--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MCFrontier.st	Wed Nov 22 14:15:31 2006 +0100
@@ -0,0 +1,62 @@
+"{ Package: 'stx:goodies/monticello' }"
+
+Object subclass:#MCFrontier
+	instanceVariableNames:'frontier bag'
+	classVariableNames:''
+	poolDictionaries:''
+	category:'Monticello-Versioning'
+!
+
+
+!MCFrontier class methodsFor:'instance creation'!
+
+frontierOn: aVersionInfo
+	^ self frontierOnAll: (Array with: aVersionInfo)
+!
+
+frontierOn: aVersionInfo and: otherVersionInfo
+	^ self frontierOnAll: (Array with: aVersionInfo with: otherVersionInfo)
+!
+
+frontierOnAll: aCollection
+	| remaining  allVersions |
+	remaining := Bag new.
+	allVersions _ (aCollection gather: [:ea | ea withBreadthFirstAncestors]) asSet.
+	allVersions do: [:ea | remaining addAll: ea ancestors].
+	^self new frontier: aCollection bag: remaining
+! !
+
+!MCFrontier methodsFor:'accessing'!
+
+frontier
+	^frontier
+! !
+
+!MCFrontier methodsFor:'advancing'!
+
+remove: aVersionInfo
+	frontier remove: aVersionInfo.
+	aVersionInfo ancestors  do:
+		[ :ancestor |
+			bag remove: ancestor.
+			(bag occurrencesOf: ancestor) = 0
+				ifTrue: [frontier add: ancestor]].
+	^aVersionInfo
+!
+
+removeAll: collection
+	collection do: [ :n | self remove: n]
+! !
+
+!MCFrontier methodsFor:'initialization'!
+
+frontier: f bag: remaining
+	frontier := f asOrderedCollection.
+	bag := remaining
+! !
+
+!MCFrontier class methodsFor:'documentation'!
+
+version
+    ^ '$Header: /cvs/stx/stx/goodies/monticello/MCFrontier.st,v 1.1 2006-11-22 13:15:31 cg Exp $'
+! !