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"
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COPYRIGHT (c) 1993 by Claus Gittinger
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84
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All Rights Reserved
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This software is furnished under a license and may be used
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only in accordance with the terms of that license and with the
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inclusion of the above copyright notice. This software may not
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be provided or otherwise made available to, or used by, any
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other person. No title to or ownership of the software is
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hereby transferred.
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"
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0
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Dictionary subclass:#CacheDictionary
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238
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instanceVariableNames:''
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classVariableNames:''
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poolDictionaries:''
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category:'Collections-Unordered'
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0
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!
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31
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!CacheDictionary class methodsFor:'documentation'!
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copyright
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"
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COPYRIGHT (c) 1993 by Claus Gittinger
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84
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All Rights Reserved
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0
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31
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This software is furnished under a license and may be used
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only in accordance with the terms of that license and with the
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inclusion of the above copyright notice. This software may not
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be provided or otherwise made available to, or used by, any
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other person. No title to or ownership of the software is
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hereby transferred.
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"
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!
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documentation
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"
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a CacheDictionary is a Dictionary which will not grow - i.e. keep
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only a limited number of elements.
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It can be used as a cache, for keeping recently used objects alive.
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254
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[author:]
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Claus Gittinger
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31
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"
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! !
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0
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!CacheDictionary methodsFor:'private'!
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13
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emptyCheck
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489
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"redefined - never shrink"
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^ self
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489
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"Modified: 30.1.1997 / 15:17:12 / cg"
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!
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findKeyOrNil:key
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"Look for the key in the receiver. If it is found, return
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the index of the association containing the key, otherwise
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return the index of the first unused slot. If no empty slot
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489
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is available, make one empty (but never grow)."
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0
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|index "{ Class:SmallInteger }"
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length "{ Class:SmallInteger }"
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startIndex freeIndex
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0
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probe|
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length := keyArray basicSize.
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startIndex := key hash * 2 \\ length + 1.
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0
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index := startIndex.
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[true] whileTrue:[
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238
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probe := keyArray basicAt:index.
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489
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probe = key ifTrue:[^ index].
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probe isNil ifTrue:[
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freeIndex isNil ifTrue:[^ index].
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keyArray basicAt:freeIndex put:nil.
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valueArray basicAt:freeIndex put:nil.
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^ freeIndex
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].
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0
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238
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(freeIndex isNil and:[probe == DeletedEntry]) ifTrue:[
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freeIndex := index
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].
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13
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238
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index := index + 1.
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index > length ifTrue:[
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index := 1.
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].
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index == startIndex ifTrue:[
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489
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"/ mhmh - actually, a kind of round-robin would be better
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238
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freeIndex isNil ifTrue:[
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freeIndex := startIndex
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].
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13
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238
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keyArray basicAt:freeIndex put:nil.
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valueArray basicAt:freeIndex put:nil.
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tally := tally - 1.
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^ freeIndex
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].
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0
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]
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238
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489
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"Modified: 30.1.1997 / 15:16:25 / cg"
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!
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fullCheck
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"redefined - never grow"
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^ self
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"Modified: 30.1.1997 / 15:17:18 / cg"
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! !
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125
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134
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!CacheDictionary class methodsFor:'documentation'!
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version
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489
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^ '$Header: /cvs/stx/stx/libbasic2/CacheDictionary.st,v 1.16 1997-01-30 14:38:03 cg Exp $'
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134
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! !
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