diff -r 6ec5dbed8f18 -r b55e501a90ee lemon/path_utils.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lemon/path_utils.h	Thu Jan 24 11:31:19 2008 +0000
@@ -0,0 +1,204 @@
+/* -*- C++ -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library
+ *
+ * Copyright (C) 2003-2008
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+///\ingroup paths
+///\file
+///\brief Classes for representing paths in digraphs.
+///
+
+#ifndef LEMON_PATH_UTILS_H
+#define LEMON_PATH_UTILS_H
+
+#include <lemon/concepts/path.h>
+
+namespace lemon {
+
+  namespace _path_bits {
+
+    template <typename Path, typename Enable = void>
+    struct RevTagIndicator {
+      static const bool value = false;
+    };
+
+    template <typename Digraph>
+    struct RevTagIndicator<
+      Digraph, 
+      typename enable_if<typename Digraph::RevTag, void>::type
+    > {
+      static const bool value = true;
+    };
+
+    template <typename Target, typename Source,
+              typename BuildEnable = void, typename RevEnable = void>
+    struct PathCopySelector {
+      static void copy(Target& target, const Source& source) {
+        target.clear();
+        for (typename Source::ArcIt it(source); it != INVALID; ++it) {
+          target.addBack(it);
+        }
+      }
+    };
+
+    template <typename Target, typename Source, typename BuildEnable>
+    struct PathCopySelector<
+      Target, Source, BuildEnable, 
+      typename enable_if<typename Source::RevPathTag, void>::type> {
+      static void copy(Target& target, const Source& source) {
+        target.clear();
+        for (typename Source::RevArcIt it(source); it != INVALID; ++it) {
+          target.addFront(it);
+        }
+      }
+    };
+
+    template <typename Target, typename Source, typename RevEnable>
+    struct PathCopySelector<
+      Target, Source, 
+      typename enable_if<typename Target::BuildTag, void>::type, RevEnable> {
+      static void copy(Target& target, const Source& source) {
+        target.clear();
+        target.build(source);
+      }
+    };
+
+    template <typename Target, typename Source>
+    struct PathCopySelector<
+      Target, Source, 
+      typename enable_if<typename Target::BuildTag, void>::type,
+      typename enable_if<typename Source::RevPathTag, void>::type> {
+      static void copy(Target& target, const Source& source) {
+        target.clear();
+        target.buildRev(source);
+      }
+    };
+
+  }
+
+
+  /// \brief Make of copy of a path.
+  ///
+  ///  Make of copy of a path.
+  template <typename Target, typename Source>
+  void copyPath(Target& target, const Source& source) {
+    checkConcept<concepts::PathDumper<typename Source::Digraph>, Source>();
+    _path_bits::PathCopySelector<Target, Source>::copy(target, source);
+  }
+
+  /// \brief Checks the path's consistency.
+  ///
+  /// Checks that each arc's target is the next's source. 
+  /// 
+  template <typename Digraph, typename Path>
+  bool checkPath(const Digraph& digraph, const Path& path) {
+    typename Path::ArcIt it(path);
+    if (it == INVALID) return true;
+    typename Digraph::Node node = digraph.target(it);
+    ++it;
+    while (it != INVALID) {
+      if (digraph.source(it) != node) return false;
+      node = digraph.target(it);
+      ++it;
+    }
+    return true;
+  }
+
+  /// \brief Gives back the source of the path
+  ///
+  /// Gives back the source of the path.
+  template <typename Digraph, typename Path>
+  typename Digraph::Node pathSource(const Digraph& digraph, const Path& path) {
+    return digraph.source(path.front());
+  }
+
+  /// \brief Gives back the target of the path
+  ///
+  /// Gives back the target of the path.
+  template <typename Digraph, typename Path>
+  typename Digraph::Node pathTarget(const Digraph& digraph, const Path& path) {
+    return digraph.target(path.back());
+  }
+
+  /// \brief Class which helps to iterate the nodes of a path
+  ///
+  /// In a sense, the path can be treated as a list of arcs. The
+  /// lemon path type stores just this list. As a consequence it
+  /// cannot enumerate the nodes in the path and the zero length paths
+  /// cannot store the node.
+  ///
+  /// This class implements the node iterator of a path structure. To
+  /// provide this feature, the underlying digraph should be given to
+  /// the constructor of the iterator.
+  template <typename Path>
+  class PathNodeIt {
+  private:
+    const typename Path::Digraph *_digraph;
+    typename Path::ArcIt _it;
+    typename Path::Digraph::Node _nd;
+
+  public:
+
+    typedef typename Path::Digraph Digraph;
+    typedef typename Digraph::Node Node;
+    
+    /// Default constructor
+    PathNodeIt() {}
+    /// Invalid constructor
+    PathNodeIt(Invalid) 
+      : _digraph(0), _it(INVALID), _nd(INVALID) {}
+    /// Constructor
+    PathNodeIt(const Digraph& digraph, const Path& path) 
+      : _digraph(&digraph), _it(path) {
+      _nd = (_it != INVALID ? _digraph->source(_it) : INVALID);
+    }
+    /// Constructor
+    PathNodeIt(const Digraph& digraph, const Path& path, const Node& src) 
+      : _digraph(&digraph), _it(path), _nd(src) {}
+
+    ///Conversion to Digraph::Node
+    operator Node() const {
+      return _nd;
+    }
+
+    /// Next node
+    PathNodeIt& operator++() {
+      if (_it == INVALID) _nd = INVALID;
+      else {
+	_nd = _digraph->target(_it);
+	++_it;
+      }
+      return *this;
+    }
+
+    /// Comparison operator
+    bool operator==(const PathNodeIt& n) const { 
+      return _it == n._it && _nd == n._nd; 
+    }
+    /// Comparison operator
+    bool operator!=(const PathNodeIt& n) const { 
+      return _it != n._it || _nd != n._nd; 
+    }
+    /// Comparison operator
+    bool operator<(const PathNodeIt& n) const { 
+      return (_it < n._it && _nd != INVALID);
+    }
+    
+  };
+  
+}
+
+#endif