/* -*- C++ -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2003-2006

 * 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_UGRAPH_ADAPTOR_H

#define LEMON_UGRAPH_ADAPTOR_H

///\ingroup graph_adaptors

///\file

///\brief Several graph adaptors.

///

///This file contains several useful ugraph adaptor functions.

///

///\author Balazs Dezso

#include <lemon/bits/invalid.h>

#include <lemon/maps.h>

#include <lemon/bits/graph_adaptor_extender.h>

#include <lemon/bits/traits.h>

#include <iostream>

namespace lemon {

  /// \ingroup graph_adaptors

  ///

  /// \brief Base type for the Graph Adaptors

  ///

  /// This is the base type for most of LEMON graph adaptors. 

  /// This class implements a trivial graph adaptor i.e. it only wraps the 

  /// functions and types of the graph. The purpose of this class is to 

  /// make easier implementing graph adaptors. E.g. if an adaptor is 

  /// considered which differs from the wrapped graph only in some of its 

  /// functions or types, then it can be derived from GraphAdaptor, and only 

  /// the differences should be implemented.

  ///

  /// \author Balazs Dezso 

  template<typename _UGraph>

  class UGraphAdaptorBase {

  public:

    typedef _UGraph Graph;

    typedef Graph ParentGraph;

  protected:

    Graph* graph;

    UGraphAdaptorBase() : graph(0) {}

    void setGraph(Graph& _graph) { graph=&_graph; }

  public:

    UGraphAdaptorBase(Graph& _graph) : graph(&_graph) {}

    typedef typename Graph::Node Node;

    typedef typename Graph::Edge Edge;

    typedef typename Graph::UEdge UEdge;

    void first(Node& i) const { graph->first(i); }

    void first(Edge& i) const { graph->first(i); }

    void first(UEdge& i) const { graph->first(i); }

    void firstIn(Edge& i, const Node& n) const { graph->firstIn(i, n); }

    void firstOut(Edge& i, const Node& n ) const { graph->firstOut(i, n); }

    void firstInc(UEdge &i, bool &d, const Node &n) const {

      graph->firstInc(i, d, n);

    }

    void next(Node& i) const { graph->next(i); }

    void next(Edge& i) const { graph->next(i); }

    void next(UEdge& i) const { graph->next(i); }

    void nextIn(Edge& i) const { graph->nextIn(i); }

    void nextOut(Edge& i) const { graph->nextOut(i); }

    void nextInc(UEdge &i, bool &d) const { graph->nextInc(i, d); }

    Node source(const UEdge& e) const { return graph->source(e); }

    Node target(const UEdge& e) const { return graph->target(e); }

    Node source(const Edge& e) const { return graph->source(e); }

    Node target(const Edge& e) const { return graph->target(e); }

    typedef NodeNumTagIndicator<Graph> NodeNumTag;

    int nodeNum() const { return graph->nodeNum(); }

    typedef EdgeNumTagIndicator<Graph> EdgeNumTag;

    int edgeNum() const { return graph->edgeNum(); }

    int uEdgeNum() const { return graph->uEdgeNum(); }

    typedef FindEdgeTagIndicator<Graph> FindEdgeTag;

    Edge findEdge(const Node& source, const Node& target, 

		  const Edge& prev = INVALID) {

      return graph->findEdge(source, target, prev);

    }

    UEdge findUEdge(const Node& source, const Node& target, 

                    const UEdge& prev = INVALID) {

      return graph->findUEdge(source, target, prev);

    }

    Node addNode() const { return graph->addNode(); }

    UEdge addEdge(const Node& source, const Node& target) const { 

      return graph->addEdge(source, target); 

    }

    void erase(const Node& i) const { graph->erase(i); }

    void erase(const UEdge& i) const { graph->erase(i); }

    void clear() const { graph->clear(); }

    bool direction(const Edge& e) const { return graph->direction(e); }

    Edge direct(const UEdge& e, bool d) const { return graph->direct(e, d); }

    int id(const Node& v) const { return graph->id(v); }

    int id(const Edge& e) const { return graph->id(e); }

    int id(const UEdge& e) const { return graph->id(e); }

    Node fromNodeId(int id) const {

      return graph->fromNodeId(id);

    }

    Edge fromEdgeId(int id) const {

      return graph->fromEdgeId(id);

    }

    UEdge fromUEdgeId(int id) const {

      return graph->fromUEdgeId(id);

    }

    int maxNodeId() const {

      return graph->maxNodeId();

    }

    int maxEdgeId() const {

      return graph->maxEdgeId();

    }

    int maxUEdgeId() const {

      return graph->maxEdgeId();

    }

    typedef typename ItemSetTraits<Graph, Node>::ItemNotifier NodeNotifier;

    NodeNotifier& getNotifier(Node) const {

      return graph->getNotifier(Node());

    } 

    typedef typename ItemSetTraits<Graph, Edge>::ItemNotifier EdgeNotifier;

    EdgeNotifier& getNotifier(Edge) const {

      return graph->getNotifier(Edge());

    } 

    typedef typename ItemSetTraits<Graph, UEdge>::ItemNotifier UEdgeNotifier;

    UEdgeNotifier& getNotifier(UEdge) const {

      return graph->getNotifier(UEdge());

    } 

    template <typename _Value>

    class NodeMap : public Graph::template NodeMap<_Value> {

    public:

      typedef typename Graph::template NodeMap<_Value> Parent;

      explicit NodeMap(const UGraphAdaptorBase<Graph>& ga) 

	: Parent(*ga.graph) {}

      NodeMap(const UGraphAdaptorBase<Graph>& ga, const _Value& value)

	: Parent(*ga.graph, value) {}

      NodeMap& operator=(const NodeMap& cmap) {

	return operator=<NodeMap>(cmap);

      }

      template <typename CMap>

      NodeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

        return *this;

      }

    };

    template <typename _Value>

    class EdgeMap : public Graph::template EdgeMap<_Value> {

    public:

      typedef typename Graph::template EdgeMap<_Value> Parent;

      explicit EdgeMap(const UGraphAdaptorBase<Graph>& ga) 

	: Parent(*ga.graph) {}

      EdgeMap(const UGraphAdaptorBase<Graph>& ga, const _Value& value)

	: Parent(*ga.graph, value) {}

      EdgeMap& operator=(const EdgeMap& cmap) {

	return operator=<EdgeMap>(cmap);

      }

      template <typename CMap>

      EdgeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

	return *this;

      }

    };

    template <typename _Value>

    class UEdgeMap : public Graph::template UEdgeMap<_Value> {

    public:

      typedef typename Graph::template UEdgeMap<_Value> Parent;

      explicit UEdgeMap(const UGraphAdaptorBase<Graph>& ga) 

	: Parent(*ga.graph) {}

      UEdgeMap(const UGraphAdaptorBase<Graph>& ga, const _Value& value)

	: Parent(*ga.graph, value) {}

      UEdgeMap& operator=(const UEdgeMap& cmap) {

	return operator=<UEdgeMap>(cmap);

      }

      template <typename CMap>

      UEdgeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

        return *this;

      }

    };

  };

  /// \ingroup graph_adaptors

  template <typename _UGraph>

  class UGraphAdaptor 

    : public UGraphAdaptorExtender< UGraphAdaptorBase<_UGraph> > { 

  public:

    typedef _UGraph Graph;

    typedef UGraphAdaptorExtender<UGraphAdaptorBase<_UGraph> > Parent;

  protected:

    UGraphAdaptor() : Parent() {}

  public:

    explicit UGraphAdaptor(Graph& _graph) { setGraph(_graph); }

  };

  template <typename _UGraph, typename NodeFilterMap, 

	    typename UEdgeFilterMap, bool checked = true>

  class SubUGraphAdaptorBase : public UGraphAdaptorBase<_UGraph> {

  public:

    typedef _UGraph Graph;

    typedef SubUGraphAdaptorBase Adaptor;

    typedef UGraphAdaptorBase<_UGraph> Parent;

  protected:

    NodeFilterMap* node_filter_map;

    UEdgeFilterMap* uedge_filter_map;

    SubUGraphAdaptorBase() 

      : Parent(), node_filter_map(0), uedge_filter_map(0) { }

    void setNodeFilterMap(NodeFilterMap& _node_filter_map) {

      node_filter_map=&_node_filter_map;

    }

    void setUEdgeFilterMap(UEdgeFilterMap& _uedge_filter_map) {

      uedge_filter_map=&_uedge_filter_map;

    }

  public:

    typedef typename Parent::Node Node;

    typedef typename Parent::Edge Edge;

    typedef typename Parent::UEdge UEdge;

    void first(Node& i) const { 

      Parent::first(i); 

      while (i!=INVALID && !(*node_filter_map)[i]) Parent::next(i); 

    }

    void first(Edge& i) const { 

      Parent::first(i); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

	     || !(*node_filter_map)[Parent::source(i)]

	     || !(*node_filter_map)[Parent::target(i)])) Parent::next(i); 

    }

    void first(UEdge& i) const { 

      Parent::first(i); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

	     || !(*node_filter_map)[Parent::source(i)]

	     || !(*node_filter_map)[Parent::target(i)])) Parent::next(i); 

    }

    void firstIn(Edge& i, const Node& n) const { 

      Parent::firstIn(i, n); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

	     || !(*node_filter_map)[Parent::source(i)])) Parent::nextIn(i); 

    }

    void firstOut(Edge& i, const Node& n) const { 

      Parent::firstOut(i, n); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

	     || !(*node_filter_map)[Parent::target(i)])) Parent::nextOut(i); 

    }

    void firstInc(UEdge& i, bool& d, const Node& n) const { 

      Parent::firstInc(i, d, n); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

            || !(*node_filter_map)[Parent::target(i)])) Parent::nextInc(i, d); 

    }

    void next(Node& i) const { 

      Parent::next(i); 

      while (i!=INVALID && !(*node_filter_map)[i]) Parent::next(i); 

    }

    void next(Edge& i) const { 

      Parent::next(i); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

	     || !(*node_filter_map)[Parent::source(i)]

	     || !(*node_filter_map)[Parent::target(i)])) Parent::next(i); 

    }

    void next(UEdge& i) const { 

      Parent::next(i); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

	     || !(*node_filter_map)[Parent::source(i)]

	     || !(*node_filter_map)[Parent::target(i)])) Parent::next(i); 

    }

    void nextIn(Edge& i) const { 

      Parent::nextIn(i); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

	     || !(*node_filter_map)[Parent::source(i)])) Parent::nextIn(i); 

    }

    void nextOut(Edge& i) const { 

      Parent::nextOut(i); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

	     || !(*node_filter_map)[Parent::target(i)])) Parent::nextOut(i); 

    }

    void nextInc(UEdge& i, bool& d) const { 

      Parent::nextInc(i, d); 

      while (i!=INVALID && (!(*uedge_filter_map)[i] 

            || !(*node_filter_map)[Parent::source(i)])) Parent::nextInc(i, d); 

    }

    ///\e

    /// This function hides \c n in the graph, i.e. the iteration 

    /// jumps over it. This is done by simply setting the value of \c n  

    /// to be false in the corresponding node-map.

    void hide(const Node& n) const { node_filter_map->set(n, false); }

    ///\e

    /// This function hides \c e in the graph, i.e. the iteration 

    /// jumps over it. This is done by simply setting the value of \c e  

    /// to be false in the corresponding edge-map.

    void hide(const UEdge& e) const { uedge_filter_map->set(e, false); }

    ///\e

    /// The value of \c n is set to be true in the node-map which stores 

    /// hide information. If \c n was hidden previuosly, then it is shown 

    /// again

     void unHide(const Node& n) const { node_filter_map->set(n, true); }

    ///\e

    /// The value of \c e is set to be true in the edge-map which stores 

    /// hide information. If \c e was hidden previuosly, then it is shown 

    /// again

    void unHide(const UEdge& e) const { uedge_filter_map->set(e, true); }

    /// Returns true if \c n is hidden.

    ///\e

    ///

    bool hidden(const Node& n) const { return !(*node_filter_map)[n]; }

    /// Returns true if \c n is hidden.

    ///\e

    ///

    bool hidden(const UEdge& e) const { return !(*uedge_filter_map)[e]; }

    typedef False NodeNumTag;

    typedef False EdgeNumTag;

    typedef FindEdgeTagIndicator<Graph> FindEdgeTag;

    Edge findEdge(const Node& source, const Node& target, 

		  const Edge& prev = INVALID) {

      if (!(*node_filter_map)[source] || !(*node_filter_map)[target]) {

        return INVALID;

      }

      Edge edge = Parent::findEdge(source, target, prev);

      while (edge != INVALID && !(*uedge_filter_map)[edge]) {

        edge = Parent::findEdge(source, target, edge);

      }

      return edge;

    }

    UEdge findUEdge(const Node& source, const Node& target, 

		  const UEdge& prev = INVALID) {

      if (!(*node_filter_map)[source] || !(*node_filter_map)[target]) {

        return INVALID;

      }

      UEdge uedge = Parent::findUEdge(source, target, prev);

      while (uedge != INVALID && !(*uedge_filter_map)[uedge]) {

        uedge = Parent::findUEdge(source, target, uedge);

      }

      return uedge;

    }

    template <typename _Value>

    class NodeMap 

      : public SubMapExtender<Adaptor, 

                              typename Parent::template NodeMap<_Value> > 

    {

    public:

      typedef Adaptor Graph;

      typedef SubMapExtender<Adaptor, typename Parent::

                             template NodeMap<_Value> > Parent;

      NodeMap(const Graph& graph) 

	: Parent(graph) {}

      NodeMap(const Graph& graph, const _Value& value) 

	: Parent(graph, value) {}

      NodeMap& operator=(const NodeMap& cmap) {

	return operator=<NodeMap>(cmap);

      }

      template <typename CMap>

      NodeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

	return *this;

      }

    };

    template <typename _Value>

    class EdgeMap 

      : public SubMapExtender<Adaptor, 

                              typename Parent::template EdgeMap<_Value> > 

    {

    public:

      typedef Adaptor Graph;

      typedef SubMapExtender<Adaptor, typename Parent::

                             template EdgeMap<_Value> > Parent;

      EdgeMap(const Graph& graph) 

	: Parent(graph) {}

      EdgeMap(const Graph& graph, const _Value& value) 

	: Parent(graph, value) {}

      EdgeMap& operator=(const EdgeMap& cmap) {

	return operator=<EdgeMap>(cmap);

      }

      template <typename CMap>

      EdgeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

	return *this;

      }

    };

    template <typename _Value>

    class UEdgeMap 

      : public SubMapExtender<Adaptor, 

                              typename Parent::template UEdgeMap<_Value> > 

    {

    public:

      typedef Adaptor Graph;

      typedef SubMapExtender<Adaptor, typename Parent::

                             template UEdgeMap<_Value> > Parent;

      UEdgeMap(const Graph& graph) 

	: Parent(graph) {}

      UEdgeMap(const Graph& graph, const _Value& value) 

	: Parent(graph, value) {}

      UEdgeMap& operator=(const UEdgeMap& cmap) {

	return operator=<UEdgeMap>(cmap);

      }

      template <typename CMap>

      UEdgeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

	return *this;

      }

    };

  };

  template <typename _UGraph, typename NodeFilterMap, typename UEdgeFilterMap>

  class SubUGraphAdaptorBase<_UGraph, NodeFilterMap, UEdgeFilterMap, false> 

    : public UGraphAdaptorBase<_UGraph> {

  public:

    typedef _UGraph Graph;

    typedef SubUGraphAdaptorBase Adaptor;

    typedef UGraphAdaptorBase<_UGraph> Parent;

  protected:

    NodeFilterMap* node_filter_map;

    UEdgeFilterMap* uedge_filter_map;

    SubUGraphAdaptorBase() : Parent(), 

			    node_filter_map(0), uedge_filter_map(0) { }

    void setNodeFilterMap(NodeFilterMap& _node_filter_map) {

      node_filter_map=&_node_filter_map;

    }

    void setUEdgeFilterMap(UEdgeFilterMap& _uedge_filter_map) {

      uedge_filter_map=&_uedge_filter_map;

    }

  public:

    typedef typename Parent::Node Node;

    typedef typename Parent::Edge Edge;

    typedef typename Parent::UEdge UEdge;

    void first(Node& i) const { 

      Parent::first(i); 

      while (i!=INVALID && !(*node_filter_map)[i]) Parent::next(i); 

    }

    void first(Edge& i) const { 

      Parent::first(i); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::next(i); 

    }

    void first(UEdge& i) const { 

      Parent::first(i); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::next(i); 

    }

    void firstIn(Edge& i, const Node& n) const { 

      Parent::firstIn(i, n); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::nextIn(i); 

    }

    void firstOut(Edge& i, const Node& n) const { 

      Parent::firstOut(i, n); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::nextOut(i); 

    }

    void firstInc(UEdge& i, bool& d, const Node& n) const { 

      Parent::firstInc(i, d, n); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::nextInc(i, d); 

    }

    void next(Node& i) const { 

      Parent::next(i); 

      while (i!=INVALID && !(*node_filter_map)[i]) Parent::next(i); 

    }

    void next(Edge& i) const { 

      Parent::next(i); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::next(i); 

    }

    void next(UEdge& i) const { 

      Parent::next(i); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::next(i); 

    }

    void nextIn(Edge& i) const { 

      Parent::nextIn(i); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::nextIn(i); 

    }

    void nextOut(Edge& i) const { 

      Parent::nextOut(i); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::nextOut(i); 

    }

    void nextInc(UEdge& i, bool& d) const { 

      Parent::nextInc(i, d); 

      while (i!=INVALID && !(*uedge_filter_map)[i]) Parent::nextInc(i, d); 

    }

    ///\e

    /// This function hides \c n in the graph, i.e. the iteration 

    /// jumps over it. This is done by simply setting the value of \c n  

    /// to be false in the corresponding node-map.

    void hide(const Node& n) const { node_filter_map->set(n, false); }

    ///\e

    /// This function hides \c e in the graph, i.e. the iteration 

    /// jumps over it. This is done by simply setting the value of \c e  

    /// to be false in the corresponding edge-map.

    void hide(const UEdge& e) const { uedge_filter_map->set(e, false); }

    ///\e

    /// The value of \c n is set to be true in the node-map which stores 

    /// hide information. If \c n was hidden previuosly, then it is shown 

    /// again

     void unHide(const Node& n) const { node_filter_map->set(n, true); }

    ///\e

    /// The value of \c e is set to be true in the edge-map which stores 

    /// hide information. If \c e was hidden previuosly, then it is shown 

    /// again

    void unHide(const UEdge& e) const { uedge_filter_map->set(e, true); }

    /// Returns true if \c n is hidden.

    ///\e

    ///

    bool hidden(const Node& n) const { return !(*node_filter_map)[n]; }

    /// Returns true if \c n is hidden.

    ///\e

    ///

    bool hidden(const UEdge& e) const { return !(*uedge_filter_map)[e]; }

    typedef False NodeNumTag;

    typedef False EdgeNumTag;

    typedef FindEdgeTagIndicator<Graph> FindEdgeTag;

    Edge findEdge(const Node& source, const Node& target, 

		  const Edge& prev = INVALID) {

      Edge edge = Parent::findEdge(source, target, prev);

      while (edge != INVALID && !(*uedge_filter_map)[edge]) {

        edge = Parent::findEdge(source, target, edge);

      }

      return edge;

    }

    UEdge findUEdge(const Node& source, const Node& target, 

		  const UEdge& prev = INVALID) {

      UEdge uedge = Parent::findUEdge(source, target, prev);

      while (uedge != INVALID && !(*uedge_filter_map)[uedge]) {

        uedge = Parent::findUEdge(source, target, uedge);

      }

      return uedge;

    }

    template <typename _Value>

    class NodeMap 

      : public SubMapExtender<Adaptor, 

                              typename Parent::template NodeMap<_Value> > 

    {

    public:

      typedef Adaptor Graph;

      typedef SubMapExtender<Adaptor, typename Parent::

                             template NodeMap<_Value> > Parent;

      NodeMap(const Graph& graph) 

	: Parent(graph) {}

      NodeMap(const Graph& graph, const _Value& value) 

	: Parent(graph, value) {}

      NodeMap& operator=(const NodeMap& cmap) {

	return operator=<NodeMap>(cmap);

      }

      template <typename CMap>

      NodeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

	return *this;

      }

    };

    template <typename _Value>

    class EdgeMap 

      : public SubMapExtender<Adaptor, 

                              typename Parent::template EdgeMap<_Value> > 

    {

    public:

      typedef Adaptor Graph;

      typedef SubMapExtender<Adaptor, typename Parent::

                             template EdgeMap<_Value> > Parent;

      EdgeMap(const Graph& graph) 

	: Parent(graph) {}

      EdgeMap(const Graph& graph, const _Value& value) 

	: Parent(graph, value) {}

      EdgeMap& operator=(const EdgeMap& cmap) {

	return operator=<EdgeMap>(cmap);

      }

      template <typename CMap>

      EdgeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

	return *this;

      }

    };

    template <typename _Value>

    class UEdgeMap 

      : public SubMapExtender<Adaptor, 

                              typename Parent::template UEdgeMap<_Value> > 

    {

    public:

      typedef Adaptor Graph;

      typedef SubMapExtender<Adaptor, typename Parent::

                             template UEdgeMap<_Value> > Parent;

      UEdgeMap(const Graph& graph) 

	: Parent(graph) {}

      UEdgeMap(const Graph& graph, const _Value& value) 

	: Parent(graph, value) {}

      UEdgeMap& operator=(const UEdgeMap& cmap) {

	return operator=<UEdgeMap>(cmap);

      }

      template <typename CMap>

      UEdgeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

	return *this;

      }

    };

  };

  /// \ingroup graph_adaptors

  ///

  /// \brief A graph adaptor for hiding nodes and edges from an undirected 

  /// graph.

  /// 

  /// SubUGraphAdaptor shows the undirected graph with filtered node-set and 

  /// edge-set. If the \c checked parameter is true then it filters the edgeset

  /// to do not get invalid edges without source or target.

  /// 

  /// If the \c checked template parameter is false then we have to note that 

  /// the node-iterator cares only the filter on the node-set, and the 

  /// edge-iterator cares only the filter on the edge-set.

  /// This way the edge-map

  /// should filter all edges which's source or target is filtered by the 

  /// node-filter.

  ///

  /// Note that \c n is of type \c SubGA::NodeIt, but it can be converted to

  /// \c Graph::Node that is why \c g.id(n) can be applied.

  /// 

  template<typename _UGraph, typename NodeFilterMap, 

	   typename UEdgeFilterMap, bool checked = true>

  class SubUGraphAdaptor : 

    public UGraphAdaptorExtender<

    SubUGraphAdaptorBase<_UGraph, NodeFilterMap, UEdgeFilterMap, checked> > {

  public:

    typedef _UGraph Graph;

    typedef UGraphAdaptorExtender<

      SubUGraphAdaptorBase<_UGraph, NodeFilterMap, UEdgeFilterMap> > Parent;

  protected:

    SubUGraphAdaptor() { }

  public:

    SubUGraphAdaptor(Graph& _graph, NodeFilterMap& _node_filter_map, 

		    UEdgeFilterMap& _uedge_filter_map) { 

      setGraph(_graph);

      setNodeFilterMap(_node_filter_map);

      setUEdgeFilterMap(_uedge_filter_map);

    }

  };

  template<typename UGraph, typename NodeFilterMap, typename EdgeFilterMap>

  SubUGraphAdaptor<const UGraph, NodeFilterMap, EdgeFilterMap>

  subUGraphAdaptor(const UGraph& graph, 

                   NodeFilterMap& nfm, EdgeFilterMap& efm) {

    return SubUGraphAdaptor<const UGraph, NodeFilterMap, EdgeFilterMap>

      (graph, nfm, efm);

  }

  template<typename UGraph, typename NodeFilterMap, typename EdgeFilterMap>

  SubUGraphAdaptor<const UGraph, const NodeFilterMap, EdgeFilterMap>

  subUGraphAdaptor(const UGraph& graph, 

                   NodeFilterMap& nfm, EdgeFilterMap& efm) {

    return SubUGraphAdaptor<const UGraph, const NodeFilterMap, EdgeFilterMap>

      (graph, nfm, efm);

  }

  template<typename UGraph, typename NodeFilterMap, typename EdgeFilterMap>

  SubUGraphAdaptor<const UGraph, NodeFilterMap, const EdgeFilterMap>

  subUGraphAdaptor(const UGraph& graph, 

                   NodeFilterMap& nfm, EdgeFilterMap& efm) {

    return SubUGraphAdaptor<const UGraph, NodeFilterMap, const EdgeFilterMap>

      (graph, nfm, efm);

  }

  template<typename UGraph, typename NodeFilterMap, typename EdgeFilterMap>

  SubUGraphAdaptor<const UGraph, const NodeFilterMap, const EdgeFilterMap>

  subUGraphAdaptor(const UGraph& graph, 

                   NodeFilterMap& nfm, EdgeFilterMap& efm) {

    return SubUGraphAdaptor<const UGraph, const NodeFilterMap, 

      const EdgeFilterMap>(graph, nfm, efm);

  }

  /// \ingroup graph_adaptors

  ///

  /// \brief An adaptor for hiding nodes from an undirected graph.

  ///

  /// An adaptor for hiding nodes from an undirected graph.

  /// This adaptor specializes SubUGraphAdaptor in the way that only

  /// the node-set 

  /// can be filtered. In usual case the checked parameter is true, we get the

  /// induced subgraph. But if the checked parameter is false then we can only

  /// filter only isolated nodes.

  template<typename _UGraph, typename NodeFilterMap, bool checked = true>

  class NodeSubUGraphAdaptor : 

    public SubUGraphAdaptor<_UGraph, NodeFilterMap, 

                            ConstMap<typename _UGraph::UEdge, bool>, checked> {

  public:

    typedef SubUGraphAdaptor<_UGraph, NodeFilterMap, 

                             ConstMap<typename _UGraph::UEdge, bool> > Parent;

    typedef _UGraph Graph;

  protected:

    ConstMap<typename _UGraph::UEdge, bool> const_true_map;

    NodeSubUGraphAdaptor() : const_true_map(true) {

      Parent::setUEdgeFilterMap(const_true_map);

    }

  public:

    NodeSubUGraphAdaptor(Graph& _graph, NodeFilterMap& _node_filter_map) : 

      Parent(), const_true_map(true) { 

      Parent::setGraph(_graph);

      Parent::setNodeFilterMap(_node_filter_map);

      Parent::setUEdgeFilterMap(const_true_map);

    }

  };

  template<typename UGraph, typename NodeFilterMap>

  NodeSubUGraphAdaptor<const UGraph, NodeFilterMap>

  nodeSubUGraphAdaptor(const UGraph& graph, NodeFilterMap& nfm) {

    return NodeSubUGraphAdaptor<const UGraph, NodeFilterMap>(graph, nfm);

  }

  template<typename UGraph, typename NodeFilterMap>

  NodeSubUGraphAdaptor<const UGraph, const NodeFilterMap>

  nodeSubUGraphAdaptor(const UGraph& graph, const NodeFilterMap& nfm) {

    return NodeSubUGraphAdaptor<const UGraph, const NodeFilterMap>(graph, nfm);

  }

  /// \ingroup graph_adaptors

  ///

  /// \brief An adaptor for hiding undirected edges from an undirected graph.

  ///

  /// \warning Graph adaptors are in even more experimental state

  /// than the other parts of the lib. Use them at you own risk.

  ///

  /// An adaptor for hiding undirected edges from an undirected graph.

  /// This adaptor specializes SubUGraphAdaptor in the way that

  /// only the edge-set 

  /// can be filtered.

  template<typename _UGraph, typename UEdgeFilterMap>

  class EdgeSubUGraphAdaptor : 

    public SubUGraphAdaptor<_UGraph, ConstMap<typename _UGraph::Node,bool>, 

                            UEdgeFilterMap, false> {

  public:

    typedef SubUGraphAdaptor<_UGraph, ConstMap<typename _UGraph::Node,bool>, 

                             UEdgeFilterMap, false> Parent;

    typedef _UGraph Graph;

  protected:

    ConstMap<typename Graph::Node, bool> const_true_map;

    EdgeSubUGraphAdaptor() : const_true_map(true) {

      Parent::setNodeFilterMap(const_true_map);

    }

  public:

    EdgeSubUGraphAdaptor(Graph& _graph, UEdgeFilterMap& _uedge_filter_map) : 

      Parent(), const_true_map(true) { 

      Parent::setGraph(_graph);

      Parent::setNodeFilterMap(const_true_map);

      Parent::setUEdgeFilterMap(_uedge_filter_map);

    }

  };

  template<typename UGraph, typename EdgeFilterMap>

  EdgeSubUGraphAdaptor<const UGraph, EdgeFilterMap>

  edgeSubUGraphAdaptor(const UGraph& graph, EdgeFilterMap& efm) {

    return EdgeSubUGraphAdaptor<const UGraph, EdgeFilterMap>(graph, efm);

  }

  template<typename UGraph, typename EdgeFilterMap>

  EdgeSubUGraphAdaptor<const UGraph, const EdgeFilterMap>

  edgeSubUGraphAdaptor(const UGraph& graph, const EdgeFilterMap& efm) {

    return EdgeSubUGraphAdaptor<const UGraph, const EdgeFilterMap>(graph, efm);

  }

  template <typename _UGraph, typename _DirectionMap>

  class DirUGraphAdaptorBase {

  public:

    typedef _UGraph Graph;

    typedef _DirectionMap DirectionMap;

    typedef typename _UGraph::Node Node;

    typedef typename _UGraph::UEdge Edge;

    void reverseEdge(const Edge& edge) {

      direction->set(edge, !(*direction)[edge]);

    }

    void first(Node& i) const { graph->first(i); }

    void first(Edge& i) const { graph->first(i); }

    void firstIn(Edge& i, const Node& n) const {

      bool d;

      graph->firstInc(i, d, n);

      while (i != INVALID && d == (*direction)[i]) graph->nextInc(i, d);

    }

    void firstOut(Edge& i, const Node& n ) const { 

      bool d;

      graph->firstInc(i, d, n);

      while (i != INVALID && d != (*direction)[i]) graph->nextInc(i, d);

    }

    void next(Node& i) const { graph->next(i); }

    void next(Edge& i) const { graph->next(i); }

    void nextIn(Edge& i) const {

      bool d = !(*direction)[i];

      graph->nextInc(i, d);

      while (i != INVALID && d == (*direction)[i]) graph->nextInc(i, d);

    }

    void nextOut(Edge& i) const {

      bool d = (*direction)[i];

      graph->nextInc(i, d);

      while (i != INVALID && d != (*direction)[i]) graph->nextInc(i, d);

    }

    Node source(const Edge& e) const { 

      return (*direction)[e] ? graph->source(e) : graph->target(e); 

    }

    Node target(const Edge& e) const { 

      return (*direction)[e] ? graph->target(e) : graph->source(e); 

    }

    typedef NodeNumTagIndicator<Graph> NodeNumTag;

    int nodeNum() const { return graph->nodeNum(); }

    typedef EdgeNumTagIndicator<Graph> EdgeNumTag;

    int edgeNum() const { return graph->uEdgeNum(); }

    typedef FindEdgeTagIndicator<Graph> FindEdgeTag;

    Edge findEdge(const Node& source, const Node& target, 

		  const Edge& prev = INVALID) {

      Edge edge = prev;

      bool d = edge == INVALID ? true : (*direction)[edge];

      if (d) {

        edge = graph->findUEdge(source, target, edge);

        while (edge != INVALID && !(*direction)[edge]) {

          graph->findUEdge(source, target, edge);

        }

        if (edge != INVALID) return edge;

      }

      graph->findUEdge(target, source, edge);

      while (edge != INVALID && (*direction)[edge]) {

        graph->findUEdge(source, target, edge);

      }

      return edge;

    }

    Node addNode() const { 

      return Node(graph->addNode()); 

    }

    Edge addEdge(const Node& source, const Node& target) const {

      Edge edge = graph->addEdge(source, target);

      (*direction)[edge] = graph->source(edge) == source;

      return edge; 

    }

    void erase(const Node& i) const { graph->erase(i); }

    void erase(const Edge& i) const { graph->erase(i); }

    void clear() const { graph->clear(); }

    int id(const Node& v) const { return graph->id(v); }

    int id(const Edge& e) const { return graph->id(e); }

    int maxNodeId() const {

      return graph->maxNodeId();

    }

    int maxEdgeId() const {

      return graph->maxEdgeId();

    }

    typedef typename ItemSetTraits<Graph, Node>::ItemNotifier NodeNotifier;

    NodeNotifier& getNotifier(Node) const {

      return graph->getNotifier(Node());

    } 

    typedef typename ItemSetTraits<Graph, Edge>::ItemNotifier EdgeNotifier;

    EdgeNotifier& getNotifier(Edge) const {

      return graph->getNotifier(Edge());