lemon/bfs.h
author Alpar Juttner <alpar@cs.elte.hu>
Thu, 04 Aug 2011 22:00:57 +0200
changeset 924 3dcb45a871c3
parent 292 e7af73f1805e
child 329 d900fd1e760f
permissions -rw-r--r--
Update the AUTHORS file
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/* -*- mode: C++; indent-tabs-mode: nil; -*-
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 *
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 * This file is a part of LEMON, a generic C++ optimization library.
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 *
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 * Copyright (C) 2003-2008
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 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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#ifndef LEMON_BFS_H
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#define LEMON_BFS_H
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///\ingroup search
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///\file
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///\brief BFS algorithm.
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#include <lemon/list_graph.h>
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#include <lemon/bits/path_dump.h>
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#include <lemon/core.h>
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#include <lemon/error.h>
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#include <lemon/maps.h>
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#include <lemon/path.h>
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namespace lemon {
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  ///Default traits class of Bfs class.
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  ///Default traits class of Bfs class.
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  ///\tparam GR Digraph type.
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  template<class GR>
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  struct BfsDefaultTraits
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  {
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    ///The type of the digraph the algorithm runs on.
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    typedef GR Digraph;
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    ///\brief The type of the map that stores the predecessor
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    ///arcs of the shortest paths.
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    ///
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    ///The type of the map that stores the predecessor
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    ///arcs of the shortest paths.
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    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
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    typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
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    ///Instantiates a PredMap.
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    ///This function instantiates a PredMap.
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    ///\param g is the digraph, to which we would like to define the
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    ///PredMap.
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    static PredMap *createPredMap(const Digraph &g)
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    {
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      return new PredMap(g);
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    }
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    ///The type of the map that indicates which nodes are processed.
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    ///The type of the map that indicates which nodes are processed.
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    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
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    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
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    ///Instantiates a ProcessedMap.
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    ///This function instantiates a ProcessedMap.
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    ///\param g is the digraph, to which
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    ///we would like to define the ProcessedMap
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#ifdef DOXYGEN
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    static ProcessedMap *createProcessedMap(const Digraph &g)
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#else
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    static ProcessedMap *createProcessedMap(const Digraph &)
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#endif
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    {
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      return new ProcessedMap();
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    }
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    ///The type of the map that indicates which nodes are reached.
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    ///The type of the map that indicates which nodes are reached.
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    ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
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    typedef typename Digraph::template NodeMap<bool> ReachedMap;
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    ///Instantiates a ReachedMap.
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    ///This function instantiates a ReachedMap.
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    ///\param g is the digraph, to which
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    ///we would like to define the ReachedMap.
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    static ReachedMap *createReachedMap(const Digraph &g)
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    {
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      return new ReachedMap(g);
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    }
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    ///The type of the map that stores the distances of the nodes.
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    ///The type of the map that stores the distances of the nodes.
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    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
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    typedef typename Digraph::template NodeMap<int> DistMap;
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    ///Instantiates a DistMap.
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    ///This function instantiates a DistMap.
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    ///\param g is the digraph, to which we would like to define the
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    ///DistMap.
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    static DistMap *createDistMap(const Digraph &g)
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    {
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      return new DistMap(g);
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    }
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  };
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  ///%BFS algorithm class.
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  ///\ingroup search
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  ///This class provides an efficient implementation of the %BFS algorithm.
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  ///
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  ///There is also a \ref bfs() "function-type interface" for the BFS
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  ///algorithm, which is convenient in the simplier cases and it can be
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  ///used easier.
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  ///
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  ///\tparam GR The type of the digraph the algorithm runs on.
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  ///The default value is \ref ListDigraph. The value of GR is not used
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  ///directly by \ref Bfs, it is only passed to \ref BfsDefaultTraits.
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  ///\tparam TR Traits class to set various data types used by the algorithm.
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  ///The default traits class is
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  ///\ref BfsDefaultTraits "BfsDefaultTraits<GR>".
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  ///See \ref BfsDefaultTraits for the documentation of
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  ///a Bfs traits class.
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#ifdef DOXYGEN
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  template <typename GR,
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            typename TR>
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#else
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  template <typename GR=ListDigraph,
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            typename TR=BfsDefaultTraits<GR> >
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#endif
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  class Bfs {
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  public:
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    ///The type of the digraph the algorithm runs on.
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    typedef typename TR::Digraph Digraph;
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    ///\brief The type of the map that stores the predecessor arcs of the
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    ///shortest paths.
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    typedef typename TR::PredMap PredMap;
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    ///The type of the map that stores the distances of the nodes.
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    typedef typename TR::DistMap DistMap;
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    ///The type of the map that indicates which nodes are reached.
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    typedef typename TR::ReachedMap ReachedMap;
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    ///The type of the map that indicates which nodes are processed.
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    typedef typename TR::ProcessedMap ProcessedMap;
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    ///The type of the paths.
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    typedef PredMapPath<Digraph, PredMap> Path;
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    ///The traits class.
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    typedef TR Traits;
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  private:
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    typedef typename Digraph::Node Node;
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    typedef typename Digraph::NodeIt NodeIt;
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    typedef typename Digraph::Arc Arc;
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    typedef typename Digraph::OutArcIt OutArcIt;
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    //Pointer to the underlying digraph.
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    const Digraph *G;
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    //Pointer to the map of predecessor arcs.
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    PredMap *_pred;
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    //Indicates if _pred is locally allocated (true) or not.
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    bool local_pred;
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    //Pointer to the map of distances.
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    DistMap *_dist;
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    //Indicates if _dist is locally allocated (true) or not.
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    bool local_dist;
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    //Pointer to the map of reached status of the nodes.
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    ReachedMap *_reached;
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    //Indicates if _reached is locally allocated (true) or not.
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    bool local_reached;
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    //Pointer to the map of processed status of the nodes.
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    ProcessedMap *_processed;
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    //Indicates if _processed is locally allocated (true) or not.
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    bool local_processed;
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    std::vector<typename Digraph::Node> _queue;
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    int _queue_head,_queue_tail,_queue_next_dist;
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    int _curr_dist;
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    //Creates the maps if necessary.
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    void create_maps()
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    {
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      if(!_pred) {
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        local_pred = true;
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        _pred = Traits::createPredMap(*G);
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      }
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      if(!_dist) {
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        local_dist = true;
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        _dist = Traits::createDistMap(*G);
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      }
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      if(!_reached) {
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        local_reached = true;
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        _reached = Traits::createReachedMap(*G);
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      }
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      if(!_processed) {
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        local_processed = true;
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        _processed = Traits::createProcessedMap(*G);
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      }
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    }
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  protected:
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    Bfs() {}
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  public:
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    typedef Bfs Create;
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    ///\name Named template parameters
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    ///@{
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    template <class T>
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    struct SetPredMapTraits : public Traits {
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      typedef T PredMap;
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      static PredMap *createPredMap(const Digraph &)
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      {
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        LEMON_ASSERT(false, "PredMap is not initialized");
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        return 0; // ignore warnings
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      }
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    };
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    ///\brief \ref named-templ-param "Named parameter" for setting
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    ///PredMap type.
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    ///
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    ///\ref named-templ-param "Named parameter" for setting
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    ///PredMap type.
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    template <class T>
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    struct SetPredMap : public Bfs< Digraph, SetPredMapTraits<T> > {
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      typedef Bfs< Digraph, SetPredMapTraits<T> > Create;
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    };
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    template <class T>
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    struct SetDistMapTraits : public Traits {
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      typedef T DistMap;
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      static DistMap *createDistMap(const Digraph &)
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      {
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        LEMON_ASSERT(false, "DistMap is not initialized");
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        return 0; // ignore warnings
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      }
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    };
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    ///\brief \ref named-templ-param "Named parameter" for setting
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    ///DistMap type.
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    ///
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    ///\ref named-templ-param "Named parameter" for setting
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    ///DistMap type.
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    template <class T>
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    struct SetDistMap : public Bfs< Digraph, SetDistMapTraits<T> > {
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      typedef Bfs< Digraph, SetDistMapTraits<T> > Create;
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    };
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    template <class T>
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    struct SetReachedMapTraits : public Traits {
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      typedef T ReachedMap;
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      static ReachedMap *createReachedMap(const Digraph &)
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      {
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        LEMON_ASSERT(false, "ReachedMap is not initialized");
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        return 0; // ignore warnings
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      }
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    };
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    ///\brief \ref named-templ-param "Named parameter" for setting
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    ///ReachedMap type.
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    ///
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    ///\ref named-templ-param "Named parameter" for setting
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    ///ReachedMap type.
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    template <class T>
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    struct SetReachedMap : public Bfs< Digraph, SetReachedMapTraits<T> > {
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      typedef Bfs< Digraph, SetReachedMapTraits<T> > Create;
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    };
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    template <class T>
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    struct SetProcessedMapTraits : public Traits {
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      typedef T ProcessedMap;
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      static ProcessedMap *createProcessedMap(const Digraph &)
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      {
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        LEMON_ASSERT(false, "ProcessedMap is not initialized");
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        return 0; // ignore warnings
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      }
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    };
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    ///\brief \ref named-templ-param "Named parameter" for setting
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    ///ProcessedMap type.
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    ///
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    ///\ref named-templ-param "Named parameter" for setting
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    ///ProcessedMap type.
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    template <class T>
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    struct SetProcessedMap : public Bfs< Digraph, SetProcessedMapTraits<T> > {
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      typedef Bfs< Digraph, SetProcessedMapTraits<T> > Create;
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    };
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    struct SetStandardProcessedMapTraits : public Traits {
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      typedef typename Digraph::template NodeMap<bool> ProcessedMap;
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      static ProcessedMap *createProcessedMap(const Digraph &g)
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      {
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        return new ProcessedMap(g);
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        return 0; // ignore warnings
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      }
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    };
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    ///\brief \ref named-templ-param "Named parameter" for setting
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    ///ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
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    ///
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    ///\ref named-templ-param "Named parameter" for setting
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    ///ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
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    ///If you don't set it explicitly, it will be automatically allocated.
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    struct SetStandardProcessedMap :
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      public Bfs< Digraph, SetStandardProcessedMapTraits > {
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      typedef Bfs< Digraph, SetStandardProcessedMapTraits > Create;
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    };
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    ///@}
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  public:
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    ///Constructor.
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    ///Constructor.
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    ///\param g The digraph the algorithm runs on.
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    Bfs(const Digraph &g) :
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      G(&g),
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      _pred(NULL), local_pred(false),
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      _dist(NULL), local_dist(false),
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      _reached(NULL), local_reached(false),
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      _processed(NULL), local_processed(false)
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    { }
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    ///Destructor.
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    ~Bfs()
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    {
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      if(local_pred) delete _pred;
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      if(local_dist) delete _dist;
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      if(local_reached) delete _reached;
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      if(local_processed) delete _processed;
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    }
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    ///Sets the map that stores the predecessor arcs.
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    ///Sets the map that stores the predecessor arcs.
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    ///If you don't use this function before calling \ref run(),
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    ///it will allocate one. The destructor deallocates this
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    ///automatically allocated map, of course.
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    ///\return <tt> (*this) </tt>
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    Bfs &predMap(PredMap &m)
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    {
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      if(local_pred) {
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        delete _pred;
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        local_pred=false;
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      }
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      _pred = &m;
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      return *this;
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    }
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    ///Sets the map that indicates which nodes are reached.
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    ///Sets the map that indicates which nodes are reached.
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    ///If you don't use this function before calling \ref run(),
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    ///it will allocate one. The destructor deallocates this
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    ///automatically allocated map, of course.
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    ///\return <tt> (*this) </tt>
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    Bfs &reachedMap(ReachedMap &m)
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    {
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      if(local_reached) {
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        delete _reached;
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        local_reached=false;
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      }
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      _reached = &m;
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      return *this;
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    }
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    ///Sets the map that indicates which nodes are processed.
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    ///Sets the map that indicates which nodes are processed.
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    ///If you don't use this function before calling \ref run(),
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    ///it will allocate one. The destructor deallocates this
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    ///automatically allocated map, of course.
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    ///\return <tt> (*this) </tt>
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    Bfs &processedMap(ProcessedMap &m)
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    {
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      if(local_processed) {
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        delete _processed;
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        local_processed=false;
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      }
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      _processed = &m;
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      return *this;
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    }
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    ///Sets the map that stores the distances of the nodes.
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    ///Sets the map that stores the distances of the nodes calculated by
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    ///the algorithm.
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    ///If you don't use this function before calling \ref run(),
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    ///it will allocate one. The destructor deallocates this
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    ///automatically allocated map, of course.
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    ///\return <tt> (*this) </tt>
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    Bfs &distMap(DistMap &m)
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    {
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      if(local_dist) {
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        delete _dist;
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        local_dist=false;
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      }
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      _dist = &m;
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      return *this;
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   407
    }
alpar@100
   408
alpar@100
   409
  public:
kpeter@244
   410
alpar@100
   411
    ///\name Execution control
alpar@100
   412
    ///The simplest way to execute the algorithm is to use
kpeter@244
   413
    ///one of the member functions called \ref lemon::Bfs::run() "run()".
alpar@100
   414
    ///\n
kpeter@244
   415
    ///If you need more control on the execution, first you must call
kpeter@244
   416
    ///\ref lemon::Bfs::init() "init()", then you can add several source
kpeter@244
   417
    ///nodes with \ref lemon::Bfs::addSource() "addSource()".
kpeter@244
   418
    ///Finally \ref lemon::Bfs::start() "start()" will perform the
kpeter@244
   419
    ///actual path computation.
alpar@100
   420
alpar@100
   421
    ///@{
alpar@100
   422
kpeter@244
   423
    ///Initializes the internal data structures.
kpeter@244
   424
alpar@100
   425
    ///Initializes the internal data structures.
alpar@100
   426
    ///
alpar@100
   427
    void init()
alpar@100
   428
    {
alpar@100
   429
      create_maps();
alpar@100
   430
      _queue.resize(countNodes(*G));
alpar@100
   431
      _queue_head=_queue_tail=0;
alpar@100
   432
      _curr_dist=1;
alpar@100
   433
      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
alpar@209
   434
        _pred->set(u,INVALID);
alpar@209
   435
        _reached->set(u,false);
alpar@209
   436
        _processed->set(u,false);
alpar@100
   437
      }
alpar@100
   438
    }
alpar@209
   439
alpar@100
   440
    ///Adds a new source node.
alpar@100
   441
alpar@100
   442
    ///Adds a new source node to the set of nodes to be processed.
alpar@100
   443
    ///
alpar@100
   444
    void addSource(Node s)
alpar@100
   445
    {
alpar@100
   446
      if(!(*_reached)[s])
alpar@209
   447
        {
alpar@209
   448
          _reached->set(s,true);
alpar@209
   449
          _pred->set(s,INVALID);
alpar@209
   450
          _dist->set(s,0);
alpar@209
   451
          _queue[_queue_head++]=s;
alpar@209
   452
          _queue_next_dist=_queue_head;
alpar@209
   453
        }
alpar@100
   454
    }
alpar@209
   455
alpar@100
   456
    ///Processes the next node.
alpar@100
   457
alpar@100
   458
    ///Processes the next node.
alpar@100
   459
    ///
alpar@100
   460
    ///\return The processed node.
alpar@100
   461
    ///
kpeter@244
   462
    ///\pre The queue must not be empty.
alpar@100
   463
    Node processNextNode()
alpar@100
   464
    {
alpar@100
   465
      if(_queue_tail==_queue_next_dist) {
alpar@209
   466
        _curr_dist++;
alpar@209
   467
        _queue_next_dist=_queue_head;
alpar@100
   468
      }
alpar@100
   469
      Node n=_queue[_queue_tail++];
alpar@100
   470
      _processed->set(n,true);
alpar@100
   471
      Node m;
alpar@100
   472
      for(OutArcIt e(*G,n);e!=INVALID;++e)
alpar@209
   473
        if(!(*_reached)[m=G->target(e)]) {
alpar@209
   474
          _queue[_queue_head++]=m;
alpar@209
   475
          _reached->set(m,true);
alpar@209
   476
          _pred->set(m,e);
alpar@209
   477
          _dist->set(m,_curr_dist);
alpar@209
   478
        }
alpar@100
   479
      return n;
alpar@100
   480
    }
alpar@100
   481
alpar@100
   482
    ///Processes the next node.
alpar@100
   483
kpeter@244
   484
    ///Processes the next node and checks if the given target node
alpar@100
   485
    ///is reached. If the target node is reachable from the processed
kpeter@244
   486
    ///node, then the \c reach parameter will be set to \c true.
alpar@100
   487
    ///
alpar@100
   488
    ///\param target The target node.
kpeter@244
   489
    ///\retval reach Indicates if the target node is reached.
kpeter@244
   490
    ///It should be initially \c false.
kpeter@244
   491
    ///
alpar@100
   492
    ///\return The processed node.
alpar@100
   493
    ///
kpeter@244
   494
    ///\pre The queue must not be empty.
alpar@100
   495
    Node processNextNode(Node target, bool& reach)
alpar@100
   496
    {
alpar@100
   497
      if(_queue_tail==_queue_next_dist) {
alpar@209
   498
        _curr_dist++;
alpar@209
   499
        _queue_next_dist=_queue_head;
alpar@100
   500
      }
alpar@100
   501
      Node n=_queue[_queue_tail++];
alpar@100
   502
      _processed->set(n,true);
alpar@100
   503
      Node m;
alpar@100
   504
      for(OutArcIt e(*G,n);e!=INVALID;++e)
alpar@209
   505
        if(!(*_reached)[m=G->target(e)]) {
alpar@209
   506
          _queue[_queue_head++]=m;
alpar@209
   507
          _reached->set(m,true);
alpar@209
   508
          _pred->set(m,e);
alpar@209
   509
          _dist->set(m,_curr_dist);
alpar@100
   510
          reach = reach || (target == m);
alpar@209
   511
        }
alpar@100
   512
      return n;
alpar@100
   513
    }
alpar@100
   514
alpar@100
   515
    ///Processes the next node.
alpar@100
   516
kpeter@244
   517
    ///Processes the next node and checks if at least one of reached
kpeter@244
   518
    ///nodes has \c true value in the \c nm node map. If one node
kpeter@244
   519
    ///with \c true value is reachable from the processed node, then the
kpeter@244
   520
    ///\c rnode parameter will be set to the first of such nodes.
alpar@100
   521
    ///
kpeter@244
   522
    ///\param nm A \c bool (or convertible) node map that indicates the
kpeter@244
   523
    ///possible targets.
alpar@100
   524
    ///\retval rnode The reached target node.
kpeter@244
   525
    ///It should be initially \c INVALID.
kpeter@244
   526
    ///
alpar@100
   527
    ///\return The processed node.
alpar@100
   528
    ///
kpeter@244
   529
    ///\pre The queue must not be empty.
alpar@100
   530
    template<class NM>
alpar@100
   531
    Node processNextNode(const NM& nm, Node& rnode)
alpar@100
   532
    {
alpar@100
   533
      if(_queue_tail==_queue_next_dist) {
alpar@209
   534
        _curr_dist++;
alpar@209
   535
        _queue_next_dist=_queue_head;
alpar@100
   536
      }
alpar@100
   537
      Node n=_queue[_queue_tail++];
alpar@100
   538
      _processed->set(n,true);
alpar@100
   539
      Node m;
alpar@100
   540
      for(OutArcIt e(*G,n);e!=INVALID;++e)
alpar@209
   541
        if(!(*_reached)[m=G->target(e)]) {
alpar@209
   542
          _queue[_queue_head++]=m;
alpar@209
   543
          _reached->set(m,true);
alpar@209
   544
          _pred->set(m,e);
alpar@209
   545
          _dist->set(m,_curr_dist);
alpar@209
   546
          if (nm[m] && rnode == INVALID) rnode = m;
alpar@209
   547
        }
alpar@100
   548
      return n;
alpar@100
   549
    }
alpar@209
   550
kpeter@244
   551
    ///The next node to be processed.
alpar@100
   552
kpeter@244
   553
    ///Returns the next node to be processed or \c INVALID if the queue
kpeter@244
   554
    ///is empty.
kpeter@244
   555
    Node nextNode() const
alpar@209
   556
    {
alpar@100
   557
      return _queue_tail<_queue_head?_queue[_queue_tail]:INVALID;
alpar@100
   558
    }
alpar@209
   559
alpar@100
   560
    ///\brief Returns \c false if there are nodes
kpeter@244
   561
    ///to be processed.
alpar@100
   562
    ///
alpar@100
   563
    ///Returns \c false if there are nodes
kpeter@244
   564
    ///to be processed in the queue.
kpeter@244
   565
    bool emptyQueue() const { return _queue_tail==_queue_head; }
kpeter@244
   566
alpar@100
   567
    ///Returns the number of the nodes to be processed.
alpar@209
   568
alpar@100
   569
    ///Returns the number of the nodes to be processed in the queue.
kpeter@244
   570
    int queueSize() const { return _queue_head-_queue_tail; }
alpar@209
   571
alpar@100
   572
    ///Executes the algorithm.
alpar@100
   573
alpar@100
   574
    ///Executes the algorithm.
alpar@100
   575
    ///
kpeter@244
   576
    ///This method runs the %BFS algorithm from the root node(s)
kpeter@244
   577
    ///in order to compute the shortest path to each node.
alpar@100
   578
    ///
kpeter@244
   579
    ///The algorithm computes
kpeter@244
   580
    ///- the shortest path tree (forest),
kpeter@244
   581
    ///- the distance of each node from the root(s).
kpeter@244
   582
    ///
kpeter@244
   583
    ///\pre init() must be called and at least one root node should be
kpeter@244
   584
    ///added with addSource() before using this function.
kpeter@244
   585
    ///
kpeter@244
   586
    ///\note <tt>b.start()</tt> is just a shortcut of the following code.
kpeter@244
   587
    ///\code
kpeter@244
   588
    ///  while ( !b.emptyQueue() ) {
kpeter@244
   589
    ///    b.processNextNode();
kpeter@244
   590
    ///  }
kpeter@244
   591
    ///\endcode
alpar@100
   592
    void start()
alpar@100
   593
    {
alpar@100
   594
      while ( !emptyQueue() ) processNextNode();
alpar@100
   595
    }
alpar@209
   596
kpeter@244
   597
    ///Executes the algorithm until the given target node is reached.
alpar@100
   598
kpeter@244
   599
    ///Executes the algorithm until the given target node is reached.
alpar@100
   600
    ///
alpar@100
   601
    ///This method runs the %BFS algorithm from the root node(s)
kpeter@286
   602
    ///in order to compute the shortest path to \c t.
kpeter@244
   603
    ///
alpar@100
   604
    ///The algorithm computes
kpeter@286
   605
    ///- the shortest path to \c t,
kpeter@286
   606
    ///- the distance of \c t from the root(s).
kpeter@244
   607
    ///
kpeter@244
   608
    ///\pre init() must be called and at least one root node should be
kpeter@244
   609
    ///added with addSource() before using this function.
kpeter@244
   610
    ///
kpeter@244
   611
    ///\note <tt>b.start(t)</tt> is just a shortcut of the following code.
kpeter@244
   612
    ///\code
kpeter@244
   613
    ///  bool reach = false;
kpeter@244
   614
    ///  while ( !b.emptyQueue() && !reach ) {
kpeter@244
   615
    ///    b.processNextNode(t, reach);
kpeter@244
   616
    ///  }
kpeter@244
   617
    ///\endcode
kpeter@286
   618
    void start(Node t)
alpar@100
   619
    {
alpar@100
   620
      bool reach = false;
kpeter@286
   621
      while ( !emptyQueue() && !reach ) processNextNode(t, reach);
alpar@100
   622
    }
alpar@209
   623
alpar@100
   624
    ///Executes the algorithm until a condition is met.
alpar@100
   625
alpar@100
   626
    ///Executes the algorithm until a condition is met.
alpar@100
   627
    ///
kpeter@244
   628
    ///This method runs the %BFS algorithm from the root node(s) in
kpeter@244
   629
    ///order to compute the shortest path to a node \c v with
kpeter@244
   630
    /// <tt>nm[v]</tt> true, if such a node can be found.
alpar@100
   631
    ///
kpeter@244
   632
    ///\param nm A \c bool (or convertible) node map. The algorithm
kpeter@244
   633
    ///will stop when it reaches a node \c v with <tt>nm[v]</tt> true.
alpar@100
   634
    ///
alpar@100
   635
    ///\return The reached node \c v with <tt>nm[v]</tt> true or
alpar@100
   636
    ///\c INVALID if no such node was found.
kpeter@244
   637
    ///
kpeter@244
   638
    ///\pre init() must be called and at least one root node should be
kpeter@244
   639
    ///added with addSource() before using this function.
kpeter@244
   640
    ///
kpeter@244
   641
    ///\note <tt>b.start(nm)</tt> is just a shortcut of the following code.
kpeter@244
   642
    ///\code
kpeter@244
   643
    ///  Node rnode = INVALID;
kpeter@244
   644
    ///  while ( !b.emptyQueue() && rnode == INVALID ) {
kpeter@244
   645
    ///    b.processNextNode(nm, rnode);
kpeter@244
   646
    ///  }
kpeter@244
   647
    ///  return rnode;
kpeter@244
   648
    ///\endcode
kpeter@244
   649
    template<class NodeBoolMap>
kpeter@244
   650
    Node start(const NodeBoolMap &nm)
alpar@100
   651
    {
alpar@100
   652
      Node rnode = INVALID;
alpar@100
   653
      while ( !emptyQueue() && rnode == INVALID ) {
alpar@209
   654
        processNextNode(nm, rnode);
alpar@100
   655
      }
alpar@100
   656
      return rnode;
alpar@100
   657
    }
alpar@209
   658
kpeter@286
   659
    ///Runs the algorithm from the given source node.
alpar@209
   660
kpeter@244
   661
    ///This method runs the %BFS algorithm from node \c s
kpeter@244
   662
    ///in order to compute the shortest path to each node.
alpar@100
   663
    ///
kpeter@244
   664
    ///The algorithm computes
kpeter@244
   665
    ///- the shortest path tree,
kpeter@244
   666
    ///- the distance of each node from the root.
kpeter@244
   667
    ///
kpeter@244
   668
    ///\note <tt>b.run(s)</tt> is just a shortcut of the following code.
alpar@100
   669
    ///\code
alpar@100
   670
    ///  b.init();
alpar@100
   671
    ///  b.addSource(s);
alpar@100
   672
    ///  b.start();
alpar@100
   673
    ///\endcode
alpar@100
   674
    void run(Node s) {
alpar@100
   675
      init();
alpar@100
   676
      addSource(s);
alpar@100
   677
      start();
alpar@100
   678
    }
alpar@209
   679
alpar@100
   680
    ///Finds the shortest path between \c s and \c t.
alpar@209
   681
kpeter@244
   682
    ///This method runs the %BFS algorithm from node \c s
kpeter@286
   683
    ///in order to compute the shortest path to node \c t
kpeter@286
   684
    ///(it stops searching when \c t is processed).
alpar@100
   685
    ///
kpeter@286
   686
    ///\return \c true if \c t is reachable form \c s.
kpeter@244
   687
    ///
kpeter@244
   688
    ///\note Apart from the return value, <tt>b.run(s,t)</tt> is just a
kpeter@244
   689
    ///shortcut of the following code.
alpar@100
   690
    ///\code
alpar@100
   691
    ///  b.init();
alpar@100
   692
    ///  b.addSource(s);
alpar@100
   693
    ///  b.start(t);
alpar@100
   694
    ///\endcode
kpeter@286
   695
    bool run(Node s,Node t) {
alpar@100
   696
      init();
alpar@100
   697
      addSource(s);
alpar@100
   698
      start(t);
kpeter@286
   699
      return reached(t);
alpar@100
   700
    }
alpar@209
   701
kpeter@244
   702
    ///Runs the algorithm to visit all nodes in the digraph.
kpeter@244
   703
kpeter@244
   704
    ///This method runs the %BFS algorithm in order to
kpeter@244
   705
    ///compute the shortest path to each node.
kpeter@244
   706
    ///
kpeter@244
   707
    ///The algorithm computes
kpeter@244
   708
    ///- the shortest path tree (forest),
kpeter@244
   709
    ///- the distance of each node from the root(s).
kpeter@244
   710
    ///
kpeter@244
   711
    ///\note <tt>b.run(s)</tt> is just a shortcut of the following code.
kpeter@244
   712
    ///\code
kpeter@244
   713
    ///  b.init();
kpeter@244
   714
    ///  for (NodeIt n(gr); n != INVALID; ++n) {
kpeter@244
   715
    ///    if (!b.reached(n)) {
kpeter@244
   716
    ///      b.addSource(n);
kpeter@244
   717
    ///      b.start();
kpeter@244
   718
    ///    }
kpeter@244
   719
    ///  }
kpeter@244
   720
    ///\endcode
kpeter@244
   721
    void run() {
kpeter@244
   722
      init();
kpeter@244
   723
      for (NodeIt n(*G); n != INVALID; ++n) {
kpeter@244
   724
        if (!reached(n)) {
kpeter@244
   725
          addSource(n);
kpeter@244
   726
          start();
kpeter@244
   727
        }
kpeter@244
   728
      }
kpeter@244
   729
    }
kpeter@244
   730
alpar@100
   731
    ///@}
alpar@100
   732
alpar@100
   733
    ///\name Query Functions
alpar@100
   734
    ///The result of the %BFS algorithm can be obtained using these
alpar@100
   735
    ///functions.\n
kpeter@244
   736
    ///Either \ref lemon::Bfs::run() "run()" or \ref lemon::Bfs::start()
kpeter@244
   737
    ///"start()" must be called before using them.
alpar@209
   738
alpar@100
   739
    ///@{
alpar@100
   740
kpeter@244
   741
    ///The shortest path to a node.
alpar@100
   742
kpeter@244
   743
    ///Returns the shortest path to a node.
kpeter@244
   744
    ///
kpeter@244
   745
    ///\warning \c t should be reachable from the root(s).
kpeter@244
   746
    ///
kpeter@244
   747
    ///\pre Either \ref run() or \ref start() must be called before
kpeter@244
   748
    ///using this function.
kpeter@244
   749
    Path path(Node t) const { return Path(*G, *_pred, t); }
alpar@100
   750
alpar@100
   751
    ///The distance of a node from the root(s).
alpar@100
   752
alpar@100
   753
    ///Returns the distance of a node from the root(s).
kpeter@244
   754
    ///
kpeter@244
   755
    ///\warning If node \c v is not reachable from the root(s), then
kpeter@244
   756
    ///the return value of this function is undefined.
kpeter@244
   757
    ///
kpeter@244
   758
    ///\pre Either \ref run() or \ref start() must be called before
kpeter@244
   759
    ///using this function.
alpar@100
   760
    int dist(Node v) const { return (*_dist)[v]; }
alpar@100
   761
kpeter@244
   762
    ///Returns the 'previous arc' of the shortest path tree for a node.
alpar@100
   763
kpeter@244
   764
    ///This function returns the 'previous arc' of the shortest path
kpeter@244
   765
    ///tree for the node \c v, i.e. it returns the last arc of a
kpeter@244
   766
    ///shortest path from the root(s) to \c v. It is \c INVALID if \c v
kpeter@244
   767
    ///is not reachable from the root(s) or if \c v is a root.
kpeter@244
   768
    ///
kpeter@244
   769
    ///The shortest path tree used here is equal to the shortest path
kpeter@244
   770
    ///tree used in \ref predNode().
kpeter@244
   771
    ///
kpeter@244
   772
    ///\pre Either \ref run() or \ref start() must be called before
kpeter@244
   773
    ///using this function.
alpar@100
   774
    Arc predArc(Node v) const { return (*_pred)[v];}
alpar@100
   775
kpeter@244
   776
    ///Returns the 'previous node' of the shortest path tree for a node.
alpar@100
   777
kpeter@244
   778
    ///This function returns the 'previous node' of the shortest path
kpeter@244
   779
    ///tree for the node \c v, i.e. it returns the last but one node
kpeter@244
   780
    ///from a shortest path from the root(s) to \c v. It is \c INVALID
kpeter@244
   781
    ///if \c v is not reachable from the root(s) or if \c v is a root.
kpeter@244
   782
    ///
alpar@100
   783
    ///The shortest path tree used here is equal to the shortest path
alpar@100
   784
    ///tree used in \ref predArc().
kpeter@244
   785
    ///
alpar@100
   786
    ///\pre Either \ref run() or \ref start() must be called before
alpar@100
   787
    ///using this function.
alpar@100
   788
    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
alpar@209
   789
                                  G->source((*_pred)[v]); }
alpar@209
   790
kpeter@244
   791
    ///\brief Returns a const reference to the node map that stores the
kpeter@244
   792
    /// distances of the nodes.
kpeter@244
   793
    ///
kpeter@244
   794
    ///Returns a const reference to the node map that stores the distances
kpeter@244
   795
    ///of the nodes calculated by the algorithm.
kpeter@244
   796
    ///
kpeter@244
   797
    ///\pre Either \ref run() or \ref init()
kpeter@244
   798
    ///must be called before using this function.
alpar@100
   799
    const DistMap &distMap() const { return *_dist;}
alpar@209
   800
kpeter@244
   801
    ///\brief Returns a const reference to the node map that stores the
kpeter@244
   802
    ///predecessor arcs.
kpeter@244
   803
    ///
kpeter@244
   804
    ///Returns a const reference to the node map that stores the predecessor
kpeter@244
   805
    ///arcs, which form the shortest path tree.
kpeter@244
   806
    ///
alpar@100
   807
    ///\pre Either \ref run() or \ref init()
alpar@100
   808
    ///must be called before using this function.
alpar@100
   809
    const PredMap &predMap() const { return *_pred;}
alpar@209
   810
kpeter@244
   811
    ///Checks if a node is reachable from the root(s).
alpar@100
   812
kpeter@244
   813
    ///Returns \c true if \c v is reachable from the root(s).
alpar@100
   814
    ///\pre Either \ref run() or \ref start()
alpar@100
   815
    ///must be called before using this function.
kpeter@244
   816
    bool reached(Node v) const { return (*_reached)[v]; }
alpar@209
   817
alpar@100
   818
    ///@}
alpar@100
   819
  };
alpar@100
   820
kpeter@244
   821
  ///Default traits class of bfs() function.
alpar@100
   822
kpeter@244
   823
  ///Default traits class of bfs() function.
kpeter@157
   824
  ///\tparam GR Digraph type.
alpar@100
   825
  template<class GR>
alpar@100
   826
  struct BfsWizardDefaultTraits
alpar@100
   827
  {
kpeter@244
   828
    ///The type of the digraph the algorithm runs on.
alpar@100
   829
    typedef GR Digraph;
kpeter@244
   830
kpeter@244
   831
    ///\brief The type of the map that stores the predecessor
alpar@100
   832
    ///arcs of the shortest paths.
alpar@209
   833
    ///
kpeter@244
   834
    ///The type of the map that stores the predecessor
alpar@100
   835
    ///arcs of the shortest paths.
alpar@100
   836
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@278
   837
    typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
kpeter@301
   838
    ///Instantiates a PredMap.
alpar@209
   839
kpeter@301
   840
    ///This function instantiates a PredMap.
kpeter@244
   841
    ///\param g is the digraph, to which we would like to define the
kpeter@301
   842
    ///PredMap.
kpeter@244
   843
    static PredMap *createPredMap(const Digraph &g)
alpar@100
   844
    {
kpeter@278
   845
      return new PredMap(g);
alpar@100
   846
    }
alpar@100
   847
alpar@100
   848
    ///The type of the map that indicates which nodes are processed.
alpar@209
   849
alpar@100
   850
    ///The type of the map that indicates which nodes are processed.
alpar@100
   851
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@278
   852
    ///By default it is a NullMap.
alpar@100
   853
    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
kpeter@301
   854
    ///Instantiates a ProcessedMap.
alpar@209
   855
kpeter@301
   856
    ///This function instantiates a ProcessedMap.
alpar@100
   857
    ///\param g is the digraph, to which
kpeter@301
   858
    ///we would like to define the ProcessedMap.
alpar@100
   859
#ifdef DOXYGEN
kpeter@244
   860
    static ProcessedMap *createProcessedMap(const Digraph &g)
alpar@100
   861
#else
kpeter@244
   862
    static ProcessedMap *createProcessedMap(const Digraph &)
alpar@100
   863
#endif
alpar@100
   864
    {
alpar@100
   865
      return new ProcessedMap();
alpar@100
   866
    }
kpeter@244
   867
alpar@100
   868
    ///The type of the map that indicates which nodes are reached.
alpar@209
   869
alpar@100
   870
    ///The type of the map that indicates which nodes are reached.
kpeter@244
   871
    ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
alpar@100
   872
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
kpeter@301
   873
    ///Instantiates a ReachedMap.
alpar@209
   874
kpeter@301
   875
    ///This function instantiates a ReachedMap.
kpeter@244
   876
    ///\param g is the digraph, to which
kpeter@301
   877
    ///we would like to define the ReachedMap.
kpeter@244
   878
    static ReachedMap *createReachedMap(const Digraph &g)
alpar@100
   879
    {
kpeter@244
   880
      return new ReachedMap(g);
alpar@100
   881
    }
alpar@209
   882
kpeter@244
   883
    ///The type of the map that stores the distances of the nodes.
kpeter@244
   884
kpeter@244
   885
    ///The type of the map that stores the distances of the nodes.
alpar@100
   886
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@278
   887
    typedef typename Digraph::template NodeMap<int> DistMap;
kpeter@301
   888
    ///Instantiates a DistMap.
alpar@209
   889
kpeter@301
   890
    ///This function instantiates a DistMap.
alpar@210
   891
    ///\param g is the digraph, to which we would like to define
kpeter@301
   892
    ///the DistMap
kpeter@244
   893
    static DistMap *createDistMap(const Digraph &g)
alpar@100
   894
    {
kpeter@278
   895
      return new DistMap(g);
alpar@100
   896
    }
kpeter@278
   897
kpeter@278
   898
    ///The type of the shortest paths.
kpeter@278
   899
kpeter@278
   900
    ///The type of the shortest paths.
kpeter@278
   901
    ///It must meet the \ref concepts::Path "Path" concept.
kpeter@278
   902
    typedef lemon::Path<Digraph> Path;
alpar@100
   903
  };
alpar@209
   904
kpeter@301
   905
  /// Default traits class used by BfsWizard
alpar@100
   906
alpar@100
   907
  /// To make it easier to use Bfs algorithm
kpeter@244
   908
  /// we have created a wizard class.
alpar@100
   909
  /// This \ref BfsWizard class needs default traits,
kpeter@244
   910
  /// as well as the \ref Bfs class.
alpar@100
   911
  /// The \ref BfsWizardBase is a class to be the default traits of the
alpar@100
   912
  /// \ref BfsWizard class.
alpar@100
   913
  template<class GR>
alpar@100
   914
  class BfsWizardBase : public BfsWizardDefaultTraits<GR>
alpar@100
   915
  {
alpar@100
   916
alpar@100
   917
    typedef BfsWizardDefaultTraits<GR> Base;
alpar@100
   918
  protected:
kpeter@244
   919
    //The type of the nodes in the digraph.
alpar@100
   920
    typedef typename Base::Digraph::Node Node;
alpar@100
   921
kpeter@244
   922
    //Pointer to the digraph the algorithm runs on.
alpar@100
   923
    void *_g;
kpeter@244
   924
    //Pointer to the map of reached nodes.
alpar@100
   925
    void *_reached;
kpeter@244
   926
    //Pointer to the map of processed nodes.
alpar@100
   927
    void *_processed;
kpeter@244
   928
    //Pointer to the map of predecessors arcs.
alpar@100
   929
    void *_pred;
kpeter@244
   930
    //Pointer to the map of distances.
alpar@100
   931
    void *_dist;
kpeter@278
   932
    //Pointer to the shortest path to the target node.
kpeter@278
   933
    void *_path;
kpeter@278
   934
    //Pointer to the distance of the target node.
kpeter@278
   935
    int *_di;
alpar@209
   936
alpar@100
   937
    public:
alpar@100
   938
    /// Constructor.
alpar@209
   939
alpar@100
   940
    /// This constructor does not require parameters, therefore it initiates
kpeter@278
   941
    /// all of the attributes to \c 0.
alpar@100
   942
    BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0),
kpeter@278
   943
                      _dist(0), _path(0), _di(0) {}
alpar@100
   944
alpar@100
   945
    /// Constructor.
alpar@209
   946
kpeter@278
   947
    /// This constructor requires one parameter,
kpeter@278
   948
    /// others are initiated to \c 0.
kpeter@244
   949
    /// \param g The digraph the algorithm runs on.
kpeter@278
   950
    BfsWizardBase(const GR &g) :
alpar@209
   951
      _g(reinterpret_cast<void*>(const_cast<GR*>(&g))),
kpeter@278
   952
      _reached(0), _processed(0), _pred(0), _dist(0),  _path(0), _di(0) {}
alpar@100
   953
alpar@100
   954
  };
alpar@209
   955
kpeter@278
   956
  /// Auxiliary class for the function-type interface of BFS algorithm.
alpar@100
   957
kpeter@278
   958
  /// This auxiliary class is created to implement the
kpeter@278
   959
  /// \ref bfs() "function-type interface" of \ref Bfs algorithm.
kpeter@278
   960
  /// It does not have own \ref run() method, it uses the functions
kpeter@278
   961
  /// and features of the plain \ref Bfs.
alpar@100
   962
  ///
kpeter@278
   963
  /// This class should only be used through the \ref bfs() function,
kpeter@278
   964
  /// which makes it easier to use the algorithm.
alpar@100
   965
  template<class TR>
alpar@100
   966
  class BfsWizard : public TR
alpar@100
   967
  {
alpar@100
   968
    typedef TR Base;
alpar@100
   969
kpeter@244
   970
    ///The type of the digraph the algorithm runs on.
alpar@100
   971
    typedef typename TR::Digraph Digraph;
kpeter@244
   972
alpar@100
   973
    typedef typename Digraph::Node Node;
alpar@100
   974
    typedef typename Digraph::NodeIt NodeIt;
alpar@100
   975
    typedef typename Digraph::Arc Arc;
alpar@100
   976
    typedef typename Digraph::OutArcIt OutArcIt;
alpar@209
   977
kpeter@244
   978
    ///\brief The type of the map that stores the predecessor
alpar@100
   979
    ///arcs of the shortest paths.
alpar@100
   980
    typedef typename TR::PredMap PredMap;
kpeter@244
   981
    ///\brief The type of the map that stores the distances of the nodes.
alpar@100
   982
    typedef typename TR::DistMap DistMap;
kpeter@244
   983
    ///\brief The type of the map that indicates which nodes are reached.
kpeter@244
   984
    typedef typename TR::ReachedMap ReachedMap;
kpeter@244
   985
    ///\brief The type of the map that indicates which nodes are processed.
kpeter@244
   986
    typedef typename TR::ProcessedMap ProcessedMap;
kpeter@278
   987
    ///The type of the shortest paths
kpeter@278
   988
    typedef typename TR::Path Path;
alpar@100
   989
alpar@100
   990
  public:
kpeter@244
   991
alpar@100
   992
    /// Constructor.
alpar@100
   993
    BfsWizard() : TR() {}
alpar@100
   994
alpar@100
   995
    /// Constructor that requires parameters.
alpar@100
   996
alpar@100
   997
    /// Constructor that requires parameters.
alpar@100
   998
    /// These parameters will be the default values for the traits class.
kpeter@278
   999
    /// \param g The digraph the algorithm runs on.
kpeter@278
  1000
    BfsWizard(const Digraph &g) :
kpeter@278
  1001
      TR(g) {}
alpar@100
  1002
alpar@100
  1003
    ///Copy constructor
alpar@100
  1004
    BfsWizard(const TR &b) : TR(b) {}
alpar@100
  1005
alpar@100
  1006
    ~BfsWizard() {}
alpar@100
  1007
kpeter@278
  1008
    ///Runs BFS algorithm from the given source node.
alpar@209
  1009
kpeter@278
  1010
    ///This method runs BFS algorithm from node \c s
kpeter@278
  1011
    ///in order to compute the shortest path to each node.
kpeter@278
  1012
    void run(Node s)
kpeter@278
  1013
    {
kpeter@278
  1014
      Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
kpeter@278
  1015
      if (Base::_pred)
kpeter@278
  1016
        alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@278
  1017
      if (Base::_dist)
kpeter@278
  1018
        alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@278
  1019
      if (Base::_reached)
kpeter@278
  1020
        alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
kpeter@278
  1021
      if (Base::_processed)
kpeter@278
  1022
        alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
kpeter@278
  1023
      if (s!=INVALID)
kpeter@278
  1024
        alg.run(s);
kpeter@278
  1025
      else
kpeter@278
  1026
        alg.run();
kpeter@278
  1027
    }
kpeter@278
  1028
kpeter@278
  1029
    ///Finds the shortest path between \c s and \c t.
kpeter@278
  1030
kpeter@278
  1031
    ///This method runs BFS algorithm from node \c s
kpeter@278
  1032
    ///in order to compute the shortest path to node \c t
kpeter@278
  1033
    ///(it stops searching when \c t is processed).
kpeter@278
  1034
    ///
kpeter@278
  1035
    ///\return \c true if \c t is reachable form \c s.
kpeter@278
  1036
    bool run(Node s, Node t)
kpeter@278
  1037
    {
kpeter@278
  1038
      Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
kpeter@278
  1039
      if (Base::_pred)
kpeter@278
  1040
        alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@278
  1041
      if (Base::_dist)
kpeter@278
  1042
        alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@278
  1043
      if (Base::_reached)
kpeter@278
  1044
        alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
kpeter@278
  1045
      if (Base::_processed)
kpeter@278
  1046
        alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
kpeter@278
  1047
      alg.run(s,t);
kpeter@278
  1048
      if (Base::_path)
kpeter@278
  1049
        *reinterpret_cast<Path*>(Base::_path) = alg.path(t);
kpeter@278
  1050
      if (Base::_di)
kpeter@278
  1051
        *Base::_di = alg.dist(t);
kpeter@278
  1052
      return alg.reached(t);
kpeter@278
  1053
    }
kpeter@278
  1054
kpeter@278
  1055
    ///Runs BFS algorithm to visit all nodes in the digraph.
kpeter@278
  1056
kpeter@278
  1057
    ///This method runs BFS algorithm in order to compute
kpeter@278
  1058
    ///the shortest path to each node.
alpar@100
  1059
    void run()
alpar@100
  1060
    {
kpeter@278
  1061
      run(INVALID);
alpar@100
  1062
    }
alpar@209
  1063
kpeter@244
  1064
    template<class T>
kpeter@257
  1065
    struct SetPredMapBase : public Base {
kpeter@244
  1066
      typedef T PredMap;
kpeter@244
  1067
      static PredMap *createPredMap(const Digraph &) { return 0; };
kpeter@257
  1068
      SetPredMapBase(const TR &b) : TR(b) {}
kpeter@244
  1069
    };
kpeter@278
  1070
    ///\brief \ref named-func-param "Named parameter"
kpeter@301
  1071
    ///for setting PredMap object.
kpeter@244
  1072
    ///
kpeter@278
  1073
    ///\ref named-func-param "Named parameter"
kpeter@301
  1074
    ///for setting PredMap object.
kpeter@244
  1075
    template<class T>
kpeter@257
  1076
    BfsWizard<SetPredMapBase<T> > predMap(const T &t)
kpeter@244
  1077
    {
kpeter@244
  1078
      Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@257
  1079
      return BfsWizard<SetPredMapBase<T> >(*this);
kpeter@244
  1080
    }
kpeter@244
  1081
kpeter@244
  1082
    template<class T>
kpeter@257
  1083
    struct SetReachedMapBase : public Base {
kpeter@244
  1084
      typedef T ReachedMap;
kpeter@244
  1085
      static ReachedMap *createReachedMap(const Digraph &) { return 0; };
kpeter@257
  1086
      SetReachedMapBase(const TR &b) : TR(b) {}
kpeter@244
  1087
    };
kpeter@278
  1088
    ///\brief \ref named-func-param "Named parameter"
kpeter@301
  1089
    ///for setting ReachedMap object.
kpeter@244
  1090
    ///
kpeter@278
  1091
    /// \ref named-func-param "Named parameter"
kpeter@301
  1092
    ///for setting ReachedMap object.
kpeter@244
  1093
    template<class T>
kpeter@257
  1094
    BfsWizard<SetReachedMapBase<T> > reachedMap(const T &t)
kpeter@244
  1095
    {
kpeter@244
  1096
      Base::_reached=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@257
  1097
      return BfsWizard<SetReachedMapBase<T> >(*this);
kpeter@244
  1098
    }
kpeter@244
  1099
kpeter@244
  1100
    template<class T>
kpeter@278
  1101
    struct SetDistMapBase : public Base {
kpeter@278
  1102
      typedef T DistMap;
kpeter@278
  1103
      static DistMap *createDistMap(const Digraph &) { return 0; };
kpeter@278
  1104
      SetDistMapBase(const TR &b) : TR(b) {}
kpeter@278
  1105
    };
kpeter@278
  1106
    ///\brief \ref named-func-param "Named parameter"
kpeter@301
  1107
    ///for setting DistMap object.
kpeter@278
  1108
    ///
kpeter@278
  1109
    /// \ref named-func-param "Named parameter"
kpeter@301
  1110
    ///for setting DistMap object.
kpeter@278
  1111
    template<class T>
kpeter@278
  1112
    BfsWizard<SetDistMapBase<T> > distMap(const T &t)
kpeter@278
  1113
    {
kpeter@278
  1114
      Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@278
  1115
      return BfsWizard<SetDistMapBase<T> >(*this);
kpeter@278
  1116
    }
kpeter@278
  1117
kpeter@278
  1118
    template<class T>
kpeter@257
  1119
    struct SetProcessedMapBase : public Base {
kpeter@244
  1120
      typedef T ProcessedMap;
kpeter@244
  1121
      static ProcessedMap *createProcessedMap(const Digraph &) { return 0; };
kpeter@257
  1122
      SetProcessedMapBase(const TR &b) : TR(b) {}
kpeter@244
  1123
    };
kpeter@278
  1124
    ///\brief \ref named-func-param "Named parameter"
kpeter@301
  1125
    ///for setting ProcessedMap object.
kpeter@244
  1126
    ///
kpeter@278
  1127
    /// \ref named-func-param "Named parameter"
kpeter@301
  1128
    ///for setting ProcessedMap object.
kpeter@244
  1129
    template<class T>
kpeter@257
  1130
    BfsWizard<SetProcessedMapBase<T> > processedMap(const T &t)
kpeter@244
  1131
    {
kpeter@244
  1132
      Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@257
  1133
      return BfsWizard<SetProcessedMapBase<T> >(*this);
kpeter@244
  1134
    }
kpeter@244
  1135
kpeter@244
  1136
    template<class T>
kpeter@278
  1137
    struct SetPathBase : public Base {
kpeter@278
  1138
      typedef T Path;
kpeter@278
  1139
      SetPathBase(const TR &b) : TR(b) {}
kpeter@244
  1140
    };
kpeter@278
  1141
    ///\brief \ref named-func-param "Named parameter"
kpeter@278
  1142
    ///for getting the shortest path to the target node.
kpeter@244
  1143
    ///
kpeter@278
  1144
    ///\ref named-func-param "Named parameter"
kpeter@278
  1145
    ///for getting the shortest path to the target node.
kpeter@244
  1146
    template<class T>
kpeter@278
  1147
    BfsWizard<SetPathBase<T> > path(const T &t)
kpeter@244
  1148
    {
kpeter@278
  1149
      Base::_path=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@278
  1150
      return BfsWizard<SetPathBase<T> >(*this);
kpeter@278
  1151
    }
kpeter@278
  1152
kpeter@278
  1153
    ///\brief \ref named-func-param "Named parameter"
kpeter@278
  1154
    ///for getting the distance of the target node.
kpeter@278
  1155
    ///
kpeter@278
  1156
    ///\ref named-func-param "Named parameter"
kpeter@278
  1157
    ///for getting the distance of the target node.
kpeter@278
  1158
    BfsWizard dist(const int &d)
kpeter@278
  1159
    {
kpeter@278
  1160
      Base::_di=const_cast<int*>(&d);
kpeter@278
  1161
      return *this;
kpeter@244
  1162
    }
kpeter@244
  1163
alpar@100
  1164
  };
alpar@209
  1165
kpeter@278
  1166
  ///Function-type interface for BFS algorithm.
alpar@100
  1167
alpar@100
  1168
  /// \ingroup search
kpeter@278
  1169
  ///Function-type interface for BFS algorithm.
alpar@100
  1170
  ///
kpeter@278
  1171
  ///This function also has several \ref named-func-param "named parameters",
alpar@100
  1172
  ///they are declared as the members of class \ref BfsWizard.
kpeter@278
  1173
  ///The following examples show how to use these parameters.
alpar@100
  1174
  ///\code
kpeter@278
  1175
  ///  // Compute shortest path from node s to each node
kpeter@278
  1176
  ///  bfs(g).predMap(preds).distMap(dists).run(s);
kpeter@278
  1177
  ///
kpeter@278
  1178
  ///  // Compute shortest path from s to t
kpeter@278
  1179
  ///  bool reached = bfs(g).path(p).dist(d).run(s,t);
alpar@100
  1180
  ///\endcode
alpar@100
  1181
  ///\warning Don't forget to put the \ref BfsWizard::run() "run()"
alpar@100
  1182
  ///to the end of the parameter list.
alpar@100
  1183
  ///\sa BfsWizard
alpar@100
  1184
  ///\sa Bfs
alpar@100
  1185
  template<class GR>
alpar@100
  1186
  BfsWizard<BfsWizardBase<GR> >
kpeter@278
  1187
  bfs(const GR &digraph)
alpar@100
  1188
  {
kpeter@278
  1189
    return BfsWizard<BfsWizardBase<GR> >(digraph);
alpar@100
  1190
  }
alpar@100
  1191
alpar@100
  1192
#ifdef DOXYGEN
kpeter@244
  1193
  /// \brief Visitor class for BFS.
alpar@209
  1194
  ///
alpar@100
  1195
  /// This class defines the interface of the BfsVisit events, and
kpeter@244
  1196
  /// it could be the base of a real visitor class.
alpar@100
  1197
  template <typename _Digraph>
alpar@100
  1198
  struct BfsVisitor {
alpar@100
  1199
    typedef _Digraph Digraph;
alpar@100
  1200
    typedef typename Digraph::Arc Arc;
alpar@100
  1201
    typedef typename Digraph::Node Node;
kpeter@244
  1202
    /// \brief Called for the source node(s) of the BFS.
alpar@209
  1203
    ///
kpeter@244
  1204
    /// This function is called for the source node(s) of the BFS.
kpeter@244
  1205
    void start(const Node& node) {}
kpeter@244
  1206
    /// \brief Called when a node is reached first time.
kpeter@244
  1207
    ///
kpeter@244
  1208
    /// This function is called when a node is reached first time.
kpeter@244
  1209
    void reach(const Node& node) {}
kpeter@244
  1210
    /// \brief Called when a node is processed.
kpeter@244
  1211
    ///
kpeter@244
  1212
    /// This function is called when a node is processed.
kpeter@244
  1213
    void process(const Node& node) {}
kpeter@244
  1214
    /// \brief Called when an arc reaches a new node.
kpeter@244
  1215
    ///
kpeter@244
  1216
    /// This function is called when the BFS finds an arc whose target node
kpeter@244
  1217
    /// is not reached yet.
alpar@100
  1218
    void discover(const Arc& arc) {}
kpeter@244
  1219
    /// \brief Called when an arc is examined but its target node is
alpar@100
  1220
    /// already discovered.
alpar@209
  1221
    ///
kpeter@244
  1222
    /// This function is called when an arc is examined but its target node is
alpar@100
  1223
    /// already discovered.
alpar@100
  1224
    void examine(const Arc& arc) {}
alpar@100
  1225
  };
alpar@100
  1226
#else
alpar@100
  1227
  template <typename _Digraph>
alpar@100
  1228
  struct BfsVisitor {
alpar@100
  1229
    typedef _Digraph Digraph;
alpar@100
  1230
    typedef typename Digraph::Arc Arc;
alpar@100
  1231
    typedef typename Digraph::Node Node;
kpeter@244
  1232
    void start(const Node&) {}
kpeter@244
  1233
    void reach(const Node&) {}
kpeter@244
  1234
    void process(const Node&) {}
alpar@100
  1235
    void discover(const Arc&) {}
alpar@100
  1236
    void examine(const Arc&) {}
alpar@100
  1237
alpar@100
  1238
    template <typename _Visitor>
alpar@100
  1239
    struct Constraints {
alpar@100
  1240
      void constraints() {
alpar@209
  1241
        Arc arc;
alpar@209
  1242
        Node node;
kpeter@244
  1243
        visitor.start(node);
kpeter@244
  1244
        visitor.reach(node);
kpeter@244
  1245
        visitor.process(node);
alpar@209
  1246
        visitor.discover(arc);
alpar@209
  1247
        visitor.examine(arc);
alpar@100
  1248
      }
alpar@100
  1249
      _Visitor& visitor;
alpar@100
  1250
    };
alpar@100
  1251
  };
alpar@100
  1252
#endif
alpar@100
  1253
alpar@100
  1254
  /// \brief Default traits class of BfsVisit class.
alpar@100
  1255
  ///
alpar@100
  1256
  /// Default traits class of BfsVisit class.
kpeter@244
  1257
  /// \tparam _Digraph The type of the digraph the algorithm runs on.
alpar@100
  1258
  template<class _Digraph>
alpar@100
  1259
  struct BfsVisitDefaultTraits {
alpar@100
  1260
kpeter@244
  1261
    /// \brief The type of the digraph the algorithm runs on.
alpar@100
  1262
    typedef _Digraph Digraph;
alpar@100
  1263
alpar@100
  1264
    /// \brief The type of the map that indicates which nodes are reached.
alpar@209
  1265
    ///
alpar@100
  1266
    /// The type of the map that indicates which nodes are reached.
kpeter@244
  1267
    /// It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
alpar@100
  1268
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
alpar@100
  1269
kpeter@301
  1270
    /// \brief Instantiates a ReachedMap.
alpar@100
  1271
    ///
kpeter@301
  1272
    /// This function instantiates a ReachedMap.
alpar@100
  1273
    /// \param digraph is the digraph, to which
kpeter@301
  1274
    /// we would like to define the ReachedMap.
alpar@100
  1275
    static ReachedMap *createReachedMap(const Digraph &digraph) {
alpar@100
  1276
      return new ReachedMap(digraph);
alpar@100
  1277
    }
alpar@100
  1278
alpar@100
  1279
  };
alpar@100
  1280
alpar@100
  1281
  /// \ingroup search
alpar@209
  1282
  ///
kpeter@244
  1283
  /// \brief %BFS algorithm class with visitor interface.
alpar@209
  1284
  ///
alpar@100
  1285
  /// This class provides an efficient implementation of the %BFS algorithm
alpar@100
  1286
  /// with visitor interface.
alpar@100
  1287
  ///
alpar@100
  1288
  /// The %BfsVisit class provides an alternative interface to the Bfs
alpar@100
  1289
  /// class. It works with callback mechanism, the BfsVisit object calls
kpeter@244
  1290
  /// the member functions of the \c Visitor class on every BFS event.
alpar@100
  1291
  ///
kpeter@252
  1292
  /// This interface of the BFS algorithm should be used in special cases
kpeter@252
  1293
  /// when extra actions have to be performed in connection with certain
kpeter@252
  1294
  /// events of the BFS algorithm. Otherwise consider to use Bfs or bfs()
kpeter@252
  1295
  /// instead.
kpeter@252
  1296
  ///
kpeter@244
  1297
  /// \tparam _Digraph The type of the digraph the algorithm runs on.
alpar@210
  1298
  /// The default value is
kpeter@244
  1299
  /// \ref ListDigraph. The value of _Digraph is not used directly by
kpeter@244
  1300
  /// \ref BfsVisit, it is only passed to \ref BfsVisitDefaultTraits.
kpeter@244
  1301
  /// \tparam _Visitor The Visitor type that is used by the algorithm.
kpeter@244
  1302
  /// \ref BfsVisitor "BfsVisitor<_Digraph>" is an empty visitor, which
kpeter@244
  1303
  /// does not observe the BFS events. If you want to observe the BFS
kpeter@244
  1304
  /// events, you should implement your own visitor class.
alpar@209
  1305
  /// \tparam _Traits Traits class to set various data types used by the
alpar@100
  1306
  /// algorithm. The default traits class is
alpar@100
  1307
  /// \ref BfsVisitDefaultTraits "BfsVisitDefaultTraits<_Digraph>".
alpar@100
  1308
  /// See \ref BfsVisitDefaultTraits for the documentation of
kpeter@244
  1309
  /// a BFS visit traits class.
alpar@100
  1310
#ifdef DOXYGEN
alpar@100
  1311
  template <typename _Digraph, typename _Visitor, typename _Traits>
alpar@100
  1312
#else
alpar@100
  1313
  template <typename _Digraph = ListDigraph,
alpar@209
  1314
            typename _Visitor = BfsVisitor<_Digraph>,
deba@288
  1315
            typename _Traits = BfsVisitDefaultTraits<_Digraph> >
alpar@100
  1316
#endif
alpar@100
  1317
  class BfsVisit {
alpar@100
  1318
  public:
alpar@209
  1319
kpeter@244
  1320
    ///The traits class.
alpar@100
  1321
    typedef _Traits Traits;
alpar@100
  1322
kpeter@244
  1323
    ///The type of the digraph the algorithm runs on.
alpar@100
  1324
    typedef typename Traits::Digraph Digraph;
alpar@100
  1325
kpeter@244
  1326
    ///The visitor type used by the algorithm.
alpar@100
  1327
    typedef _Visitor Visitor;
alpar@100
  1328
kpeter@244
  1329
    ///The type of the map that indicates which nodes are reached.
alpar@100
  1330
    typedef typename Traits::ReachedMap ReachedMap;
alpar@100
  1331
alpar@100
  1332
  private:
alpar@100
  1333
alpar@100
  1334
    typedef typename Digraph::Node Node;
alpar@100
  1335
    typedef typename Digraph::NodeIt NodeIt;
alpar@100
  1336
    typedef typename Digraph::Arc Arc;
alpar@100
  1337
    typedef typename Digraph::OutArcIt OutArcIt;
alpar@100
  1338
kpeter@244
  1339
    //Pointer to the underlying digraph.
alpar@100
  1340
    const Digraph *_digraph;
kpeter@244
  1341
    //Pointer to the visitor object.
alpar@100
  1342
    Visitor *_visitor;
kpeter@244
  1343
    //Pointer to the map of reached status of the nodes.
alpar@100
  1344
    ReachedMap *_reached;
kpeter@244
  1345
    //Indicates if _reached is locally allocated (true) or not.
alpar@100
  1346
    bool local_reached;
alpar@100
  1347
alpar@100
  1348
    std::vector<typename Digraph::Node> _list;
alpar@100
  1349
    int _list_front, _list_back;
alpar@100
  1350
alpar@280
  1351
    //Creates the maps if necessary.
alpar@100
  1352
    void create_maps() {
alpar@100
  1353
      if(!_reached) {
alpar@209
  1354
        local_reached = true;
alpar@209
  1355
        _reached = Traits::createReachedMap(*_digraph);
alpar@100
  1356
      }
alpar@100
  1357
    }
alpar@100
  1358
alpar@100
  1359
  protected:
alpar@100
  1360
alpar@100
  1361
    BfsVisit() {}
alpar@209
  1362
alpar@100
  1363
  public:
alpar@100
  1364
alpar@100
  1365
    typedef BfsVisit Create;
alpar@100
  1366
alpar@100
  1367
    /// \name Named template parameters
alpar@100
  1368
alpar@100
  1369
    ///@{
alpar@100
  1370
    template <class T>
kpeter@257
  1371
    struct SetReachedMapTraits : public Traits {
alpar@100
  1372
      typedef T ReachedMap;
alpar@100
  1373
      static ReachedMap *createReachedMap(const Digraph &digraph) {
deba@290
  1374
        LEMON_ASSERT(false, "ReachedMap is not initialized");
deba@290
  1375
        return 0; // ignore warnings
alpar@100
  1376
      }
alpar@100
  1377
    };
alpar@209
  1378
    /// \brief \ref named-templ-param "Named parameter" for setting
kpeter@244
  1379
    /// ReachedMap type.
alpar@100
  1380
    ///
kpeter@244
  1381
    /// \ref named-templ-param "Named parameter" for setting ReachedMap type.
alpar@100
  1382
    template <class T>
kpeter@257
  1383
    struct SetReachedMap : public BfsVisit< Digraph, Visitor,
kpeter@257
  1384
                                            SetReachedMapTraits<T> > {
kpeter@257
  1385
      typedef BfsVisit< Digraph, Visitor, SetReachedMapTraits<T> > Create;
alpar@100
  1386
    };
alpar@100
  1387
    ///@}
alpar@100
  1388
alpar@209
  1389
  public:
alpar@209
  1390
alpar@100
  1391
    /// \brief Constructor.
alpar@100
  1392
    ///
alpar@100
  1393
    /// Constructor.
alpar@100
  1394
    ///
kpeter@244
  1395
    /// \param digraph The digraph the algorithm runs on.
kpeter@244
  1396
    /// \param visitor The visitor object of the algorithm.
alpar@209
  1397
    BfsVisit(const Digraph& digraph, Visitor& visitor)
alpar@100
  1398
      : _digraph(&digraph), _visitor(&visitor),
alpar@209
  1399
        _reached(0), local_reached(false) {}
alpar@209
  1400
alpar@100
  1401
    /// \brief Destructor.
alpar@100
  1402
    ~BfsVisit() {
alpar@100
  1403
      if(local_reached) delete _reached;
alpar@100
  1404
    }
alpar@100
  1405
kpeter@244
  1406
    /// \brief Sets the map that indicates which nodes are reached.
alpar@100
  1407
    ///
kpeter@244
  1408
    /// Sets the map that indicates which nodes are reached.
alpar@100
  1409
    /// If you don't use this function before calling \ref run(),
kpeter@244
  1410
    /// it will allocate one. The destructor deallocates this
alpar@100
  1411
    /// automatically allocated map, of course.
alpar@100
  1412
    /// \return <tt> (*this) </tt>
alpar@100
  1413
    BfsVisit &reachedMap(ReachedMap &m) {
alpar@100
  1414
      if(local_reached) {
alpar@209
  1415
        delete _reached;
alpar@209
  1416
        local_reached = false;
alpar@100
  1417
      }
alpar@100
  1418
      _reached = &m;
alpar@100
  1419
      return *this;
alpar@100
  1420
    }
alpar@100
  1421
alpar@100
  1422
  public:
kpeter@244
  1423
alpar@100
  1424
    /// \name Execution control
alpar@100
  1425
    /// The simplest way to execute the algorithm is to use
kpeter@244
  1426
    /// one of the member functions called \ref lemon::BfsVisit::run()
kpeter@244
  1427
    /// "run()".
alpar@100
  1428
    /// \n
kpeter@244
  1429
    /// If you need more control on the execution, first you must call
kpeter@244
  1430
    /// \ref lemon::BfsVisit::init() "init()", then you can add several
kpeter@244
  1431
    /// source nodes with \ref lemon::BfsVisit::addSource() "addSource()".
kpeter@244
  1432
    /// Finally \ref lemon::BfsVisit::start() "start()" will perform the
kpeter@244
  1433
    /// actual path computation.
alpar@100
  1434
alpar@100
  1435
    /// @{
kpeter@244
  1436
alpar@100
  1437
    /// \brief Initializes the internal data structures.
alpar@100
  1438
    ///
alpar@100
  1439
    /// Initializes the internal data structures.
alpar@100
  1440
    void init() {
alpar@100
  1441
      create_maps();
alpar@100
  1442
      _list.resize(countNodes(*_digraph));
alpar@100
  1443
      _list_front = _list_back = -1;
alpar@100
  1444
      for (NodeIt u(*_digraph) ; u != INVALID ; ++u) {
alpar@209
  1445
        _reached->set(u, false);
alpar@100
  1446
      }
alpar@100
  1447
    }
alpar@209
  1448
alpar@100
  1449
    /// \brief Adds a new source node.
alpar@100
  1450
    ///
alpar@100
  1451
    /// Adds a new source node to the set of nodes to be processed.
alpar@100
  1452
    void addSource(Node s) {
alpar@100
  1453
      if(!(*_reached)[s]) {
alpar@209
  1454
          _reached->set(s,true);
alpar@209
  1455
          _visitor->start(s);
alpar@209
  1456
          _visitor->reach(s);
alpar@100
  1457
          _list[++_list_back] = s;
alpar@209
  1458
        }
alpar@100
  1459
    }
alpar@209
  1460
alpar@100
  1461
    /// \brief Processes the next node.
alpar@100
  1462
    ///
alpar@100
  1463
    /// Processes the next node.
alpar@100
  1464
    ///
alpar@100
  1465
    /// \return The processed node.
alpar@100
  1466
    ///
kpeter@244
  1467
    /// \pre The queue must not be empty.
alpar@209
  1468
    Node processNextNode() {
alpar@100
  1469
      Node n = _list[++_list_front];
alpar@100
  1470
      _visitor->process(n);
alpar@100
  1471
      Arc e;
alpar@100
  1472
      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
alpar@100
  1473
        Node m = _digraph->target(e);
alpar@100
  1474
        if (!(*_reached)[m]) {
alpar@100
  1475
          _visitor->discover(e);
alpar@100
  1476
          _visitor->reach(m);
alpar@100
  1477
          _reached->set(m, true);
alpar@100
  1478
          _list[++_list_back] = m;
alpar@100
  1479
        } else {
alpar@100
  1480
          _visitor->examine(e);
alpar@100
  1481
        }
alpar@100
  1482
      }
alpar@100
  1483
      return n;
alpar@100
  1484
    }
alpar@100
  1485
alpar@100
  1486
    /// \brief Processes the next node.
alpar@100
  1487
    ///
kpeter@244
  1488
    /// Processes the next node and checks if the given target node
alpar@100
  1489
    /// is reached. If the target node is reachable from the processed
kpeter@244
  1490
    /// node, then the \c reach parameter will be set to \c true.
alpar@100
  1491
    ///
alpar@100
  1492
    /// \param target The target node.
kpeter@244
  1493
    /// \retval reach Indicates if the target node is reached.
kpeter@244
  1494
    /// It should be initially \c false.
kpeter@244
  1495
    ///
alpar@100
  1496
    /// \return The processed node.
alpar@100
  1497
    ///
kpeter@244
  1498
    /// \pre The queue must not be empty.
alpar@100
  1499
    Node processNextNode(Node target, bool& reach) {
alpar@100
  1500
      Node n = _list[++_list_front];
alpar@100
  1501
      _visitor->process(n);
alpar@100
  1502
      Arc e;
alpar@100
  1503
      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
alpar@100
  1504
        Node m = _digraph->target(e);
alpar@100
  1505
        if (!(*_reached)[m]) {
alpar@100
  1506
          _visitor->discover(e);
alpar@100
  1507
          _visitor->reach(m);
alpar@100
  1508
          _reached->set(m, true);
alpar@100
  1509
          _list[++_list_back] = m;
alpar@100
  1510
          reach = reach || (target == m);
alpar@100
  1511
        } else {
alpar@100
  1512
          _visitor->examine(e);
alpar@100
  1513
        }
alpar@100
  1514
      }
alpar@100
  1515
      return n;
alpar@100
  1516
    }
alpar@100
  1517
alpar@100
  1518
    /// \brief Processes the next node.
alpar@100
  1519
    ///
kpeter@244
  1520
    /// Processes the next node and checks if at least one of reached
kpeter@244
  1521
    /// nodes has \c true value in the \c nm node map. If one node
kpeter@244
  1522
    /// with \c true value is reachable from the processed node, then the
kpeter@244
  1523
    /// \c rnode parameter will be set to the first of such nodes.
alpar@100
  1524
    ///
kpeter@244
  1525
    /// \param nm A \c bool (or convertible) node map that indicates the
kpeter@244
  1526
    /// possible targets.
alpar@100
  1527
    /// \retval rnode The reached target node.
kpeter@244
  1528
    /// It should be initially \c INVALID.
kpeter@244
  1529
    ///
alpar@100
  1530
    /// \return The processed node.
alpar@100
  1531
    ///
kpeter@244
  1532
    /// \pre The queue must not be empty.
alpar@100
  1533
    template <typename NM>
alpar@100
  1534
    Node processNextNode(const NM& nm, Node& rnode) {
alpar@100
  1535
      Node n = _list[++_list_front];
alpar@100
  1536
      _visitor->process(n);
alpar@100
  1537
      Arc e;
alpar@100
  1538
      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
alpar@100
  1539
        Node m = _digraph->target(e);
alpar@100
  1540
        if (!(*_reached)[m]) {
alpar@100
  1541
          _visitor->discover(e);
alpar@100
  1542
          _visitor->reach(m);
alpar@100
  1543
          _reached->set(m, true);
alpar@100
  1544
          _list[++_list_back] = m;
alpar@100
  1545
          if (nm[m] && rnode == INVALID) rnode = m;
alpar@100
  1546
        } else {
alpar@100
  1547
          _visitor->examine(e);
alpar@100
  1548
        }
alpar@100
  1549
      }
alpar@100
  1550
      return n;
alpar@100
  1551
    }
alpar@100
  1552
kpeter@244
  1553
    /// \brief The next node to be processed.
alpar@100
  1554
    ///
kpeter@244
  1555
    /// Returns the next node to be processed or \c INVALID if the queue
kpeter@244
  1556
    /// is empty.
kpeter@244
  1557
    Node nextNode() const {
alpar@100
  1558
      return _list_front != _list_back ? _list[_list_front + 1] : INVALID;
alpar@100
  1559
    }
alpar@100
  1560
alpar@100
  1561
    /// \brief Returns \c false if there are nodes
kpeter@244
  1562
    /// to be processed.
alpar@100
  1563
    ///
alpar@100
  1564
    /// Returns \c false if there are nodes
kpeter@244
  1565
    /// to be processed in the queue.
kpeter@244
  1566
    bool emptyQueue() const { return _list_front == _list_back; }
alpar@100
  1567
alpar@100
  1568
    /// \brief Returns the number of the nodes to be processed.
alpar@100
  1569
    ///
alpar@100
  1570
    /// Returns the number of the nodes to be processed in the queue.
kpeter@244
  1571
    int queueSize() const { return _list_back - _list_front; }
alpar@209
  1572
alpar@100
  1573
    /// \brief Executes the algorithm.
alpar@100
  1574
    ///
alpar@100
  1575
    /// Executes the algorithm.
alpar@100
  1576
    ///
kpeter@244
  1577
    /// This method runs the %BFS algorithm from the root node(s)
kpeter@244
  1578
    /// in order to compute the shortest path to each node.
kpeter@244
  1579
    ///
kpeter@244
  1580
    /// The algorithm computes
kpeter@244
  1581
    /// - the shortest path tree (forest),
kpeter@244
  1582
    /// - the distance of each node from the root(s).
kpeter@244
  1583
    ///
kpeter@244
  1584
    /// \pre init() must be called and at least one root node should be added
alpar@100
  1585
    /// with addSource() before using this function.
kpeter@244
  1586
    ///
kpeter@244
  1587
    /// \note <tt>b.start()</tt> is just a shortcut of the following code.
kpeter@244
  1588
    /// \code
kpeter@244
  1589
    ///   while ( !b.emptyQueue() ) {
kpeter@244
  1590
    ///     b.processNextNode();
kpeter@244
  1591
    ///   }
kpeter@244
  1592
    /// \endcode
alpar@100
  1593
    void start() {
alpar@100
  1594
      while ( !emptyQueue() ) processNextNode();
alpar@100
  1595
    }
alpar@209
  1596
kpeter@244
  1597
    /// \brief Executes the algorithm until the given target node is reached.
alpar@100
  1598
    ///
kpeter@244
  1599
    /// Executes the algorithm until the given target node is reached.
alpar@100
  1600
    ///
kpeter@244
  1601
    /// This method runs the %BFS algorithm from the root node(s)
kpeter@286
  1602
    /// in order to compute the shortest path to \c t.
kpeter@244
  1603
    ///
kpeter@244
  1604
    /// The algorithm computes
kpeter@286
  1605
    /// - the shortest path to \c t,
kpeter@286
  1606
    /// - the distance of \c t from the root(s).
kpeter@244
  1607
    ///
kpeter@244
  1608
    /// \pre init() must be called and at least one root node should be
kpeter@244
  1609
    /// added with addSource() before using this function.
kpeter@244
  1610
    ///
kpeter@244
  1611
    /// \note <tt>b.start(t)</tt> is just a shortcut of the following code.
kpeter@244
  1612
    /// \code
kpeter@244
  1613
    ///   bool reach = false;
kpeter@244
  1614
    ///   while ( !b.emptyQueue() && !reach ) {
kpeter@244
  1615
    ///     b.processNextNode(t, reach);
kpeter@244
  1616
    ///   }
kpeter@244
  1617
    /// \endcode
kpeter@286
  1618
    void start(Node t) {
alpar@100
  1619
      bool reach = false;
kpeter@286
  1620
      while ( !emptyQueue() && !reach ) processNextNode(t, reach);
alpar@100
  1621
    }
alpar@209
  1622
alpar@100
  1623
    /// \brief Executes the algorithm until a condition is met.
alpar@100
  1624
    ///
alpar@100
  1625
    /// Executes the algorithm until a condition is met.
alpar@100
  1626
    ///
kpeter@244
  1627
    /// This method runs the %BFS algorithm from the root node(s) in
kpeter@244
  1628
    /// order to compute the shortest path to a node \c v with
kpeter@244
  1629
    /// <tt>nm[v]</tt> true, if such a node can be found.
alpar@100
  1630
    ///
kpeter@244
  1631
    /// \param nm must be a bool (or convertible) node map. The
kpeter@244
  1632
    /// algorithm will stop when it reaches a node \c v with
alpar@100
  1633
    /// <tt>nm[v]</tt> true.
alpar@100
  1634
    ///
kpeter@244
  1635
    /// \return The reached node \c v with <tt>nm[v]</tt> true or
kpeter@244
  1636
    /// \c INVALID if no such node was found.
kpeter@244
  1637
    ///
kpeter@244
  1638
    /// \pre init() must be called and at least one root node should be
kpeter@244
  1639
    /// added with addSource() before using this function.
kpeter@244
  1640
    ///
kpeter@244
  1641
    /// \note <tt>b.start(nm)</tt> is just a shortcut of the following code.
kpeter@244
  1642
    /// \code
kpeter@244
  1643
    ///   Node rnode = INVALID;
kpeter@244
  1644
    ///   while ( !b.emptyQueue() && rnode == INVALID ) {
kpeter@244
  1645
    ///     b.processNextNode(nm, rnode);
kpeter@244
  1646
    ///   }
kpeter@244
  1647
    ///   return rnode;
kpeter@244
  1648
    /// \endcode
alpar@100
  1649
    template <typename NM>
alpar@100
  1650
    Node start(const NM &nm) {
alpar@100
  1651
      Node rnode = INVALID;
alpar@100
  1652
      while ( !emptyQueue() && rnode == INVALID ) {
alpar@209
  1653
        processNextNode(nm, rnode);
alpar@100
  1654
      }
alpar@100
  1655
      return rnode;
alpar@100
  1656
    }
alpar@100
  1657
kpeter@286
  1658
    /// \brief Runs the algorithm from the given source node.
alpar@100
  1659
    ///
kpeter@244
  1660
    /// This method runs the %BFS algorithm from node \c s
kpeter@244
  1661
    /// in order to compute the shortest path to each node.
kpeter@244
  1662
    ///
kpeter@244
  1663
    /// The algorithm computes
kpeter@244
  1664
    /// - the shortest path tree,
kpeter@244
  1665
    /// - the distance of each node from the root.
kpeter@244
  1666
    ///
kpeter@244
  1667
    /// \note <tt>b.run(s)</tt> is just a shortcut of the following code.
alpar@100
  1668
    ///\code
alpar@100
  1669
    ///   b.init();
alpar@100
  1670
    ///   b.addSource(s);
alpar@100
  1671
    ///   b.start();
alpar@100
  1672
    ///\endcode
alpar@100
  1673
    void run(Node s) {
alpar@100
  1674
      init();
alpar@100
  1675
      addSource(s);
alpar@100
  1676
      start();
alpar@100
  1677
    }
alpar@100
  1678
kpeter@286
  1679
    /// \brief Finds the shortest path between \c s and \c t.
kpeter@286
  1680
    ///
kpeter@286
  1681
    /// This method runs the %BFS algorithm from node \c s
kpeter@286
  1682
    /// in order to compute the shortest path to node \c t
kpeter@286
  1683
    /// (it stops searching when \c t is processed).
kpeter@286
  1684
    ///
kpeter@286
  1685
    /// \return \c true if \c t is reachable form \c s.
kpeter@286
  1686
    ///
kpeter@286
  1687
    /// \note Apart from the return value, <tt>b.run(s,t)</tt> is just a
kpeter@286
  1688
    /// shortcut of the following code.
kpeter@286
  1689
    ///\code
kpeter@286
  1690
    ///   b.init();
kpeter@286
  1691
    ///   b.addSource(s);
kpeter@286
  1692
    ///   b.start(t);
kpeter@286
  1693
    ///\endcode
kpeter@286
  1694
    bool run(Node s,Node t) {
kpeter@286
  1695
      init();
kpeter@286
  1696
      addSource(s);
kpeter@286
  1697
      start(t);
kpeter@286
  1698
      return reached(t);
kpeter@286
  1699
    }
kpeter@286
  1700
kpeter@244
  1701
    /// \brief Runs the algorithm to visit all nodes in the digraph.
alpar@209
  1702
    ///
alpar@100
  1703
    /// This method runs the %BFS algorithm in order to
kpeter@244
  1704
    /// compute the shortest path to each node.
alpar@100
  1705
    ///
kpeter@244
  1706
    /// The algorithm computes
kpeter@244
  1707
    /// - the shortest path tree (forest),
kpeter@244
  1708
    /// - the distance of each node from the root(s).
kpeter@244
  1709
    ///
kpeter@244
  1710
    /// \note <tt>b.run(s)</tt> is just a shortcut of the following code.
alpar@100
  1711
    ///\code
alpar@100
  1712
    ///  b.init();
kpeter@244
  1713
    ///  for (NodeIt n(gr); n != INVALID; ++n) {
kpeter@244
  1714
    ///    if (!b.reached(n)) {
kpeter@244
  1715
    ///      b.addSource(n);
alpar@100
  1716
    ///      b.start();
alpar@100
  1717
    ///    }
alpar@100
  1718
    ///  }
alpar@100
  1719
    ///\endcode
alpar@100
  1720
    void run() {
alpar@100
  1721
      init();
alpar@100
  1722
      for (NodeIt it(*_digraph); it != INVALID; ++it) {
alpar@100
  1723
        if (!reached(it)) {
alpar@100
  1724
          addSource(it);
alpar@100
  1725
          start();
alpar@100
  1726
        }
alpar@100
  1727
      }
alpar@100
  1728
    }
kpeter@244
  1729
alpar@100
  1730
    ///@}
alpar@100
  1731
alpar@100
  1732
    /// \name Query Functions
alpar@100
  1733
    /// The result of the %BFS algorithm can be obtained using these
alpar@100
  1734
    /// functions.\n
kpeter@244
  1735
    /// Either \ref lemon::BfsVisit::run() "run()" or
kpeter@244
  1736
    /// \ref lemon::BfsVisit::start() "start()" must be called before
kpeter@244
  1737
    /// using them.
alpar@100
  1738
    ///@{
alpar@100
  1739
kpeter@244
  1740
    /// \brief Checks if a node is reachable from the root(s).
alpar@100
  1741
    ///
alpar@100
  1742
    /// Returns \c true if \c v is reachable from the root(s).
alpar@100
  1743
    /// \pre Either \ref run() or \ref start()
alpar@100
  1744
    /// must be called before using this function.
alpar@100
  1745
    bool reached(Node v) { return (*_reached)[v]; }
kpeter@244
  1746
alpar@100
  1747
    ///@}
kpeter@244
  1748
alpar@100
  1749
  };
alpar@100
  1750
alpar@100
  1751
} //END OF NAMESPACE LEMON
alpar@100
  1752
alpar@100
  1753
#endif