--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WeakDepDict.st	Thu Jan 09 00:06:22 1997 +0100
@@ -0,0 +1,117 @@
+"
+ COPYRIGHT (c) 1997 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.
+"
+
+
+WeakIdentityDictionary subclass:#WeakDependencyDictionary
+	instanceVariableNames:''
+	classVariableNames:''
+	poolDictionaries:''
+	category:'Collections-Unordered'
+!
+
+!WeakDependencyDictionary class methodsFor:'documentation'!
+
+copyright
+"
+ COPYRIGHT (c) 1997 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
+"
+    A specialized WeakIdentityDictionary, which 'knowns' how
+    to get rid of obsolete entries. This is only used with the
+    dependency mechanism.
+
+    [author:]
+        Claus Gittinger
+
+    [See also:]
+        WeakArray WeakIdentityDictionary WeakValueDictionary WeakIdentitySet
+"
+! !
+
+!WeakDependencyDictionary methodsFor:'special dependency support'!
+
+removeEmptyDependencyValues
+    "special entry for dependency management:
+     remove any empty (due to finalization) value WeakArray elements."
+
+    |index t wasBlocked val|
+
+    "/ careful: this is sent by the finalizer at low prio.
+    "/ be prepared for the receiver to change while we walk over
+    "/ the value array here ...
+
+    index := 1.
+    [index <= keyArray size] whileTrue:[
+        "/ get the size again - it could have changed
+
+        wasBlocked := OperatingSystem blockInterrupts.
+        index <= keyArray size ifTrue:[
+            val := valueArray basicAt:index.
+            val notNil ifTrue:[
+                "/ is it an empty WeakArray ?
+
+                (val isMemberOf:WeakArray) ifTrue:[
+                    t := val findFirst:[:el | el notNil and:[el ~~ 0]].
+                    t == 0 ifTrue:[
+                        "/ yes - nil it
+                        valueArray basicAt:index put:nil.
+                        (keyArray basicAt:index) notNil ifTrue:[
+                            keyArray basicAt:index put:DeletedEntry.
+                            tally := tally - 1.
+                        ]
+                    ]
+                ] ifFalse:[
+                   "/ is it an empty WeakIdSet ?
+
+                   (val isMemberOf:WeakIdentitySet) ifTrue:[
+                        val size == 0 ifTrue:[
+                            "/ yes - nil it
+                            valueArray basicAt:index put:nil.
+                            (keyArray basicAt:index) notNil ifTrue:[
+                                keyArray basicAt:index put:DeletedEntry.
+                                tally := tally - 1.
+                            ]
+                        ].
+                    ]
+                ]
+            ]
+        ].
+
+        wasBlocked ifTrue:[OperatingSystem unblockInterrupts].
+        index := index + 1.
+    ].
+
+    "
+     Dependencies removeEmptyDependencyValues
+    "
+
+    "Modified: 8.1.1997 / 23:57:56 / cg"
+    "Created: 9.1.1997 / 00:00:28 / cg"
+! !
+
+!WeakDependencyDictionary class methodsFor:'documentation'!
+
+version
+    ^ '$Header: /cvs/stx/stx/libbasic/Attic/WeakDepDict.st,v 1.1 1997-01-08 23:06:22 cg Exp $'
+! !