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[CS2] Compile all super calls to ES2015 super (#4424)

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* Compile all super calls to ES2015 super

This breaks using `super` in non-methods, meaning several tests are
failing. Self-compilation still works.

* Use bound functions for IIFEs containing `super`

`super` can only be called directly in a method, or in an arrow
function.

* Fix handling of `class @A extends A`

This behaviour worked 'for free' when the parent reference was being
cached by the executable class body wrapper. There now needs to be
special handling in place to check if the parent name matches the class
name, and if so to cache the parent reference.

* Fix tests broken by compiling ES2015 `super`

* Disallow bare super

This removes syntax support for 'bare' super calls, e.g.:

    class B extends A
      constructor: -> super

`super` must now always be followed with arguments like a regular
function call. This also removes the capability of implicitly forwarding
arguments. The above can be equivalently be written as:

    class B extends A
      constructor: -> super arguments...

* Support super with accessors

`super` with following accessor(s) is now compiled to ES2015
equivalents. In particular, expressions such as `super.name`,
`super[name]`, and also `super.name.prop` are all now valid, and can be
used as expected as calls (i.e. `super.name()`) or in expressions (i.e.
`if super.name? ...`).

`super` without accessors is compiled to a constructor super call in a
constructor, and otherwise, as before, to a super call to the method of
the same name, i.e.

    speak: -> super()

...is equivalent to

    speak: -> super.speak()

A neat side-effect of the changes is that existential calls now work
properly with super, meaning `super?()` will only call if the super
property exists (and is a function). This is not valid for super in
constructors.

* Prevent calling `super` methods with `new`

This fixes a bug in the previous super handling whereby using the `new`
operator with a `super` call would silently drop the `new`. This is now
an explicit compiler error, as it is invalid JS at runtime.

* Clean up some old super handling code

This was mostly code for tracking the source classes and variables for
methods, which were needed to build the old lookups on `__super__`.

* Add TODO to improve bare super parse error

* Add some TODOs to improve some of the class tests
This commit is contained in:
Chris Connelly
2017-02-04 20:03:17 +00:00
committed by Geoffrey Booth
parent cbea7b5d1c
commit 396bd4f2f2
11 changed files with 710 additions and 1024 deletions
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14
src/grammar.coffee
View File

@@ -309,6 +309,13 @@ grammar =
o 'Parenthetical', -> new Value $1
o 'Range', -> new Value $1
o 'This'
o 'Super'
]
# A `super`-based expression that can be used as a value.
Super: [
o 'SUPER . Property', -> new Super LOC(3) new Access $3
o 'SUPER INDEX_START Expression INDEX_END', -> new Super LOC(3) new Index $3
]
# The general group of accessors into an object, by property, by prototype
@@ -429,12 +436,7 @@ grammar =
o 'Value OptFuncExist String', -> new TaggedTemplateCall $1, $3, $2
o 'Value OptFuncExist Arguments', -> new Call $1, $3, $2
o 'Invocation OptFuncExist Arguments', -> new Call $1, $3, $2
o 'Super'
]
Super: [
o 'SUPER', -> new SuperCall
o 'SUPER Arguments', -> new SuperCall $2
o 'SUPER OptFuncExist Arguments', -> new SuperCall LOC(1)(new Super), $3, $2
]
# An optional existence check on a function.

136
src/nodes.coffee
View File

@@ -81,7 +81,9 @@ exports.Base = class Base
o.sharedScope = yes
func = new Code [], Block.wrap [this]
args = []
if (argumentsNode = @contains isLiteralArguments) or @contains isLiteralThis
if @contains ((node) -> node instanceof SuperCall)
func.bound = yes
else if (argumentsNode = @contains isLiteralArguments) or @contains isLiteralThis
args = [new ThisLiteral]
if argumentsNode
meth = 'apply'
@@ -516,7 +518,7 @@ exports.Literal = class Literal extends Base
[@makeCode @value]
toString: ->
" #{if @isStatement() then super else @constructor.name}: #{@value}"
" #{if @isStatement() then super() else @constructor.name}: #{@value}"
exports.NumberLiteral = class NumberLiteral extends Literal
@@ -610,14 +612,14 @@ exports.YieldReturn = class YieldReturn extends Return
compileNode: (o) ->
unless o.scope.parent?
@error 'yield can only occur inside functions'
super
super o
exports.AwaitReturn = class AwaitReturn extends Return
compileNode: (o) ->
unless o.scope.parent?
@error 'await can only occur inside functions'
super
super o
#### Value
@@ -780,9 +782,10 @@ exports.Call = class Call extends Base
# Soaked chained invocations unfold into if/else ternary structures.
unfoldSoak: (o) ->
if @soak
if this instanceof SuperCall
left = new Literal @superReference o
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
@@ -818,20 +821,11 @@ exports.Call = class Call extends Base
compiledArgs.push (arg.compileToFragments o, LEVEL_LIST)...
fragments = []
if this instanceof SuperCall
preface = @superReference o
if preface is 'super'
preface += '('
else
preface += ".call(#{@superThis(o)}"
if compiledArgs.length then preface += ", "
fragments.push @makeCode preface
else
if @isNew then fragments.push @makeCode 'new '
fragments.push @variable.compileToFragments(o, LEVEL_ACCESS)...
fragments.push @makeCode "("
fragments.push compiledArgs...
fragments.push @makeCode ")"
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
#### Super
@@ -842,20 +836,15 @@ exports.Call = class Call extends Base
# expressions are evaluated without altering the return value of the `SuperCall`
# expression.
exports.SuperCall = class SuperCall extends Call
children: ['expressions']
constructor: (args) ->
super null, args ? [new Splat new IdentifierLiteral 'arguments']
# Allow to recognize a bare `super` call without parentheses and arguments.
@isBare = args?
children: Call::children.concat ['expressions']
isStatement: (o) ->
@expressions?.length and o.level is LEVEL_TOP
compileNode: (o) ->
return super unless @expressions?.length
return super o unless @expressions?.length
superCall = new Literal fragmentsToText super
superCall = new Literal fragmentsToText super o
replacement = new Block @expressions.slice()
if o.level > LEVEL_TOP
@@ -866,33 +855,26 @@ exports.SuperCall = class SuperCall extends Call
replacement.unshift superCall
replacement.compileToFragments o, if o.level is LEVEL_TOP then o.level else LEVEL_LIST
# Grab the reference to the superclass's implementation of the current
# method.
superReference: (o) ->
exports.Super = class Super extends Base
children: ['accessor']
constructor: (@accessor) ->
super()
compileNode: (o) ->
method = o.scope.namedMethod()
if method?.ctor
'super'
else if method?.klass
{klass, name, variable} = method
if klass.shouldCache()
bref = new IdentifierLiteral o.scope.parent.freeVariable 'base'
base = new Value new Parens new Assign bref, klass
variable.base = base
variable.properties.splice 0, klass.properties.length
@error 'cannot use super outside of an instance method' unless method?.isMethod
@inCtor = !!method.ctor
unless @inCtor 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
accesses = [new Access new PropertyName '__super__']
accesses.push new Access new PropertyName 'constructor' if method.isStatic
accesses.push if nref? then new Index nref else name
(new Value bref ? klass, accesses).compile o
else
@error 'cannot call super outside of an instance method.'
@accessor = if nref? then new Index nref else name
# The appropriate `this` value for a `super` call.
superThis : (o) ->
method = o.scope.method
(method and not method.klass and method.context) or "this"
(new Value (new Literal 'super'), if @accessor then [ @accessor ] else []).compileToFragments o
#### RegexWithInterpolations
@@ -1195,7 +1177,11 @@ exports.Class = class Class extends Base
@name = @determineName()
executableBody = @walkBody()
if executableBody
# 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 == parentName
if executableBody or @hasNameClash
@compileNode = @compileClassDeclaration
result = new ExecutableClassBody(@, executableBody).compileToFragments o
@compileNode = @constructor::compileNode
@@ -1302,8 +1288,7 @@ exports.Class = class Class extends Base
@boundMethods.push method.name
method.bound = false
# TODO Once `super` has been changed over to ES, the check for @parent can be removed
if @parent or initializer.length != expressions.length
if initializer.length != expressions.length
@body.expressions = (expression.hoist() for expression in initializer)
new Block expressions
@@ -1328,18 +1313,16 @@ exports.Class = class Class extends Base
# Returns a configured class initializer method
addInitializerMethod: (assign) ->
variable = assign.variable
method = assign.value
{ variable, value: method } = assign
method.isMethod = yes
method.isStatic = variable.looksStatic @name
method.klass = new IdentifierLiteral @name
method.variable = variable
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 function' if method.bound and method.ctor
@@ -1349,7 +1332,8 @@ exports.Class = class Class extends Base
ctor = @addInitializerMethod new Assign (new Value new PropertyName 'constructor'), new Code
@body.unshift ctor
ctor.body.push new SuperCall if @parent
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' ]
@@ -1394,19 +1378,17 @@ exports.ExecutableClassBody = class ExecutableClassBody extends Base
o.classScope = wrapper.makeScope o.scope
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 @class.parent
parent = new IdentifierLiteral o.classScope.freeVariable 'superClass', reserve: no
params.push new Param parent
args.push @class.parent
@class.parent = parent
@body.unshift new Literal "#{@name}.__super__ = #{parent.value}.prototype"
if @name != @class.name
@body.expressions.unshift new Assign (new IdentifierLiteral @name), @class
else
@@ -1442,8 +1424,6 @@ exports.ExecutableClassBody = class ExecutableClassBody extends Base
child.expressions[i] = @addProperties node.base.properties
else if node instanceof Assign and node.variable.looksStatic @name
node.value.isStatic = yes
else if node instanceof Code and node.isMethod
node.klass = new IdentifierLiteral @name
child.expressions = flatten child.expressions
cont
@@ -1670,15 +1650,10 @@ exports.Assign = class Assign extends Base
return @compileSpecialMath o if @context in ['**=', '//=', '%%=']
if @value instanceof Code
if @value.isStatic
@value.klass = @variable.base
@value.name = @variable.properties[0]
@value.variable = @variable
@value.name = @variable.properties[0]
else if @variable.properties?.length >= 2
[properties..., prototype, name] = @variable.properties
if prototype.name?.value is 'prototype'
@value.klass = new Value @variable.base, properties
@value.name = name
@value.variable = @variable
@value.name = name if prototype.name?.value is 'prototype'
unless @context
varBase = @variable.unwrapAll()
unless varBase.isAssignable()
@@ -1904,8 +1879,8 @@ exports.Code = class Code extends Base
# function body.
compileNode: (o) ->
if @ctor
@variable.error 'Class constructor may not be async' if @isAsync
@variable.error 'Class constructor may not be a generator' if @isGenerator
@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
@@ -2263,7 +2238,7 @@ exports.While = class While extends Base
makeReturn: (res) ->
if res
super
super res
else
@returns = not @jumps loop: yes
this
@@ -2985,7 +2960,6 @@ UTILITIES =
}
ctor.prototype = parent.prototype;
child.prototype = new ctor();
child.__super__ = parent.prototype;
return child;
}
"
@@ -3052,9 +3026,7 @@ isLiteralArguments = (node) ->
node instanceof IdentifierLiteral and node.value is 'arguments'
isLiteralThis = (node) ->
node instanceof ThisLiteral or
(node instanceof Code and node.bound) or
node instanceof SuperCall
node instanceof ThisLiteral or (node instanceof Code and node.bound)
shouldCacheOrIsAssignable = (node) -> node.shouldCache() or node.isAssignable?()