/* -*- 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.

 *

 */

#ifndef LEMON_EDGE_SET_H

#define LEMON_EDGE_SET_H

#include <lemon/bits/default_map.h>

#include <lemon/bits/edge_set_extender.h>

/// \ingroup semi_adaptors

/// \file

/// \brief EdgeSet classes.

///

/// Graphs which use another graph's node-set as own. 

namespace lemon {

  template <typename _Graph>

  class ListEdgeSetBase {

  public:

    typedef _Graph Graph;

    typedef typename Graph::Node Node;

    typedef typename Graph::NodeIt NodeIt;

  protected:

    struct NodeT {

      int first_out, first_in;

      NodeT() : first_out(-1), first_in(-1) {}

    };

    typedef DefaultMap<Graph, Node, NodeT> NodesImplBase;

    NodesImplBase* nodes;

    struct EdgeT {

      Node source, target;

      int next_out, next_in;

      int prev_out, prev_in;

      EdgeT() : prev_out(-1), prev_in(-1) {}

    };

    std::vector<EdgeT> edges;

    int first_edge;

    int first_free_edge;

    const Graph* graph;

    void initalize(const Graph& _graph, NodesImplBase& _nodes) {

      graph = &_graph;

      nodes = &_nodes;

    }

  public:

    class Edge {

      friend class ListEdgeSetBase<Graph>;

    protected:

      Edge(int _id) : id(_id) {}

      int id;

    public:

      Edge() {}

      Edge(Invalid) : id(-1) {}

      bool operator==(const Edge& edge) const { return id == edge.id; }

      bool operator!=(const Edge& edge) const { return id != edge.id; }

      bool operator<(const Edge& edge) const { return id < edge.id; }

    };

    ListEdgeSetBase() : first_edge(-1), first_free_edge(-1) {} 

    Edge addEdge(const Node& u, const Node& v) {

      int n;

      if (first_free_edge == -1) {

	n = edges.size();

	edges.push_back(EdgeT());

      } else {

	n = first_free_edge;

	first_free_edge = edges[first_free_edge].next_in;

      }

      edges[n].next_in = (*nodes)[v].first_in;

      if ((*nodes)[v].first_in != -1) {

        edges[(*nodes)[v].first_in].prev_in = n;

      }

      (*nodes)[v].first_in = n;

      edges[n].next_out = (*nodes)[u].first_out;

      if ((*nodes)[u].first_out != -1) {

        edges[(*nodes)[u].first_out].prev_out = n;

      }

      (*nodes)[u].first_out = n;

      edges[n].source = u;

      edges[n].target = v;

      return Edge(n);

    }

    void erase(const Edge& edge) {

      int n = edge.id;

      if (edges[n].prev_in != -1) {

	edges[edges[n].prev_in].next_in = edges[n].next_in;

      } else {

	(*nodes)[edges[n].target].first_in = edges[n].next_in;

      }

      if (edges[n].next_in != -1) {

	edges[edges[n].next_in].prev_in = edges[n].prev_in;

      }

      if (edges[n].prev_out != -1) {

	edges[edges[n].prev_out].next_out = edges[n].next_out;

      } else {

	(*nodes)[edges[n].source].first_out = edges[n].next_out;

      }

      if (edges[n].next_out != -1) {

	edges[edges[n].next_out].prev_out = edges[n].prev_out;

      }

    }

    void clear() {

      Node node;

      for (first(node); node != INVALID; next(node)) {

        (*nodes)[node].first_in = -1;

        (*nodes)[node].first_out = -1;

      }

      edges.clear();

      first_edge = -1;

      first_free_edge = -1;

    }

    void first(Node& node) const {

      graph->first(node);

    }

    void next(Node& node) const {

      graph->next(node);

    }

    void first(Edge& edge) const {

      Node node;

      for (first(node); node != INVALID && (*nodes)[node].first_in == -1; 

	   next(node)) { }

      edge.id = (node == INVALID) ? -1 : (*nodes)[node].first_in;

    }

    void next(Edge& edge) const {

      if (edges[edge.id].next_in != -1) {

	edge.id = edges[edge.id].next_in;

      } else {

	Node node = edges[edge.id].target;

	for (next(node); node != INVALID && (*nodes)[node].first_in == -1; 

	     next(node)) { }

	edge.id = (node == INVALID) ? -1 : (*nodes)[node].first_in;

      }      

    }

    void firstOut(Edge& edge, const Node& node) const {

      edge.id = (*nodes)[node].first_out;    

    }

    void nextOut(Edge& edge) const {

      edge.id = edges[edge.id].next_out;        

    }

    void firstIn(Edge& edge, const Node& node) const {

      edge.id = (*nodes)[node].first_in;          

    }

    void nextIn(Edge& edge) const {

      edge.id = edges[edge.id].next_in;    

    }

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

    int id(const Edge& edge) const { return edge.id; }

    Node nodeFromId(int ix) const { return graph->nodeFromId(ix); }

    Edge edgeFromId(int ix) const { return Edge(ix); }

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

    int maxEdgeId() const { return edges.size() - 1; }

    Node source(const Edge& edge) const { return edges[edge.id].source;}

    Node target(const Edge& edge) const { return edges[edge.id].target;}

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

    NodeNotifier& notifier(Node) const {

      return graph->notifier(Node());

    } 

    template <typename _Value>

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

    public:

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

      explicit NodeMap(const ListEdgeSetBase<Graph>& edgeset) 

	: Parent(*edgeset.graph) {}

      NodeMap(const ListEdgeSetBase<Graph>& edgeset, const _Value& value)

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

      NodeMap& operator=(const NodeMap& cmap) {

        return operator=<NodeMap>(cmap);

      }

      template <typename CMap>

      NodeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

        return *this;

      }

    };

  };

  /// \ingroup semi_adaptors

  ///

  /// \brief Graph using a node set of another graph and an

  /// own edge set.

  ///

  /// This structure can be used to establish another graph over a node set

  /// of an existing one. The node iterator will go through the nodes of the

  /// original graph.

  ///

  /// \param _Graph The type of the graph which shares its node set with 

  /// this class. Its interface must conform to the \ref concepts::Graph

  /// "Graph" concept.

  ///

  template <typename _Graph>

  class ListEdgeSet : public EdgeSetExtender<ListEdgeSetBase<_Graph> > {

  public:

    typedef EdgeSetExtender<ListEdgeSetBase<_Graph> > Parent;

    typedef typename Parent::Node Node;

    typedef typename Parent::Edge Edge;

    typedef _Graph Graph;

    typedef typename Parent::NodesImplBase NodesImplBase;

    void eraseNode(const Node& node) {

      Edge edge;

      Parent::firstOut(edge, node);

      while (edge != INVALID ) {

	erase(edge);

	Parent::firstOut(edge, node);

      } 

      Parent::firstIn(edge, node);

      while (edge != INVALID ) {

	erase(edge);

	Parent::firstIn(edge, node);

      }

    }

    void clearNodes() {

      Parent::clear();

    }

    class NodesImpl : public NodesImplBase {

    public:

      typedef NodesImplBase Parent;

      NodesImpl(const Graph& graph, ListEdgeSet& edgeset) 

	: Parent(graph), _edgeset(edgeset) {}

      virtual ~NodesImpl() {}

    protected:

      virtual void erase(const Node& node) {

	_edgeset.eraseNode(node);

	Parent::erase(node);

      }

      virtual void erase(const std::vector<Node>& nodes) {

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

          _edgeset.eraseNode(nodes[i]);

        }

	Parent::erase(nodes);

      }

      virtual void clear() {

	_edgeset.clearNodes();

	Parent::clear();

      }

    private:

      ListEdgeSet& _edgeset;

    };

    NodesImpl nodes;

  public:

    /// \brief Constructor of the adaptor.

    /// 

    /// Constructor of the adaptor.

    ListEdgeSet(const Graph& graph) : nodes(graph, *this) {

      Parent::initalize(graph, nodes);

    }

  };

  template <typename _Graph>

  class ListUEdgeSetBase {

  public:

    typedef _Graph Graph;

    typedef typename Graph::Node Node;

    typedef typename Graph::NodeIt NodeIt;

  protected:

    struct NodeT {

      int first_out;

      NodeT() : first_out(-1) {}

    };

    typedef DefaultMap<Graph, Node, NodeT> NodesImplBase;

    NodesImplBase* nodes;

    struct EdgeT {

      Node target;

      int prev_out, next_out;

      EdgeT() : prev_out(-1), next_out(-1) {}

    };

    std::vector<EdgeT> edges;

    int first_edge;

    int first_free_edge;

    const Graph* graph;

    void initalize(const Graph& _graph, NodesImplBase& _nodes) {

      graph = &_graph;

      nodes = &_nodes;

    }

  public:

    class UEdge {

      friend class ListUEdgeSetBase;

    protected:

      int id;

      explicit UEdge(int _id) { id = _id;}

    public:

      UEdge() {}

      UEdge (Invalid) { id = -1; }

      bool operator==(const UEdge& edge) const {return id == edge.id;}

      bool operator!=(const UEdge& edge) const {return id != edge.id;}

      bool operator<(const UEdge& edge) const {return id < edge.id;}

    };

    class Edge {

      friend class ListUEdgeSetBase;

    protected:

      Edge(int _id) : id(_id) {}

      int id;

    public:

      operator UEdge() const { return uEdgeFromId(id / 2); }

      Edge() {}

      Edge(Invalid) : id(-1) {}

      bool operator==(const Edge& edge) const { return id == edge.id; }

      bool operator!=(const Edge& edge) const { return id != edge.id; }

      bool operator<(const Edge& edge) const { return id < edge.id; }

    };

    ListUEdgeSetBase() : first_edge(-1), first_free_edge(-1) {} 

    UEdge addEdge(const Node& u, const Node& v) {

      int n;

      if (first_free_edge == -1) {

	n = edges.size();

	edges.push_back(EdgeT());

	edges.push_back(EdgeT());

      } else {

	n = first_free_edge;

	first_free_edge = edges[n].next_out;

      }

      edges[n].target = u;

      edges[n | 1].target = v;

      edges[n].next_out = (*nodes)[v].first_out;

      if ((*nodes)[v].first_out != -1) {

	edges[(*nodes)[v].first_out].prev_out = n;

      }

      (*nodes)[v].first_out = n;

      edges[n].prev_out = -1;

      if ((*nodes)[u].first_out != -1) {

	edges[(*nodes)[u].first_out].prev_out = (n | 1);

      }

      edges[n | 1].next_out = (*nodes)[u].first_out;

      (*nodes)[u].first_out = (n | 1);

      edges[n | 1].prev_out = -1;

      return UEdge(n / 2);

    }

    void erase(const UEdge& edge) {

      int n = edge.id * 2;

      if (edges[n].next_out != -1) {

	edges[edges[n].next_out].prev_out = edges[n].prev_out;

      } 

      if (edges[n].prev_out != -1) {

	edges[edges[n].prev_out].next_out = edges[n].next_out;

      } else {

	(*nodes)[edges[n | 1].target].first_out = edges[n].next_out;

      }

      if (edges[n | 1].next_out != -1) {

	edges[edges[n | 1].next_out].prev_out = edges[n | 1].prev_out;

      } 

      if (edges[n | 1].prev_out != -1) {

	edges[edges[n | 1].prev_out].next_out = edges[n | 1].next_out;

      } else {

	(*nodes)[edges[n].target].first_out = edges[n | 1].next_out;

      }

      edges[n].next_out = first_free_edge;

      first_free_edge = n;      

    }

    void clear() {

      Node node;

      for (first(node); node != INVALID; next(node)) {

        (*nodes)[node].first_out = -1;

      }

      edges.clear();

      first_edge = -1;

      first_free_edge = -1;

    }

    void first(Node& node) const {

      graph->first(node);

    }

    void next(Node& node) const {

      graph->next(node);

    }

    void first(Edge& edge) const {

      Node node;

      first(node);

      while (node != INVALID && (*nodes)[node].first_out == -1) {

        next(node);

      }

      edge.id = (node == INVALID) ? -1 : (*nodes)[node].first_out;

    }

    void next(Edge& edge) const {

      if (edges[edge.id].next_out != -1) {

	edge.id = edges[edge.id].next_out;

      } else {

	Node node = edges[edge.id ^ 1].target;

	next(node);

        while(node != INVALID && (*nodes)[node].first_out == -1) {

          next(node);

        }

	edge.id = (node == INVALID) ? -1 : (*nodes)[node].first_out;

      }      

    }

    void first(UEdge& uedge) const {

      Node node;

      first(node);

      while (node != INVALID) {

        uedge.id = (*nodes)[node].first_out;

        while ((uedge.id & 1) != 1) {

          uedge.id = edges[uedge.id].next_out;

        }

        if (uedge.id != -1) {

          uedge.id /= 2;

          return;

        } 

        next(node);

      }

      uedge.id = -1;

    }

    void next(UEdge& uedge) const {

      Node node = edges[uedge.id * 2].target;

      uedge.id = edges[(uedge.id * 2) | 1].next_out;

      while ((uedge.id & 1) != 1) {

        uedge.id = edges[uedge.id].next_out;

      }

      if (uedge.id != -1) {

        uedge.id /= 2;

        return;

      } 

      next(node);

      while (node != INVALID) {

        uedge.id = (*nodes)[node].first_out;

        while ((uedge.id & 1) != 1) {

          uedge.id = edges[uedge.id].next_out;

        }

        if (uedge.id != -1) {

          uedge.id /= 2;

          return;

        } 

	next(node);

      }

      uedge.id = -1;

    }

    void firstOut(Edge& edge, const Node& node) const {

      edge.id = (*nodes)[node].first_out;

    }

    void nextOut(Edge& edge) const {

      edge.id = edges[edge.id].next_out;        

    }

    void firstIn(Edge& edge, const Node& node) const {

      edge.id = (((*nodes)[node].first_out) ^ 1);

      if (edge.id == -2) edge.id = -1;

    }

    void nextIn(Edge& edge) const {

      edge.id = ((edges[edge.id ^ 1].next_out) ^ 1);

      if (edge.id == -2) edge.id = -1;

    }

    void firstInc(UEdge &edge, bool& dir, const Node& node) const {

      int de = (*nodes)[node].first_out;

      if (de != -1 ) {

        edge.id = de / 2;

        dir = ((de & 1) == 1);

      } else {

        edge.id = -1;

        dir = true;

      }

    }

    void nextInc(UEdge &edge, bool& dir) const {

      int de = (edges[(edge.id * 2) | (dir ? 1 : 0)].next_out);

      if (de != -1 ) {

        edge.id = de / 2;

        dir = ((de & 1) == 1);

      } else {

        edge.id = -1;

        dir = true;

      }

    }

    static bool direction(Edge edge) {

      return (edge.id & 1) == 1;

    }

    static Edge direct(UEdge uedge, bool dir) {

      return Edge(uedge.id * 2 + (dir ? 1 : 0));

    }

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

    static int id(Edge e) { return e.id; }

    static int id(UEdge e) { return e.id; }

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

    static Edge edgeFromId(int id) { return Edge(id);}

    static UEdge uEdgeFromId(int id) { return UEdge(id);}

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

    int maxUEdgeId() const { return edges.size() / 2 - 1; }

    int maxEdgeId() const { return edges.size()-1; }

    Node source(Edge e) const { return edges[e.id ^ 1].target; }

    Node target(Edge e) const { return edges[e.id].target; }

    Node source(UEdge e) const { return edges[2 * e.id].target; }

    Node target(UEdge e) const { return edges[2 * e.id + 1].target; }

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

    NodeNotifier& notifier(Node) const {

      return graph->notifier(Node());

    } 

    template <typename _Value>

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

    public:

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

      explicit NodeMap(const ListUEdgeSetBase<Graph>& edgeset) 

	: Parent(*edgeset.graph) {}

      NodeMap(const ListUEdgeSetBase<Graph>& edgeset, const _Value& value)

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

      NodeMap& operator=(const NodeMap& cmap) {

        return operator=<NodeMap>(cmap);

      }

      template <typename CMap>

      NodeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

        return *this;

      }

    };

  };

  /// \ingroup semi_adaptors

  ///

  /// \brief Graph using a node set of another graph and an

  /// own uedge set.

  ///

  /// This structure can be used to establish another graph over a node set

  /// of an existing one. The node iterator will go through the nodes of the

  /// original graph.

  ///

  /// \param _Graph The type of the graph which shares its node set with 

  /// this class. Its interface must conform to the \ref concepts::Graph

  /// "Graph" concept.

  ///

  /// In the edge extension and removing it conforms to the 

  /// \ref concepts::UGraph "UGraph" concept.

  template <typename _Graph>

  class ListUEdgeSet : public UEdgeSetExtender<ListUEdgeSetBase<_Graph> > {

  public:

    typedef UEdgeSetExtender<ListUEdgeSetBase<_Graph> > Parent;

    typedef typename Parent::Node Node;

    typedef typename Parent::Edge Edge;

    typedef _Graph Graph;

    typedef typename Parent::NodesImplBase NodesImplBase;

    void eraseNode(const Node& node) {

      Edge edge;

      Parent::firstOut(edge, node);

      while (edge != INVALID ) {

	erase(edge);

	Parent::firstOut(edge, node);

      } 

    }

    void clearNodes() {

      Parent::clear();

    }

    class NodesImpl : public NodesImplBase {

    public:

      typedef NodesImplBase Parent;

      NodesImpl(const Graph& graph, ListUEdgeSet& edgeset) 

	: Parent(graph), _edgeset(edgeset) {}

      virtual ~NodesImpl() {}

    protected:

      virtual void erase(const Node& node) {

	_edgeset.eraseNode(node);

	Parent::erase(node);

      }

      virtual void erase(const std::vector<Node>& nodes) {

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

	  _edgeset.eraseNode(nodes[i]);

	}

	Parent::erase(nodes);

      }

      virtual void clear() {

	_edgeset.clearNodes();

	Parent::clear();

      }

    private:

      ListUEdgeSet& _edgeset;

    };

    NodesImpl nodes;

  public:

    /// \brief Constructor of the adaptor.

    /// 

    /// Constructor of the adaptor.

    ListUEdgeSet(const Graph& graph) : nodes(graph, *this) {

      Parent::initalize(graph, nodes);

    }

  };

  template <typename _Graph>

  class SmartEdgeSetBase {

  public:

    typedef _Graph Graph;

    typedef typename Graph::Node Node;

    typedef typename Graph::NodeIt NodeIt;

  protected:

    struct NodeT {

      int first_out, first_in;

      NodeT() : first_out(-1), first_in(-1) {}

    };

    typedef DefaultMap<Graph, Node, NodeT> NodesImplBase;

    NodesImplBase* nodes;

    struct EdgeT {

      Node source, target;

      int next_out, next_in;

      EdgeT() {}

    };

    std::vector<EdgeT> edges;

    const Graph* graph;

    void initalize(const Graph& _graph, NodesImplBase& _nodes) {

      graph = &_graph;

      nodes = &_nodes;

    }

  public:

    class Edge {

      friend class SmartEdgeSetBase<Graph>;

    protected:

      Edge(int _id) : id(_id) {}

      int id;

    public:

      Edge() {}

      Edge(Invalid) : id(-1) {}

      bool operator==(const Edge& edge) const { return id == edge.id; }

      bool operator!=(const Edge& edge) const { return id != edge.id; }

      bool operator<(const Edge& edge) const { return id < edge.id; }

    };

    SmartEdgeSetBase() {} 

    Edge addEdge(const Node& u, const Node& v) {

      int n = edges.size();

      edges.push_back(EdgeT());

      edges[n].next_in = (*nodes)[v].first_in;

      (*nodes)[v].first_in = n;

      edges[n].next_out = (*nodes)[u].first_out;

      (*nodes)[u].first_out = n;

      edges[n].source = u;

      edges[n].target = v;

      return Edge(n);

    }

    void clear() {

      Node node;

      for (first(node); node != INVALID; next(node)) {

        (*nodes)[node].first_in = -1;

        (*nodes)[node].first_out = -1;

      }

      edges.clear();

    }

    void first(Node& node) const {

      graph->first(node);

    }

    void next(Node& node) const {

      graph->next(node);

    }

    void first(Edge& edge) const {

      edge.id = edges.size() - 1;

    }

    void next(Edge& edge) const {

      --edge.id;

    }

    void firstOut(Edge& edge, const Node& node) const {

      edge.id = (*nodes)[node].first_out;    

    }

    void nextOut(Edge& edge) const {

      edge.id = edges[edge.id].next_out;        

    }

    void firstIn(Edge& edge, const Node& node) const {

      edge.id = (*nodes)[node].first_in;          

    }

    void nextIn(Edge& edge) const {

      edge.id = edges[edge.id].next_in;    

    }

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

    int id(const Edge& edge) const { return edge.id; }

    Node nodeFromId(int ix) const { return graph->nodeFromId(ix); }

    Edge edgeFromId(int ix) const { return Edge(ix); }

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

    int maxEdgeId() const { return edges.size() - 1; }

    Node source(const Edge& edge) const { return edges[edge.id].source;}

    Node target(const Edge& edge) const { return edges[edge.id].target;}

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

    NodeNotifier& notifier(Node) const {

      return graph->notifier(Node());

    } 

    template <typename _Value>

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

    public:

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

      explicit NodeMap(const SmartEdgeSetBase<Graph>& edgeset) 

	: Parent(*edgeset.graph) { }

      NodeMap(const SmartEdgeSetBase<Graph>& edgeset, const _Value& value)

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

      NodeMap& operator=(const NodeMap& cmap) {

        return operator=<NodeMap>(cmap);

      }

      template <typename CMap>

      NodeMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

        return *this;

      }

    };

  };

  /// \ingroup semi_adaptors

  ///

  /// \brief Graph using a node set of another graph and an

  /// own edge set.

  ///

  /// This structure can be used to establish another graph over a node set

  /// of an existing one. The node iterator will go through the nodes of the

  /// original graph.

  ///

  /// \param _Graph The type of the graph which shares its node set with 

  /// this class. Its interface must conform to the \ref concepts::Graph

  /// "Graph" concept.

  ///

  /// In the edge extension and removing it conforms to the 

  /// \ref concepts::Graph "Graph" concept.

  template <typename _Graph>

  class SmartEdgeSet : public EdgeSetExtender<SmartEdgeSetBase<_Graph> > {

  public:

    typedef EdgeSetExtender<SmartEdgeSetBase<_Graph> > Parent;

    typedef typename Parent::Node Node;

    typedef typename Parent::Edge Edge;

    typedef _Graph Graph;

  protected:

    typedef typename Parent::NodesImplBase NodesImplBase;

    void eraseNode(const Node& node) {

      if (Parent::InEdgeIt(*this, node) == INVALID &&

          Parent::OutEdgeIt(*this, node) == INVALID) {

        return;

      }

      throw typename NodesImplBase::Notifier::ImmediateDetach();

    }

    void clearNodes() {

      Parent::clear();

    }

    class NodesImpl : public NodesImplBase {

    public:

      typedef NodesImplBase Parent;

      NodesImpl(const Graph& graph, SmartEdgeSet& edgeset) 

	: Parent(graph), _edgeset(edgeset) {}

      virtual ~NodesImpl() {}

      bool attached() const {

        return Parent::attached();

      }

    protected:

      virtual void erase(const Node& node) {

        try {

          _edgeset.eraseNode(node);

          Parent::erase(node);

        } catch (const typename NodesImplBase::Notifier::ImmediateDetach&) {

          Parent::clear();

          throw;

        }

      }

      virtual void erase(const std::vector<Node>& nodes) {

        try {

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

            _edgeset.eraseNode(nodes[i]);

          }

          Parent::erase(nodes);

        } catch (const typename NodesImplBase::Notifier::ImmediateDetach&) {

          Parent::clear();

          throw;

        }

      }

      virtual void clear() {

	_edgeset.clearNodes();

	Parent::clear();

      }

    private:

      SmartEdgeSet& _edgeset;

    };

    NodesImpl nodes;

  public:

    /// \brief Constructor of the adaptor.

    /// 

    /// Constructor of the adaptor.

    SmartEdgeSet(const Graph& graph) : nodes(graph, *this) {

      Parent::initalize(graph, nodes);

    }

    bool valid() const {

      return nodes.attached();

    }

  };

  template <typename _Graph>

  class SmartUEdgeSetBase {

  public:

    typedef _Graph Graph;

    typedef typename Graph::Node Node;

    typedef typename Graph::NodeIt NodeIt;

  protected:

    struct NodeT {

      int first_out;

      NodeT() : first_out(-1) {}

    };

    typedef DefaultMap<Graph, Node, NodeT> NodesImplBase;

    NodesImplBase* nodes;

    struct EdgeT {

      Node target;

      int next_out;

      EdgeT() {}

    };