--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/graph/sorting.py	Wed Nov 26 23:56:19 2008 +0000
@@ -0,0 +1,49 @@
+# 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.
+
+
+"""
+Sorting algorithms for python-graph.
+
+@sort: topological_sorting
+"""
+
+
+# Topological sorting
+
+def topological_sorting(graph):
+	"""
+	Topological sorting.
+
+	@attention: Topological sorting is meaningful only for directed acyclic graphs.
+
+	@type  graph: graph
+	@param graph: Graph.
+
+	@rtype:  list
+	@return: Topological sorting for the graph.
+	"""
+	# The topological sorting of a DAG is equivalent to its reverse postordering.
+	tmp, tmp, post = graph.depth_first_search()
+	post.reverse()
+	return post