIMPLENUM.test fun
if name
ref = fun
fun += name.compile o
ref = 'null'
"#{fun}.apply(#{ref}, #{splatArgs})"
#### Extends
# 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) ->
children: ['child', 'parent']
# Hooks one constructor into another's prototype chain.
compile: (o) ->
new Call(new Value(new Literal utility 'extends'), [@child, @parent]).compile o
#### Access
# A `.` 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) ->
@name.asKey = yes
@soak = tag is 'soak'
children: ['name']
compile: (o) ->
name = @name.compile o
if IDENTIFIER.test name then ".#{name}" else "[#{name}]"
isComplex: NO
#### Index
# A `[ ... ]` indexed access into an array or object.
exports.Index = class Index extends Base
constructor: (@index) ->
children: ['index']
compile: (o) ->
"[#{ @index.compile o, LEVEL_PAREN }]"
isComplex: ->
#### Range
# 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) ->
@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
[@fromC, @fromVar] = @from.cache o, LEVEL_LIST
[@toC, @toVar] = @to.cache o, LEVEL_LIST
[@step, @stepVar] = step.cache o, LEVEL_LIST if step = del o, 'step'
[@fromNum, @toNum] = [@fromVar.match(SIMPLENUM), @toVar.match(SIMPLENUM)]
@stepNum = @stepVar.match(SIMPLENUM) if @stepVar
# When 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.index
# Set up endpoints.
known = @fromNum and @toNum
idx = del o, 'index'
idxName = del o, 'name'
namedIndex = idxName and idxName isnt idx
varPart = "#{idx} = #{@fromC}"
varPart += ", #{@toC}" if @toC isnt @toVar
varPart += ", #{@step}" if @step isnt @stepVar
[lt, gt] = ["#{idx} <#{@equals}", "#{idx} >#{@equals}"]
# Generate the condition.
condPart = if @stepNum
if +@stepNum > 0 then "#{lt} #{@toVar}" else "#{gt} #{@toVar}"
else if known
[from, to] = [+@fromNum, +@toNum]
if from <= to then "#{lt} #{to}" else "#{gt} #{to}"
cond = "#{@fromVar} <= #{@toVar}"
"#{cond} ? #{lt} #{@toVar} : #{gt} #{@toVar}"
# Generate the step.
stepPart = if @stepVar
"#{idx} += #{@stepVar}"
else if known
if namedIndex
if from <= to then "++#{idx}" else "--#{idx}"
if from <= to then "#{idx}++" else "#{idx}--"
if namedIndex
"#{cond} ? ++#{idx} : --#{idx}"
"#{cond} ? #{idx}++ : #{idx}--"
varPart = "#{idxName} = #{varPart}" if namedIndex
stepPart = "#{idxName} = #{stepPart}" if namedIndex
# The final loop body.
"#{varPart}; #{condPart}; #{stepPart}"
# When used as a value, expand the range into the equivalent array.
compileArray: (o) ->
if @fromNum and @toNum and Math.abs(@fromNum - @toNum) <= 20
range = [+@fromNum..+@toNum]
range.pop() if @exclusive
return "[#{ range.join(', ') }]"
idt = @tab + TAB
i = o.scope.freeVariable 'i'
result = o.scope.freeVariable 'results'
pre = "\n#{idt}#{result} = [];"
if @fromNum and @toNum
o.index = i
body = @compileNode o
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 (n) -> n instanceof Literal and n.value is 'arguments' and not n.asKey
args = ', arguments' if hasArgs(@from) or hasArgs(@to)
"(function() {#{pre}\n#{idt}for (#{body})#{post}}).apply(this#{args ? ''})"
#### Slice
# 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) ->
# 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} = @range
fromStr = from and from.compile(o, LEVEL_PAREN) or '0'
compiled = to and to.compile o, LEVEL_PAREN
if to and not (not @range.exclusive and +compiled is -1)
toStr = ', ' + if @range.exclusive
else if SIMPLENUM.test compiled
"#{+compiled + 1}"
compiled = to.compile o, LEVEL_ACCESS
"#{compiled} + 1 || 9e9"
".slice(#{ fromStr }#{ toStr or '' })"
#### Obj
# An object literal, nothing fancy.
exports.Obj = class Obj extends Base
constructor: (props, @generated = false) ->
@objects = @properties = props or []
children: ['properties']
compileNode: (o) ->
props = @properties
propNames = []
for prop in @properties
prop = prop.variable if prop.isComplex()
if prop?
propName = prop.unwrapAll().value.toString()
if propName in propNames
throw SyntaxError "multiple object literal properties named \"#{propName}\""
propNames.push propName
return (if @front then '({})' else '{}') unless props.length
if @generated
for node in props when node instanceof Value
throw new Error 'cannot have an implicit value in an implicit object'
idt = o.indent += TAB
lastNoncom = @lastNonComment @properties
props = for prop, i in props
join = if i is props.length - 1
else if prop is lastNoncom or prop instanceof Comment
indent = if prop instanceof Comment then '' else idt
if prop instanceof Value and prop.this
prop = new Assign[0].name, prop, 'object'
if prop not instanceof Comment
if prop not instanceof Assign
prop = new Assign prop, prop, 'object'
(prop.variable.base or prop.variable).asKey = yes
indent + prop.compile(o, LEVEL_TOP) + join
props = props.join ''
obj = "{#{ props and '\n' + props + '\n' + @tab }}"
if @front then "(#{obj})" else obj
assigns: (name) ->
for prop in @properties when prop.assigns name then return yes
#### Arr
# An array literal.
exports.Arr = class Arr extends Base
constructor: (objs) ->
@objects = objs or []
children: ['objects']
filterImplicitObjects: Call::filterImplicitObjects
compileNode: (o) ->
return '[]' unless @objects.length
o.indent += TAB
objs = @filterImplicitObjects @objects
return code if code = Splat.compileSplattedArray o, objs
code = (obj.compile o, LEVEL_LIST for obj in objs).join ', '
if code.indexOf('\n') >= 0
assigns: (name) ->
for obj in @objects when obj.assigns name then return yes
#### Class
# The CoffeeScript class definition.
# Initialize a **Class** with its name, an optional superclass, and a
# list of prototype property assignments.
exports.Class = class Class extends Base
constructor: (@variable, @parent, @body = new Block) ->
@boundFuncs = []
@body.classBody = yes
children: ['variable', 'parent', 'body']
# Figure out the appropriate name for the constructor function of this class.
determineName: ->
return null unless @variable
decl = if tail = last
tail instanceof Access and
throw SyntaxError "variable name may not be #{decl}"
decl and= IDENTIFIER.test(decl) and decl
# For all `this`-references and bound functions in the class definition,
# `this` is the Class being constructed.
setContext: (name) ->
@body.traverseChildren false, (node) ->
return false if node.classBody
if node instanceof Literal and node.value is 'this'
node.value = name
else if node instanceof Code
node.klass = name
node.context = name if node.bound
# Ensure that all functions bound to the instance are proxied in the
# constructor.
addBoundFunctions: (o) ->
if @boundFuncs.length
for bvar in @boundFuncs
lhs = (new Value (new Literal "this"), [new Access bvar]).compile o
@ctor.body.unshift new Literal "#{lhs} = #{utility 'bind'}(#{lhs}, this)"
# Merge the properties from a top-level object as prototypal properties
# on the class.
addProperties: (node, name, o) ->
props =[..]
exprs = while assign = props.shift()
if assign instanceof Assign
base = assign.variable.base
delete assign.context
func = assign.value
if base.value is 'constructor'
if @ctor
throw new Error 'cannot define more than one constructor in a class'
if func.bound
throw new Error 'cannot define a constructor as a bound function'
if func instanceof Code
assign = @ctor = func
@externalCtor = o.scope.freeVariable 'class'
assign = new Assign new Literal(@externalCtor), func
if assign.variable.this
func.static = yes
if func.bound
func.context = name
assign.variable = new Value(new Literal(name), [(new Access new Literal 'prototype'), new Access base ])
if func instanceof Code and func.bound
@boundFuncs.push base
func.bound = no
compact exprs
# Walk the body of the class, looking for prototype properties to be converted.
walkBody: (name, o) ->
@traverseChildren false, (child) =>
return false if child instanceof Class
if child instanceof Block
for node, i in exps = child.expressions
if node instanceof Value and node.isObject(true)
exps[i] = @addProperties node, name, o
child.expressions = exps = flatten exps
# `use strict` (and other directives) must be the first expression statement(s)
# of a function body. This method ensures the prologue is correctly positioned
# above the `constructor`.
hoistDirectivePrologue: ->
index = 0
{expressions} = @body
++index while (node = expressions[index]) and node instanceof Comment or
node instanceof Value and node.isString()
@directives = expressions.splice 0, index
# Make sure that a constructor is defined for the class, and properly
# configured.
ensureConstructor: (name) ->
if not @ctor
@ctor = new Code
@ctor.body.push new Literal "#{name}.__super__.constructor.apply(this, arguments)" if @parent
@ctor.body.push new Literal "#{@externalCtor}.apply(this, arguments)" if @externalCtor
@body.expressions.unshift @ctor
@ctor.ctor = = name
@ctor.klass = null
@ctor.noReturn = yes
# Instead of generating the JavaScript string directly, we build up the
# equivalent syntax tree and compile that, in pieces. You can see the
# constructor, property assignments, and inheritance getting built out below.
compileNode: (o) ->
decl = @determineName()
name = decl or '_Class'
name = "_#{name}" if name.reserved
lname = new Literal name
@setContext name
@walkBody name, o
@ensureConstructor name
@body.spaced = yes
@body.expressions.unshift @ctor unless @ctor instanceof Code
@body.expressions.push lname
@body.expressions.unshift @directives...
@addBoundFunctions o
call = Closure.wrap @body
if @parent
@superClass = new Literal o.scope.freeVariable 'super', no
@body.expressions.unshift new Extends lname, @superClass
call.args.push @parent
params = call.variable.params or call.variable.base.params
params.push new Param @superClass
klass = new Parens call, yes
klass = new Assign @variable, klass if @variable
klass.compile o
#### Assign
# 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) ->
@param = options and options.param
@subpattern = options and options.subpattern
forbidden = (name = @variable.unwrapAll().value) in STRICT_PROSCRIBED
if forbidden and @context isnt 'object'
throw SyntaxError "variable name may not be \"#{name}\""
children: ['variable', 'value']
isStatement: (o) ->
o?.level is LEVEL_TOP and @context? and "?" in @context
assigns: (name) ->
@[if @context is 'object' then 'value' else 'variable'].assigns name
unfoldSoak: (o) ->
unfoldSoak o, this, 'variable'
# Compile an assignment, delegating to `compilePatternMatch` 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) ->
if isValue = @variable instanceof Value
return @compilePatternMatch o if @variable.isArray() or @variable.isObject()
return @compileSplice o if @variable.isSplice()
return @compileConditional o if @context in ['||=', '&&=', '?=']
name = @variable.compile o, LEVEL_LIST
unless @context
unless (varBase = @variable.unwrapAll()).isAssignable()
throw SyntaxError "\"#{ @variable.compile o }\" cannot be assigned."
unless varBase.hasProperties?()
if @param
o.scope.add name, 'var'
o.scope.find name
if @value instanceof Code and match = METHOD_DEF.exec name
@value.klass = match[1] if match[1] = match[2] ? match[3] ? match[4] ? match[5]
val = @value.compile o, LEVEL_LIST
return "#{name}: #{val}" if @context is 'object'
val = name + " #{ @context or '=' } " + val
if o.level <= LEVEL_LIST then val else "(#{val})"
# Brief implementation of recursive pattern matching, when assigning array or
# object literals to a value. Peeks at their properties to assign inner names.
# See the [ECMAScript Harmony Wiki](
# for details.
compilePatternMatch: (o) ->
top = o.level is LEVEL_TOP
{value} = this
{objects} = @variable.base
unless olen = objects.length
code = value.compile o
return if o.level >= LEVEL_OP then "(#{code})" else code
isObject = @variable.isObject()
if top and olen is 1 and (obj = objects[0]) not instanceof Splat
# Unroll simplest cases: `{v} = x` -> `v = x.v`
if obj instanceof Assign
{variable: {base: idx}, value: obj} = obj
if obj.base instanceof Parens
[obj, idx] = new Value(obj.unwrapAll()).cacheReference o
idx = if isObject
if obj.this then[0].name else obj
new Literal 0
acc = IDENTIFIER.test idx.unwrap().value or 0
value = new Value value new (if acc then Access else Index) idx
if obj.unwrap().value in RESERVED
throw new SyntaxError "assignment to a reserved word: #{obj.compile o} = #{value.compile o}"
return new Assign(obj, value, null, param: @param).compile o, LEVEL_TOP
vvar = value.compile o, LEVEL_LIST
assigns = []
splat = false
if not IDENTIFIER.test(vvar) or @variable.assigns(vvar)
assigns.push "#{ ref = o.scope.freeVariable 'ref' } = #{vvar}"
vvar = ref
for obj, i in objects
# A regular array pattern-match.
idx = i
if isObject
if obj instanceof Assign
# A regular object pattern-match.
{variable: {base: idx}, value: obj} = obj
# A shorthand `{a, b, @c} = val` pattern-match.
if obj.base instanceof Parens
[obj, idx] = new Value(obj.unwrapAll()).cacheReference o
idx = if obj.this then[0].name else obj
if not splat and obj instanceof Splat
name =
obj = obj.unwrap()
val = "#{olen} <= #{vvar}.length ? #{ utility 'slice' }.call(#{vvar}, #{i}"
if rest = olen - i - 1
ivar = o.scope.freeVariable 'i'
val += ", #{ivar} = #{vvar}.length - #{rest}) : (#{ivar} = #{i}, [])"
val += ") : []"
val = new Literal val
splat = "#{ivar}++"
name = obj.unwrap().value
if obj instanceof Splat
obj = o
throw new SyntaxError \
"multiple splats are disallowed in an assignment: #{obj}..."
if typeof idx is 'number'
idx = new Literal splat or idx
acc = no
acc = isObject and IDENTIFIER.test idx.unwrap().value or 0
val = new Value new Literal(vvar), [new (if acc then Access else Index) idx]
if name? and name in RESERVED
throw new SyntaxError "assignment to a reserved word: #{obj.compile o} = #{val.compile o}"
assigns.push new Assign(obj, val, null, param: @param, subpattern: yes).compile o, LEVEL_LIST
assigns.push vvar unless top or @subpattern
code = assigns.join ', '
if o.level < LEVEL_LIST then code else "(#{code})"
# When 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 o
# Disallow conditional assignment of undefined variables.
if not and left.base instanceof Literal and
left.base.value != "this" and not o.scope.check left.base.value
throw new Error "the variable \"#{left.base.value}\" can't be assigned with #{@context} because it has not been defined."
if "?" in @context then o.isExistentialEquals = true
new Op(@context[...-1], left, new Assign(right, @value, '=') ).compile o
# Compile the assignment from an array splice literal, using JavaScript's
# `Array#splice` method.
compileSplice: (o) ->
{range: {from, to, exclusive}} =
name = @variable.compile o
[fromDecl, fromRef] = from?.cache(o, LEVEL_OP) or ['0', '0']
if to
if from?.isSimpleNumber() and to.isSimpleNumber()
to = +to.compile(o) - +fromRef
to += 1 unless exclusive
to = to.compile(o, LEVEL_ACCESS) + ' - ' + fromRef
to += ' + 1' unless exclusive
to = "9e9"
[valDef, valRef] = @value.cache o, LEVEL_LIST
code = "[].splice.apply(#{name}, [#{fromDecl}, #{to}].concat(#{valDef})), #{valRef}"
if o.level > LEVEL_TOP then "(#{code})" else code
#### Code
# 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, tag) ->
@params = params or []
@body = body or new Block
@bound = tag is 'boundfunc'
@context = '_this' if @bound
children: ['params', 'body']
isStatement: -> !!@ctor
jumps: NO
# Compilation creates a new scope unless explicitly asked to share with the
# outer scope. Handles splat parameters in the parameter list by peeking at
# the JavaScript `arguments` object. If the function is bound with the `=>`
# arrow, generates a wrapper that saves the current value of `this` through
# a closure.
compileNode: (o) ->
o.scope = new Scope o.scope, @body, this
o.scope.shared = del(o, 'sharedScope')
o.indent += TAB
delete o.bare
delete o.isExistentialEquals
params = []
exprs = []
for name in @paramNames() # this step must be performed before the others
unless o.scope.check name then o.scope.parameter name
for param in @params when param.splat
for {name: p} in @params
if p.this then p =[0].name
if p.value then o.scope.add p.value, 'var', yes
splats = new Assign new Value(new Arr(p.asReference o for p in @params)),
new Value new Literal 'arguments'
for param in @params
if param.isComplex()
val = ref = param.asReference o
val = new Op '?', ref, param.value if param.value
exprs.push new Assign new Value(, val, '=', param: yes
ref = param
if param.value
lit = new Literal + ' == null'
val = new Assign new Value(, param.value, '='
exprs.push new If lit, val
params.push ref unless splats
wasEmpty = @body.isEmpty()
exprs.unshift splats if splats
@body.expressions.unshift exprs... if exprs.length
o.scope.parameter params[i] = p.compile o for p, i in params
uniqs = []
for name in @paramNames()
throw SyntaxError "multiple parameters named '#{name}'" if name in uniqs
uniqs.push name
@body.makeReturn() unless wasEmpty or @noReturn
if @bound
if o.scope.parent.method?.bound
@bound = @context = o.scope.parent.method.context
else if not @static
o.scope.parent.assign '_this', 'this'
idt = o.indent
code = 'function'
code += ' ' + @name if @ctor
code += '(' + params.join(', ') + ') {'
code += "\n#{ @body.compileWithDeclarations o }\n#{@tab}" unless @body.isEmpty()
code += '}'
return @tab + code if @ctor
if @front or (o.level >= LEVEL_ACCESS) then "(#{code})" else code
# A list of parameter names, excluding those generated by the compiler.
paramNames: ->
names = []
names.push param.names()... for param in @params
# Short-circuit `traverseChildren` method to prevent it from crossing scope boundaries
# unless `crossScope` is `true`.
traverseChildren: (crossScope, func) ->
super(crossScope, func) if crossScope
#### Param
# A 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) ->
if (name = @name.unwrapAll().value) in STRICT_PROSCRIBED
throw SyntaxError "parameter name \"#{name}\" is not allowed"
children: ['name', 'value']
compile: (o) ->
@name.compile o, LEVEL_LIST
asReference: (o) ->
return @reference if @reference
node = @name
if node.this
node =[0].name
if node.value.reserved
node = new Literal o.scope.freeVariable node.value
else if node.isComplex()
node = new Literal o.scope.freeVariable 'arg'
node = new Value node
node = new Splat node if @splat
@reference = node
isComplex: ->
# Finds the name or names of a `Param`; useful for detecting duplicates.
# In a sense, a destructured parameter represents multiple JS parameters,
# thus this method returns an `Array` of names.
# Reserved words used as param names, as well as the Object and Array
# literals used for destructured params, get a compiler generated name
# during the `Code` compilation step, so this is necessarily an incomplete
# list of a parameter's names.
names: (name = @name)->
atParam = (obj) ->
{value} =[0].name
return if value.reserved then [] else [value]
# * simple literals `foo`
return [name.value] if name instanceof Literal
# * at-params `@foo`
return atParam(name) if name instanceof Value
names = []
for obj in name.objects
# * assignments within destructured parameters `{foo:bar}`
if obj instanceof Assign
names.push obj.value.base.value
# * splats within destructured parameters `[xs...]`
else if obj instanceof Splat
# * destructured parameters within destructured parameters `[{a}]`
else if obj.isArray() or obj.isObject()
names.push @names(obj.base)...
# * at-params within destructured parameters `{@foo}`
else if obj.this
names.push atParam(obj)...
# * simple destructured parameters {foo}
else names.push obj.base.value
#### Splat
# A 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
children: ['name']
isAssignable: YES
constructor: (name) ->
@name = if name.compile then name else new Literal name
assigns: (name) ->
@name.assigns name
compile: (o) ->
if @index? then @compileParam o else @name.compile o
unwrap: -> @name
# Utility function that converts an arbitrary number of elements, mixed with
# splats, to a proper array.
@compileSplattedArray: (o, list, apply) ->
index = -1
continue while (node = list[++index]) and node not instanceof Splat
return '' if index >= list.length
if list.length is 1
code = list[0].compile o, LEVEL_LIST
return code if apply
return "#{ utility 'slice' }.call(#{code})"
args = list[index..]
for node, i in args
code = node.compile o, LEVEL_LIST
args[i] = if node instanceof Splat
then "#{ utility 'slice' }.call(#{code})"
else "[#{code}]"
return args[0] + ".concat(#{ args[1..].join ', ' })" if index is 0
base = (node.compile o, LEVEL_LIST for node in list[...index])
"[#{ base.join ', ' }].concat(#{ args.join ', ' })"
#### While
# 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) ->
@condition = if options?.invert then condition.invert() else condition
@guard = options?.guard
children: ['condition', 'guard', 'body']
isStatement: YES
makeReturn: (res) ->
if res
@returns = not @jumps loop: yes
addBody: (@body) ->
jumps: ->
{expressions} = @body
return no unless expressions.length
for node in expressions
return node if node.jumps loop: yes
# The 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 = ''
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 Literal "continue"
body = Block.wrap [new If @guard, body] if @guard
body = "\n#{ body.compile o, LEVEL_TOP }\n#{@tab}"
code = set + @tab + "while (#{ @condition.compile o, LEVEL_PAREN }) {#{body}}"
if @returns
code += "\n#{@tab}return #{rvar};"
#### Op
# Simple 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 ) ->
return new In first, second if op is 'in'
if op is 'do'
return @generateDo first
if op is 'new'
return first.newInstance() if first instanceof Call and not and not first.isNew
first = new Parens first if first instanceof Code and first.bound or
@operator = CONVERSIONS[op] or op
@first = first
@second = second
@flip = !!flip
return this
# The map of conversions from CoffeeScript to JavaScript symbols.
'==': '==='
'!=': '!=='
'of': 'in'
# The map of invertible operators.
'!==': '==='
'===': '!=='
children: ['first', 'second']
isSimpleNumber: NO
isUnary: ->
not @second
isComplex: ->
not (@isUnary() and (@operator in ['+', '-'])) or @first.isComplex()
# 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
else if op = INVERSIONS[@operator]
@operator = op
if @first.unwrap() instanceof Op
else if @second
new Parens(this).invert()
else if @operator is '!' and (fst = @first.unwrap()) instanceof Op and
fst.operator in ['!', 'in', 'instanceof']
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
for param in func.params or []
if param.value
passedParams.push param.value
delete param.value
passedParams.push param
call = new Call exp, passedParams = yes
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)
throw SyntaxError 'delete operand may not be argument or var'
if @operator in ['--', '++'] and @first.unwrapAll().value in STRICT_PROSCRIBED
throw SyntaxError 'prefix increment/decrement may not have eval or arguments operand'
return @compileUnary o if @isUnary()
return @compileChain o if isChain
return @compileExistence o if @operator is '?'
code = @first.compile(o, LEVEL_OP) + ' ' + @operator + ' ' +
@second.compile(o, LEVEL_OP)
if o.level <= LEVEL_OP then code else "(#{code})"
# Mimic 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.compile o, LEVEL_OP
code = "#{fst} #{if @invert then '&&' else '||'} #{ shared.compile o } #{@operator} #{ @second.compile o, LEVEL_OP }"
compileExistence: (o) ->
if @first.isComplex()
ref = new Literal o.scope.freeVariable 'ref'
fst = new Parens new Assign ref, @first
fst = @first
ref = fst
new If(new Existence(fst), ref, type: 'if').addElse(@second).compile o
# Compile a unary **Op**.
compileUnary: (o) ->
if o.level >= LEVEL_ACCESS
return (new Parens this).compile o
parts = [op = @operator]
plusMinus = op in ['+', '-']
parts.push ' ' if op in ['new', 'typeof', 'delete'] or
plusMinus and @first instanceof Op and @first.operator is op
if (plusMinus && @first instanceof Op) or (op is 'new' and @first.isStatement o)
@first = new Parens @first
parts.push @first.compile o, LEVEL_OP
parts.reverse() if @flip
parts.join ''
toString: (idt) ->
super idt, + ' ' + @operator
#### In
exports.In = class In extends Base
constructor: (@object, @array) ->
children: ['object', 'array']
invert: NEGATE
compileNode: (o) ->
if @array instanceof Value and @array.isArray()
for obj in @array.base.objects when obj instanceof Splat
hasSplat = yes
# `compileOrTest` only if we have an array literal with no splats
return @compileOrTest o unless hasSplat
@compileLoopTest o
compileOrTest: (o) ->
return "#{!!@negated}" if @array.base.objects.length is 0
[sub, ref] = @object.cache o, LEVEL_OP
[cmp, cnj] = if @negated then [' !== ', ' && '] else [' === ', ' || ']
tests = for item, i in @array.base.objects
(if i then ref else sub) + cmp + item.compile o, LEVEL_ACCESS
tests = tests.join cnj
if o.level < LEVEL_OP then tests else "(#{tests})"
compileLoopTest: (o) ->
[sub, ref] = @object.cache o, LEVEL_LIST
code = utility('indexOf') + ".call(#{ @array.compile o, LEVEL_LIST }, #{ref}) " +
if @negated then '< 0' else '>= 0'
return code if sub is ref
code = sub + ', ' + code
if o.level < LEVEL_LIST then code else "(#{code})"
toString: (idt) ->
super idt, + if @negated then '!' else ''
#### Try
# A classic *try/catch/finally* block.
exports.Try = class Try extends Base
constructor: (@attempt, @error, @recovery, @ensure) ->
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
# Compilation is more or less as you would expect -- the *finally* clause
# is optional, the *catch* is not.
compileNode: (o) ->
o.indent += TAB
errorPart = if @error then " (#{ @error.compile o }) " else ' '
tryPart = @attempt.compile o, LEVEL_TOP
catchPart = if @recovery
if @error.value in STRICT_PROSCRIBED
throw SyntaxError "catch variable may not be \"#{@error.value}\""
o.scope.add @error.value, 'param' unless o.scope.check @error.value
" catch#{errorPart}{\n#{ @recovery.compile o, LEVEL_TOP }\n#{@tab}}"
else unless @ensure or @recovery
' catch (_error) {}'
ensurePart = if @ensure then " finally {\n#{ @ensure.compile o, LEVEL_TOP }\n#{@tab}}" else ''
"""#{@tab}try {
#{@tab}}#{ catchPart or '' }#{ensurePart}"""
#### Throw
# Simple node to throw an exception.
exports.Throw = class Throw extends Base
constructor: (@expression) ->
children: ['expression']
isStatement: YES
jumps: NO
# A **Throw** is already a return, of sorts...
makeReturn: THIS
compileNode: (o) ->
@tab + "throw #{ @expression.compile o };"
#### Existence
# Checks 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.
exports.Existence = class Existence extends Base
constructor: (@expression) ->
children: ['expression']
invert: NEGATE
compileNode: (o) ->
@expression.front = @front
code = @expression.compile o, LEVEL_OP
if IDENTIFIER.test(code) and not o.scope.check code
[cmp, cnj] = if @negated then ['===', '||'] else ['!==', '&&']
code = "typeof #{code} #{cmp} \"undefined\" #{cnj} #{code} #{cmp} null"
# do not use strict equality here; it will break existing code
code = "#{code} #{if @negated then '==' else '!='} null"
if o.level <= LEVEL_COND then code else "(#{code})"
#### Parens
# 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) ->
children: ['body']
unwrap : -> @body
isComplex : -> @body.isComplex()
compileNode: (o) ->
expr = @body.unwrap()
if expr instanceof Value and expr.isAtomic()
expr.front = @front
return expr.compile o
code = expr.compile o, LEVEL_PAREN
bare = o.level < LEVEL_OP and (expr instanceof Op or expr instanceof Call or
(expr instanceof For and expr.returns))
if bare then code else "(#{code})"
#### For
# CoffeeScript'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) ->
{@source, @guard, @step, @name, @index} = source
@body = Block.wrap [body]
@own = !!source.own
@object = !!source.object
[@name, @index] = [@index, @name] if @object
throw SyntaxError 'index cannot be a pattern matching expression' if @index instanceof Value
@range = @source instanceof Value and @source.base instanceof Range and not
@pattern = @name instanceof Value
throw SyntaxError 'indexes do not apply to range loops' if @range and @index
throw SyntaxError 'cannot pattern match over range loops' if @range and @pattern
@returns = false
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]
lastJumps = last(body.expressions)?.jumps()
@returns = no if lastJumps and lastJumps instanceof Return
source = if @range then @source.base else @source
scope = o.scope
name = @name and @name.compile o, LEVEL_LIST
index = @index and @index.compile o, LEVEL_LIST
scope.find(name) if name and not @pattern
scope.find(index) if index
rvar = scope.freeVariable 'results' if @returns
ivar = (@object and index) or scope.freeVariable 'i'
kvar = (@range and name) or index or ivar
kvarAssign = if kvar isnt ivar then "#{kvar} = " else ""
# the `_by` variable is created twice in `Range`s if we don't prevent it from being declared here
stepvar = scope.freeVariable "step" if @step and not @range
name = ivar if @pattern
varPart = ''
guardPart = ''
defPart = ''
idt1 = @tab + TAB
if @range
forPart = source.compile merge(o, {index: ivar, name, @step})
svar = @source.compile o, LEVEL_LIST
if (name or @own) and not IDENTIFIER.test svar
defPart = "#{@tab}#{ref = scope.freeVariable 'ref'} = #{svar};\n"
svar = ref
if name and not @pattern
namePart = "#{name} = #{svar}[#{kvar}]"
unless @object
lvar = scope.freeVariable 'len'
forVarPart = "#{kvarAssign}#{ivar} = 0, #{lvar} = #{svar}.length"
forVarPart += ", #{stepvar} = #{@step.compile o, LEVEL_OP}" if @step
stepPart = "#{kvarAssign}#{if @step then "#{ivar} += #{stepvar}" else (if kvar isnt ivar then "++#{ivar}" else "#{ivar}++")}"
forPart = "#{forVarPart}; #{ivar} < #{lvar}; #{stepPart}"
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 Literal "continue"
body = Block.wrap [new If @guard, body] if @guard
if @pattern
body.expressions.unshift new Assign @name, new Literal "#{svar}[#{kvar}]"
defPart += @pluckDirectCall o, body
varPart = "\n#{idt1}#{namePart};" if namePart
if @object
forPart = "#{kvar} in #{svar}"
guardPart = "\n#{idt1}if (!#{utility 'hasProp'}.call(#{svar}, #{kvar})) continue;" if @own
body = body.compile merge(o, indent: idt1), LEVEL_TOP
body = '\n' + body + '\n' if body
#{defPart}#{resultPart or ''}#{@tab}for (#{forPart}) {#{guardPart}#{varPart}#{body}#{@tab}}#{returnResult or ''}
pluckDirectCall: (o, body) ->
defs = ''
for expr, idx in body.expressions
expr = expr.unwrapAll()
continue unless expr instanceof Call
val = expr.variable.unwrapAll()
continue unless (val instanceof Code) or
(val instanceof Value and
val.base?.unwrapAll() instanceof Code and is 1 and[0].name?.value in ['call', 'apply'])
fn = val.base?.unwrapAll() or val
ref = new Literal o.scope.freeVariable 'fn'
base = new Value ref
if val.base
[val.base, base] = [base, val]
body.expressions[idx] = new Call base, expr.args
defs += @tab + new Assign(ref, fn).compile(o, LEVEL_TOP) + ';\n'
#### Switch
# A JavaScript *switch* statement. Converts into a returnable expression on-demand.
exports.Switch = class Switch extends Base
constructor: (@subject, @cases, @otherwise) ->
children: ['subject', 'cases', 'otherwise']
isStatement: YES
jumps: (o = {block: yes}) ->
for [conds, block] in @cases
return block if 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
compileNode: (o) ->
idt1 = o.indent + TAB
idt2 = o.indent = idt1 + TAB
code = @tab + "switch (#{ @subject?.compile(o, LEVEL_PAREN) or false }) {\n"
for [conditions, block], i in @cases
for cond in flatten [conditions]
cond = cond.invert() unless @subject
code += idt1 + "case #{ cond.compile o, LEVEL_PAREN }:\n"
code += body + '\n' if body = block.compile o, LEVEL_TOP
break if i is @cases.length - 1 and not @otherwise
expr = @lastNonComment block.expressions
continue if expr instanceof Return or (expr instanceof Literal and expr.jumps() and expr.value isnt 'debugger')
code += idt2 + 'break;\n'
code += idt1 + "default:\n#{ @otherwise.compile o, LEVEL_TOP }\n" if @otherwise and @otherwise.expressions.length
code + @tab + '}'
#### If
# *If/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 = {}) ->
@condition = if options.type is 'unless' then condition.invert() else condition
@elseBody = null
@isChain = false
{@soak} = options
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
@isChain = elseBody instanceof If
@elseBody = @ensureBlock elseBody
# The **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]
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').compile o
cond = @condition.compile o, LEVEL_PAREN
o.indent += TAB
body = @ensureBlock(@body)
ifPart = "if (#{cond}) {\n#{body.compile(o)}\n#{@tab}}"
ifPart = @tab + ifPart unless child
return ifPart unless @elseBody
ifPart + ' else ' + if @isChain
o.indent = @tab
o.chainChild = yes
@elseBody.unwrap().compile o, LEVEL_TOP
"{\n#{ @elseBody.compile o, LEVEL_TOP }\n#{@tab}}"
# Compile the `If` as a conditional operator.
compileExpression: (o) ->
cond = @condition.compile o, LEVEL_COND
body = @bodyNode().compile o, LEVEL_LIST
alt = if @elseBodyNode() then @elseBodyNode().compile(o, LEVEL_LIST) else 'void 0'
code = "#{cond} ? #{body} : #{alt}"
if o.level >= LEVEL_COND then "(#{code})" else code
unfoldSoak: ->
@soak and this
# Faux-Nodes
# ----------
# Faux-nodes are never created by the grammar, but are used during code
# generation to generate other combinations of nodes.
#### Closure
# A faux-node used to wrap an expressions body in a closure.
Closure =
# Wrap the expressions body, unless it contains a pure statement,
# in which case, no dice. If the body mentions `this` or `arguments`,
# then make sure that the closure wrapper preserves the original values.
wrap: (expressions, statement, noReturn) ->
return expressions if expressions.jumps()
func = new Code [], Block.wrap [expressions]
args = []
if (mentionsArgs = expressions.contains @literalArgs) or expressions.contains @literalThis
meth = new Literal if mentionsArgs then 'apply' else 'call'
args = [new Literal 'this']
args.push new Literal 'arguments' if mentionsArgs
func = new Value func, [new Access meth]
func.noReturn = noReturn
call = new Call func, args
if statement then Block.wrap [call] else call
literalArgs: (node) ->
node instanceof Literal and node.value is 'arguments' and not node.asKey
literalThis: (node) ->
(node instanceof Literal and node.value is 'this' and not node.asKey) or
(node instanceof Code and node.bound) or
(node instanceof Call and node.isSuper)
# 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
# Constants
# ---------
# Correctly set up a prototype chain for inheritance, including a reference
# to the superclass for `super()` calls, and copies of any static properties.
extends: -> """
function(child, parent) { for (var key in parent) { if (#{utility 'hasProp'}.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; }
# Create a function bound to the current value of "this".
bind: -> '''
function(fn, me){ return function(){ return fn.apply(me, arguments); }; }
# Discover if an item is in an array.
indexOf: -> """
[].indexOf || function(item) { for (var i = 0, l = this.length; i < l; i++) { if (i in this && this[i] === item) return i; } return -1; }
# Shortcuts to speed up the lookup time for native functions.
hasProp: -> '{}.hasOwnProperty'
slice : -> '[].slice'
# 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 = ' '
IDENTIFIER_STR = "[$A-Za-z_\\x7f-\\uffff][$\\w\\x7f-\\uffff]*"
SIMPLENUM = /^[+-]?\d+$/
| \[("(?:[^\\"\r\n]|\\.)*"|'(?:[^\\'\r\n]|\\.)*')\]
| \[(0x[\da-fA-F]+ | \d*\.?\d+ (?:[eE][+-]?\d+)?)\]
# Is a literal value a string?
IS_STRING = /^['"]/
# Utility Functions
# -----------------
# Helper for ensuring that utility functions are assigned at the top level.
utility = (name) ->
ref = "__#{name}"
Scope.root.assign ref, UTILITIES[name]()
multident = (code, tab) ->
code = code.replace /\n/g, '$&' + tab
code.replace /\s+$/, ''
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