source: lemon-0.x/src/lemon/undir_graph_extender.h @ 963:5a7556e9e340

/* -*- C++ -*-
 *
 * src/lemon/undir_graph_extender.h - Part of LEMON, a generic C++
 * optimization library
 *
 * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi
 * Kutatocsoport (Egervary Combinatorial Optimization Research Group,
 * 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_UNDIR_GRAPH_EXTENDER_H
#define LEMON_UNDIR_GRAPH_EXTENDER_H

#include <lemon/invalid.h>

namespace lemon {

  template <typename _Base>
  class UndirGraphExtender : public _Base {
    typedef _Base Parent;
    typedef UndirGraphExtender Graph;

  public:

    typedef typename Parent::Edge UndirEdge;
    typedef typename Parent::Node Node;

    class Edge : public UndirEdge {
      friend class Graph;

    protected:
      // FIXME: Marci use opposite logic in his graph wrappers. It would
      // be reasonable to syncronize...
      bool forward;

    public:
      Edge() {}
      /// Construct a direct edge from undirect edge and a direction.
      Edge(const UndirEdge &ue, bool _forward) :
        UndirEdge(ue), forward(_forward) {}
      /// Invalid edge constructor
      Edge(Invalid i) : UndirEdge(i), forward(false) {}

      bool operator==(const Edge &that) const {
        return forward==that.forward && UndirEdge(*this)==UndirEdge(that);
      }
      bool operator!=(const Edge &that) const {
        return forward!=that.forward || UndirEdge(*this)!=UndirEdge(that);
      }
      bool operator<(const Edge &that) const {
        return forward<that.forward ||
          (!(that.forward<forward) && UndirEdge(*this)<UndirEdge(that));
      }
    };


    /// \brief Returns the Edge of opposite direction.
    ///
    /// \bug Is this a good name for this? Or "reverse" is better?
    Edge opposite(const Edge &e) const {
      return Edge(e,!e.forward);
    }

    /// Tail of the given Edge.
    Node tail(const Edge &e) const {
      return e.forward ? Parent::tail(e) : Parent::head(e);
    }

    /// \todo Shouldn't the "tail" of an undirected edge be called "aNode"
    /// or something???
    using Parent::tail;

    /// Head of the given Edge.
    Node head(const Edge &e) const {
      return e.forward ? Parent::head(e) : Parent::tail(e);
    }

    /// \todo Shouldn't the "head" of an undirected edge be called "bNode"
    /// or something???
    using Parent::head;

    /// Returns whether the given directed edge is same orientation as the
    /// corresponding undirected edge.
    ///
    /// \todo reference to the corresponding point of the undirected graph
    /// concept. "What does the direction of an undirected edge mean?"
    bool forward(const Edge &e) const { return e.forward; }

    Node oppsiteNode(const Node &n, const Edge &e) const {
      if( n == Parent::tail(e))
        return Parent::head(e);
      else if( n == Parent::head(e))
        return Parent::tail(e);
      else
        return INVALID;
    }


    using Parent::first;
    void first(Edge &e) const {
      Parent::first(e);
      e.forward=true;
    }

    using Parent::next;
    void next(Edge &e) const {
      if( e.forward ) {
        e.forward = false;
      }
      else {
        Parent::next(e);
        e.forward = true;
      }
    }

    void firstOut(Edge &e, const Node &n) const {
      Parent::firstOut(e,n);
      if( UndirEdge(e) != INVALID ) {
        e.forward = true;
      }
      else {
        Parent::firstIn(e,n);
        e.forward = false;
      }
    }
    void firstIn(Edge &e, const Node &n) const {
      Parent::firstIn(e,n);
      if( UndirEdge(e) != INVALID ) {
        e.forward = true;
      }
      else {
        Parent::firstOut(e,n);
        e.forward = false;
      }
    }

    void nextOut(Edge &e) const {
      if( e.forward ) {
        Parent::nextOut(e);
        if( UndirEdge(e) == INVALID ) {
          Parent::firstIn(e, Parent::tail(e));
          e.forward = false;
        }
      }
      else {
        Parent::nextIn(e);
      }
    }
    void nextIn(Edge &e) const {
      if( e.forward ) {
        Parent::nextIn(e);
        if( UndirEdge(e) == INVALID ) {
          Parent::firstOut(e, Parent::head(e));
          e.forward = false;
        }
      }
      else {
        Parent::nextOut(e);
      }
    }

    // Miscellaneous stuff:

    /// \todo these methods (id, maxEdgeId) should be moved into separate
    /// Extender

    using Parent::id;

    int id(const Edge &e) const {
      return 2*Parent::id(e) + int(e.forward);
    }

    int maxEdgeId() const {
      return 2*Parent::maxEdgeId() + 1;
    }
    int maxUndirEdgeId() const {
      return Parent::maxEdgeId();
    }

  };

}

#endif // LEMON_UNDIR_GRAPH_EXTENDER_H