"

 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:#MessageNode

       instanceVariableNames:'receiver selector argArray lineNr'

       classVariableNames:''

       poolDictionaries:''

       category:'System-Compiler-Support'

!

MessageNode comment:'

COPYRIGHT (c) 1989 by Claus Gittinger

	      All Rights Reserved

'!

!MessageNode 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.

"

!

version

"

"

!

documentation

"

    node for parse-trees, representing message sends

"

! !

!MessageNode class methodsFor:'instance creation'!

receiver:recNode selector:selectorString 

    ^ (self basicNew) receiver:recNode selector:selectorString args:nil lineno:0

!

receiver:recNode selector:selectorString arg:argNode

    ^ self receiver:recNode selector:selectorString arg:argNode fold:true

!

receiver:recNode selector:selectorString arg:argNode fold:folding

   "

     The constant folding code can usually not optimize much

     - this may change when some kind of constant/macro declaration is added to smalltalk.

    "

    folding ifTrue:[

	"do constant folding ..."

	(recNode isConstant and:[argNode isConstant]) ifTrue:[

	    "check if we can do it ..."

	    selectorString knownAsSymbol ifTrue:[

		selector := selectorString asSymbol.

		recVal := recNode evaluate.

		(recVal respondsTo:selector) ifTrue:[

		    "

		     we could do much more here - but then, we need a dependency from

		     the folded selectors method to the method we generate code for ...

		     limit optimizations to those that will never change

		     (or - if you change them - you will crash so bad ...)

		    "

		    argVal := argNode evaluate.

		    (recVal respondsToArithmetic and:[argVal respondsToArithmetic]) ifTrue:[

			(#( @ + - * / // \\ min: max: quo:) includes:selector) ifTrue:[

			    (#( / // \\ ) includes:selector) ifTrue:[

				argVal = 0 ifTrue:[

				    ^ 'division by zero in constant expression'

				].

			    ].

			]

		    ].

		    (recVal isMemberOf:String) ifTrue:[

			].

			]

		    ]

		]

	    ]

    ].

    ^ (self basicNew) receiver:recNode selector:selectorString args:(Array with:argNode) lineno:0

!

receiver:recNode selector:selectorString arg1:argNode1 arg2:argNode2 fold:folding

    |result recVal argVal selector|

    "

     This is just a demonstration - of how complex constants can be folded.

     This was inspired by some discussion in c.l.s about enhancing the language - I prefer

     enhancing the compiler ....

     The following optimization will convert '#(...) with:#(...) collect:[...]' into an array constant,

     allowing a constant arrays of complex objects.

     Notice: this method is normally disabled - its just a demo after all.

    "

    folding ifTrue:[

	"do constant folding ..."

	(recNode isConstant and:[argNode1 isConstant]) ifTrue:[

	    "check if we can do it ..."

	    selectorString knownAsSymbol ifTrue:[

		selector := selectorString asSymbol.

		recVal := recNode evaluate.

		(recVal respondsTo:selector) ifTrue:[

		    "

		     we could do much more here - but then, we need a dependency from

		     the folded selectors method to the method we generate code for ...

		     limit optimizations to those that will never change

		     (or - if you change them - you will crash so bad ...)

		    "

		    argVal := argNode1 evaluate.

		    ((recVal isMemberOf:Array) and:[argVal isMemberOf:Array]) ifTrue:[

			(selector == #with:collect:) ifTrue:[

			    (argNode2 isMemberOf:BlockNode) ifTrue:[

				(SignalSet anySignal catch:[

				    result := recVal perform:selector with:argVal with:(argNode2 evaluate).

				]) ifTrue:[

				    ^ 'error in constant expression'

				].

				^ ConstantNode type:(ConstantNode typeOfConstant:result) value:result

			    ]

			]

		    ]

		]

	    ]

	]

    ].

    ^ (self basicNew) receiver:recNode selector:selectorString args:(Array with:argNode1 with:argNode2) lineno:0

!

receiver:recNode selector:selectorString args:anArray

    ^ self receiver:recNode selector:selectorString args:anArray fold:true

!

receiver:recNode selector:selectorString args:argArray fold:folding

    folding ifTrue:[

	(argArray size == 1) ifTrue:[

	    ^ self receiver:recNode selector:selectorString arg:(argArray at:1) fold:true 

	].

	"uncomment the follwoing for a nice array initializer optimization ..."

"/        (argArray size == 2) ifTrue:[

"/            ^ self receiver:recNode selector:selectorString arg1:(argArray at:1) arg2:(argArray at:2) fold:true 

"/        ].

    ].

    ^ (self basicNew) receiver:recNode selector:selectorString args:argArray lineno:0

! !

!MessageNode methodsFor:'accessing'!

receiver:r selector:s args:a lineno:l

    receiver := r.

    selector := s asSymbol.

    argArray := a.

    lineNr := l

!

receiver

    ^ receiver

!

selector

    ^ selector

!

args

    ^ argArray

!

arg1

    ^ argArray at:1

!

lineNumber

     ^ lineNr

!

lineNumber:num

     lineNr := num

! !

!MessageNode methodsFor:'queries'!

isMessage

    ^ true

! !

!MessageNode class methodsFor:'queries'!

hasLineNumber:sel

    "return true, if special send code needs lineNr"

    (sel == #==) ifTrue:[^ false].

    (sel == #~~) ifTrue:[^ false].

    (sel == #class) ifTrue:[^ false].

    ^ true

!

isBuiltInUnarySelector:sel

    "return true, if unary selector sel is built-in. 

     (i.e. there is a single bytecode for it)"

    (sel == #peek) ifTrue:[^ true].

    (sel == #value) ifTrue:[^ true].

    (sel == #next) ifTrue:[^ true].

    (sel == #class) ifTrue:[^ true].

    (sel == #size) ifTrue:[^ true].

    (sel == #x) ifTrue:[^ true].

    (sel == #y) ifTrue:[^ true].

    (sel == #width) ifTrue:[^ true].

    (sel == #height) ifTrue:[^ true].

    (sel == #origin) ifTrue:[^ true].

    (sel == #extent) ifTrue:[^ true].

    (sel == #asInteger) ifTrue:[^ true].

    (sel == #rounded) ifTrue:[^ true].

    ^ false

!

isBuiltIn1ArgSelector:sel

    "return true, if selector sel is built-in.

     (i.e. there is a single bytecode for it)"

    (sel == #at:) ifTrue:[^ true].

    (sel == #value:) ifTrue:[^ true].

    (sel == #bitAnd:) ifTrue:[^ true].

    (sel == #bitOr:) ifTrue:[^ true].

    ^ false

!

isBuiltIn2ArgSelector:sel

    "return true, if selector sel is built-in.

     (i.e. there is a single bytecode for it)"

    (sel == #at:put:) ifTrue:[^ true].

    ^ false

! !

!MessageNode methodsFor:'printing'!

printOn:aStream indent:i

    |needParen selectorParts index index2 arg|

    (#(whileTrue: whileFalse:) includes:selector) ifTrue:[

	(receiver isKindOf:BlockNode) ifTrue:[

	    ^ self printWhileOn:aStream indent:i

	].

    ].

    index := 1.

    selectorParts := OrderedCollection new.

    [index == 0] whileFalse:[

	index2 := selector indexOf:$: startingAt:index.

	index2 ~~ 0 ifTrue:[

	    selectorParts add:(selector copyFrom:index to:index2).

	    index2 := index2 + 1

	].

	index := index2

    ].

    needParen := false.

    receiver isMessage ifTrue:[

	receiver isUnaryMessage ifFalse:[

	    receiver isBinaryMessage ifFalse:[

		needParen := true

	    ].

	].

    ].

    needParen ifTrue:[

	aStream nextPutAll:'('

    ].

    receiver printOn:aStream indent:i.

    needParen ifTrue:[

	aStream nextPutAll:')'

    ].

    1 to:(argArray size) do:[:argIndex |

	aStream space.

	(selectorParts at:argIndex) printOn:aStream.

	aStream space.

	arg := argArray at:argIndex.

	needParen := false.

	arg isMessage ifTrue:[

	    arg isBinaryMessage ifFalse:[

		arg isUnaryMessage ifFalse:[

		    needParen := true

		]

	    ].

	].

	needParen ifTrue:[

	    aStream nextPutAll:'('

	].

	arg printOn:aStream indent:i.

	needParen ifTrue:[

	    aStream nextPutAll:') '

	].

    ]

!

printWhileOn:aStream indent:i

    |needParen arg|

    "special handling of whileTrue/whileFalse"

    aStream nextPutAll:'['.

    receiver statements printOn:aStream indent:i.

    aStream nextPutAll:'] whileTrue: '.

    arg := argArray at:1.

    needParen := false.

    arg isMessage ifTrue:[

	arg isBinaryMessage ifFalse:[

	    arg isUnaryMessage ifFalse:[

		needParen := true

	    ]

	].

    ].

    needParen ifTrue:[

	aStream nextPutAll:'('

    ].

    arg printOn:aStream indent:i.

    needParen ifTrue:[

	aStream nextPutAll:') '

    ].

! !

!MessageNode methodsFor:'checks'!

plausibilityCheck

    |rec arg operand|

    "

     it once took me almost an hour, to find a '==' which

     should have been an '=' (you cannot compare floats with ==)

     (well, I looked at the '==' at least 50 times -

      - but didn't think about it ...).

     thats reason enough to add this check here.

     I will add more as heuristic knowledge increases ...

     (send me comments on common programming errors ...)

    "

    "

     check #== appled to Floats, Strings or Fractions

    "

    ((selector == #==) or:[selector == #~~]) ifTrue:[

	receiver isConstant ifTrue:[

	    rec := receiver evaluate.

	    ((rec isMemberOf:String) or:[

	     (rec isMemberOf:Float) or:[

	     (rec isMemberOf:Fraction)]]) ifTrue:[

		operand := rec

	    ].

	].

	(argArray at:1) isConstant ifTrue:[

	    arg := (argArray at:1) evaluate.

	    ((arg isMemberOf:String) or:[

	     (arg isMemberOf:Float) or:[

	     (arg isMemberOf:Fraction)]]) ifTrue:[

		operand := arg

	    ].

	].

	operand notNil ifTrue:[

	    (selector == #==) ifTrue:[

		^ 'identity compare is unsafe here'

	    ].

	    ^ 'identity compare will usually return true here'

	]

    ].

    "

     [...] ifTrue:...

     an error often occuring when you are a beginner ...

    "

    ((selector == #ifTrue:) or:[selector == #ifFalse:]) ifTrue:[

	receiver isBlock ifTrue:[

	    (Block canUnderstand:selector) ifFalse:[

		^ 'blocks usually do not respond to ' , selector , ' messages'

	    ].

	].

	(argArray at:1) isBlock ifFalse:[

	    ^ 'will fail at runtime, if argument to ' , selector , ' does not evaluate to a block'

	]

    ].

    ((selector == #ifTrue:ifFalse:) or:[selector == #ifFalse:ifTrue:]) ifTrue:[

	receiver isBlock ifTrue:[

	    (Block canUnderstand:selector) ifFalse:[

		^ 'blocks usually do not respond to ' , selector , ' messages'

	    ].

	].

	(argArray at:1) isBlock ifFalse:[

	    ^ 'will fail at runtime, if 1st. argument to ' , selector , ' does not evaluate to a block'

	].

	(argArray at:2) isBlock ifFalse:[

	    ^ 'will fail at runtime, if 2nd. argument to ' , selector , ' does not evaluate to a block'

	]

    ].

    "

     (...) whileTrue:[

    "

    ((selector == #whileTrue:) or:[selector == #whileFalse:]) ifTrue:[

	receiver isBlock ifFalse:[

	    "

	     only warn, if code was originally parenthized

	    "

	    receiver parenthized ifTrue:[

		^ 'will fail at runtime, if receiver of ' , selector , ' does not evaluate to a block'

	    ]

	].

	(argArray at:1) isBlock ifFalse:[

	    ^ 'will fail at runtime, if argument to ' , selector , ' does not evaluate to a block'

	].

    ].

    ^ nil

! !

!MessageNode methodsFor:'evaluating'!

evaluate

    |r nargs argValueArray class|

    receiver isSuper ifTrue:[

	r := receiver value.

	receiver isHere ifTrue:[

	    class := receiver definingClass.

	] ifFalse:[

	    class := receiver definingClass superclass.

	].

	argArray notNil ifTrue:[

	    argValueArray := argArray collect:[:arg | arg evaluate].

	] ifFalse:[

	    argValueArray := #()

	].

	^ r perform:selector inClass:class withArguments:argValueArray

    ].

    argArray isNil ifTrue:[

	^ (receiver evaluate) perform:selector

    ].

    nargs := argArray size.

    (nargs == 1) ifTrue:[