# HG changeset patch
# User deba
# Date 1123766199 0
# Node ID 9c98841eda96e65460df41a73ebe59a00f62a77d
# Parent  574f8a3f0971c82811b8c51cee0bfde347a91dfb
Ordering in the graph concept.

diff -r 574f8a3f0971 -r 9c98841eda96 lemon/concept/graph.h
--- a/lemon/concept/graph.h	Thu Aug 11 13:15:03 2005 +0000
+++ b/lemon/concept/graph.h	Thu Aug 11 13:16:39 2005 +0000
@@ -176,6 +176,18 @@
         ///
         bool operator!=(Node) const { return true; }
 
+	/// Artificial ordering operator.
+	
+	/// To allow the use of graph descriptors as key type in std::map or
+	/// similar associative container we require this.
+	///
+	/// \note This operator only have to define some strict ordering of
+	/// the items; this order has nothing to do with the iteration
+	/// ordering of the items.
+	///
+	/// \bug This is a technical requirement. Do we really need this?
+	bool operator<(Node) const { return false; }
+
       };
     
       /// This iterator goes through each node.
@@ -255,6 +267,18 @@
         /// \sa operator==(Edge n)
         ///
         bool operator!=(Edge) const { return true; }
+
+	/// Artificial ordering operator.
+	
+	/// To allow the use of graph descriptors as key type in std::map or
+	/// similar associative container we require this.
+	///
+	/// \note This operator only have to define some strict ordering of
+	/// the items; this order has nothing to do with the iteration
+	/// ordering of the items.
+	///
+	/// \bug This is a technical requirement. Do we really need this?
+	bool operator<(Edge) const { return false; }
       };
     
       /// This iterator goes trough the outgoing edges of a node.