--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/thirdparty/python-graph/graph/traversal.py	Wed Nov 26 23:56:19 2008 +0000
@@ -0,0 +1,81 @@
+# Copyright (c) 2007-2008 Pedro Matiello <pmatiello@gmail.com>
+#
+# Permission is hereby granted, free of charge, to any person
+# obtaining a copy of this software and associated documentation
+# files (the "Software"), to deal in the Software without
+# restriction, including without limitation the rights to use,
+# copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the
+# Software is furnished to do so, subject to the following
+# conditions:
+
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+# OTHER DEALINGS IN THE SOFTWARE.
+
+
+"""
+Traversal algorithms for python-graph.
+
+@sort: traversal
+"""
+
+
+# Minimal spanning tree
+
+def traversal(graph, node, order):
+	"""
+	Graph traversal iterator.
+
+	@type  node: node
+	@param node: Node.
+	
+	@type  order: string
+	@param order: traversal ordering. Possible values are:
+		2. 'pre' - Preordering (default)
+		1. 'post' - Postordering
+	
+	@rtype:  iterator
+	@return: Traversal iterator.
+	"""
+	visited = {}
+	if (order == 'pre'):
+		pre = 1
+		post = 0
+	elif (order == 'post'):
+		pre = 0
+		post = 1
+	
+	for each in _dfs(graph, visited, node, pre, post):
+		yield each
+
+
+def _dfs(graph, visited, node, pre, post):
+	"""
+	Depht-first search subfunction for traversals.
+	
+	@type  graph: graph
+	@param graph: Graph.
+
+	@type  visited: dictionary
+	@param visited: List of nodes (visited nodes are marked non-zero).
+
+	@type  node: node
+	@param node: Node to be explored by DFS.
+	"""
+	visited[node] = 1
+	if (pre): yield node
+	# Explore recursively the connected component
+	for each in graph[node]:
+		if (each not in visited):
+			for other in _dfs(graph, visited, each, pre, post):
+				yield other
+	if (post): yield node