2 files changed, 66 insertions, 3 deletions

diff --git a/source/blender/blenlib/BLI_graph.h b/source/blender/blenlib/BLI_graph.h
index 7629dbf6ba8..f4fccfcbb2c 100644
--- a/source/blender/blenlib/BLI_graph.h
+++ b/source/blender/blenlib/BLI_graph.h
@@ -62,13 +62,25 @@ typedef struct BArc {
 
 struct BArcIterator;
 
+void* IT_head(void* iter);
+void* IT_tail(void* iter);
+void* IT_peek(void* iter, int n);
+void* IT_next(void* iter);
+void* IT_nextN(void* iter, int n);
+void* IT_previous(void* iter);
+int   IT_stopped(void* iter);
+
+typedef void* (*HeadFct)(void* iter);
+typedef void* (*TailFct)(void* iter);
 typedef void* (*PeekFct)(void* iter, int n);
 typedef void* (*NextFct)(void* iter);
 typedef void* (*NextNFct)(void* iter, int n);
 typedef void* (*PreviousFct)(void* iter);
-typedef int	(*StoppedFct)(void* iter);
+typedef int   (*StoppedFct)(void* iter);
 
 typedef struct BArcIterator {
+	HeadFct		head;
+	TailFct		tail;
 	PeekFct		peek;
 	NextFct		next;
 	NextNFct	nextN;
diff --git a/source/blender/blenlib/intern/graph.c b/source/blender/blenlib/intern/graph.c
index e2ed8f11ee2..ca82fcac844 100644
--- a/source/blender/blenlib/intern/graph.c
+++ b/source/blender/blenlib/intern/graph.c
@@ -465,8 +465,6 @@ int subtreeShape(BNode *node, BArc *rootArc, int include_root)
 
 int BLI_subtreeShape(BGraph *graph, BNode *node, BArc *rootArc, int include_root)
 {
-	BNode *test_node;
-	
 	BLI_flagNodes(graph, 0);
 	return subtreeShape(node, rootArc, include_root);
 }
@@ -1090,3 +1088,56 @@ void BLI_markdownSymmetry(BGraph *graph, BNode *root_node, float limit)
 	}
 }
 
+void* IT_head(void* arg)
+{
+	BArcIterator *iter = (BArcIterator*)arg; 
+	return iter->head(iter);
+}
+
+void* IT_tail(void* arg)
+{
+	BArcIterator *iter = (BArcIterator*)arg; 
+	return iter->tail(iter); 
+}
+
+void* IT_peek(void* arg, int n)
+{
+	BArcIterator *iter = (BArcIterator*)arg;
+	
+	if (iter->index + n < 0)
+	{
+		return iter->head(iter);
+	}
+	else if (iter->index + n >= iter->length)
+	{
+		return iter->tail(iter);
+	}
+	else
+	{
+		return iter->peek(iter, n);
+	}
+}
+
+void* IT_next(void* arg)
+{
+	BArcIterator *iter = (BArcIterator*)arg; 
+	return iter->next(iter);
+}
+
+void* IT_nextN(void* arg, int n)
+{
+	BArcIterator *iter = (BArcIterator*)arg; 
+	return iter->nextN(iter, n);
+}
+
+void* IT_previous(void* arg)
+{
+	BArcIterator *iter = (BArcIterator*)arg; 
+	return iter->previous(iter);
+}
+
+int   IT_stopped(void* arg)
+{
+	BArcIterator *iter = (BArcIterator*)arg; 
+	return iter->stopped(iter);
+}