"
 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.
"

StatementNode subclass:#ReturnNode
	instanceVariableNames:'myHome blockHome'
	classVariableNames:''
	poolDictionaries:''
	category:'System-Compiler-Support'
!

!ReturnNode 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 return expressions
    This is a helper class for the compiler.

    [author:]
        Claus Gittinger
"
! !

!ReturnNode class methodsFor:'code generation helper'!

codeSimpleReturnFor:expression inBlock:b on:aStream inLine:lineNrOrNil for:aCompiler
    |type value index code code2|

    expression isPrimary ifTrue:[
        type := expression type.
        (type == #Nil) ifTrue:[
            code := #retNil
        ] ifFalse:[
            (type == #True) ifTrue:[
                code := #retTrue
            ] ifFalse:[
                (type == #False) ifTrue:[
                    code := #retFalse
                ] ifFalse:[
                    (type == #Self) ifTrue:[
                        code := #retSelf
                    ] ifFalse:[
                        (type == #Integer) ifTrue:[
                            value := expression evaluate.
                            (value between: -128 and:127) ifTrue:[
                                (value == 0) ifTrue:[
                                    code := #ret0
                                ] ifFalse:[
                                    code := #retNum.
                                    code2 := value. 
                                ]
                            ]
                        ] ifFalse:[
                            (type == #InstanceVariable) ifTrue:[
                                index := expression index.
                                (index <= 8) ifTrue:[
                                    code := #( retInstVar1
                                               retInstVar2
                                               retInstVar3
                                               retInstVar4
                                               retInstVar5
                                               retInstVar6
                                               retInstVar7
                                               retInstVar8) at:index
                                ]
                            ] ifFalse:[
                                (type == #MethodVariable) ifTrue:[
                                    index := expression index.
                                    (index <= 6) ifTrue:[
                                        code := #( retMethodVar1
                                                   retMethodVar2
                                                   retMethodVar3
                                                   retMethodVar4
                                                   retMethodVar5
                                                   retMethodVar6) at:index
                                    ]
                                ] ifFalse:[
                                    (type == #MethodArg) ifTrue:[
                                        index := expression index.
                                        (index <= 2) ifTrue:[
                                            code := #(retMethodArg1
                                                      retMethodArg2) at:index
                                        ]
                                    ]
                                ]
                            ]
                        ]
                    ]
                ]
            ]
        ]
    ].

    code isNil ifTrue:[
        expression codeOn:aStream inBlock:b for:aCompiler.
        code := #retTop
    ].

    lineNrOrNil notNil ifTrue:[
        ParseNode codeLineNumber:lineNrOrNil on:aStream for:aCompiler
    ].

    aStream nextPut:code.
    code2 notNil ifTrue:[
        aStream nextPut:code2
    ].

    "Created: 21.10.1996 / 14:37:35 / cg"
    "Modified: 21.10.1996 / 14:43:11 / cg"
! !

!ReturnNode methodsFor:'accessing'!

home:someOne blockHome:aBlockNode
    myHome := someOne.
    blockHome := aBlockNode
! !

!ReturnNode methodsFor:'code generation'!

codeForSideEffectOn:aStream inBlock:b for:aCompiler
    "redefined - drop not needed since notreached"

    ^ self codeOn:aStream inBlock:b for:aCompiler
!

codeOn:aStream inBlock:b for:aCompiler
    b isNil ifTrue:[
        ^ self class
            codeSimpleReturnFor:expression 
            inBlock:nil 
            on:aStream 
            inLine:lineNr 
            for:aCompiler
    ].

    expression codeOn:aStream inBlock:b for:aCompiler.

    lineNr notNil ifTrue:[
        ParseNode codeLineNumber:lineNr on:aStream for:aCompiler
    ].

    aStream nextPut:#homeRetTop.

    "Modified: 21.10.1996 / 14:54:36 / cg"
! !

!ReturnNode methodsFor:'evaluating'!

evaluateExpression
    |val|

    val := expression evaluate.
    myHome exitWith:val.
    "when we arrive here, the parser context is already gone
     - try block-return"
    blockHome notNil ifTrue:[blockHome exitWith:val].
    "well - what else can be done"
    ^ val
! !

!ReturnNode methodsFor:'printing'!

printOn:aStream indent:i
    aStream nextPutAll:'^ '.
    expression printOn:aStream
! !

!ReturnNode methodsFor:'queries'!

isConstant
    ^ false
!

isReturnNode
    ^ true
! !

!ReturnNode class methodsFor:'documentation'!

version
    ^ '$Header: /cvs/stx/stx/libcomp/ReturnNode.st,v 1.19 1996-10-23 15:31:02 cg Exp $'
! !