# HG changeset patch
# User Alpar Juttner <alpar@cs.elte.hu>
# Date 2009-10-12 16:30:18
# Node ID c05bb175d3ee489dba6371623a73519da808b408
# Parent  1db9f9db4f952f1e67b9d5130f39b0967d6de4c2
# Parent  41bdb4d6c8c32c29a1eaebc3eef9bef7ef1f9862

Merge bugfix in #250

diff --git a/lemon/path.h b/lemon/path.h
--- a/lemon/path.h
+++ b/lemon/path.h
@@ -1015,18 +1015,20 @@
 
   /// \brief The source of a path
   ///
-  /// This function returns the source of the given path.
+  /// This function returns the source node of the given path.
+  /// If the path is empty, then it returns \c INVALID.
   template <typename Digraph, typename Path>
   typename Digraph::Node pathSource(const Digraph& digraph, const Path& path) {
-    return digraph.source(path.front());
+    return path.empty() ? INVALID : digraph.source(path.front());
   }
 
   /// \brief The target of a path
   ///
-  /// This function returns the target of the given path.
+  /// This function returns the target node of the given path.
+  /// If the path is empty, then it returns \c INVALID.
   template <typename Digraph, typename Path>
   typename Digraph::Node pathTarget(const Digraph& digraph, const Path& path) {
-    return digraph.target(path.back());
+    return path.empty() ? INVALID : digraph.target(path.back());
   }
 
   /// \brief Class which helps to iterate through the nodes of a path