"
 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.
"

ExecutableCodeObject subclass:#Block
       instanceVariableNames:'home nargs
                              sourcePos initialPC
                              selfValue method'
       classVariableNames:'InvalidNewSignal'
       poolDictionaries:''
       category:'Kernel-Methods'
!

Block comment:'

COPYRIGHT (c) 1989 by Claus Gittinger
              All Rights Reserved

$Header: /cvs/stx/stx/libbasic/Block.st,v 1.15 1994-06-02 11:18:43 claus Exp $

written spring 89 by claus
'!

!Block class methodsFor:'documentation'!

documentation
"
    Blocks are pieces of executable code which can be evaluated by sending
    them a value-message (''value'', ''value:'', ''value:value:'' etc).

    Blocks with arguments need a message of type ''value:arg1 ... value:argn''
    for evaluation; the number of arguments passed when evaluating must match
    the number of arguments the block was declared with otherwise an error is
    raised. Blocks without args need a ''value'' message for evaluation.

    Blocks keep a reference to the method context where the block was declared -
    this allows blocks to access the methods arguments and/or variables.
    This is also true when the method has already returned - since the
    block keeps this reference, the methods context will NOT die in this case.

    A return (via ^-statement) out of a block will force a return from the
    blocks method context (if it is still living) - this make the implementation
    of long-jumps and control structures possible.
    (If the method is not alive (i.e. has already returned), a return out of the block 
    is ignored and a simple return from the block is performed).

    Long-jump is done by defining a catchBlock as ''[^ self]''
    somewhere up in the calling-tree. Then, to do the long-jump from out of some 
    deeply nested method, simply do: ''catchBlock value''.

    Instance variables:

    code        <not_an_object>   the function pointer if its a compiled block
    flags       <SmallInteger>    special flag bits coded in a number
    byteCode    <ByteArray>       bytecode of home method if its an interpreted block
    home        <Context>         the context where this block was created (i.e. defined)
                                  this may be a BlockContext or a methodContext
    nargs       <SmallInteger>    the number of arguments the block expects
    sourcePos   <SmallInteger>    the character poistion of its source, in chars
                                  relative to methods source beginning
    initialPC   <SmallInteger>    the start position within the byteCode
                                  for compiled blocks, this is nil.
    literals    <Array>           the blocks literal array
    selfValue   <Object>          value to use for self if its a copying block
    method      <Method>          method where block was created (cheap blocks only)

    NOTICE: layout known by runtime system and compiler - do not change
"
! !

!Block class methodsFor:'initialization' !

initialize
    "setup the signals"

    InvalidNewSignal isNil ifTrue:[
        InvalidNewSignal := (Signal new).
        InvalidNewSignal mayProceed:false.
        InvalidNewSignal notifierString:'blocks are only created by the system'.
    ]
! !

!Block class methodsFor:'queries'!

isBuiltInClass
    "this class is known by the run-time-system"

    ^ true
! !

!Block class methodsFor:'instance creation'!

code:codeAddress byteCode:bCode nargs:numArgs sourcePosition:sourcePos initialPC:initialPC literals:literals dynamic:dynamic
    "create a new cheap (homeless) block.
     Not for public use - special hook for the compiler."

    |newBlock|

    newBlock := super basicNew code:codeAddress 
                           byteCode:bCode
                              nargs:numArgs
                     sourcePosition:sourcePos
                          initialPC:initialPC
                           literals:literals
                            dynamic:dynamic.
    ^ newBlock
!

new
    "catch creation of blocks - only the system creates blocks"

    InvalidNewSignal raise.
    ^ nil
!

new:size
    "catch creation of blocks - only the system creates blocks"

    InvalidNewSignal raise.
    ^ nil
! !

!Block methodsFor:'testing'!

isBlock
    "return true, if this is a block - yes I am"

    ^ true
! !

!Block methodsFor:'accessing'!

nargs
    "return the number of arguments I expect for evaluation"

    ^ nargs
!

selfValue
    "return the copied self"

    ^ selfValue
! !

!Block methodsFor:'private accessing'!

code:codeAddress byteCode:bCode nargs:numArgs sourcePosition:srcPos initialPC:iPC literals:lits dynamic:dynamic
    "set all relevant internals"

    self code:codeAddress.
    byteCode := bCode.
    nargs := numArgs.
    sourcePos := srcPos.
    initialPC := iPC.
    literals := lits.
    self dynamic:dynamic
!

nargs:numArgs
    "set the number of arguments I expect for evaluation - DANGER ALERT"

    nargs := numArgs
!

sourcePosition:position 
    "set the position of the source within my method"

    sourcePos := position
!

initialPC:initial 
    "set the initial pc for evaluation - DANGER ALERT"

    initialPC := initial
! !

!Block methodsFor:'error handling'!

argumentCountError:numberGiven
    "report that the number of arguments given does not match the number expected"

    self error:('Block got ' , numberGiven printString ,
                ' args while ' , nargs printString , ' where expected')
!

invalidMethod
    "this error is triggered by the interpreter when a non-Block object
     is about to be executed.
     In this case, the VM sends this to the bad method (the receiver).
     Can only happen when the Compiler/runtime system is broken or
     someone played around."

    self error:'invalid block - not executable'
!

tooManySendArguments
    "this error is triggered, when a method tries to perform a send with
     more arguments than supported by the interpreter - this can only
     happen, if the compiler has been changed without updating the VM."

    self error:'too many send args - should not happen'
!

tooManyArguments
    "this error is triggered, when a method is called with more arguments
     than supported by the interpreter - this can only happen, if the
     compiler has been changed without updating the VM."

    self error:'block has too many args - should not happen'
! !

!Block methodsFor:'evaluation'!

value
    "evaluate the receiver with no block args. The receiver must be a block without arguments."

%{  /* NOCONTEXT */

    REGISTER OBJFUNC thecode;
    OBJ home;
    extern OBJ interpret();

    if (_INST(nargs) == _MKSMALLINT(0)) {
#if defined(THIS_CONTEXT)
        if (1 /* _intVal(__pilc->ilc_lineNo) > 0 */)
            _ContextInstPtr(__thisContext)->c_lineno = __pilc->ilc_lineNo;
#endif
        thecode = _BlockInstPtr(self)->b_code;
#ifdef NEW_BLOCK_CALL
        if (thecode != (OBJFUNC)nil) {
            /* compiled machine code */
            RETURN ( (*thecode)(self, COMMA_SND) );
        }
        /* interpreted code */
        RETURN ( interpret(self, 0, nil, nil COMMA_SND, nil) );
#else
        home = _BlockInstPtr(self)->b_home;
        if (thecode != (OBJFUNC)nil) {
            /* compiled machine code */
            RETURN ( (*thecode)(home COMMA_SND) );
        }
        /* interpreted code */
        RETURN ( interpret(self, 0, nil, home COMMA_SND, nil) );
#endif
    }
%}
.
    ^ self argumentCountError:0
!

value:arg
    "evaluate the receiver with one argument. The receiver must be a 1-arg block."

%{  /* NOCONTEXT */

    REGISTER OBJFUNC thecode;
    OBJ home;
    extern OBJ interpret();

    if (_INST(nargs) == _MKSMALLINT(1)) {
#if defined(THIS_CONTEXT)
        if (1 /* _intVal(__pilc->ilc_lineNo) > 0 */)
            _ContextInstPtr(__thisContext)->c_lineno = __pilc->ilc_lineNo;
#endif
        thecode = _BlockInstPtr(self)->b_code;
#ifdef NEW_BLOCK_CALL
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(self COMMA_SND, arg) );
        }
        /* interpreted code */
        RETURN ( interpret(self, 1, nil, nil COMMA_SND, nil, arg) );
#else
        home = _BlockInstPtr(self)->b_home;
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(home COMMA_SND, arg) );
        }
        /* interpreted code */
        RETURN ( interpret(self, 1, nil, home COMMA_SND, nil, arg) );
#endif
    }
%}
.
    ^ self argumentCountError:1
!

value:arg1 value:arg2
    "evaluate the receiver with two arguments. The receiver must be a 2-arg block."

%{  /* NOCONTEXT */

    REGISTER OBJFUNC thecode;
    OBJ home;
    extern OBJ interpret();

    if (_INST(nargs) == _MKSMALLINT(2)) {
#if defined(THIS_CONTEXT)
        if (1 /* _intVal(__pilc->ilc_lineNo) > 0 */)
            _ContextInstPtr(__thisContext)->c_lineno = __pilc->ilc_lineNo;
#endif
        thecode = _BlockInstPtr(self)->b_code;
#ifdef NEW_BLOCK_CALL
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(self COMMA_SND, arg1, arg2) );
        }
        RETURN ( interpret(self, 2, nil, nil COMMA_SND, nil, arg1, arg2) );
#else
        home = _BlockInstPtr(self)->b_home;
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(home COMMA_SND, arg1, arg2) );
        }
        RETURN ( interpret(self, 2, nil, home COMMA_SND, nil, arg1, arg2) );
#endif
    }
%}
.
    ^ self argumentCountError:2
!

value:arg1 value:arg2 value:arg3
    "evaluate the receiver with three arguments. The receiver must be a 3-arg block."

%{  /* NOCONTEXT */

    REGISTER OBJFUNC thecode;
    OBJ home;
    extern OBJ interpret();

    if (_INST(nargs) == _MKSMALLINT(3)) {
#if defined(THIS_CONTEXT)
        if (1 /* _intVal(__pilc->ilc_lineNo) > 0 */)
            _ContextInstPtr(__thisContext)->c_lineno = __pilc->ilc_lineNo;
#endif
        thecode = _BlockInstPtr(self)->b_code;
#ifdef NEW_BLOCK_CALL
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(self COMMA_SND, arg1, arg2, arg3) );
        }
        RETURN ( interpret(self, 3, nil, nil COMMA_SND, nil, arg1, arg2, arg3) );
#else
        home = _BlockInstPtr(self)->b_home;
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(home COMMA_SND, arg1, arg2, arg3) );
        }
        RETURN ( interpret(self, 3, nil, home COMMA_SND, nil, arg1, arg2, arg3) );
#endif
    }
%}
.
    ^ self argumentCountError:3
!

value:arg1 value:arg2 value:arg3 value:arg4
    "evaluate the receiver with four arguments. The receiver must be a 4-arg block."

%{  /* NOCONTEXT */

    REGISTER OBJFUNC thecode;
    OBJ home;
    extern OBJ interpret();

    if (_INST(nargs) == _MKSMALLINT(4)) {
#if defined(THIS_CONTEXT)
        if (1 /* _intVal(__pilc->ilc_lineNo) > 0 */)
            _ContextInstPtr(__thisContext)->c_lineno = __pilc->ilc_lineNo;
#endif
        thecode = _BlockInstPtr(self)->b_code;
#ifdef NEW_BLOCK_CALL
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(self COMMA_SND, arg1, arg2, arg3, arg4) );
        }
        RETURN ( interpret(self, 4, nil, nil COMMA_SND, nil, arg1, arg2, arg3, arg4) );
#else
        home = _BlockInstPtr(self)->b_home;
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(home COMMA_SND, arg1, arg2, arg3, arg4) );
        }
        RETURN ( interpret(self, 4, nil, home COMMA_SND, nil, arg1, arg2, arg3, arg4) );
#endif
    }
%}
.
    ^ self argumentCountError:4
!

value:arg1 value:arg2 value:arg3 value:arg4 value:arg5
    "evaluate the receiver with four arguments. The receiver must be a 5-arg block."

%{  /* NOCONTEXT */

    REGISTER OBJFUNC thecode;
    OBJ home;
    extern OBJ interpret();

    if (_INST(nargs) == _MKSMALLINT(5)) {
#if defined(THIS_CONTEXT)
        if (1 /* _intVal(__pilc->ilc_lineNo) > 0 */)
            _ContextInstPtr(__thisContext)->c_lineno = __pilc->ilc_lineNo;
#endif
        thecode = _BlockInstPtr(self)->b_code;
#ifdef NEW_BLOCK_CALL
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(self COMMA_SND, arg1, arg2, arg3, arg4, arg5) );
        }
        RETURN ( interpret(self, 5, nil, nil COMMA_SND, nil, arg1, arg2, arg3, arg4, arg5) );
#else
        home = _BlockInstPtr(self)->b_home;
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(home COMMA_SND, arg1, arg2, arg3, arg4, arg5) );
        }
        RETURN ( interpret(self, 5, nil, home COMMA_SND, nil, arg1, arg2, arg3, arg4, arg5) );
#endif
    }
%}
.
    ^ self argumentCountError:5
!

value:arg1 value:arg2 value:arg3 value:arg4 value:arg5 value:arg6
    "evaluate the receiver with four arguments. The receiver must be a 6-arg block."

%{  /* NOCONTEXT */

    REGISTER OBJFUNC thecode;
    OBJ home;
    extern OBJ interpret();

    if (_INST(nargs) == _MKSMALLINT(6)) {
#if defined(THIS_CONTEXT)
        if (1 /* _intVal(__pilc->ilc_lineNo) > 0 */)
            _ContextInstPtr(__thisContext)->c_lineno = __pilc->ilc_lineNo;
#endif
        thecode = _BlockInstPtr(self)->b_code;
#ifdef NEW_BLOCK_CALL
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(self COMMA_SND, arg1, arg2, arg3, arg4, arg5, arg6) );
        }
        RETURN ( interpret(self, 6, nil, nil COMMA_SND, nil, arg1, arg2, arg3, arg4, arg5, arg6) );
#else
        home = _BlockInstPtr(self)->b_home;
        if (thecode != (OBJFUNC)nil) {
            RETURN ( (*thecode)(home COMMA_SND, arg1, arg2, arg3, arg4, arg5, arg6) );
        }
        RETURN ( interpret(self, 6, nil, home COMMA_SND, nil, arg1, arg2, arg3, arg4, arg5, arg6) );
#endif
    }
%}
.
    ^ self argumentCountError:6
!

valueWithArguments:argArray
    "evaluate the receiver with arguments taken from argArray.
     The size of the argArray must match the number of arguments the receiver expects."

    |a1 a2 a3 a4 a5 a6 a7|

    (argArray class == Array) ifFalse:[
        ^ self error:'argument must be an array'
    ].
    (argArray size == nargs) ifFalse:[
        ^ self argumentCountError:(argArray size)
    ].
%{

    REGISTER OBJFUNC thecode;
    OBJ home;
    extern OBJ interpret();
    REGISTER OBJ *ap;

#if defined(THIS_CONTEXT)
    if (1 /* _intVal(__pilc->ilc_lineNo) > 0 */)
        _ContextInstPtr(__thisContext)->c_lineno = __pilc->ilc_lineNo;
#endif
    switch (_intVal(_INST(nargs))) {
        default:
            goto error;
        case 7:
            a7 = _ArrayInstPtr(argArray)->a_element[6];
        case 6:
            a6 = _ArrayInstPtr(argArray)->a_element[5];
        case 5:
            a5 = _ArrayInstPtr(argArray)->a_element[4];
        case 4:
            a4 = _ArrayInstPtr(argArray)->a_element[3];
        case 3:
            a3 = _ArrayInstPtr(argArray)->a_element[2];
        case 2:
            a2 = _ArrayInstPtr(argArray)->a_element[1];
        case 1:
            a1 = _ArrayInstPtr(argArray)->a_element[0];
        case 0:
            break;
    }
    thecode = _BlockInstPtr(self)->b_code;
#ifdef NEW_BLOCK_CALL
    if (thecode != (OBJFUNC)nil) {
        RETURN ( (*thecode)(self COMMA_SND, a1, a2, a3, a4, a5, a6, a7) );
    }
    RETURN ( interpret(self, _intVal(_INST(nargs)), nil, nil COMMA_SND, nil, 
                       a1, a2, a3, a4, a5, a6, a7) );
#else
    home = _BlockInstPtr(self)->b_home;
    if (thecode != (OBJFUNC)nil) {
        RETURN ( (*thecode)(home COMMA_SND, a1, a2, a3, a4, a5, a6, a7) );
    }
    RETURN ( interpret(self, _intVal(_INST(nargs)), nil, home COMMA_SND, nil, 
                       a1, a2, a3, a4, a5, a6, a7) );
#endif

error: ;
%}
.
    self error:'only blocks with up-to 7 arguments supported'
!

valueNowOrOnUnwindDo:aBlock
    "evaluate the receiver - after that, or when some method sent within unwinds (i.e. does
     a long return), evaluate the argument, aBlock.
     This is used to make certain that cleanup actions (for example closing files etc.) are
     executed regardless of error actions"

    |v|

    v := self value.       "the real logic is in Context>>unwind"
    aBlock value.
    ^ v
!

valueOnUnwindDo:aBlock
    "evaluate the receiver - when some method sent within unwinds (i.e. does
     a long return), evaluate the argument, aBlock.
     This is used to make certain that cleanup actions (for example closing files etc.) are
     executed regardless of error actions"

    ^ self value        "the real logic is in Context>>unwind"
! !

!Block methodsFor:'looping'!

whileTrue:aBlock
    "evaluate the argument, aBlock while the receiver evaluates to true.
     - usually open coded by compilers, but needed here for #perform 
       and expression evaluation."

    "now, this implementation is for purists ... :-)"
    self value ifFalse:[^ nil].
    aBlock value.
    thisContext restart

    "
     |n|

     n := 1.
     [n <= 10] whileTrue:[
        n printNewline.
        n := n + 1
     ]
    "
!

whileFalse:aBlock
    "evaluate the argument, aBlock while the receiver evaluates to false.
     - usually open coded by compilers, but needed here for #perform 
       and expression evaluation."

    "now, this implementation is for purists ... :-)"
    self value ifTrue:[^ nil].
    aBlock value.
    thisContext restart

    "
     |n|

     n := 1.
     [n > 10] whileFalse:[
        n printNewline.
        n := n + 1
     ]
    "
!

whileTrue
    "evaluate the receiver while it evaluates to true (ST80 compatibility)"

    "now, this implementation is for purists ... :-)"
    self value ifFalse:[^ nil].
    thisContext restart

    "
     |n|

     n := 1.
     [n printNewline. (n := n + 1) <= 10] whileTrue
    "
!

whileFalse
    "evaluate the receiver while it evaluates to false (ST80 compatibility)"

    "now, this implementation is for purists ... :-)"
    self value ifTrue:[^ nil].
    thisContext restart

    "
     |n|

     n := 1.
     [n printNewline. (n := n + 1) > 10] whileFalse
    "
!

doWhile:aBlock
    "repeat the receiver block until aBlock evaluates to false.
     The receiver is evaluated at least once."

    "now, this implementation is for purists ... :-)"
    self value.
    aBlock value ifFalse:[^ nil].
    thisContext restart

    "
     |n|

     n := 1.
     [n printNewline] doWhile:[ (n := n + 1) <= 5 ]
    "
!

doUntil:aBlock
    "repeat the receiver block until aBlock evaluates to true.
     The receiver is evaluated at least once.
     This is the same as '... doWhile:[... not]' "

    "now, this implementation is for purists ... :-)"
    self value.
    aBlock value ifTrue:[^ nil].
    thisContext restart

    "
     |n|

     n := 1.
     [n printNewline] doUntil:[ (n := n + 1) > 5 ]
    "
!

loop
    "repeat the receiver forever (should contain a return somewhere).
     Inspired by a corresponding Self method."

    self value.
    thisContext restart

    "
     |n|

     n := 1.
     [
        n printNewline.
        n >= 10 ifTrue:[^ nil].
        n := n + 1
     ] loop
    "
!

valueWithExit
    "the receiver must be a block of one argument.  It is evaluated, and is passed a block,
     which, if sent a value:-message, will exit the receiver block, returning the parameter of the 
     value:-message. Used for premature returns to the caller.
     Taken from a manchester goody (also appears in Self)."

    ^ self value: [:exitValue | ^exitValue]

    "[:exit |
        1 to:10 do:[:i |
            Transcript showCr:i.
            i == 5 ifTrue:[exit value:'thats it']
        ].
        'regular block-value; never returned'
     ] valueWithExit"
!

loopWithExit
    "the receiver must be a block of one argument.  It is evaluated in a loop forever, 
     and is passed a block, which, if sent a value:-message, will exit the receiver block, 
     returning the parameter of the value:-message. Used for loops with exit in the middle.
     Inspired by a corresponding Self method."

    |exitBlock|

    exitBlock := [:exitValue | ^ exitValue].
    [true] whileTrue:[self value:exitBlock]

    "
     |i|
     i := 1.
     [:exit |
        Transcript showCr:i.
        i == 5 ifTrue:[exit value:'thats it'].
        i := i + 1
     ] loopWithExit
    "
! !

!Block methodsFor:'process creation'!

newProcess
    "create a new (unscheduled) process executing the receiver"

    ^ Processor newProcessFor:self.
!

fork
    "create a new process executing the receiver"

    ^ self newProcess resume
!

forkWith:argumentArray
    "create a new process executing the receiver passing elements
     in argumentArray to the receiver block"

    |b|

    b := [self valueWithArguments:argumentArray].
    ^ b fork
!

forkAt:priority
    "create a new process executing the receiver"

    ^ (self newProcess priority:priority) resume
! !

!Block methodsFor:'printing'!

printOn:aStream
    "append a a printed representation of the block to aStream"

    |homeClass receiverClass selector|

    "cheap blocks have no home context, but a method instead"

    (home isNil or:[home isContext not]) ifTrue:[
        aStream nextPutAll:'[] in '.

        method notNil ifTrue:[
            "find out, for which class this Method was for ..."
            receiverClass := method containingClass.
            receiverClass notNil ifTrue:[
                selector := receiverClass selectorForMethod:method.
                aStream nextPutAll:(receiverClass name , '-' , selector).
                aStream nextPutAll:' (optimized)'.
                ^ self
            ].
        ].
        "currently, some cheap blocks don't know where they have been created"
        aStream nextPutAll:' ??? (optimized)'.
        ^ self
    ].

    "a full blown block (with home, but without method)"

    aStream nextPutAll:'[] in '. 
    home receiver class name printOn:aStream.
    aStream nextPut:$-.
    home methodHome selector printOn:aStream.

"
    aStream nextPutAll:'[] in '.
    homeClass := home containingClass.
    homeClass notNil ifTrue:[
        homeClass name printOn:aStream.
        aStream space.
        (homeClass selectorForMethod:home) printOn:aStream
    ] ifFalse:[
        aStream nextPutAll:' ???' 
    ]
"
! !