/* -*- mode: C++; indent-tabs-mode: nil; -*-

  *

  * 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.

  *

  */

 #ifndef LEMON_GRAPH_UTILS_H

 #define LEMON_GRAPH_UTILS_H

 #include <iterator>

 #include <vector>

 #include <map>

 #include <cmath>

 #include <algorithm>

 #include <lemon/bits/invalid.h>

 #include <lemon/bits/utility.h>

 #include <lemon/maps.h>

 #include <lemon/bits/traits.h>

 #include <lemon/bits/alteration_notifier.h>

 #include <lemon/bits/default_map.h>

 ///\ingroup gutils

 ///\file

 ///\brief Graph utilities.

 namespace lemon {

   /// \addtogroup gutils

   /// @{

   ///Creates convenience typedefs for the digraph types and iterators

   ///This \c \#define creates convenience typedefs for the following types

   ///of \c Digraph: \c Node,  \c NodeIt, \c Arc, \c ArcIt, \c InArcIt,

   ///\c OutArcIt, \c BoolNodeMap, \c IntNodeMap, \c DoubleNodeMap,

   ///\c BoolArcMap, \c IntArcMap, \c DoubleArcMap.

   ///

   ///\note If the graph type is a dependent type, ie. the graph type depend

   ///on a template parameter, then use \c TEMPLATE_DIGRAPH_TYPEDEFS()

   ///macro.

 #define DIGRAPH_TYPEDEFS(Digraph)                                       \

   typedef Digraph::Node Node;                                           \

   typedef Digraph::NodeIt NodeIt;                                       \

   typedef Digraph::Arc Arc;                                             \

   typedef Digraph::ArcIt ArcIt;                                         \

   typedef Digraph::InArcIt InArcIt;                                     \

   typedef Digraph::OutArcIt OutArcIt;                                   \

   typedef Digraph::NodeMap<bool> BoolNodeMap;                           \

   typedef Digraph::NodeMap<int> IntNodeMap;                             \

   typedef Digraph::NodeMap<double> DoubleNodeMap;                       \

   typedef Digraph::ArcMap<bool> BoolArcMap;                             \

   typedef Digraph::ArcMap<int> IntArcMap;                               \

   typedef Digraph::ArcMap<double> DoubleArcMap

   ///Creates convenience typedefs for the digraph types and iterators

   ///\see DIGRAPH_TYPEDEFS

   ///

   ///\note Use this macro, if the graph type is a dependent type,

   ///ie. the graph type depend on a template parameter.

 #define TEMPLATE_DIGRAPH_TYPEDEFS(Digraph)                              \

   typedef typename Digraph::Node Node;                                  \

   typedef typename Digraph::NodeIt NodeIt;                              \

   typedef typename Digraph::Arc Arc;                                    \

   typedef typename Digraph::ArcIt ArcIt;                                \

   typedef typename Digraph::InArcIt InArcIt;                            \

   typedef typename Digraph::OutArcIt OutArcIt;                          \

   typedef typename Digraph::template NodeMap<bool> BoolNodeMap;         \

   typedef typename Digraph::template NodeMap<int> IntNodeMap;           \

   typedef typename Digraph::template NodeMap<double> DoubleNodeMap;     \

   typedef typename Digraph::template ArcMap<bool> BoolArcMap;           \

   typedef typename Digraph::template ArcMap<int> IntArcMap;             \

   typedef typename Digraph::template ArcMap<double> DoubleArcMap

   ///Creates convenience typedefs for the graph types and iterators

   ///This \c \#define creates the same convenience typedefs as defined

   ///by \ref DIGRAPH_TYPEDEFS(Graph) and six more, namely it creates

   ///\c Edge, \c EdgeIt, \c IncEdgeIt, \c BoolEdgeMap, \c IntEdgeMap,

   ///\c DoubleEdgeMap.

   ///

   ///\note If the graph type is a dependent type, ie. the graph type depend

   ///on a template parameter, then use \c TEMPLATE_DIGRAPH_TYPEDEFS()

   ///macro.

 #define GRAPH_TYPEDEFS(Graph)                                           \

   DIGRAPH_TYPEDEFS(Graph);                                              \

   typedef Graph::Edge Edge;                                             \

   typedef Graph::EdgeIt EdgeIt;                                         \

   typedef Graph::IncEdgeIt IncEdgeIt;                                   \

   typedef Graph::EdgeMap<bool> BoolEdgeMap;                             \

   typedef Graph::EdgeMap<int> IntEdgeMap;                               \

   typedef Graph::EdgeMap<double> DoubleEdgeMap

   ///Creates convenience typedefs for the graph types and iterators

   ///\see GRAPH_TYPEDEFS

   ///

   ///\note Use this macro, if the graph type is a dependent type,

   ///ie. the graph type depend on a template parameter.

 #define TEMPLATE_GRAPH_TYPEDEFS(Graph)                                  \

   TEMPLATE_DIGRAPH_TYPEDEFS(Graph);                                     \

   typedef typename Graph::Edge Edge;                                    \

   typedef typename Graph::EdgeIt EdgeIt;                                \

   typedef typename Graph::IncEdgeIt IncEdgeIt;                          \

   typedef typename Graph::template EdgeMap<bool> BoolEdgeMap;           \

   typedef typename Graph::template EdgeMap<int> IntEdgeMap;             \

   typedef typename Graph::template EdgeMap<double> DoubleEdgeMap

   /// \brief Function to count the items in the graph.

   ///

   /// This function counts the items (nodes, arcs etc) in the graph.

   /// The complexity of the function is O(n) because

   /// it iterates on all of the items.

   template <typename Graph, typename Item>

   inline int countItems(const Graph& g) {

     typedef typename ItemSetTraits<Graph, Item>::ItemIt ItemIt;

     int num = 0;

     for (ItemIt it(g); it != INVALID; ++it) {

       ++num;

     }

     return num;

   }

   // Node counting:

   namespace _graph_utils_bits {

     template <typename Graph, typename Enable = void>

     struct CountNodesSelector {

       static int count(const Graph &g) {

         return countItems<Graph, typename Graph::Node>(g);

       }

     };

     template <typename Graph>

     struct CountNodesSelector<

       Graph, typename

       enable_if<typename Graph::NodeNumTag, void>::type>

     {

       static int count(const Graph &g) {

         return g.nodeNum();

       }

     };

   }

   /// \brief Function to count the nodes in the graph.

   ///

   /// This function counts the nodes in the graph.

   /// The complexity of the function is O(n) but for some

   /// graph structures it is specialized to run in O(1).

   ///

   /// If the graph contains a \e nodeNum() member function and a

   /// \e NodeNumTag tag then this function calls directly the member

   /// function to query the cardinality of the node set.

   template <typename Graph>

   inline int countNodes(const Graph& g) {

     return _graph_utils_bits::CountNodesSelector<Graph>::count(g);

   }

   // Arc counting:

   namespace _graph_utils_bits {

     template <typename Graph, typename Enable = void>

     struct CountArcsSelector {

       static int count(const Graph &g) {

         return countItems<Graph, typename Graph::Arc>(g);

       }

     };

     template <typename Graph>

     struct CountArcsSelector<

       Graph,

       typename enable_if<typename Graph::ArcNumTag, void>::type>

     {

       static int count(const Graph &g) {

         return g.arcNum();

       }

     };

   }

   /// \brief Function to count the arcs in the graph.

   ///

   /// This function counts the arcs in the graph.

   /// The complexity of the function is O(e) but for some

   /// graph structures it is specialized to run in O(1).

   ///

   /// If the graph contains a \e arcNum() member function and a

   /// \e EdgeNumTag tag then this function calls directly the member

   /// function to query the cardinality of the arc set.

   template <typename Graph>

   inline int countArcs(const Graph& g) {

     return _graph_utils_bits::CountArcsSelector<Graph>::count(g);

   }

   // Edge counting:

   namespace _graph_utils_bits {

     template <typename Graph, typename Enable = void>

     struct CountEdgesSelector {

       static int count(const Graph &g) {

         return countItems<Graph, typename Graph::Edge>(g);

       }

     };

     template <typename Graph>

     struct CountEdgesSelector<

       Graph,

       typename enable_if<typename Graph::EdgeNumTag, void>::type>

     {

       static int count(const Graph &g) {

         return g.edgeNum();

       }

     };

   }

   /// \brief Function to count the edges in the graph.

   ///

   /// This function counts the edges in the graph.

   /// The complexity of the function is O(m) but for some

   /// graph structures it is specialized to run in O(1).

   ///

   /// If the graph contains a \e edgeNum() member function and a

   /// \e EdgeNumTag tag then this function calls directly the member

   /// function to query the cardinality of the edge set.

   template <typename Graph>

   inline int countEdges(const Graph& g) {

     return _graph_utils_bits::CountEdgesSelector<Graph>::count(g);

   }

   template <typename Graph, typename DegIt>

   inline int countNodeDegree(const Graph& _g, const typename Graph::Node& _n) {

     int num = 0;

     for (DegIt it(_g, _n); it != INVALID; ++it) {

       ++num;

     }

     return num;

   }

   /// \brief Function to count the number of the out-arcs from node \c n.

   ///

   /// This function counts the number of the out-arcs from node \c n

   /// in the graph.

   template <typename Graph>

   inline int countOutArcs(const Graph& _g,  const typename Graph::Node& _n) {

     return countNodeDegree<Graph, typename Graph::OutArcIt>(_g, _n);

   }

   /// \brief Function to count the number of the in-arcs to node \c n.

   ///

   /// This function counts the number of the in-arcs to node \c n

   /// in the graph.

   template <typename Graph>

   inline int countInArcs(const Graph& _g,  const typename Graph::Node& _n) {

     return countNodeDegree<Graph, typename Graph::InArcIt>(_g, _n);

   }

   /// \brief Function to count the number of the inc-edges to node \c n.

   ///

   /// This function counts the number of the inc-edges to node \c n

   /// in the graph.

   template <typename Graph>

   inline int countIncEdges(const Graph& _g,  const typename Graph::Node& _n) {

     return countNodeDegree<Graph, typename Graph::IncEdgeIt>(_g, _n);

   }

   namespace _graph_utils_bits {

     template <typename Graph, typename Enable = void>

     struct FindArcSelector {

       typedef typename Graph::Node Node;

       typedef typename Graph::Arc Arc;

       static Arc find(const Graph &g, Node u, Node v, Arc e) {

         if (e == INVALID) {

           g.firstOut(e, u);

         } else {

           g.nextOut(e);

         }

         while (e != INVALID && g.target(e) != v) {

           g.nextOut(e);

         }

         return e;

       }

     };

     template <typename Graph>

     struct FindArcSelector<

       Graph,

       typename enable_if<typename Graph::FindEdgeTag, void>::type>

     {

       typedef typename Graph::Node Node;

       typedef typename Graph::Arc Arc;

       static Arc find(const Graph &g, Node u, Node v, Arc prev) {

         return g.findArc(u, v, prev);

       }

     };

   }

   /// \brief Finds an arc between two nodes of a graph.

   ///

   /// Finds an arc from node \c u to node \c v in graph \c g.

   ///

   /// If \c prev is \ref INVALID (this is the default value), then

   /// it finds the first arc from \c u to \c v. Otherwise it looks for

   /// the next arc from \c u to \c v after \c prev.

   /// \return The found arc or \ref INVALID if there is no such an arc.

   ///

   /// Thus you can iterate through each arc from \c u to \c v as it follows.

   ///\code

   /// for(Arc e=findArc(g,u,v);e!=INVALID;e=findArc(g,u,v,e)) {

   ///   ...

   /// }

   ///\endcode

   ///

   ///\sa ArcLookUp

   ///\sa AllArcLookUp

   ///\sa DynArcLookUp

   ///\sa ConArcIt

   template <typename Graph>

   inline typename Graph::Arc

   findArc(const Graph &g, typename Graph::Node u, typename Graph::Node v,

            typename Graph::Arc prev = INVALID) {

     return _graph_utils_bits::FindArcSelector<Graph>::find(g, u, v, prev);

   }

   /// \brief Iterator for iterating on arcs connected the same nodes.

   ///

   /// Iterator for iterating on arcs connected the same nodes. It is

   /// higher level interface for the findArc() function. You can

   /// use it the following way:

   ///\code

   /// for (ConArcIt<Graph> it(g, src, trg); it != INVALID; ++it) {

   ///   ...

   /// }

   ///\endcode

   ///

   ///\sa findArc()

   ///\sa ArcLookUp

   ///\sa AllArcLookUp

   ///\sa DynArcLookUp

   template <typename _Graph>

   class ConArcIt : public _Graph::Arc {

   public:

     typedef _Graph Graph;

     typedef typename Graph::Arc Parent;

     typedef typename Graph::Arc Arc;

     typedef typename Graph::Node Node;

     /// \brief Constructor.

     ///

     /// Construct a new ConArcIt iterating on the arcs which

     /// connects the \c u and \c v node.

     ConArcIt(const Graph& g, Node u, Node v) : _graph(g) {

       Parent::operator=(findArc(_graph, u, v));

     }

     /// \brief Constructor.

     ///

     /// Construct a new ConArcIt which continues the iterating from

     /// the \c e arc.

     ConArcIt(const Graph& g, Arc a) : Parent(a), _graph(g) {}

     /// \brief Increment operator.

     ///

     /// It increments the iterator and gives back the next arc.

     ConArcIt& operator++() {

       Parent::operator=(findArc(_graph, _graph.source(*this),

                                 _graph.target(*this), *this));

       return *this;

     }

   private:

     const Graph& _graph;

   };

   namespace _graph_utils_bits {

     template <typename Graph, typename Enable = void>

     struct FindEdgeSelector {

       typedef typename Graph::Node Node;

       typedef typename Graph::Edge Edge;

       static Edge find(const Graph &g, Node u, Node v, Edge e) {

         bool b;

         if (u != v) {

           if (e == INVALID) {

             g.firstInc(e, b, u);

           } else {

             b = g.u(e) == u;

             g.nextInc(e, b);

           }

           while (e != INVALID && (b ? g.v(e) : g.u(e)) != v) {

             g.nextInc(e, b);

           }

         } else {

           if (e == INVALID) {

             g.firstInc(e, b, u);

           } else {

             b = true;

             g.nextInc(e, b);

           }

           while (e != INVALID && (!b || g.v(e) != v)) {

             g.nextInc(e, b);

           }

         }

         return e;

       }

     };

     template <typename Graph>

     struct FindEdgeSelector<

       Graph,

       typename enable_if<typename Graph::FindEdgeTag, void>::type>

     {

       typedef typename Graph::Node Node;

       typedef typename Graph::Edge Edge;

       static Edge find(const Graph &g, Node u, Node v, Edge prev) {

         return g.findEdge(u, v, prev);

       }

     };

   }

   /// \brief Finds an edge between two nodes of a graph.

   ///

   /// Finds an edge from node \c u to node \c v in graph \c g.

   /// If the node \c u and node \c v is equal then each loop edge

   /// will be enumerated once.

   ///

   /// If \c prev is \ref INVALID (this is the default value), then

   /// it finds the first arc from \c u to \c v. Otherwise it looks for

   /// the next arc from \c u to \c v after \c prev.

   /// \return The found arc or \ref INVALID if there is no such an arc.

   ///

   /// Thus you can iterate through each arc from \c u to \c v as it follows.

   ///\code

   /// for(Edge e = findEdge(g,u,v); e != INVALID;

   ///     e = findEdge(g,u,v,e)) {

   ///   ...

   /// }

   ///\endcode

   ///

   ///\sa ConEdgeIt

   template <typename Graph>

   inline typename Graph::Edge

   findEdge(const Graph &g, typename Graph::Node u, typename Graph::Node v,

             typename Graph::Edge p = INVALID) {

     return _graph_utils_bits::FindEdgeSelector<Graph>::find(g, u, v, p);

   }

   /// \brief Iterator for iterating on edges connected the same nodes.

   ///

   /// Iterator for iterating on edges connected the same nodes. It is

   /// higher level interface for the findEdge() function. You can

   /// use it the following way:

   ///\code

   /// for (ConEdgeIt<Graph> it(g, src, trg); it != INVALID; ++it) {

   ///   ...

   /// }

   ///\endcode

   ///

   ///\sa findEdge()

   template <typename _Graph>

   class ConEdgeIt : public _Graph::Edge {

   public:

     typedef _Graph Graph;

     typedef typename Graph::Edge Parent;

     typedef typename Graph::Edge Edge;

     typedef typename Graph::Node Node;

     /// \brief Constructor.

     ///

     /// Construct a new ConEdgeIt iterating on the edges which

     /// connects the \c u and \c v node.

     ConEdgeIt(const Graph& g, Node u, Node v) : _graph(g) {

       Parent::operator=(findEdge(_graph, u, v));

     }

     /// \brief Constructor.

     ///

     /// Construct a new ConEdgeIt which continues the iterating from

     /// the \c e edge.

     ConEdgeIt(const Graph& g, Edge e) : Parent(e), _graph(g) {}

     /// \brief Increment operator.

     ///

     /// It increments the iterator and gives back the next edge.

     ConEdgeIt& operator++() {

       Parent::operator=(findEdge(_graph, _graph.u(*this),

                                  _graph.v(*this), *this));

       return *this;

     }

   private:

     const Graph& _graph;

   };

   namespace _graph_utils_bits {

     template <typename Digraph, typename Item, typename RefMap>

     class MapCopyBase {

     public:

       virtual void copy(const Digraph& from, const RefMap& refMap) = 0;

       virtual ~MapCopyBase() {}

     };

     template <typename Digraph, typename Item, typename RefMap,

               typename ToMap, typename FromMap>

     class MapCopy : public MapCopyBase<Digraph, Item, RefMap> {

     public:

       MapCopy(ToMap& tmap, const FromMap& map)

         : _tmap(tmap), _map(map) {}

       virtual void copy(const Digraph& digraph, const RefMap& refMap) {

         typedef typename ItemSetTraits<Digraph, Item>::ItemIt ItemIt;

         for (ItemIt it(digraph); it != INVALID; ++it) {

           _tmap.set(refMap[it], _map[it]);

         }

       }

     private:

       ToMap& _tmap;

       const FromMap& _map;

     };

     template <typename Digraph, typename Item, typename RefMap, typename It>

     class ItemCopy : public MapCopyBase<Digraph, Item, RefMap> {

     public:

       ItemCopy(It& it, const Item& item) : _it(it), _item(item) {}

       virtual void copy(const Digraph&, const RefMap& refMap) {

         _it = refMap[_item];

       }

     private:

       It& _it;

       Item _item;

     };

     template <typename Digraph, typename Item, typename RefMap, typename Ref>

     class RefCopy : public MapCopyBase<Digraph, Item, RefMap> {

     public:

       RefCopy(Ref& map) : _map(map) {}

       virtual void copy(const Digraph& digraph, const RefMap& refMap) {

         typedef typename ItemSetTraits<Digraph, Item>::ItemIt ItemIt;

         for (ItemIt it(digraph); it != INVALID; ++it) {

           _map.set(it, refMap[it]);

         }

       }

     private:

       Ref& _map;

     };

     template <typename Digraph, typename Item, typename RefMap,

               typename CrossRef>

     class CrossRefCopy : public MapCopyBase<Digraph, Item, RefMap> {

     public:

       CrossRefCopy(CrossRef& cmap) : _cmap(cmap) {}

       virtual void copy(const Digraph& digraph, const RefMap& refMap) {

         typedef typename ItemSetTraits<Digraph, Item>::ItemIt ItemIt;

         for (ItemIt it(digraph); it != INVALID; ++it) {

           _cmap.set(refMap[it], it);

         }

       }

     private:

       CrossRef& _cmap;

     };

     template <typename Digraph, typename Enable = void>

     struct DigraphCopySelector {

       template <typename From, typename NodeRefMap, typename ArcRefMap>

       static void copy(Digraph &to, const From& from,

                        NodeRefMap& nodeRefMap, ArcRefMap& arcRefMap) {

         for (typename From::NodeIt it(from); it != INVALID; ++it) {

           nodeRefMap[it] = to.addNode();

         }

         for (typename From::ArcIt it(from); it != INVALID; ++it) {

           arcRefMap[it] = to.addArc(nodeRefMap[from.source(it)],

                                     nodeRefMap[from.target(it)]);

         }

       }

     };

     template <typename Digraph>

     struct DigraphCopySelector<

       Digraph,

       typename enable_if<typename Digraph::BuildTag, void>::type>

     {

       template <typename From, typename NodeRefMap, typename ArcRefMap>

       static void copy(Digraph &to, const From& from,

                        NodeRefMap& nodeRefMap, ArcRefMap& arcRefMap) {

         to.build(from, nodeRefMap, arcRefMap);

       }

     };

     template <typename Graph, typename Enable = void>

     struct GraphCopySelector {

       template <typename From, typename NodeRefMap, typename EdgeRefMap>

       static void copy(Graph &to, const From& from,

                        NodeRefMap& nodeRefMap, EdgeRefMap& edgeRefMap) {

         for (typename From::NodeIt it(from); it != INVALID; ++it) {

           nodeRefMap[it] = to.addNode();

         }

         for (typename From::EdgeIt it(from); it != INVALID; ++it) {

           edgeRefMap[it] = to.addEdge(nodeRefMap[from.u(it)],

                                       nodeRefMap[from.v(it)]);

         }

       }

     };

     template <typename Graph>

     struct GraphCopySelector<

       Graph,

       typename enable_if<typename Graph::BuildTag, void>::type>

     {

       template <typename From, typename NodeRefMap, typename EdgeRefMap>

       static void copy(Graph &to, const From& from,

                        NodeRefMap& nodeRefMap, EdgeRefMap& edgeRefMap) {

         to.build(from, nodeRefMap, edgeRefMap);

       }

     };

   }

   /// \brief Class to copy a digraph.

   ///

   /// Class to copy a digraph to another digraph (duplicate a digraph). The

   /// simplest way of using it is through the \c copyDigraph() function.

   ///

   /// This class not just make a copy of a graph, but it can create

   /// references and cross references between the nodes and arcs of

   /// the two graphs, it can copy maps for use with the newly created

   /// graph and copy nodes and arcs.

   ///

   /// To make a copy from a graph, first an instance of DigraphCopy

   /// should be created, then the data belongs to the graph should

   /// assigned to copy. In the end, the \c run() member should be

   /// called.

   ///

   /// The next code copies a graph with several data:

   ///\code

   ///  DigraphCopy<NewGraph, OrigGraph> dc(new_graph, orig_graph);

   ///  // create a reference for the nodes

   ///  OrigGraph::NodeMap<NewGraph::Node> nr(orig_graph);

   ///  dc.nodeRef(nr);

   ///  // create a cross reference (inverse) for the arcs

   ///  NewGraph::ArcMap<OrigGraph::Arc> acr(new_graph);

   ///  dc.arcCrossRef(acr);

   ///  // copy an arc map

   ///  OrigGraph::ArcMap<double> oamap(orig_graph);

   ///  NewGraph::ArcMap<double> namap(new_graph);

   ///  dc.arcMap(namap, oamap);

   ///  // copy a node

   ///  OrigGraph::Node on;

   ///  NewGraph::Node nn;

   ///  dc.node(nn, on);

   ///  // Executions of copy

   ///  dc.run();

   ///\endcode

   template <typename To, typename From>

   class DigraphCopy {

   private:

     typedef typename From::Node Node;

     typedef typename From::NodeIt NodeIt;

     typedef typename From::Arc Arc;

     typedef typename From::ArcIt ArcIt;

     typedef typename To::Node TNode;

     typedef typename To::Arc TArc;

     typedef typename From::template NodeMap<TNode> NodeRefMap;

     typedef typename From::template ArcMap<TArc> ArcRefMap;

   public:

     /// \brief Constructor for the DigraphCopy.

     ///

     /// It copies the content of the \c _from digraph into the

     /// \c _to digraph.

     DigraphCopy(To& to, const From& from)

       : _from(from), _to(to) {}

     /// \brief Destructor of the DigraphCopy

     ///

     /// Destructor of the DigraphCopy

     ~DigraphCopy() {

       for (int i = 0; i < int(_node_maps.size()); ++i) {

         delete _node_maps[i];

       }

       for (int i = 0; i < int(_arc_maps.size()); ++i) {

         delete _arc_maps[i];

       }

     }

     /// \brief Copies the node references into the given map.

     ///

     /// Copies the node references into the given map. The parameter

     /// should be a map, which key type is the Node type of the source

     /// graph, while the value type is the Node type of the

     /// destination graph.

     template <typename NodeRef>

     DigraphCopy& nodeRef(NodeRef& map) {

       _node_maps.push_back(new _graph_utils_bits::RefCopy<From, Node,

                            NodeRefMap, NodeRef>(map));

       return *this;

     }

     /// \brief Copies the node cross references into the given map.

     ///

     ///  Copies the node cross references (reverse references) into

     ///  the given map. The parameter should be a map, which key type

     ///  is the Node type of the destination graph, while the value type is

     ///  the Node type of the source graph.

     template <typename NodeCrossRef>

     DigraphCopy& nodeCrossRef(NodeCrossRef& map) {

       _node_maps.push_back(new _graph_utils_bits::CrossRefCopy<From, Node,

                            NodeRefMap, NodeCrossRef>(map));

       return *this;

     }

     /// \brief Make copy of the given map.

     ///

     /// Makes copy of the given map for the newly created digraph.

     /// The new map's key type is the destination graph's node type,

     /// and the copied map's key type is the source graph's node type.

     template <typename ToMap, typename FromMap>

     DigraphCopy& nodeMap(ToMap& tmap, const FromMap& map) {

       _node_maps.push_back(new _graph_utils_bits::MapCopy<From, Node,

                            NodeRefMap, ToMap, FromMap>(tmap, map));

       return *this;

     }

     /// \brief Make a copy of the given node.

     ///

     /// Make a copy of the given node.

     DigraphCopy& node(TNode& tnode, const Node& snode) {

       _node_maps.push_back(new _graph_utils_bits::ItemCopy<From, Node,

                            NodeRefMap, TNode>(tnode, snode));

       return *this;

     }

     /// \brief Copies the arc references into the given map.

     ///

     /// Copies the arc references into the given map.

     template <typename ArcRef>

     DigraphCopy& arcRef(ArcRef& map) {

       _arc_maps.push_back(new _graph_utils_bits::RefCopy<From, Arc,

                           ArcRefMap, ArcRef>(map));

       return *this;

     }

     /// \brief Copies the arc cross references into the given map.

     ///

     ///  Copies the arc cross references (reverse references) into

     ///  the given map.

     template <typename ArcCrossRef>

     DigraphCopy& arcCrossRef(ArcCrossRef& map) {

       _arc_maps.push_back(new _graph_utils_bits::CrossRefCopy<From, Arc,

                           ArcRefMap, ArcCrossRef>(map));

       return *this;

     }

     /// \brief Make copy of the given map.

     ///

     /// Makes copy of the given map for the newly created digraph.

     /// The new map's key type is the to digraph's arc type,

     /// and the copied map's key type is the from digraph's arc

     /// type.

     template <typename ToMap, typename FromMap>

     DigraphCopy& arcMap(ToMap& tmap, const FromMap& map) {

       _arc_maps.push_back(new _graph_utils_bits::MapCopy<From, Arc,

                           ArcRefMap, ToMap, FromMap>(tmap, map));

       return *this;

     }

     /// \brief Make a copy of the given arc.

     ///

     /// Make a copy of the given arc.

     DigraphCopy& arc(TArc& tarc, const Arc& sarc) {

       _arc_maps.push_back(new _graph_utils_bits::ItemCopy<From, Arc,

                           ArcRefMap, TArc>(tarc, sarc));

       return *this;

     }

     /// \brief Executes the copies.

     ///

     /// Executes the copies.

     void run() {

       NodeRefMap nodeRefMap(_from);

       ArcRefMap arcRefMap(_from);

       _graph_utils_bits::DigraphCopySelector<To>::

         copy(_to, _from, nodeRefMap, arcRefMap);

       for (int i = 0; i < int(_node_maps.size()); ++i) {

         _node_maps[i]->copy(_from, nodeRefMap);

       }

       for (int i = 0; i < int(_arc_maps.size()); ++i) {

         _arc_maps[i]->copy(_from, arcRefMap);

       }

     }

   protected:

     const From& _from;

     To& _to;

     std::vector<_graph_utils_bits::MapCopyBase<From, Node, NodeRefMap>* >

     _node_maps;

     std::vector<_graph_utils_bits::MapCopyBase<From, Arc, ArcRefMap>* >

     _arc_maps;

   };

   /// \brief Copy a digraph to another digraph.

   ///

   /// Copy a digraph to another digraph. The complete usage of the

   /// function is detailed in the DigraphCopy class, but a short

   /// example shows a basic work:

   ///\code

   /// copyDigraph(trg, src).nodeRef(nr).arcCrossRef(ecr).run();

   ///\endcode

   ///

   /// After the copy the \c nr map will contain the mapping from the

   /// nodes of the \c from digraph to the nodes of the \c to digraph and

   /// \c ecr will contain the mapping from the arcs of the \c to digraph

   /// to the arcs of the \c from digraph.

   ///

   /// \see DigraphCopy

   template <typename To, typename From>

   DigraphCopy<To, From> copyDigraph(To& to, const From& from) {

     return DigraphCopy<To, From>(to, from);

   }

   /// \brief Class to copy a graph.

   ///

   /// Class to copy a graph to another graph (duplicate a graph). The

   /// simplest way of using it is through the \c copyGraph() function.

   ///

   /// This class not just make a copy of a graph, but it can create

   /// references and cross references between the nodes, edges and arcs of

   /// the two graphs, it can copy maps for use with the newly created

   /// graph and copy nodes, edges and arcs.

   ///

   /// To make a copy from a graph, first an instance of GraphCopy

   /// should be created, then the data belongs to the graph should

   /// assigned to copy. In the end, the \c run() member should be

   /// called.

   ///

   /// The next code copies a graph with several data:

   ///\code

   ///  GraphCopy<NewGraph, OrigGraph> dc(new_graph, orig_graph);

   ///  // create a reference for the nodes

   ///  OrigGraph::NodeMap<NewGraph::Node> nr(orig_graph);

   ///  dc.nodeRef(nr);

   ///  // create a cross reference (inverse) for the edges

   ///  NewGraph::EdgeMap<OrigGraph::Arc> ecr(new_graph);

   ///  dc.edgeCrossRef(ecr);

   ///  // copy an arc map

   ///  OrigGraph::ArcMap<double> oamap(orig_graph);

   ///  NewGraph::ArcMap<double> namap(new_graph);

   ///  dc.arcMap(namap, oamap);

   ///  // copy a node

   ///  OrigGraph::Node on;

   ///  NewGraph::Node nn;

   ///  dc.node(nn, on);

   ///  // Executions of copy

   ///  dc.run();

   ///\endcode

   template <typename To, typename From>

   class GraphCopy {

   private:

     typedef typename From::Node Node;

     typedef typename From::NodeIt NodeIt;

     typedef typename From::Arc Arc;

     typedef typename From::ArcIt ArcIt;

     typedef typename From::Edge Edge;

     typedef typename From::EdgeIt EdgeIt;

     typedef typename To::Node TNode;

     typedef typename To::Arc TArc;

     typedef typename To::Edge TEdge;

     typedef typename From::template NodeMap<TNode> NodeRefMap;

     typedef typename From::template EdgeMap<TEdge> EdgeRefMap;

     struct ArcRefMap {

       ArcRefMap(const To& to, const From& from,

                 const EdgeRefMap& edge_ref, const NodeRefMap& node_ref)

         : _to(to), _from(from),

           _edge_ref(edge_ref), _node_ref(node_ref) {}

       typedef typename From::Arc Key;

       typedef typename To::Arc Value;

       Value operator[](const Key& key) const {

         bool forward = _from.u(key) != _from.v(key) ?

           _node_ref[_from.source(key)] ==

           _to.source(_to.direct(_edge_ref[key], true)) :

           _from.direction(key);

         return _to.direct(_edge_ref[key], forward);

       }

       const To& _to;

       const From& _from;

       const EdgeRefMap& _edge_ref;

       const NodeRefMap& _node_ref;

     };

   public:

     /// \brief Constructor for the GraphCopy.

     ///

     /// It copies the content of the \c _from graph into the

     /// \c _to graph.

     GraphCopy(To& to, const From& from)

       : _from(from), _to(to) {}

     /// \brief Destructor of the GraphCopy

     ///

     /// Destructor of the GraphCopy

     ~GraphCopy() {

       for (int i = 0; i < int(_node_maps.size()); ++i) {

         delete _node_maps[i];

       }

       for (int i = 0; i < int(_arc_maps.size()); ++i) {

         delete _arc_maps[i];

       }

       for (int i = 0; i < int(_edge_maps.size()); ++i) {

         delete _edge_maps[i];

       }

     }

     /// \brief Copies the node references into the given map.

     ///

     /// Copies the node references into the given map.

     template <typename NodeRef>

     GraphCopy& nodeRef(NodeRef& map) {

       _node_maps.push_back(new _graph_utils_bits::RefCopy<From, Node,

                            NodeRefMap, NodeRef>(map));

       return *this;

     }

     /// \brief Copies the node cross references into the given map.

     ///

     ///  Copies the node cross references (reverse references) into

     ///  the given map.

     template <typename NodeCrossRef>

     GraphCopy& nodeCrossRef(NodeCrossRef& map) {

       _node_maps.push_back(new _graph_utils_bits::CrossRefCopy<From, Node,

                            NodeRefMap, NodeCrossRef>(map));

       return *this;

     }

     /// \brief Make copy of the given map.

     ///

     /// Makes copy of the given map for the newly created graph.

     /// The new map's key type is the to graph's node type,

     /// and the copied map's key type is the from graph's node

     /// type.

     template <typename ToMap, typename FromMap>

     GraphCopy& nodeMap(ToMap& tmap, const FromMap& map) {

       _node_maps.push_back(new _graph_utils_bits::MapCopy<From, Node,

                            NodeRefMap, ToMap, FromMap>(tmap, map));

       return *this;

     }

     /// \brief Make a copy of the given node.

     ///

     /// Make a copy of the given node.

     GraphCopy& node(TNode& tnode, const Node& snode) {

       _node_maps.push_back(new _graph_utils_bits::ItemCopy<From, Node,

                            NodeRefMap, TNode>(tnode, snode));

       return *this;

     }

     /// \brief Copies the arc references into the given map.

     ///

     /// Copies the arc references into the given map.

     template <typename ArcRef>

     GraphCopy& arcRef(ArcRef& map) {

       _arc_maps.push_back(new _graph_utils_bits::RefCopy<From, Arc,

                           ArcRefMap, ArcRef>(map));

       return *this;

     }

     /// \brief Copies the arc cross references into the given map.

     ///

     ///  Copies the arc cross references (reverse references) into

     ///  the given map.

     template <typename ArcCrossRef>

     GraphCopy& arcCrossRef(ArcCrossRef& map) {

       _arc_maps.push_back(new _graph_utils_bits::CrossRefCopy<From, Arc,

                           ArcRefMap, ArcCrossRef>(map));

       return *this;

     }

     /// \brief Make copy of the given map.

     ///

     /// Makes copy of the given map for the newly created graph.

     /// The new map's key type is the to graph's arc type,

     /// and the copied map's key type is the from graph's arc

     /// type.

     template <typename ToMap, typename FromMap>

     GraphCopy& arcMap(ToMap& tmap, const FromMap& map) {

       _arc_maps.push_back(new _graph_utils_bits::MapCopy<From, Arc,

                           ArcRefMap, ToMap, FromMap>(tmap, map));

       return *this;

     }

     /// \brief Make a copy of the given arc.

     ///

     /// Make a copy of the given arc.

     GraphCopy& arc(TArc& tarc, const Arc& sarc) {

       _arc_maps.push_back(new _graph_utils_bits::ItemCopy<From, Arc,

                           ArcRefMap, TArc>(tarc, sarc));

       return *this;

     }

     /// \brief Copies the edge references into the given map.

     ///

     /// Copies the edge references into the given map.

     template <typename EdgeRef>

     GraphCopy& edgeRef(EdgeRef& map) {

       _edge_maps.push_back(new _graph_utils_bits::RefCopy<From, Edge,

                            EdgeRefMap, EdgeRef>(map));

       return *this;

     }

     /// \brief Copies the edge cross references into the given map.

     ///

     /// Copies the edge cross references (reverse

     /// references) into the given map.

     template <typename EdgeCrossRef>

     GraphCopy& edgeCrossRef(EdgeCrossRef& map) {

       _edge_maps.push_back(new _graph_utils_bits::CrossRefCopy<From,

                            Edge, EdgeRefMap, EdgeCrossRef>(map));

       return *this;

     }

     /// \brief Make copy of the given map.

     ///

     /// Makes copy of the given map for the newly created graph.

     /// The new map's key type is the to graph's edge type,

     /// and the copied map's key type is the from graph's edge

     /// type.

     template <typename ToMap, typename FromMap>

     GraphCopy& edgeMap(ToMap& tmap, const FromMap& map) {

       _edge_maps.push_back(new _graph_utils_bits::MapCopy<From, Edge,

                            EdgeRefMap, ToMap, FromMap>(tmap, map));

       return *this;

     }

     /// \brief Make a copy of the given edge.

     ///

     /// Make a copy of the given edge.

     GraphCopy& edge(TEdge& tedge, const Edge& sedge) {

       _edge_maps.push_back(new _graph_utils_bits::ItemCopy<From, Edge,

                            EdgeRefMap, TEdge>(tedge, sedge));

       return *this;

     }

     /// \brief Executes the copies.

     ///

     /// Executes the copies.

     void run() {

       NodeRefMap nodeRefMap(_from);

       EdgeRefMap edgeRefMap(_from);

       ArcRefMap arcRefMap(_to, _from, edgeRefMap, nodeRefMap);

       _graph_utils_bits::GraphCopySelector<To>::

         copy(_to, _from, nodeRefMap, edgeRefMap);

       for (int i = 0; i < int(_node_maps.size()); ++i) {

         _node_maps[i]->copy(_from, nodeRefMap);

       }

       for (int i = 0; i < int(_edge_maps.size()); ++i) {

         _edge_maps[i]->copy(_from, edgeRefMap);

       }

       for (int i = 0; i < int(_arc_maps.size()); ++i) {

         _arc_maps[i]->copy(_from, arcRefMap);

       }

     }

   private:

     const From& _from;

     To& _to;

     std::vector<_graph_utils_bits::MapCopyBase<From, Node, NodeRefMap>* >

     _node_maps;

     std::vector<_graph_utils_bits::MapCopyBase<From, Arc, ArcRefMap>* >

     _arc_maps;

     std::vector<_graph_utils_bits::MapCopyBase<From, Edge, EdgeRefMap>* >

     _edge_maps;

   };

   /// \brief Copy a graph to another graph.

   ///

   /// Copy a graph to another graph. The complete usage of the

   /// function is detailed in the GraphCopy class, but a short