# HG changeset patch
# User Peter Kovacs <kpeter@inf.elte.hu>
# Date 1270503665 -7200
# Node ID dc376822c17d7053ff8b611e835bfdebb3286591
# Parent  87569cb5734dee71de7e2c449c1cd6500921e2a7
Add an undirected() function (#364)

diff -r 87569cb5734d -r dc376822c17d lemon/core.h
--- a/lemon/core.h	Wed Mar 17 14:05:23 2010 +0100
+++ b/lemon/core.h	Mon Apr 05 23:41:05 2010 +0200
@@ -445,6 +445,25 @@
 
   }
 
+  /// Check whether a graph is undirected.
+  ///
+  /// This function returns \c true if the given graph is undirected.
+#ifdef DOXYGEN
+  template <typename GR>
+  bool undirected(const GR& g) { return false; }
+#else
+  template <typename GR>
+  typename enable_if<UndirectedTagIndicator<GR>, bool>::type
+  undirected(const GR&) {
+    return true;
+  }
+  template <typename GR>
+  typename disable_if<UndirectedTagIndicator<GR>, bool>::type
+  undirected(const GR&) {
+    return false;
+  }
+#endif
+
   /// \brief Class to copy a digraph.
   ///
   /// Class to copy a digraph to another digraph (duplicate a digraph). The