"

 COPYRIGHT (c) 1989 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

"{ Package: 'stx:libcomp' }"

ParseNode subclass:#AssignmentNode

	instanceVariableNames:'variable expression lineNr'

	classVariableNames:''

	poolDictionaries:''

	category:'System-Compiler-Support'

!

!AssignmentNode class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1989 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

!

documentation

"

    node for parse-trees, representing assignments.

    This is a helper class for the compiler.

    [author:]

        Claus Gittinger

"

! !

!AssignmentNode class methodsFor:'instance creation'!

variable:v expression:e

    ^ (self basicNew) variable:v expression:e

! !

!AssignmentNode methodsFor:'accessing'!

expression

    ^ expression

!

lineNumber

    "return lineNr"

    ^ lineNr

    "Created: / 14.5.1998 / 19:30:49 / cg"

!

lineNumber:something

    "set lineNr"

    lineNr := something.

    "Created: / 14.5.1998 / 19:30:54 / cg"

!

variable

    ^ variable

    "Created: 19.6.1997 / 17:08:58 / cg"

!

variable:v expression:e

    variable := v.

    expression := e.

    "/ any block, which gets assigned to something

    "/ cannot be inlined.

    (e notNil and:[e isBlockNode]) ifTrue:[

        e possiblyInlined:false

    ]

! !

!AssignmentNode methodsFor:'code generation'!

checkIncDecOn:aStream

    "check if we can use incMvar / decMvar instruction.

     If so, code it and return true.

     Otherwise, return false."

    |sel erec arg code|

    (variable type == #MethodVariable) ifTrue:[

        expression isBinaryMessage ifTrue:[

            sel := expression selector.

            erec := expression receiver.

            ((sel == #+) or:[sel == #-]) ifTrue:[

                (erec type == #MethodVariable) ifTrue:[

                    (erec index == variable index) ifTrue:[

                        arg := expression arg1.

                        arg isConstant ifTrue:[

                            (arg value == 1) ifTrue:[

                                (sel == #+) ifTrue:[

                                    code := #incMethodVar

                                ] ifFalse:[

                                    code := #decMethodVar

                                ].

                                aStream nextPut:code; nextPut:(expression lineNumber); nextPut:(variable index).

                                ^ true

                            ]

                        ]

                    ]

                ]

            ]

        ]

    ].

    ^ false

    "Modified: 1.3.1996 / 00:08:02 / cg"

!

codeForSideEffectOn:aStream inBlock:b for:aCompiler

    (self checkIncDecOn:aStream) ifTrue:[^ self].

    self codeNormalOn:aStream valueNeeded:false inBlock:b for:aCompiler

    "Modified: 4.9.1995 / 14:38:10 / claus"

    "Modified: 1.3.1996 / 00:42:10 / cg"

!

codeNormalOn:aStream valueNeeded:forValue inBlock:b for:aCompiler

    |isSend litIdx selLitIdx|

    isSend := expression isMessage.

    (lineNr notNil 

     and:[isSend not]) ifTrue:[

        self codeLineNumber:lineNr on:aStream for:aCompiler

    ].

    "/ must do workspace variables here, because these

    "/ need the receiver (the valueHolder) to be pushed first,

    "/ then the value which is to be stored.

    "/ finally, a #value: message is generated.

    (variable type == #WorkspaceVariable) ifTrue:[

        "/ this is done by keeping the valueHolder in the literalArray,

        "/ and coding a #value: message here.

        litIdx := aCompiler addLiteral:variable token.

        self emitPushLiteralIndex:litIdx on:aStream for:aCompiler.

        expression codeOn:aStream inBlock:b for:aCompiler.

        selLitIdx := aCompiler addLiteral:#value:.

        self emitSendLiteralIndex:selLitIdx numArgs:1 line:(lineNr ? 1) on:aStream.

        aStream nextPut:#drop.

        forValue ifTrue:[

            (expression isConstant or:[expression isVariable]) ifTrue:[

                expression codeOn:aStream inBlock:b for:aCompiler.

            ] ifFalse:[

                "/ fetch value from the holder - sigh

                self emitPushLiteralIndex:litIdx on:aStream for:aCompiler.

                selLitIdx := aCompiler addLiteral:#value.

                self emitSendLiteralIndex:selLitIdx numArgs:0 line:(lineNr ? 1) on:aStream.

            ]

        ].

        ^ self

    ].

    expression codeOn:aStream inBlock:b for:aCompiler.

    expression isBlock ifTrue:[

        variable isLocal ifTrue:[

            aStream nextPut:#blockRef

        ]

    ].

    (lineNr notNil

     and:[isSend]) ifTrue:[

        self codeLineNumber:lineNr on:aStream for:aCompiler

    ].

    variable codeStoreOn:aStream inBlock:b valueNeeded:forValue for:aCompiler

    "Modified: 4.9.1995 / 14:38:10 / claus"

    "Created: 1.3.1996 / 00:41:43 / cg"

    "Modified: 21.10.1996 / 16:26:33 / cg"

!

codeOn:aStream inBlock:b for:aCompiler

    (self checkIncDecOn:aStream) ifTrue:[

        expression receiver codeOn:aStream inBlock:b for:aCompiler.

        ^ self

    ].

    self codeNormalOn:aStream valueNeeded:true inBlock:b for:aCompiler

    "Modified: 1.3.1996 / 00:42:21 / cg"

! !

!AssignmentNode methodsFor:'enumerating'!

nodeDo:anEnumerator

    "helper for parse tree walking"

    ^ anEnumerator doAssignment:self variable:variable value:expression

    "Modified: 19.6.1997 / 16:37:50 / cg"

! !

!AssignmentNode methodsFor:'evaluation'!

evaluateIn:anEnvironment

    |value|

    value := expression evaluateIn:anEnvironment.

    variable store:value.

    ^ value

! !

!AssignmentNode methodsFor:'printing & storing'!

printOn:aStream indent:i

    variable printOn:aStream.

    self printOperatorOn:aStream.

    expression printOn:aStream

!

printOperatorOn:aStream

    aStream nextPutAll:' := '.

! !

!AssignmentNode methodsFor:'queries'!

collectBlocksInto:aCollection

    expression collectBlocksInto:aCollection.

    "Created: 11.1.1997 / 20:54:30 / cg"

!

isAssignment

    "return true, if this is a node for an assignment"

    ^ true

!

precedence

    ^ 0

    "Created: / 20-04-2005 / 14:11:09 / cg"

! !

!AssignmentNode class methodsFor:'documentation'!

version

    ^ '$Header: /cvs/stx/stx/libcomp/AssignmentNode.st,v 1.38 2008-02-27 14:50:58 cg Exp $'

! !