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ValueHolder subclass:#ValueHolderWithWeakDependents
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instanceVariableNames:''
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classVariableNames:''
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poolDictionaries:''
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category:'Interface-Support-Models'
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!
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!ValueHolderWithWeakDependents methodsFor:'dependents access'!
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addDependent:anObject
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"make the argument, anObject be a weak dependent of the receiver"
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|wasBlocked|
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wasBlocked := OperatingSystem blockInterrupts.
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[
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|deps dep|
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deps := dependents.
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"/
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"/ store the very first dependent directly in
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"/ the dependents instVar
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"/
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(deps isNil and:[anObject isCollection not]) ifTrue:[
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dependents := WeakArray with:anObject
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] ifFalse:[
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deps class == WeakArray ifTrue:[
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dep := deps at:1.
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dep ~~ anObject ifTrue:[
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(dep isNil or:[dep == 0]) ifTrue:[
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deps at:1 put:anObject
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] ifFalse:[
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self dependents:(WeakIdentitySet with:dep with:anObject)
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]
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]
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] ifFalse:[
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deps add:anObject
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]
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]
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] valueNowOrOnUnwindDo:[
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wasBlocked ifFalse:[
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OperatingSystem unblockInterrupts
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]
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]
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"Modified: 8.1.1997 / 23:40:30 / cg"
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!
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dependentsDo:aBlock
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"evaluate aBlock for all of my dependents"
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|deps|
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deps := dependents.
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deps size ~~ 0 ifTrue:[
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deps do:[:d |
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(d notNil and:[d ~~ 0]) ifTrue:[
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aBlock value:d
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]
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]
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].
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!
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removeDependent:anObject
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"make the argument, anObject be independent of the receiver"
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|wasBlocked|
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"/ must do this save from interrupts, since the dependents collection
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"/ is possibly accessed from multiple threads.
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"/ Used to use #valueUninterruptably here; inlined that code for slightly
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"/ faster execution.
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wasBlocked := OperatingSystem blockInterrupts.
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[
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|deps n d|
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deps := dependents.
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deps size ~~ 0 ifTrue:[
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"/ to save a fair amount of memory in case of
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"/ many dependencies, we store a single dependent in
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"/ a WeakArray, and switch to a WeakSet if more dependents are
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"/ added. Here we have to do the inverse ...
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deps class == WeakArray ifTrue:[
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((d := deps at:1) == anObject
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or:[d isNil
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or:[d == 0]]) ifTrue:[
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dependents := nil
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]
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] ifFalse:[
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deps remove:anObject ifAbsent:[].
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(n := deps size) == 0 ifTrue:[
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dependents := nil
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] ifFalse:[
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n == 1 ifTrue:[
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d := deps firstIfEmpty:nil.
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d notNil ifTrue:[
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deps := WeakArray with:d
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] ifFalse:[
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deps := nil
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].
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dependents := deps.
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]
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]
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]
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]
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] valueNowOrOnUnwindDo:[
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wasBlocked ifFalse:[
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OperatingSystem unblockInterrupts
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]
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]
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"Modified: / 26.1.1998 / 19:51:50 / cg"
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! !
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!ValueHolderWithWeakDependents class methodsFor:'documentation'!
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version
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^ '$Header: /cvs/stx/stx/libview2/ValueHolderWithWeakDependents.st,v 1.1 1999-10-25 14:52:53 cg Exp $'
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! !
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