"

 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.

"

ParseNode subclass:#BlockNode

	instanceVariableNames:'blockArgs statements home inlineBlock exitBlock blockVars

		needsHome lineNr endLineNr blockArgAccessedInBlock'

	classVariableNames:''

	poolDictionaries:''

	category:'System-Compiler-Support'

!

!BlockNode 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 blocks

    This is a helper class for the compiler.

    [author:]

        Claus Gittinger

"

! !

!BlockNode class methodsFor:'instance creation'!

arguments:argList home:h variables:vars

    ^ (self basicNew) setArguments:argList home:h variables:vars

! !

!BlockNode methodsFor:'accessing'!

arguments

    ^ blockArgs

!

arguments:argList

    blockArgs := argList

!

blockArgAccessed

    "return true if any block argument is accessed in the block"

    ^ blockArgAccessedInBlock ? false

    "Modified: 18.6.1997 / 12:06:31 / cg"

!

blockArgAccessed:aBoolen

    "set/clear the flag stating if any block argument is accessed in the block"

    blockArgAccessedInBlock := aBoolen

    "Created: 18.6.1997 / 11:35:00 / cg"

    "Modified: 18.6.1997 / 12:06:43 / cg"

!

endLineNumber

    ^ endLineNr

    "Created: 23.10.1996 / 15:51:32 / cg"

!

endLineNumber:aNumber

    endLineNr := aNumber

    "Created: 21.10.1996 / 14:17:57 / cg"

!

home

    ^ home

!

home:aBlock

    home := aBlock

!

inlineBlock

    ^ inlineBlock

!

inlineBlock:aBoolean

    inlineBlock := aBoolean

!

lineNumber

    ^ lineNr

    "Created: 23.10.1996 / 15:51:50 / cg"

!

lineNumber:aNumber

    lineNr := aNumber

!

needsHome

    ^ needsHome

!

needsHome:aBoolean

    needsHome := aBoolean

!

statements

    ^ statements

!

statements:s

    statements := s

!

variables

    ^ blockVars

!

variables:varList

    blockVars := varList

! !

!BlockNode methodsFor:'block messages'!

doesNotUnderstand:aMessage

    |numArgs kludgeBlock|

    (Block implements:(aMessage selector)) ifTrue:[

	"/ mhmh - a message which I dont understand, but Block implements

	"/  send it to a kludgeblock, which will evaluate me again ..."

	numArgs := blockArgs size.

	numArgs == 0 ifTrue:[

	    kludgeBlock := [self value]

	] ifFalse:[

	    numArgs == 1 ifTrue:[

		kludgeBlock := [:a1 | self value:a1].

	    ] ifFalse:[

		numArgs == 2 ifTrue:[

		    kludgeBlock := [:a1 :a2 | self value:a1 value:a2].

		] ifFalse:[

		    numArgs == 3 ifTrue:[

			kludgeBlock := [:a1 :a2 :a3| self value:a1 value:a2 value:a3].

		    ] ifFalse:[

			numArgs == 4 ifTrue:[

			    kludgeBlock := [:a1 :a2 :a3 :a4| self value:a1 value:a2 value:a3 value:a4].

			] ifFalse:[

			    ^ self error:'only support blocks with up-to 4 args'

			]

		    ]

		]

	    ]

	].

	^ kludgeBlock perform:aMessage selector withArguments:aMessage arguments

    ].

    ^ super doesNotUnderstand:aMessage

! !

!BlockNode methodsFor:'code generation'!

checkForSimpleBlock

    "simple things can be made cheap blocks right now -

     resulting in a simple pushLit instruction ..."

    |cheapy e val code stackSize|

    statements isNil ifTrue:[

        "a []-block"

        val := nil

    ] ifFalse:[

        statements nextStatement notNil ifTrue:[^ nil].

        (statements isMemberOf:StatementNode) ifFalse:[^ nil].

        e := statements expression.

        e isConstant ifFalse:[^ nil].

        val := e value.

    ].

    stackSize := 0.

    val == 0 ifTrue:[

        "a [0]-block"

        code := ByteArray with:(ByteCodeCompiler byteCodeFor:#ret0).

    ].

    val == 1 ifTrue:[

        "a [1]-block"

        stackSize := 1.

        code := ByteArray with:(ByteCodeCompiler byteCodeFor:#push1)

                          with:(ByteCodeCompiler byteCodeFor:#retTop).

    ].

    val == true ifTrue:[

        "a [true]-block"

        code := ByteArray with:(ByteCodeCompiler byteCodeFor:#retTrue).

    ].

    val == false ifTrue:[

        "a [false]-block"

        code := ByteArray with:(ByteCodeCompiler byteCodeFor:#retFalse).

    ].

    val == nil ifTrue:[

        "a [nil]-block"

        code := ByteArray with:(ByteCodeCompiler byteCodeFor:#retNil).

    ].

    code notNil ifTrue:[

        cheapy := CheapBlock

                    byteCode:code

                    numArgs:(blockArgs size)

                    numStack:stackSize

                    sourcePosition:nil 

                    initialPC:nil 

                    literals:nil.

        ^ ConstantNode type:#Block value:cheapy

    ].

    ^ nil

    "Modified: 13.4.1997 / 00:05:29 / cg"

!

codeForSideEffectOn:aStream inBlock:b for:aCompiler

    "generate code for this statement - value not needed.

     For blocks, no code is generated at all."

    ^ self

!

codeInlineOn:aStream inBlock:b for:aCompiler

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

!

codeInlineOn:aStream inBlock:b valueNeeded:valueNeeded for:aCompiler

    |thisStatement nextStatement|

    blockVars notNil ifTrue:[

        "cannot currently compile this block inline (have to move blockvars into

         surrounding method. generate a make-block and send it value"

"/        Transcript showCR:'cannot (yet) compile block with blockvars inline'.

        self codeOn:aStream inBlock:b for:aCompiler.

        aStream nextPut:#value.

        (aCompiler hasLineNumber:#value) ifTrue:[

            aStream nextPut:lineNr.

        ].

        valueNeeded ifFalse:[

            aStream nextPut:#drop

        ].

        ^ self

    ].

    inlineBlock := true.

    statements isNil ifTrue:[

        valueNeeded ifTrue:[

            aStream nextPut:#pushNil

        ]

    ] ifFalse:[

        thisStatement := statements.

        [thisStatement notNil] whileTrue:[

            nextStatement := thisStatement nextStatement.

            (nextStatement notNil or:[valueNeeded not]) ifTrue:[

                thisStatement codeForSideEffectOn:aStream inBlock:b for:aCompiler

            ] ifFalse:[

                thisStatement codeOn:aStream inBlock:b for:aCompiler

            ].

            thisStatement := nextStatement

        ]

    ].

"/    endLineNr notNil ifTrue:[

"/        ParseNode codeLineNumber:endLineNr on:aStream for:aCompiler

"/    ].

    "Modified: 21.10.1996 / 16:57:53 / cg"

!

codeOn:aStream inBlock:b for:aCompiler

    |thisStatement nextStatement lastStatement pos code cheapy p0|

    cheapy := self checkForSimpleBlock.

    cheapy notNil ifTrue:[

        cheapy codeOn:aStream inBlock:b for:aCompiler.

        ^ self

    ].

    pos := aStream position.

    aStream nextPut:#makeBlock.            "+0"

    aStream nextPut:0.                     "+1"

    aStream nextPut:(blockVars size).      "+2"

    aStream nextPut:(blockArgs size).      "+3"

                                           "+4"

    p0 := pos+4.

    statements isNil ifTrue:[

        endLineNr notNil ifTrue:[

            ParseNode codeLineNumber:endLineNr on:aStream for:aCompiler

        ].

        aStream nextPut:#pushNil.          

        aStream nextPut:#retTop.

    ] ifFalse:[

        thisStatement := statements.

        [thisStatement notNil] whileTrue:[

            nextStatement := thisStatement nextStatement.

            nextStatement notNil ifTrue:[

                thisStatement codeForSideEffectOn:aStream inBlock:self for:aCompiler

            ] ifFalse:[

                lastStatement := thisStatement

            ].

            thisStatement := nextStatement

        ].

        lastStatement isPrimary ifTrue:[

            ReturnNode

                codeSimpleReturnFor:lastStatement expression 

                inBlock:nil 

                on:aStream 

                inLine:endLineNr 

                for:aCompiler

        ].

        lastStatement codeOn:aStream inBlock:self for:aCompiler.

        endLineNr notNil ifTrue:[

            ParseNode codeLineNumber:endLineNr on:aStream for:aCompiler

        ].

        aStream nextPut:#retTop.

    ].

    "check for [0]-block;

     these are sometimes used as in ... ifAbsent:[0]

    "

    code := (aStream contents).

    (code at:p0) == #lineno ifTrue:[

        p0 := p0 + 2

    ] ifFalse:[

        (code at:p0) == #lineno16 ifTrue:[

            p0 := p0 + 3

        ]

    ].

    (code at:p0) == #ret0 ifTrue:[

        aStream position:pos.

        code grow:pos.

        aStream nextPut:#mk0Block.

        ^ self

    ].    

    "check for [nil]-block;

     these come to play when code in blocks is commented

     out, or as dummy exception blocks

    "

    (code at:p0) == #retNil ifTrue:[

        aStream position:pos.

        code grow:pos.

        aStream nextPut:#mkNilBlock.

        ^ self

    ].    

    code at:pos+1 put:(aStream position)

    "Modified: 23.10.1996 / 15:40:46 / cg"

! !

!BlockNode methodsFor:'evaluating'!

evaluate

    ^ self

!

exitWith:something

    "return via return-statement"

    home notNil ifTrue:[

	home exitWith:something

    ].

    exitBlock value:something.

    ^ something

!

value

    (blockArgs size ~~ 0) ifTrue:[

	^ self wrongNumberOfArguments:0

    ].

    statements isNil ifTrue:[^ nil].

    exitBlock := [:val | ^ val].

    ^ statements evaluate

!

value:anArg

    |oldValue val|

    (blockArgs size ~~ 1) ifTrue:[

	^ self wrongNumberOfArguments:1

    ].

    statements isNil ifTrue:[^ nil].

    oldValue := (blockArgs at:1) value.

    (blockArgs at:1) value:anArg.

    exitBlock := [:v | 

	(blockArgs at:1) value:oldValue.

	^ v

    ].

    val := statements evaluate.

    (blockArgs at:1) value:oldValue.

    ^ val

!

value:arg1 value:arg2

    |oldValue1 oldValue2 val|

    (blockArgs size ~~ 2) ifTrue:[

	^ self wrongNumberOfArguments:2

    ].

    statements isNil ifTrue:[^ nil].

    oldValue1 := (blockArgs at:1) value.

    oldValue2 := (blockArgs at:2) value.

    (blockArgs at:1) value:arg1.

    (blockArgs at:2) value:arg2.

    exitBlock := [:v | 

	(blockArgs at:1) value:oldValue1.

	(blockArgs at:2) value:oldValue2.

	^ v

    ].

    val := statements evaluate.

    (blockArgs at:1) value:oldValue1.

    (blockArgs at:2) value:oldValue2.

    ^ val

!

value:arg1 value:arg2 value:arg3

    |oldValue1 oldValue2 oldValue3 val|

    (blockArgs size ~~ 3) ifTrue:[

	^ self wrongNumberOfArguments:3

    ].

    statements isNil ifTrue:[^ nil].

    oldValue1 := (blockArgs at:1) value.

    oldValue2 := (blockArgs at:2) value.

    oldValue3 := (blockArgs at:3) value.

    (blockArgs at:1) value:arg1.

    (blockArgs at:2) value:arg2.

    (blockArgs at:3) value:arg3.

    exitBlock := [:v | 

	(blockArgs at:1) value:oldValue1.

	(blockArgs at:2) value:oldValue2.

	(blockArgs at:3) value:oldValue3.

	^ v

    ].