"

 COPYRIGHT (c) 1993 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.

"

Context subclass:#BlockContext

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	category:'Kernel-Methods'

!

!BlockContext class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1993 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

"

    BlockContexts represent the stack context objects of blocks. 

    The layout is the same as for other contexts - this class has been added 

    to avoid a flag in an instance variable.

    (has become necessary with cheap blocks, which have no home).

    WARNING: layout and size known by compiler and runtime system - 

             do not change.

    [author:]

        Claus Gittinger

    [see also:]

        Context Block Method

        Exception Signal

"

! !

!BlockContext methodsFor:'accessing'!

canReturn

    "return true, if the receiver allows returning through it.

     For normal method contexts, this normally returns true;

     for blocks, it (currently) always returns false."

    ^ false

!

home

    "return the immediate home of the receiver.

     normally this is the methodcontext, where the block was created,

     for nested block contexts, this is the surrounding blocks context."

    home isContext ifFalse:[^ nil]. "copying blocks have no home"

    ^ home

!

isBlockContext

    "return true, iff the receiver is a BlockContext, false otherwise"

    ^ true

!

method

    "return the method in which the current contexts block was created."

    home notNil ifTrue:[^ home method].

    ^ nil

!

methodHome

    "return the method-home for block contexts"

    |con h|

    home isNil ifTrue:[^ nil]. "XXX will change soon"

    home isContext ifFalse:[^ nil]. "copying blocks have no method home"

    con := self.

    h := home.

    [h notNil] whileTrue:[

	con := h.

	h := con home

    ].

    ^ con

!

selector

    "return the selector of the context - which is one of the value

     selectors. This selector is not found in the context, but synthesized."

    |nargs|

    nargs := self numArgs.

    (nargs == 0) ifTrue:[^ #value].

    (nargs == 1) ifTrue:[^ #value:].

    (nargs == 2) ifTrue:[^ #value:value:].

    (nargs == 3) ifTrue:[^ #value:value:value:].

    (nargs == 4) ifTrue:[^ #value:value:value:value:].

    (nargs == 5) ifTrue:[^ #value:value:value:value:value:].

    ^ nil

! !

!BlockContext methodsFor:'printing & storing'!

receiverPrintString

    "return a printString describing the contexts receiver.

     Since this is also used by the debugger(s), be very careful to

     return something useful, even in case internals of the system

     got corrupted ... (i.e. avoid messageNotUnderstood here)"

    |cls who mHome m className 

     sender selSender tryVars possibleBlocks method mWho|

    (home isNil or:[home isContext not]) ifTrue:[

    ].

    mHome := self methodHome.

    mHome isNil ifTrue:[

    ].

    "

     kludge to avoid slow search for containing class

    "

    mHome selector == #doIt ifTrue:[

    ] ifFalse:[

    ].

    who notNil ifTrue:[

    ] ifFalse:[

    ].

    className := cls name.

    className isNil ifTrue:[

    ].

    ^ '[] in ' , className , '-' , mHome selector printString

! !

!BlockContext class methodsFor:'documentation'!

version

! !