amber/st/Compiler-Semantic.st

Smalltalk current createPackage: 'Compiler-Semantic' properties: #{}!
Object subclass: #LexicalScope
	instanceVariableNames: 'temps args outerScope'
	package: 'Compiler-Semantic'!
!LexicalScope commentStamp!
I represent a lexical scope where variable names are associated with ScopeVars
Instances are used for block scopes. Method scopes are instances of MethodLexicalScope.

I am attached to a ScopeVar and method/block nodes.
Each context (method/closure) get a fresh scope that inherits from its outer scope.!

!LexicalScope methodsFor: 'accessing'!

allVariableNames
	^ self args keys, self temps keys
!

args
	^ args ifNil: [ args := Dictionary new ]
!

bindingFor: aStringOrNode
	^ self args at: aStringOrNode value ifAbsent: [
		self temps at: aStringOrNode value ifAbsent: [ nil ]]
!

lookupVariable: aNode
	| lookup |
	lookup := (self bindingFor: aNode).
	lookup ifNil: [
		lookup := self outerScope ifNotNil: [ 
			(self outerScope lookupVariable: aNode) ]].
	^ lookup
!

methodScope
	^ self outerScope ifNotNil: [
		self outerScope methodScope ]
!

outerScope
	^ outerScope
!

outerScope: aLexicalScope
	outerScope := aLexicalScope
!

temps
	^ temps ifNil: [ temps := Dictionary new ]
! !

!LexicalScope methodsFor: 'adding'!

addArg: aString
	self args at: aString put: (ArgVar on: aString).
	(self args at: aString) scope: self
!

addTemp: aString
	self temps at: aString put: (TempVar on: aString).
	(self temps at: aString) scope: self
! !

!LexicalScope methodsFor: 'testing'!

isMethodScope
	^ false
! !

LexicalScope subclass: #MethodLexicalScope
	instanceVariableNames: 'iVars unknownVariables nonLocalReturn'
	package: 'Compiler-Semantic'!
!MethodLexicalScope commentStamp!
I represent a method scope.!

!MethodLexicalScope methodsFor: 'accessing'!

allVariableNames
	^ super allVariableNames, self iVars keys
!

bindingFor: aNode
	^ (super bindingFor: aNode) ifNil: [
		self iVars at: aNode value ifAbsent: [ nil ]]
!

iVars
	^ iVars ifNil: [ iVars := Dictionary new ]
!

methodScope
	^ self
!

nonLocalReturn
	^ nonLocalReturn ifNil: [ false ]
!

nonLocalReturn: aBoolean
	nonLocalReturn := aBoolean
!

unknownVariables
	^ unknownVariables ifNil: [ unknownVariables := OrderedCollection new ]
! !

!MethodLexicalScope methodsFor: 'adding'!

addIvar: aString
	self iVars at: aString put: (InstanceVar on: aString).
	(self iVars at: aString) scope: self
! !

!MethodLexicalScope methodsFor: 'testing'!

hasNonLocalReturn
	^ self nonLocalReturn
!

isMethodScope
	^ true
! !

Object subclass: #ScopeVar
	instanceVariableNames: 'scope name'
	package: 'Compiler-Semantic'!
!ScopeVar commentStamp!
I am an entry in a LexicalScope that gets associated with variable nodes of the same name.  
There are 4 different subclasses of vars: temp vars, local vars, args, and unknown/global vars.!

!ScopeVar methodsFor: 'accessing'!

alias
	^ self name asVariableName
!

name
	^ name
!

name: aString
	name := aString
!

scope
	^ scope
!

scope: aScope
	scope := aScope
! !

!ScopeVar methodsFor: 'testing'!

isArgVar
	^ false
!

isInstanceVar
	^ false
!

isTempVar
	^ false
!

isUnknownVar
	^ false
! !

!ScopeVar class methodsFor: 'instance creation'!

on: aString
	^ self new 
		name: aString;
		yourself
! !

ScopeVar subclass: #AliasVar
	instanceVariableNames: ''
	package: 'Compiler-Semantic'!
!AliasVar commentStamp!
I am an internally defined variable by the compiler!

ScopeVar subclass: #ArgVar
	instanceVariableNames: ''
	package: 'Compiler-Semantic'!
!ArgVar commentStamp!
I am an argument of a method or block.!

!ArgVar methodsFor: 'testing'!

isArgVar
	^ true
! !

ScopeVar subclass: #ClassRefVar
	instanceVariableNames: ''
	package: 'Compiler-Semantic'!

!ClassRefVar methodsFor: 'accessing'!

alias
	^ '(Smalltalk.', self name, ' || ', self name, ')'
! !

ScopeVar subclass: #InstanceVar
	instanceVariableNames: ''
	package: 'Compiler-Semantic'!
!InstanceVar commentStamp!
I am an instance variable of a method or block.!

!InstanceVar methodsFor: 'testing'!

alias
	^ 'self["@', self name, ']'
!

isInstanceVar
	^ true
! !

ScopeVar subclass: #TempVar
	instanceVariableNames: ''
	package: 'Compiler-Semantic'!
!TempVar commentStamp!
I am an temporary variable of a method or block.!

!TempVar methodsFor: 'testing'!

isTempVar
	^ true
! !

ScopeVar subclass: #UnknownVar
	instanceVariableNames: ''
	package: 'Compiler-Semantic'!
!UnknownVar commentStamp!
I am an unknown variable. Amber uses unknown variables as JavaScript globals!

!UnknownVar methodsFor: 'testing'!

isUnknownVar
	^ true
! !

NodeVisitor subclass: #SemanticAnalyzer
	instanceVariableNames: 'currentScope theClass classReferences messageSends'
	package: 'Compiler-Semantic'!
!SemanticAnalyzer commentStamp!
I semantically analyze the abstract syntax tree and annotate it with informations such as non local returns and variable scopes.!

!SemanticAnalyzer methodsFor: 'accessing'!

classReferences
	^ classReferences ifNil: [ classReferences := Set new ]
!

messageSends
	^ messageSends ifNil: [ messageSends := Set new ]
!

pseudoVariables
	^#('self' 'super' 'true' 'false' 'nil' 'thisContext')
!

theClass
	^ theClass
!

theClass: aClass
	theClass := aClass
! !

!SemanticAnalyzer methodsFor: 'error handling'!

errorInvalidAssignment: aString
	InvalidAssignmentError new
		variableName: aString;
		signal
!

errorShadowingVariable: aString
	ShadowingVariableError new
		variableName: aString;
		signal
!

errorUnknownVariable: aNode
	self allowUnknownVariables 
		ifTrue: [ currentScope methodScope unknownVariables add: aNode value ]
		ifFalse: [ 
			UnknownVariableError new
				variableName: aNode value;
				signal ]
! !

!SemanticAnalyzer methodsFor: 'factory'!

newBlockScope
	^ self newScopeOfClass: LexicalScope
!

newMethodScope
	^ self newScopeOfClass: MethodLexicalScope
!

newScopeOfClass: aLexicalScopeClass
	^ aLexicalScopeClass new 
		outerScope: currentScope;
		yourself
! !

!SemanticAnalyzer methodsFor: 'scope'!

popScope
	currentScope ifNotNil: [
		currentScope := currentScope outerScope ]
!

pushScope: aScope
	aScope outerScope: currentScope.
	currentScope := aScope
!

validateVariableScope: aString
	"Validate the variable scope in by doing a recursive lookup, up to the method scope"

	(currentScope lookupVariable: aString) ifNotNil: [
		self errorShadowingVariable: aString ]
! !

!SemanticAnalyzer methodsFor: 'testing'!

allowUnknownVariables
	^ true
! !

!SemanticAnalyzer methodsFor: 'visiting'!

visitAssignmentNode: aNode
	(self pseudoVariables includes: aNode left value) ifTrue: [
		self errorInvalidAssignment: aNode left ].
	aNode left beAssigned.
	aNode right beUsed.
	super visitAssignmentNode: aNode
!

visitBlockNode: aNode
	self pushScope: self newBlockScope.
	aNode scope: currentScope.
	
	aNode parameters do: [ :each | 
		self validateVariableScope: each.
		currentScope addArg: each ].

	super visitBlockNode: aNode.
	self popScope
!

visitClassReferenceNode: aNode
	self classReferences add: aNode value.
	aNode binding: (ClassRefVar new name: aNode value; yourself)
!

visitMethodNode: aNode
	self pushScope: self newMethodScope.
	aNode scope: currentScope.

	self theClass allInstanceVariableNames do: [:each | 
		currentScope addIVar: each ].
	aNode arguments do: [ :each | 
		self validateVariableScope: each.
		currentScope addArg: each ].

	super visitMethodNode: aNode.

	aNode 
		classReferences: self classReferences;
		messageSends: self messageSends.
	self popScope
!

visitReturnNode: aNode
	currentScope isMethodScope ifFalse: [
		currentScope methodScope nonLocalReturn: true.
		aNode nonLocalReturn: true ].
	aNode nodes first beUsed.
	super visitReturnNode: aNode
!

visitSendNode: aNode
	self messageSends add: aNode selector.
	aNode receiver beUsed.
	aNode arguments do: [ :each |
		each beUsed ].
	super visitSendNode: aNode
!

visitSequenceNode: aNode
	aNode temps do: [ :each | 
		self validateVariableScope: each.
		currentScope addTemp: each ].

	super visitSequenceNode: aNode
!

visitVariableNode: aNode
	"Bind a ScopeVar to aNode by doing a lookup in the current scope.
	If no ScopeVar is found, bind a UnknowVar and throw an error"

	aNode binding: ((currentScope lookupVariable: aNode) ifNil: [ 
		self errorUnknownVariable: aNode.
		UnknownVar new name: aNode value; yourself ])
! !

!SemanticAnalyzer class methodsFor: 'instance creation'!

on: aClass
	^ self new
		theClass: aClass;
		yourself
! !

Error subclass: #SemanticError
	instanceVariableNames: ''
	package: 'Compiler-Semantic'!
!SemanticError commentStamp!
I represent an abstract semantic error thrown by the SemanticAnalyzer.
Semantic errors can be unknown variable errors, etc.
See my subclasses for concrete errors.

The IDE should catch instances of Semantic error to deal with them when compiling!

SemanticError subclass: #InvalidAssignmentError
	instanceVariableNames: 'variableName'
	package: 'Compiler-Semantic'!
!InvalidAssignmentError commentStamp!
I get signaled when a pseudo variable gets assigned.!

!InvalidAssignmentError methodsFor: 'accessing'!

variableName
	^ variableName
!

variableName: aString
	variableName := aString
! !

SemanticError subclass: #ShadowingVariableError
	instanceVariableNames: 'variableName'
	package: 'Compiler-Semantic'!
!ShadowingVariableError commentStamp!
I get signaled when a variable in a block or method scope shadows a variable of the same name in an outer scope.!

!ShadowingVariableError methodsFor: 'accessing'!

variableName
	^ variableName
!

variableName: aString
	variableName := aString
! !

SemanticError subclass: #UnknownVariableError
	instanceVariableNames: 'variableName'
	package: 'Compiler-Semantic'!
!UnknownVariableError commentStamp!
I get signaled when a variable is not defined.
The default behavior is to allow it, as this is how Amber currently is able to seamlessly send messages to JavaScript objects.!

!UnknownVariableError methodsFor: 'accessing'!

variableName
	^ variableName
!

variableName: aString
	variableName := aString
! !