--- a/Collection.st	Wed Jun 04 16:51:00 2014 +0200
+++ b/Collection.st	Thu Jun 05 13:25:45 2014 +0200
@@ -328,6 +328,7 @@
     ^ self == Collection
 ! !
 
+
 !Collection methodsFor:'Compatibility-Dolphin'!
 
 identityIncludes:anObject
@@ -5021,13 +5022,28 @@
      Use the algorithm by R. E. Tarjan from 1972.
      Answer an OrderedCollection containing the sorted items"
 
+    ^ self topologicalSortStable: false
+
+    "Modified: / 05-06-2014 / 12:22:14 / Jan Vrany <jan.vrany@fit.cvut.cz>"
+!
+
+topologicalSortStable: sortStable
+    "Sort a partial ordered collection.
+     The receiver consists of tupels defining a partial order.
+     Use the algorithm by R. E. Tarjan from 1972.
+     Answer an OrderedCollection containing the sorted items.
+
+     If sortStable is true, try to make order stable among
+     multiple invocations. Othewise, stability is not guaranteed.
+     "
+
     |graph roots sorted count|
 
     "create a graph.
      For each node there is an entry containing the number of references
      and a list of arcs to other nodes"
 
-    graph := Dictionary new.
+    graph := sortStable ifTrue:[ OrderedDictionary new ] ifFalse:[ Dictionary new ].
 
     self do:[:eachTuple| 
         |node1|
@@ -5121,6 +5137,8 @@
         Array with:eachClass superclass with:eachClass
      ]) topologicalSort
     "
+
+    "Created: / 05-06-2014 / 12:21:55 / Jan Vrany <jan.vrany@fit.cvut.cz>"
 ! !
 
 !Collection methodsFor:'statistical functions'!
@@ -5542,11 +5560,11 @@
 !Collection class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.336 2014-05-12 20:31:09 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.337 2014-06-05 11:25:45 vrany Exp $'
 !
 
 version_CVS
-    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.336 2014-05-12 20:31:09 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.337 2014-06-05 11:25:45 vrany Exp $'
 ! !