RhodeCode

      Arc arc = Parent::addArc(from, to);

      notifier(Arc()).add(arc);

      return arc;

    }

    void clear() {

      notifier(Arc()).clear();

      notifier(Node()).clear();

      Parent::clear();

    }

    template <typename Digraph, typename NodeRefMap, typename ArcRefMap>

    void build(const Digraph& digraph, NodeRefMap& nodeRef, ArcRefMap& arcRef) {

      Parent::build(digraph, nodeRef, arcRef);

      notifier(Node()).build();

      notifier(Arc()).build();

    }

    void erase(const Node& node) {

      Arc arc;

      Parent::firstOut(arc, node);

      while (arc != INVALID ) {

	erase(arc);

	Parent::firstOut(arc, node);

      } 

      Parent::firstIn(arc, node);

      while (arc != INVALID ) {

	erase(arc);

	Parent::firstIn(arc, node);

      }

      notifier(Node()).erase(node);

      Parent::erase(node);

    }

    void erase(const Arc& arc) {

      notifier(Arc()).erase(arc);

      Parent::erase(arc);

    }

    DigraphExtender() {

      node_notifier.setContainer(*this);

      arc_notifier.setContainer(*this);

    } 

    ~DigraphExtender() {

      arc_notifier.clear();

      node_notifier.clear();

    }

  };

  /// \ingroup _graphbits

  ///

  /// \brief Extender for the Graphs

  template <typename Base> 

  class GraphExtender : public Base {

  public:

    typedef Base Parent;

    typedef GraphExtender Graph;

    typedef True UndirectedTag;

    typedef typename Parent::Node Node;

    typedef typename Parent::Arc Arc;

    typedef typename Parent::Edge Edge;

    // Graph extension    

    int maxId(Node) const {

      return Parent::maxNodeId();

    }

    int maxId(Arc) const {

      return Parent::maxArcId();

    }

    int maxId(Edge) const {

      return Parent::maxEdgeId();

    }

    Node fromId(int id, Node) const {

      return Parent::nodeFromId(id);

    }

    Arc fromId(int id, Arc) const {

      return Parent::arcFromId(id);

    }

    Edge fromId(int id, Edge) const {

      return Parent::edgeFromId(id);

    }

    Node oppositeNode(const Node &n, const Edge &e) const {

      else

	return INVALID;

    }

    Arc oppositeArc(const Arc &arc) const {

      return Parent::direct(arc, !Parent::direction(arc));

    }

    using Parent::direct;

    Arc direct(const Edge &edge, const Node &node) const {

    }

    // Alterable extension

    typedef AlterationNotifier<GraphExtender, Node> NodeNotifier;

    typedef AlterationNotifier<GraphExtender, Arc> ArcNotifier;

    typedef AlterationNotifier<GraphExtender, Edge> EdgeNotifier;

  protected:

    mutable NodeNotifier node_notifier;

    mutable ArcNotifier arc_notifier;

    mutable EdgeNotifier edge_notifier;

  public:

    NodeNotifier& notifier(Node) const {

      return node_notifier;

    }

    ArcNotifier& notifier(Arc) const {

      return arc_notifier;

    }

    EdgeNotifier& notifier(Edge) const {

      return edge_notifier;

    }

    class NodeIt : public Node { 

      const Graph* _graph;

    public:

      NodeIt() {}

      NodeIt(Invalid i) : Node(i) { }

      explicit NodeIt(const Graph& graph) : _graph(&graph) {

	_graph->first(static_cast<Node&>(*this));

      }

      NodeIt(const Graph& graph, const Node& node) 

	: Node(node), _graph(&graph) {}

      NodeIt& operator++() { 

	_graph->next(*this);

	return *this; 

      }

    };

    class ArcIt : public Arc { 

      const Graph* _graph;

    public:

      ArcIt() { }

      ArcIt(Invalid i) : Arc(i) { }

      explicit ArcIt(const Graph& graph) : _graph(&graph) {

	_graph->first(static_cast<Arc&>(*this));

      }

      ArcIt(const Graph& graph, const Arc& arc) : 

	Arc(arc), _graph(&graph) { }

      ArcIt& operator++() { 

	_graph->next(*this);

	return *this; 

      }

    };

    class OutArcIt : public Arc { 

      const Graph* _graph;

    public:

      OutArcIt() { }

      OutArcIt(Invalid i) : Arc(i) { }

      OutArcIt(const Graph& graph, const Node& node) 

	: _graph(&graph) {

	_graph->firstOut(*this, node);

      }

      OutArcIt(const Graph& graph, const Arc& arc) 

	: Arc(arc), _graph(&graph) {}

      OutArcIt& operator++() { 

	_graph->nextOut(*this);

	return *this; 

      InArcIt(const Graph& graph, const Node& node) 

	: _graph(&graph) {

	_graph->firstIn(*this, node);

      }

      InArcIt(const Graph& graph, const Arc& arc) : 

	Arc(arc), _graph(&graph) {}

      InArcIt& operator++() { 

	_graph->nextIn(*this);

	return *this; 

      }

    };

    class EdgeIt : public Parent::Edge { 

      const Graph* _graph;

    public:

      EdgeIt() { }

      EdgeIt(Invalid i) : Edge(i) { }

      explicit EdgeIt(const Graph& graph) : _graph(&graph) {

	_graph->first(static_cast<Edge&>(*this));

      }

      EdgeIt(const Graph& graph, const Edge& edge) : 

	Edge(edge), _graph(&graph) { }

      EdgeIt& operator++() { 

	_graph->next(*this);

	return *this; 

      }

    };

    class IncEdgeIt : public Parent::Edge {

      friend class GraphExtender;

      const Graph* _graph;

      bool _direction;

    public:

      IncEdgeIt() { }

      IncEdgeIt(Invalid i) : Edge(i), _direction(false) { }

      IncEdgeIt(const Graph& graph, const Node &node) : _graph(&graph) {

	_graph->firstInc(*this, _direction, node);

      }

      IncEdgeIt(const Graph& graph, const Edge &edge, const Node &node)

	: _graph(&graph), Edge(edge) {

	_direction = (_graph->source(edge) == node);

      }

      IncEdgeIt& operator++() {

	_graph->nextInc(*this, _direction);

	return *this; 

      }

    };

    /// \brief Base node of the iterator

    ///

    /// Returns the base node (ie. the source in this case) of the iterator

    Node baseNode(const OutArcIt &arc) const {

      return Parent::source(static_cast<const Arc&>(arc));

    }

    /// \brief Running node of the iterator

    ///

    /// Returns the running node (ie. the target in this case) of the

    /// iterator

    Node runningNode(const OutArcIt &arc) const {

      return Parent::target(static_cast<const Arc&>(arc));

    }

    /// \brief Base node of the iterator

    ///

    /// Returns the base node (ie. the target in this case) of the iterator

    Node baseNode(const InArcIt &arc) const {

      return Parent::target(static_cast<const Arc&>(arc));

    }

    /// \brief Running node of the iterator

    ///

    /// Returns the running node (ie. the source in this case) of the

    /// iterator

    Node runningNode(const InArcIt &arc) const {

      return Parent::source(static_cast<const Arc&>(arc));

    }

    /// Base node of the iterator

    ///

    /// Returns the base node of the iterator

    Node baseNode(const IncEdgeIt &edge) const {

    }

    /// Running node of the iterator

    ///

    /// Returns the running node of the iterator

    Node runningNode(const IncEdgeIt &edge) const {

    }

    // Mappable extension

    template <typename _Value>

    class NodeMap 

      : public MapExtender<DefaultMap<Graph, Node, _Value> > {

    public:

      typedef GraphExtender Graph;

      typedef MapExtender<DefaultMap<Graph, Node, _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 ArcMap 

      : public MapExtender<DefaultMap<Graph, Arc, _Value> > {

    public:

      typedef GraphExtender Graph;

      typedef MapExtender<DefaultMap<Graph, Arc, _Value> > Parent;

      ArcMap(const Graph& graph) 

	: Parent(graph) {}

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

	: Parent(graph, value) {}

      ArcMap& operator=(const ArcMap& cmap) {

	return operator=<ArcMap>(cmap);

      }

      template <typename CMap>

      ArcMap& operator=(const CMap& cmap) {

        Parent::operator=(cmap);

	return *this;

      }

    };

    template <typename _Value>

    class EdgeMap 

      : public MapExtender<DefaultMap<Graph, Edge, _Value> > {

    public:

      typedef GraphExtender Graph;

      typedef MapExtender<DefaultMap<Graph, Edge, _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;

      }

    };

    // Alteration extension

    Node addNode() {

      Node node = Parent::addNode();

      notifier(Node()).add(node);

      return node;

    }

    Edge addEdge(const Node& from, const Node& to) {

      Edge edge = Parent::addEdge(from, to);

      notifier(Edge()).add(edge);

      std::vector<Arc> ev;

      ev.push_back(Parent::direct(edge, true));

      ev.push_back(Parent::direct(edge, false));      

      notifier(Arc()).add(ev);

      return edge;

    }

    void clear() {

      void next(Node&) const {}

      void first(Arc&) const {}

      void next(Arc&) const {}

      void firstIn(Arc&, const Node&) const {}

      void nextIn(Arc&) const {}

      void firstOut(Arc&, const Node&) const {}

      void nextOut(Arc&) const {}

      // The second parameter is dummy.

      Node fromId(int, Node) const { return INVALID; }

      // The second parameter is dummy.

      Arc fromId(int, Arc) const { return INVALID; }

      // Dummy parameter.

      int maxId(Node) const { return -1; } 

      // Dummy parameter.

      int maxId(Arc) const { return -1; } 

      /// \brief The base node of the iterator.

      ///

      /// Gives back the base node of the iterator.

      /// It is always the target of the pointed arc.

      Node baseNode(const InArcIt&) const { return INVALID; }

      /// \brief The running node of the iterator.

      ///

      /// Gives back the running node of the iterator.

      /// It is always the source of the pointed arc.

      Node runningNode(const InArcIt&) const { return INVALID; }

      /// \brief The base node of the iterator.

      ///

      /// Gives back the base node of the iterator.

      /// It is always the source of the pointed arc.

      Node baseNode(const OutArcIt&) const { return INVALID; }

      /// \brief The running node of the iterator.

      ///

      /// Gives back the running node of the iterator.

      /// It is always the target of the pointed arc.

      Node runningNode(const OutArcIt&) const { return INVALID; }

      /// \brief The opposite node on the given arc.

      ///

      /// Gives back the opposite node on the given arc.

      Node oppositeNode(const Node&, const Arc&) const { return INVALID; }

      /// \brief Read write map of the nodes to type \c T.

      /// 

      /// ReadWrite map of the nodes to type \c T.

      /// \sa Reference

      template<class T> 

      class NodeMap : public ReadWriteMap< Node, T > {

      public:

        ///\e

        NodeMap(const Digraph&) { }

        ///\e

        NodeMap(const Digraph&, T) { }

        ///Copy constructor

        NodeMap(const NodeMap& nm) : ReadWriteMap< Node, T >(nm) { }

        ///Assignment operator

        template <typename CMap>

        NodeMap& operator=(const CMap&) { 

          checkConcept<ReadMap<Node, T>, CMap>();

          return *this; 

        }

      };

      /// \brief Read write map of the arcs to type \c T.

      ///

      /// Reference map of the arcs to type \c T.

      /// \sa Reference

      template<class T> 

      class ArcMap : public ReadWriteMap<Arc,T> {

      public:

        ///\e

        ArcMap(const Digraph&) { }

        ///\e

        ArcMap(const Digraph&, T) { }

        ///Copy constructor

        ArcMap(const ArcMap& em) : ReadWriteMap<Arc,T>(em) { }

        ///Assignment operator

        template <typename CMap>

        ArcMap& operator=(const CMap&) { 

          checkConcept<ReadMap<Arc, T>, CMap>();

          return *this; 

        }

      };

      struct Constraints {

        void constraints() {

        }

      };

    };

  } //namespace concepts  

} //namespace lemon

#endif // LEMON_CONCEPT_DIGRAPH_H

      /// \pre The argument should be a valid node id in the graph.

      Node nodeFromId(int) const { return INVALID; } 

      /// \brief Returns the edge with the given id.

      ///

      /// \pre The argument should be a valid edge id in the graph.

      Edge edgeFromId(int) const { return INVALID; } 

      /// \brief Returns the arc with the given id.

      ///

      /// \pre The argument should be a valid arc id in the graph.

      Arc arcFromId(int) const { return INVALID; } 

      /// \brief Returns an upper bound on the node IDs.

      int maxNodeId() const { return -1; } 

      /// \brief Returns an upper bound on the edge IDs.

      int maxEdgeId() const { return -1; } 

      /// \brief Returns an upper bound on the arc IDs.

      int maxArcId() const { return -1; } 

      void first(Node&) const {}

      void next(Node&) const {}

      void first(Edge&) const {}

      void next(Edge&) const {}

      void first(Arc&) const {}

      void next(Arc&) const {}

      void firstOut(Arc&, Node) const {}

      void nextOut(Arc&) const {}

      void firstIn(Arc&, Node) const {}

      void nextIn(Arc&) const {}

      void firstInc(Edge &, bool &, const Node &) const {}

      void nextInc(Edge &, bool &) const {}

      // The second parameter is dummy.

      Node fromId(int, Node) const { return INVALID; }

      // The second parameter is dummy.

      Edge fromId(int, Edge) const { return INVALID; }

      // The second parameter is dummy.

      Arc fromId(int, Arc) const { return INVALID; }

      // Dummy parameter.

      int maxId(Node) const { return -1; } 

      // Dummy parameter.

      int maxId(Edge) const { return -1; } 

      // Dummy parameter.

      int maxId(Arc) const { return -1; } 

      /// \brief Base node of the iterator

      ///

      /// Returns the base node (the source in this case) of the iterator

      Node baseNode(OutArcIt e) const {

	return source(e);

      }

      /// \brief Running node of the iterator

      ///

      /// Returns the running node (the target in this case) of the

      /// iterator

      Node runningNode(OutArcIt e) const {

	return target(e);

      }

      /// \brief Base node of the iterator

      ///

      /// Returns the base node (the target in this case) of the iterator

      Node baseNode(InArcIt e) const {

	return target(e);

      }

      /// \brief Running node of the iterator

      ///

      /// Returns the running node (the source in this case) of the

      /// iterator

      Node runningNode(InArcIt e) const {

	return source(e);

      }

      /// \brief Base node of the iterator

      ///

      /// Returns the base node of the iterator

      Node baseNode(IncEdgeIt) const {

	return INVALID;

      }

      /// \brief Running node of the iterator

      ///

      /// Returns the running node of the iterator

      Node runningNode(IncEdgeIt) const {

	return INVALID;

      }

      struct Constraints {

	void constraints() {

	}

      };

    };

  }

}

#endif

      ///a later state, in other word you cannot add again the arcs deleted

      ///by restore().

      void restore()

      {

	_graph->restoreSnapshot(*this);

      }

    };

  };

  class SmartGraphBase {

  protected:

    struct NodeT {

      int first_out;

    };

    struct ArcT {

      int target;

      int next_out;

    };

    std::vector<NodeT> nodes;

    std::vector<ArcT> arcs;

    int first_free_arc;

  public:

    typedef SmartGraphBase Digraph;

    class Node;

    class Arc;

    class Edge;

    class Node {

      friend class SmartGraphBase;

    protected:

      int _id;

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

    public:

      Node() {}

      Node (Invalid) { _id = -1; }

      bool operator==(const Node& node) const {return _id == node._id;}

      bool operator!=(const Node& node) const {return _id != node._id;}

      bool operator<(const Node& node) const {return _id < node._id;}

    };

    class Edge {

      friend class SmartGraphBase;

    protected:

      int _id;

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

    public:

      Edge() {}

      Edge (Invalid) { _id = -1; }

      bool operator==(const Edge& arc) const {return _id == arc._id;}

      bool operator!=(const Edge& arc) const {return _id != arc._id;}

      bool operator<(const Edge& arc) const {return _id < arc._id;}

    };

    class Arc {

      friend class SmartGraphBase;

    protected:

      int _id;

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

    public:

      operator Edge() const { return edgeFromId(_id / 2); }

      Arc() {}

      Arc (Invalid) { _id = -1; }

      bool operator==(const Arc& arc) const {return _id == arc._id;}

      bool operator!=(const Arc& arc) const {return _id != arc._id;}

      bool operator<(const Arc& arc) const {return _id < arc._id;}

    };

    SmartGraphBase()

      : nodes(), arcs() {}

    int maxNodeId() const { return nodes.size()-1; } 

    int maxEdgeId() const { return arcs.size() / 2 - 1; }

    int maxArcId() const { return arcs.size()-1; }

    Node source(Arc e) const { return Node(arcs[e._id ^ 1].target); }

    Node target(Arc e) const { return Node(arcs[e._id].target); }

    static bool direction(Arc e) {

      return (e._id & 1) == 1;

    }

    static Arc direct(Edge e, bool d) {

      return Arc(e._id * 2 + (d ? 1 : 0));

    }

    void first(Node& node) const { 

      node._id = nodes.size() - 1;

    }

    void next(Node& node) const {

      --node._id;

    }

    void first(Arc& arc) const { 

      arc._id = arcs.size() - 1;

    }

    void next(Arc& arc) const {

      --arc._id;

    }

    void first(Edge& arc) const { 

      arc._id = arcs.size() / 2 - 1;

    }

    void next(Edge& arc) const {

      --arc._id;

    }

    void firstOut(Arc &arc, const Node& v) const {

      arc._id = nodes[v._id].first_out;

    }

    void nextOut(Arc &arc) const {

      arc._id = arcs[arc._id].next_out;

    }

    void firstIn(Arc &arc, const Node& v) const {

      arc._id = ((nodes[v._id].first_out) ^ 1);

      if (arc._id == -2) arc._id = -1;

    }

    void nextIn(Arc &arc) const {

      arc._id = ((arcs[arc._id ^ 1].next_out) ^ 1);

      if (arc._id == -2) arc._id = -1;

    }

    void firstInc(Edge &arc, bool& d, const Node& v) const {

      int de = nodes[v._id].first_out;

      if (de != -1) {

        arc._id = de / 2;

        d = ((de & 1) == 1);

      } else {

        arc._id = -1;

        d = true;

      }

    }

    void nextInc(Edge &arc, bool& d) const {

      int de = (arcs[(arc._id * 2) | (d ? 1 : 0)].next_out);

      if (de != -1) {

        arc._id = de / 2;

        d = ((de & 1) == 1);

      } else {

        arc._id = -1;

        d = true;      

      }

    }

    static int id(Node v) { return v._id; }

    static int id(Arc e) { return e._id; }

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

    static Node nodeFromId(int id) { return Node(id);}

    static Arc arcFromId(int id) { return Arc(id);}

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

    Node addNode() {     

      int n = nodes.size();

      nodes.push_back(NodeT());

      nodes[n].first_out = -1;

      return Node(n);

    }

    Edge addArc(Node u, Node v) {

      int n = arcs.size();

      arcs.push_back(ArcT());

      arcs.push_back(ArcT());

      arcs[n].target = u._id;

      arcs[n | 1].target = v._id;

      arcs[n].next_out = nodes[v._id].first_out;

      nodes[v._id].first_out = n;