lemon/bfs.h
author Balazs Dezso <deba@inf.elte.hu>
Mon, 16 Jun 2008 18:23:11 +0200
changeset 173 b026e9779b28
parent 157 2ccc1afc2c52
child 209 765619b7cbb2
permissions -rw-r--r--
LGF content reader class
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/* -*- C++ -*-
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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/graph_utils.h>
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#include <lemon/bits/path_dump.h>
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#include <lemon/bits/invalid.h>
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#include <lemon/error.h>
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#include <lemon/maps.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 digraph type the algorithm runs on. 
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    typedef GR Digraph;
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    ///\brief The type of the map that stores the last
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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 last
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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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    ///
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    typedef typename Digraph::template NodeMap<typename GR::Arc> PredMap;
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    ///Instantiates a PredMap.
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    ///This function instantiates a \ref PredMap. 
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    ///\param G is the digraph, to which we would like to define the PredMap.
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    ///\todo The digraph alone may be insufficient to initialize
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    static PredMap *createPredMap(const GR &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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    ///\todo named parameter to set this type, function to read and write.
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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 \ref ProcessedMap. 
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    ///\param g is the digraph, to which
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    ///we would like to define the \ref ProcessedMap
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#ifdef DOXYGEN
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    static ProcessedMap *createProcessedMap(const GR &g)
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#else
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    static ProcessedMap *createProcessedMap(const GR &)
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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::WriteMap "WriteMap" concept.
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    ///\todo named parameter to set this type, function to read and write.
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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 \ref ReachedMap. 
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    ///\param G is the digraph, to which
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    ///we would like to define the \ref ReachedMap.
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    static ReachedMap *createReachedMap(const GR &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 dists of the nodes.
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    ///The type of the map that stores the dists of the nodes.
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    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
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    ///
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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 \ref DistMap. 
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    ///\param G is the digraph, to which we would like to define the \ref DistMap
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    static DistMap *createDistMap(const GR &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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  ///\tparam GR The digraph type the algorithm runs on. The default value is
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  ///\ref ListDigraph. The value of GR is not used directly by Bfs, it
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  ///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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    /**
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     * \brief \ref Exception for uninitialized parameters.
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     *
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     * This error represents problems in the initialization
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     * of the parameters of the algorithms.
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     */
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    class UninitializedParameter : public lemon::UninitializedParameter {
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    public:
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      virtual const char* what() const throw() {
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	return "lemon::Bfs::UninitializedParameter";
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      }
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    };
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    typedef TR Traits;
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    ///The type of the underlying digraph.
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    typedef typename TR::Digraph Digraph;
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    ///\brief The type of the map that stores the last
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    ///arcs of the shortest paths.
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    typedef typename TR::PredMap PredMap;
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    ///The type of the map indicating which nodes are reached.
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    typedef typename TR::ReachedMap ReachedMap;
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    ///The type of the map indicating which nodes are processed.
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    typedef typename TR::ProcessedMap ProcessedMap;
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    ///The type of the map that stores the dists of the nodes.
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    typedef typename TR::DistMap DistMap;
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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 predecessors arcs.
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    PredMap *_pred;
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    ///Indicates if \ref _pred is locally allocated (\c 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 \ref _dist is locally allocated (\c 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 \ref _reached is locally allocated (\c 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 \ref _processed is locally allocated (\c 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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    ///\todo Better memory allocation (instead of new).
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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 DefPredMapTraits : 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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	throw UninitializedParameter();
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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 PredMap type
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    ///
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    template <class T>
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    struct DefPredMap : public Bfs< Digraph, DefPredMapTraits<T> > { 
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      typedef Bfs< Digraph, DefPredMapTraits<T> > Create;
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    };
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    template <class T>
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    struct DefDistMapTraits : 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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	throw UninitializedParameter();
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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 DistMap type
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    ///
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    template <class T>
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    struct DefDistMap : public Bfs< Digraph, DefDistMapTraits<T> > { 
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      typedef Bfs< Digraph, DefDistMapTraits<T> > Create;
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    };
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    template <class T>
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    struct DefReachedMapTraits : 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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	throw UninitializedParameter();
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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 ReachedMap type
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    ///
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    template <class T>
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    struct DefReachedMap : public Bfs< Digraph, DefReachedMapTraits<T> > { 
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      typedef Bfs< Digraph, DefReachedMapTraits<T> > Create;
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    };
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    template <class T>
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    struct DefProcessedMapTraits : 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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	throw UninitializedParameter();
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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 ProcessedMap type
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    ///
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    template <class T>
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    struct DefProcessedMap : public Bfs< Digraph, DefProcessedMapTraits<T> > {
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      typedef Bfs< Digraph, DefProcessedMapTraits<T> > Create;
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    };
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    struct DefDigraphProcessedMapTraits : 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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      }
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    };
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    ///\brief \ref named-templ-param "Named parameter"
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    ///for setting the ProcessedMap type to be Digraph::NodeMap<bool>.
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    ///
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    ///\ref named-templ-param "Named parameter"
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    ///for setting the ProcessedMap type to be Digraph::NodeMap<bool>.
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    ///If you don't set it explicitly, it will be automatically allocated.
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    template <class T>
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    struct DefProcessedMapToBeDefaultMap :
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      public Bfs< Digraph, DefDigraphProcessedMapTraits> { 
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      typedef Bfs< Digraph, DefDigraphProcessedMapTraits> Create;
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    };
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    ///@}
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  public:      
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    ///Constructor.
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    ///\param _G the digraph the algorithm will run on.
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    ///
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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 storing the predecessor arcs.
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    ///Sets the map storing 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 indicating the reached nodes.
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    ///Sets the map indicating the reached nodes.
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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 indicating the processed nodes.
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    ///Sets the map indicating the processed nodes.
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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 storing the distances calculated by the algorithm.
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    ///Sets the map storing the distances calculated by 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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   406
      }
alpar@100
   407
      _dist = &m;
alpar@100
   408
      return *this;
alpar@100
   409
    }
alpar@100
   410
alpar@100
   411
  public:
alpar@100
   412
    ///\name Execution control
alpar@100
   413
    ///The simplest way to execute the algorithm is to use
alpar@100
   414
    ///one of the member functions called \c run(...).
alpar@100
   415
    ///\n
alpar@100
   416
    ///If you need more control on the execution,
alpar@100
   417
    ///first you must call \ref init(), then you can add several source nodes
alpar@100
   418
    ///with \ref addSource().
alpar@100
   419
    ///Finally \ref start() will perform the actual path
alpar@100
   420
    ///computation.
alpar@100
   421
alpar@100
   422
    ///@{
alpar@100
   423
alpar@100
   424
    ///\brief Initializes the internal data structures.
alpar@100
   425
    ///
alpar@100
   426
    ///Initializes the internal data structures.
alpar@100
   427
    ///
alpar@100
   428
    void init()
alpar@100
   429
    {
alpar@100
   430
      create_maps();
alpar@100
   431
      _queue.resize(countNodes(*G));
alpar@100
   432
      _queue_head=_queue_tail=0;
alpar@100
   433
      _curr_dist=1;
alpar@100
   434
      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
alpar@100
   435
	_pred->set(u,INVALID);
alpar@100
   436
	_reached->set(u,false);
alpar@100
   437
	_processed->set(u,false);
alpar@100
   438
      }
alpar@100
   439
    }
alpar@100
   440
    
alpar@100
   441
    ///Adds a new source node.
alpar@100
   442
alpar@100
   443
    ///Adds a new source node to the set of nodes to be processed.
alpar@100
   444
    ///
alpar@100
   445
    void addSource(Node s)
alpar@100
   446
    {
alpar@100
   447
      if(!(*_reached)[s])
alpar@100
   448
	{
alpar@100
   449
	  _reached->set(s,true);
alpar@100
   450
	  _pred->set(s,INVALID);
alpar@100
   451
	  _dist->set(s,0);
alpar@100
   452
	  _queue[_queue_head++]=s;
alpar@100
   453
	  _queue_next_dist=_queue_head;
alpar@100
   454
	}
alpar@100
   455
    }
alpar@100
   456
    
alpar@100
   457
    ///Processes the next node.
alpar@100
   458
alpar@100
   459
    ///Processes the next node.
alpar@100
   460
    ///
alpar@100
   461
    ///\return The processed node.
alpar@100
   462
    ///
alpar@100
   463
    ///\warning The queue must not be empty!
alpar@100
   464
    Node processNextNode()
alpar@100
   465
    {
alpar@100
   466
      if(_queue_tail==_queue_next_dist) {
alpar@100
   467
	_curr_dist++;
alpar@100
   468
	_queue_next_dist=_queue_head;
alpar@100
   469
      }
alpar@100
   470
      Node n=_queue[_queue_tail++];
alpar@100
   471
      _processed->set(n,true);
alpar@100
   472
      Node m;
alpar@100
   473
      for(OutArcIt e(*G,n);e!=INVALID;++e)
alpar@100
   474
	if(!(*_reached)[m=G->target(e)]) {
alpar@100
   475
	  _queue[_queue_head++]=m;
alpar@100
   476
	  _reached->set(m,true);
alpar@100
   477
	  _pred->set(m,e);
alpar@100
   478
	  _dist->set(m,_curr_dist);
alpar@100
   479
	}
alpar@100
   480
      return n;
alpar@100
   481
    }
alpar@100
   482
alpar@100
   483
    ///Processes the next node.
alpar@100
   484
alpar@100
   485
    ///Processes the next node. And checks that the given target node
alpar@100
   486
    ///is reached. If the target node is reachable from the processed
alpar@100
   487
    ///node then the reached parameter will be set true. The reached
alpar@100
   488
    ///parameter should be initially false.
alpar@100
   489
    ///
alpar@100
   490
    ///\param target The target node.
alpar@100
   491
    ///\retval reach Indicates that the target node is reached.
alpar@100
   492
    ///\return The processed node.
alpar@100
   493
    ///
alpar@100
   494
    ///\warning 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@100
   498
	_curr_dist++;
alpar@100
   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@100
   505
	if(!(*_reached)[m=G->target(e)]) {
alpar@100
   506
	  _queue[_queue_head++]=m;
alpar@100
   507
	  _reached->set(m,true);
alpar@100
   508
	  _pred->set(m,e);
alpar@100
   509
	  _dist->set(m,_curr_dist);
alpar@100
   510
          reach = reach || (target == m);
alpar@100
   511
	}
alpar@100
   512
      return n;
alpar@100
   513
    }
alpar@100
   514
alpar@100
   515
    ///Processes the next node.
alpar@100
   516
alpar@100
   517
    ///Processes the next node. And checks that at least one of
alpar@100
   518
    ///reached node has true value in the \c nm node map. If one node
alpar@100
   519
    ///with true value is reachable from the processed node then the
alpar@100
   520
    ///rnode parameter will be set to the first of such nodes.
alpar@100
   521
    ///
alpar@100
   522
    ///\param nm The node map of possible targets.
alpar@100
   523
    ///\retval rnode The reached target node.
alpar@100
   524
    ///\return The processed node.
alpar@100
   525
    ///
alpar@100
   526
    ///\warning The queue must not be empty!
alpar@100
   527
    template<class NM>
alpar@100
   528
    Node processNextNode(const NM& nm, Node& rnode)
alpar@100
   529
    {
alpar@100
   530
      if(_queue_tail==_queue_next_dist) {
alpar@100
   531
	_curr_dist++;
alpar@100
   532
	_queue_next_dist=_queue_head;
alpar@100
   533
      }
alpar@100
   534
      Node n=_queue[_queue_tail++];
alpar@100
   535
      _processed->set(n,true);
alpar@100
   536
      Node m;
alpar@100
   537
      for(OutArcIt e(*G,n);e!=INVALID;++e)
alpar@100
   538
	if(!(*_reached)[m=G->target(e)]) {
alpar@100
   539
	  _queue[_queue_head++]=m;
alpar@100
   540
	  _reached->set(m,true);
alpar@100
   541
	  _pred->set(m,e);
alpar@100
   542
	  _dist->set(m,_curr_dist);
alpar@100
   543
	  if (nm[m] && rnode == INVALID) rnode = m;
alpar@100
   544
	}
alpar@100
   545
      return n;
alpar@100
   546
    }
alpar@100
   547
      
alpar@100
   548
    ///Next node to be processed.
alpar@100
   549
alpar@100
   550
    ///Next node to be processed.
alpar@100
   551
    ///
alpar@100
   552
    ///\return The next node to be processed or INVALID if the queue is
alpar@100
   553
    /// empty.
alpar@100
   554
    Node nextNode()
alpar@100
   555
    { 
alpar@100
   556
      return _queue_tail<_queue_head?_queue[_queue_tail]:INVALID;
alpar@100
   557
    }
alpar@100
   558
 
alpar@100
   559
    ///\brief Returns \c false if there are nodes
alpar@100
   560
    ///to be processed in the queue
alpar@100
   561
    ///
alpar@100
   562
    ///Returns \c false if there are nodes
alpar@100
   563
    ///to be processed in the queue
alpar@100
   564
    bool emptyQueue() { return _queue_tail==_queue_head; }
alpar@100
   565
    ///Returns the number of the nodes to be processed.
alpar@100
   566
    
alpar@100
   567
    ///Returns the number of the nodes to be processed in the queue.
alpar@100
   568
    int queueSize() { return _queue_head-_queue_tail; }
alpar@100
   569
    
alpar@100
   570
    ///Executes the algorithm.
alpar@100
   571
alpar@100
   572
    ///Executes the algorithm.
alpar@100
   573
    ///
alpar@100
   574
    ///\pre init() must be called and at least one node should be added
alpar@100
   575
    ///with addSource() before using this function.
alpar@100
   576
    ///
alpar@100
   577
    ///This method runs the %BFS algorithm from the root node(s)
alpar@100
   578
    ///in order to
alpar@100
   579
    ///compute the
alpar@100
   580
    ///shortest path to each node. The algorithm computes
alpar@100
   581
    ///- The shortest path tree.
alpar@100
   582
    ///- The distance of each node from the root(s).
alpar@100
   583
    void start()
alpar@100
   584
    {
alpar@100
   585
      while ( !emptyQueue() ) processNextNode();
alpar@100
   586
    }
alpar@100
   587
    
alpar@100
   588
    ///Executes the algorithm until \c dest is reached.
alpar@100
   589
alpar@100
   590
    ///Executes the algorithm until \c dest is reached.
alpar@100
   591
    ///
alpar@100
   592
    ///\pre init() must be called and at least one node should be added
alpar@100
   593
    ///with addSource() before using this function.
alpar@100
   594
    ///
alpar@100
   595
    ///This method runs the %BFS algorithm from the root node(s)
alpar@100
   596
    ///in order to compute the shortest path to \c dest.
alpar@100
   597
    ///The algorithm computes
alpar@100
   598
    ///- The shortest path to \c  dest.
alpar@100
   599
    ///- The distance of \c dest from the root(s).
alpar@100
   600
    void start(Node dest)
alpar@100
   601
    {
alpar@100
   602
      bool reach = false;
alpar@100
   603
      while ( !emptyQueue() && !reach ) processNextNode(dest, reach);
alpar@100
   604
    }
alpar@100
   605
    
alpar@100
   606
    ///Executes the algorithm until a condition is met.
alpar@100
   607
alpar@100
   608
    ///Executes the algorithm until a condition is met.
alpar@100
   609
    ///
alpar@100
   610
    ///\pre init() must be called and at least one node should be added
alpar@100
   611
    ///with addSource() before using this function.
alpar@100
   612
    ///
alpar@100
   613
    ///\param nm must be a bool (or convertible) node map. The
alpar@100
   614
    ///algorithm will stop when it reaches a node \c v with
alpar@100
   615
    /// <tt>nm[v]</tt> true.
alpar@100
   616
    ///
alpar@100
   617
    ///\return The reached node \c v with <tt>nm[v]</tt> true or
alpar@100
   618
    ///\c INVALID if no such node was found.
alpar@100
   619
    template<class NM>
alpar@100
   620
    Node start(const NM &nm)
alpar@100
   621
    {
alpar@100
   622
      Node rnode = INVALID;
alpar@100
   623
      while ( !emptyQueue() && rnode == INVALID ) {
alpar@100
   624
	processNextNode(nm, rnode);
alpar@100
   625
      }
alpar@100
   626
      return rnode;
alpar@100
   627
    }
alpar@100
   628
    
alpar@100
   629
    ///Runs %BFS algorithm from node \c s.
alpar@100
   630
    
alpar@100
   631
    ///This method runs the %BFS algorithm from a root node \c s
alpar@100
   632
    ///in order to
alpar@100
   633
    ///compute the
alpar@100
   634
    ///shortest path to each node. The algorithm computes
alpar@100
   635
    ///- The shortest path tree.
alpar@100
   636
    ///- The distance of each node from the root.
alpar@100
   637
    ///
alpar@100
   638
    ///\note b.run(s) is just a shortcut of the following code.
alpar@100
   639
    ///\code
alpar@100
   640
    ///  b.init();
alpar@100
   641
    ///  b.addSource(s);
alpar@100
   642
    ///  b.start();
alpar@100
   643
    ///\endcode
alpar@100
   644
    void run(Node s) {
alpar@100
   645
      init();
alpar@100
   646
      addSource(s);
alpar@100
   647
      start();
alpar@100
   648
    }
alpar@100
   649
    
alpar@100
   650
    ///Finds the shortest path between \c s and \c t.
alpar@100
   651
    
alpar@100
   652
    ///Finds the shortest path between \c s and \c t.
alpar@100
   653
    ///
alpar@100
   654
    ///\return The length of the shortest s---t path if there exists one,
alpar@100
   655
    ///0 otherwise.
alpar@100
   656
    ///\note Apart from the return value, b.run(s) is
alpar@100
   657
    ///just a shortcut of the following code.
alpar@100
   658
    ///\code
alpar@100
   659
    ///  b.init();
alpar@100
   660
    ///  b.addSource(s);
alpar@100
   661
    ///  b.start(t);
alpar@100
   662
    ///\endcode
alpar@100
   663
    int run(Node s,Node t) {
alpar@100
   664
      init();
alpar@100
   665
      addSource(s);
alpar@100
   666
      start(t);
alpar@100
   667
      return reached(t) ? _curr_dist : 0;
alpar@100
   668
    }
alpar@100
   669
    
alpar@100
   670
    ///@}
alpar@100
   671
alpar@100
   672
    ///\name Query Functions
alpar@100
   673
    ///The result of the %BFS algorithm can be obtained using these
alpar@100
   674
    ///functions.\n
alpar@100
   675
    ///Before the use of these functions,
alpar@100
   676
    ///either run() or start() must be calleb.
alpar@100
   677
    
alpar@100
   678
    ///@{
alpar@100
   679
alpar@100
   680
    typedef PredMapPath<Digraph, PredMap> Path;
alpar@100
   681
alpar@100
   682
    ///Gives back the shortest path.
alpar@100
   683
    
alpar@100
   684
    ///Gives back the shortest path.
alpar@100
   685
    ///\pre The \c t should be reachable from the source.
alpar@100
   686
    Path path(Node t) 
alpar@100
   687
    {
alpar@100
   688
      return Path(*G, *_pred, t);
alpar@100
   689
    }
alpar@100
   690
alpar@100
   691
    ///The distance of a node from the root(s).
alpar@100
   692
alpar@100
   693
    ///Returns the distance of a node from the root(s).
alpar@100
   694
    ///\pre \ref run() must be called before using this function.
alpar@100
   695
    ///\warning If node \c v in unreachable from the root(s) the return value
alpar@100
   696
    ///of this function is undefined.
alpar@100
   697
    int dist(Node v) const { return (*_dist)[v]; }
alpar@100
   698
alpar@100
   699
    ///Returns the 'previous arc' of the shortest path tree.
alpar@100
   700
alpar@100
   701
    ///For a node \c v it returns the 'previous arc'
alpar@100
   702
    ///of the shortest path tree,
alpar@100
   703
    ///i.e. it returns the last arc of a shortest path from the root(s) to \c
alpar@100
   704
    ///v. It is \ref INVALID
alpar@100
   705
    ///if \c v is unreachable from the root(s) or \c v is a root. The
alpar@100
   706
    ///shortest path tree used here is equal to the shortest path tree used in
alpar@100
   707
    ///\ref predNode().
alpar@100
   708
    ///\pre Either \ref run() or \ref start() must be called before using
alpar@100
   709
    ///this function.
alpar@100
   710
    Arc predArc(Node v) const { return (*_pred)[v];}
alpar@100
   711
alpar@100
   712
    ///Returns the 'previous node' of the shortest path tree.
alpar@100
   713
alpar@100
   714
    ///For a node \c v it returns the 'previous node'
alpar@100
   715
    ///of the shortest path tree,
alpar@100
   716
    ///i.e. it returns the last but one node from a shortest path from the
alpar@100
   717
    ///root(a) to \c /v.
alpar@100
   718
    ///It is INVALID if \c v is unreachable from the root(s) or
alpar@100
   719
    ///if \c v itself a root.
alpar@100
   720
    ///The shortest path tree used here is equal to the shortest path
alpar@100
   721
    ///tree used in \ref predArc().
alpar@100
   722
    ///\pre Either \ref run() or \ref start() must be called before
alpar@100
   723
    ///using this function.
alpar@100
   724
    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
alpar@100
   725
				  G->source((*_pred)[v]); }
alpar@100
   726
    
alpar@100
   727
    ///Returns a reference to the NodeMap of distances.
alpar@100
   728
alpar@100
   729
    ///Returns a reference to the NodeMap of distances.
alpar@100
   730
    ///\pre Either \ref run() or \ref init() must
alpar@100
   731
    ///be called before using this function.
alpar@100
   732
    const DistMap &distMap() const { return *_dist;}
alpar@100
   733
 
alpar@100
   734
    ///Returns a reference to the shortest path tree map.
alpar@100
   735
alpar@100
   736
    ///Returns a reference to the NodeMap of the arcs of the
alpar@100
   737
    ///shortest path tree.
alpar@100
   738
    ///\pre Either \ref run() or \ref init()
alpar@100
   739
    ///must be called before using this function.
alpar@100
   740
    const PredMap &predMap() const { return *_pred;}
alpar@100
   741
 
alpar@100
   742
    ///Checks if a node is reachable from the root.
alpar@100
   743
alpar@100
   744
    ///Returns \c true if \c v is reachable from the root.
alpar@100
   745
    ///\warning The source nodes are indicated as unreached.
alpar@100
   746
    ///\pre Either \ref run() or \ref start()
alpar@100
   747
    ///must be called before using this function.
alpar@100
   748
    ///
alpar@100
   749
    bool reached(Node v) { return (*_reached)[v]; }
alpar@100
   750
    
alpar@100
   751
    ///@}
alpar@100
   752
  };
alpar@100
   753
alpar@100
   754
  ///Default traits class of Bfs function.
alpar@100
   755
alpar@100
   756
  ///Default traits class of Bfs function.
kpeter@157
   757
  ///\tparam GR Digraph type.
alpar@100
   758
  template<class GR>
alpar@100
   759
  struct BfsWizardDefaultTraits
alpar@100
   760
  {
alpar@100
   761
    ///The digraph type the algorithm runs on. 
alpar@100
   762
    typedef GR Digraph;
alpar@100
   763
    ///\brief The type of the map that stores the last
alpar@100
   764
    ///arcs of the shortest paths.
alpar@100
   765
    /// 
alpar@100
   766
    ///The type of the map that stores the last
alpar@100
   767
    ///arcs of the shortest paths.
alpar@100
   768
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
alpar@100
   769
    ///
alpar@100
   770
    typedef NullMap<typename Digraph::Node,typename GR::Arc> PredMap;
alpar@100
   771
    ///Instantiates a PredMap.
alpar@100
   772
 
alpar@100
   773
    ///This function instantiates a \ref PredMap. 
alpar@100
   774
    ///\param g is the digraph, to which we would like to define the PredMap.
alpar@100
   775
    ///\todo The digraph alone may be insufficient to initialize
alpar@100
   776
#ifdef DOXYGEN
alpar@100
   777
    static PredMap *createPredMap(const GR &g) 
alpar@100
   778
#else
alpar@100
   779
    static PredMap *createPredMap(const GR &) 
alpar@100
   780
#endif
alpar@100
   781
    {
alpar@100
   782
      return new PredMap();
alpar@100
   783
    }
alpar@100
   784
alpar@100
   785
    ///The type of the map that indicates which nodes are processed.
alpar@100
   786
 
alpar@100
   787
    ///The type of the map that indicates which nodes are processed.
alpar@100
   788
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
alpar@100
   789
    ///\todo named parameter to set this type, function to read and write.
alpar@100
   790
    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
alpar@100
   791
    ///Instantiates a ProcessedMap.
alpar@100
   792
 
alpar@100
   793
    ///This function instantiates a \ref ProcessedMap. 
alpar@100
   794
    ///\param g is the digraph, to which
alpar@100
   795
    ///we would like to define the \ref ProcessedMap
alpar@100
   796
#ifdef DOXYGEN
alpar@100
   797
    static ProcessedMap *createProcessedMap(const GR &g)
alpar@100
   798
#else
alpar@100
   799
    static ProcessedMap *createProcessedMap(const GR &)
alpar@100
   800
#endif
alpar@100
   801
    {
alpar@100
   802
      return new ProcessedMap();
alpar@100
   803
    }
alpar@100
   804
    ///The type of the map that indicates which nodes are reached.
alpar@100
   805
 
alpar@100
   806
    ///The type of the map that indicates which nodes are reached.
alpar@100
   807
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
alpar@100
   808
    ///\todo named parameter to set this type, function to read and write.
alpar@100
   809
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
alpar@100
   810
    ///Instantiates a ReachedMap.
alpar@100
   811
 
alpar@100
   812
    ///This function instantiates a \ref ReachedMap. 
alpar@100
   813
    ///\param G is the digraph, to which
alpar@100
   814
    ///we would like to define the \ref ReachedMap.
alpar@100
   815
    static ReachedMap *createReachedMap(const GR &G)
alpar@100
   816
    {
alpar@100
   817
      return new ReachedMap(G);
alpar@100
   818
    }
alpar@100
   819
    ///The type of the map that stores the dists of the nodes.
alpar@100
   820
 
alpar@100
   821
    ///The type of the map that stores the dists of the nodes.
alpar@100
   822
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
alpar@100
   823
    ///
alpar@100
   824
    typedef NullMap<typename Digraph::Node,int> DistMap;
alpar@100
   825
    ///Instantiates a DistMap.
alpar@100
   826
 
alpar@100
   827
    ///This function instantiates a \ref DistMap. 
alpar@100
   828
    ///\param g is the digraph, to which we would like to define the \ref DistMap
alpar@100
   829
#ifdef DOXYGEN
alpar@100
   830
    static DistMap *createDistMap(const GR &g)
alpar@100
   831
#else
alpar@100
   832
    static DistMap *createDistMap(const GR &)
alpar@100
   833
#endif
alpar@100
   834
    {
alpar@100
   835
      return new DistMap();
alpar@100
   836
    }
alpar@100
   837
  };
alpar@100
   838
  
alpar@100
   839
  /// Default traits used by \ref BfsWizard
alpar@100
   840
alpar@100
   841
  /// To make it easier to use Bfs algorithm
alpar@100
   842
  ///we have created a wizard class.
alpar@100
   843
  /// This \ref BfsWizard class needs default traits,
alpar@100
   844
  ///as well as the \ref Bfs class.
alpar@100
   845
  /// The \ref BfsWizardBase is a class to be the default traits of the
alpar@100
   846
  /// \ref BfsWizard class.
alpar@100
   847
  template<class GR>
alpar@100
   848
  class BfsWizardBase : public BfsWizardDefaultTraits<GR>
alpar@100
   849
  {
alpar@100
   850
alpar@100
   851
    typedef BfsWizardDefaultTraits<GR> Base;
alpar@100
   852
  protected:
alpar@100
   853
    /// Type of the nodes in the digraph.
alpar@100
   854
    typedef typename Base::Digraph::Node Node;
alpar@100
   855
alpar@100
   856
    /// Pointer to the underlying digraph.
alpar@100
   857
    void *_g;
alpar@100
   858
    ///Pointer to the map of reached nodes.
alpar@100
   859
    void *_reached;
alpar@100
   860
    ///Pointer to the map of processed nodes.
alpar@100
   861
    void *_processed;
alpar@100
   862
    ///Pointer to the map of predecessors arcs.
alpar@100
   863
    void *_pred;
alpar@100
   864
    ///Pointer to the map of distances.
alpar@100
   865
    void *_dist;
alpar@100
   866
    ///Pointer to the source node.
alpar@100
   867
    Node _source;
alpar@100
   868
    
alpar@100
   869
    public:
alpar@100
   870
    /// Constructor.
alpar@100
   871
    
alpar@100
   872
    /// This constructor does not require parameters, therefore it initiates
alpar@100
   873
    /// all of the attributes to default values (0, INVALID).
alpar@100
   874
    BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0),
alpar@100
   875
			   _dist(0), _source(INVALID) {}
alpar@100
   876
alpar@100
   877
    /// Constructor.
alpar@100
   878
    
alpar@100
   879
    /// This constructor requires some parameters,
alpar@100
   880
    /// listed in the parameters list.
alpar@100
   881
    /// Others are initiated to 0.
alpar@100
   882
    /// \param g is the initial value of  \ref _g
alpar@100
   883
    /// \param s is the initial value of  \ref _source
alpar@100
   884
    BfsWizardBase(const GR &g, Node s=INVALID) :
alpar@100
   885
      _g(reinterpret_cast<void*>(const_cast<GR*>(&g))), 
alpar@100
   886
      _reached(0), _processed(0), _pred(0), _dist(0), _source(s) {}
alpar@100
   887
alpar@100
   888
  };
alpar@100
   889
  
alpar@100
   890
  /// A class to make the usage of Bfs algorithm easier
alpar@100
   891
alpar@100
   892
  /// This class is created to make it easier to use Bfs algorithm.
alpar@100
   893
  /// It uses the functions and features of the plain \ref Bfs,
alpar@100
   894
  /// but it is much simpler to use it.
alpar@100
   895
  ///
alpar@100
   896
  /// Simplicity means that the way to change the types defined
alpar@100
   897
  /// in the traits class is based on functions that returns the new class
alpar@100
   898
  /// and not on templatable built-in classes.
alpar@100
   899
  /// When using the plain \ref Bfs
alpar@100
   900
  /// the new class with the modified type comes from
alpar@100
   901
  /// the original class by using the ::
alpar@100
   902
  /// operator. In the case of \ref BfsWizard only
alpar@100
   903
  /// a function have to be called and it will
alpar@100
   904
  /// return the needed class.
alpar@100
   905
  ///
alpar@100
   906
  /// It does not have own \ref run method. When its \ref run method is called
alpar@100
   907
  /// it initiates a plain \ref Bfs class, and calls the \ref Bfs::run
alpar@100
   908
  /// method of it.
alpar@100
   909
  template<class TR>
alpar@100
   910
  class BfsWizard : public TR
alpar@100
   911
  {
alpar@100
   912
    typedef TR Base;
alpar@100
   913
alpar@100
   914
    ///The type of the underlying digraph.
alpar@100
   915
    typedef typename TR::Digraph Digraph;
alpar@100
   916
    //\e
alpar@100
   917
    typedef typename Digraph::Node Node;
alpar@100
   918
    //\e
alpar@100
   919
    typedef typename Digraph::NodeIt NodeIt;
alpar@100
   920
    //\e
alpar@100
   921
    typedef typename Digraph::Arc Arc;
alpar@100
   922
    //\e
alpar@100
   923
    typedef typename Digraph::OutArcIt OutArcIt;
alpar@100
   924
    
alpar@100
   925
    ///\brief The type of the map that stores
alpar@100
   926
    ///the reached nodes
alpar@100
   927
    typedef typename TR::ReachedMap ReachedMap;
alpar@100
   928
    ///\brief The type of the map that stores
alpar@100
   929
    ///the processed nodes
alpar@100
   930
    typedef typename TR::ProcessedMap ProcessedMap;
alpar@100
   931
    ///\brief The type of the map that stores the last
alpar@100
   932
    ///arcs of the shortest paths.
alpar@100
   933
    typedef typename TR::PredMap PredMap;
alpar@100
   934
    ///The type of the map that stores the dists of the nodes.
alpar@100
   935
    typedef typename TR::DistMap DistMap;
alpar@100
   936
alpar@100
   937
  public:
alpar@100
   938
    /// Constructor.
alpar@100
   939
    BfsWizard() : TR() {}
alpar@100
   940
alpar@100
   941
    /// Constructor that requires parameters.
alpar@100
   942
alpar@100
   943
    /// Constructor that requires parameters.
alpar@100
   944
    /// These parameters will be the default values for the traits class.
alpar@100
   945
    BfsWizard(const Digraph &g, Node s=INVALID) :
alpar@100
   946
      TR(g,s) {}
alpar@100
   947
alpar@100
   948
    ///Copy constructor
alpar@100
   949
    BfsWizard(const TR &b) : TR(b) {}
alpar@100
   950
alpar@100
   951
    ~BfsWizard() {}
alpar@100
   952
alpar@100
   953
    ///Runs Bfs algorithm from a given node.
alpar@100
   954
    
alpar@100
   955
    ///Runs Bfs algorithm from a given node.
alpar@100
   956
    ///The node can be given by the \ref source function.
alpar@100
   957
    void run()
alpar@100
   958
    {
alpar@100
   959
      if(Base::_source==INVALID) throw UninitializedParameter();
alpar@100
   960
      Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
alpar@100
   961
      if(Base::_reached)
alpar@100
   962
	alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
alpar@100
   963
      if(Base::_processed) 
alpar@100
   964
        alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
alpar@100
   965
      if(Base::_pred) 
alpar@100
   966
        alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
alpar@100
   967
      if(Base::_dist) 
alpar@100
   968
        alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
alpar@100
   969
      alg.run(Base::_source);
alpar@100
   970
    }
alpar@100
   971
alpar@100
   972
    ///Runs Bfs algorithm from the given node.
alpar@100
   973
alpar@100
   974
    ///Runs Bfs algorithm from the given node.
alpar@100
   975
    ///\param s is the given source.
alpar@100
   976
    void run(Node s)
alpar@100
   977
    {
alpar@100
   978
      Base::_source=s;
alpar@100
   979
      run();
alpar@100
   980
    }
alpar@100
   981
alpar@100
   982
    template<class T>
alpar@100
   983
    struct DefPredMapBase : public Base {
alpar@100
   984
      typedef T PredMap;
alpar@100
   985
      static PredMap *createPredMap(const Digraph &) { return 0; };
alpar@100
   986
      DefPredMapBase(const TR &b) : TR(b) {}
alpar@100
   987
    };
alpar@100
   988
    
alpar@100
   989
    ///\brief \ref named-templ-param "Named parameter"
alpar@100
   990
    ///function for setting PredMap
alpar@100
   991
    ///
alpar@100
   992
    /// \ref named-templ-param "Named parameter"
alpar@100
   993
    ///function for setting PredMap
alpar@100
   994
    ///
alpar@100
   995
    template<class T>
alpar@100
   996
    BfsWizard<DefPredMapBase<T> > predMap(const T &t) 
alpar@100
   997
    {
alpar@100
   998
      Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
alpar@100
   999
      return BfsWizard<DefPredMapBase<T> >(*this);
alpar@100
  1000
    }
alpar@100
  1001
    
alpar@100
  1002
 
alpar@100
  1003
    template<class T>
alpar@100
  1004
    struct DefReachedMapBase : public Base {
alpar@100
  1005
      typedef T ReachedMap;
alpar@100
  1006
      static ReachedMap *createReachedMap(const Digraph &) { return 0; };
alpar@100
  1007
      DefReachedMapBase(const TR &b) : TR(b) {}
alpar@100
  1008
    };
alpar@100
  1009
    
alpar@100
  1010
    ///\brief \ref named-templ-param "Named parameter"
alpar@100
  1011
    ///function for setting ReachedMap
alpar@100
  1012
    ///
alpar@100
  1013
    /// \ref named-templ-param "Named parameter"
alpar@100
  1014
    ///function for setting ReachedMap
alpar@100
  1015
    ///
alpar@100
  1016
    template<class T>
alpar@100
  1017
    BfsWizard<DefReachedMapBase<T> > reachedMap(const T &t) 
alpar@100
  1018
    {
deba@158
  1019
      Base::_reached=reinterpret_cast<void*>(const_cast<T*>(&t));
alpar@100
  1020
      return BfsWizard<DefReachedMapBase<T> >(*this);
alpar@100
  1021
    }
alpar@100
  1022
    
alpar@100
  1023
alpar@100
  1024
    template<class T>
alpar@100
  1025
    struct DefProcessedMapBase : public Base {
alpar@100
  1026
      typedef T ProcessedMap;
alpar@100
  1027
      static ProcessedMap *createProcessedMap(const Digraph &) { return 0; };
alpar@100
  1028
      DefProcessedMapBase(const TR &b) : TR(b) {}
alpar@100
  1029
    };
alpar@100
  1030
    
alpar@100
  1031
    ///\brief \ref named-templ-param "Named parameter"
alpar@100
  1032
    ///function for setting ProcessedMap
alpar@100
  1033
    ///
alpar@100
  1034
    /// \ref named-templ-param "Named parameter"
alpar@100
  1035
    ///function for setting ProcessedMap
alpar@100
  1036
    ///
alpar@100
  1037
    template<class T>
alpar@100
  1038
    BfsWizard<DefProcessedMapBase<T> > processedMap(const T &t) 
alpar@100
  1039
    {
deba@158
  1040
      Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t));
alpar@100
  1041
      return BfsWizard<DefProcessedMapBase<T> >(*this);
alpar@100
  1042
    }
alpar@100
  1043
    
alpar@100
  1044
   
alpar@100
  1045
    template<class T>
alpar@100
  1046
    struct DefDistMapBase : public Base {
alpar@100
  1047
      typedef T DistMap;
alpar@100
  1048
      static DistMap *createDistMap(const Digraph &) { return 0; };
alpar@100
  1049
      DefDistMapBase(const TR &b) : TR(b) {}
alpar@100
  1050
    };
alpar@100
  1051
    
alpar@100
  1052
    ///\brief \ref named-templ-param "Named parameter"
alpar@100
  1053
    ///function for setting DistMap type
alpar@100
  1054
    ///
alpar@100
  1055
    /// \ref named-templ-param "Named parameter"
alpar@100
  1056
    ///function for setting DistMap type
alpar@100
  1057
    ///
alpar@100
  1058
    template<class T>
alpar@100
  1059
    BfsWizard<DefDistMapBase<T> > distMap(const T &t) 
alpar@100
  1060
    {
alpar@100
  1061
      Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
alpar@100
  1062
      return BfsWizard<DefDistMapBase<T> >(*this);
alpar@100
  1063
    }
alpar@100
  1064
    
alpar@100
  1065
    /// Sets the source node, from which the Bfs algorithm runs.
alpar@100
  1066
alpar@100
  1067
    /// Sets the source node, from which the Bfs algorithm runs.
alpar@100
  1068
    /// \param s is the source node.
alpar@100
  1069
    BfsWizard<TR> &source(Node s) 
alpar@100
  1070
    {
alpar@100
  1071
      Base::_source=s;
alpar@100
  1072
      return *this;
alpar@100
  1073
    }
alpar@100
  1074
    
alpar@100
  1075
  };
alpar@100
  1076
  
alpar@100
  1077
  ///Function type interface for Bfs algorithm.
alpar@100
  1078
alpar@100
  1079
  /// \ingroup search
alpar@100
  1080
  ///Function type interface for Bfs algorithm.
alpar@100
  1081
  ///
alpar@100
  1082
  ///This function also has several
alpar@100
  1083
  ///\ref named-templ-func-param "named parameters",
alpar@100
  1084
  ///they are declared as the members of class \ref BfsWizard.
alpar@100
  1085
  ///The following
alpar@100
  1086
  ///example shows how to use these parameters.
alpar@100
  1087
  ///\code
alpar@100
  1088
  ///  bfs(g,source).predMap(preds).run();
alpar@100
  1089
  ///\endcode
alpar@100
  1090
  ///\warning Don't forget to put the \ref BfsWizard::run() "run()"
alpar@100
  1091
  ///to the end of the parameter list.
alpar@100
  1092
  ///\sa BfsWizard
alpar@100
  1093
  ///\sa Bfs
alpar@100
  1094
  template<class GR>
alpar@100
  1095
  BfsWizard<BfsWizardBase<GR> >
alpar@100
  1096
  bfs(const GR &g,typename GR::Node s=INVALID)
alpar@100
  1097
  {
alpar@100
  1098
    return BfsWizard<BfsWizardBase<GR> >(g,s);
alpar@100
  1099
  }
alpar@100
  1100
alpar@100
  1101
#ifdef DOXYGEN
alpar@100
  1102
  /// \brief Visitor class for bfs.
alpar@100
  1103
  ///  
alpar@100
  1104
  /// This class defines the interface of the BfsVisit events, and
alpar@100
  1105
  /// it could be the base of a real Visitor class.
alpar@100
  1106
  template <typename _Digraph>
alpar@100
  1107
  struct BfsVisitor {
alpar@100
  1108
    typedef _Digraph Digraph;
alpar@100
  1109
    typedef typename Digraph::Arc Arc;
alpar@100
  1110
    typedef typename Digraph::Node Node;
alpar@100
  1111
    /// \brief Called when the arc reach a node.
alpar@100
  1112
    /// 
alpar@100
  1113
    /// It is called when the bfs find an arc which target is not
alpar@100
  1114
    /// reached yet.
alpar@100
  1115
    void discover(const Arc& arc) {}
alpar@100
  1116
    /// \brief Called when the node reached first time.
alpar@100
  1117
    /// 
alpar@100
  1118
    /// It is Called when the node reached first time.
alpar@100
  1119
    void reach(const Node& node) {}
alpar@100
  1120
    /// \brief Called when the arc examined but target of the arc 
alpar@100
  1121
    /// already discovered.
alpar@100
  1122
    /// 
alpar@100
  1123
    /// It called when the arc examined but the target of the arc 
alpar@100
  1124
    /// already discovered.
alpar@100
  1125
    void examine(const Arc& arc) {}
alpar@100
  1126
    /// \brief Called for the source node of the bfs.
alpar@100
  1127
    /// 
alpar@100
  1128
    /// It is called for the source node of the bfs.
alpar@100
  1129
    void start(const Node& node) {}
alpar@100
  1130
    /// \brief Called when the node processed.
alpar@100
  1131
    /// 
alpar@100
  1132
    /// It is Called when the node processed.
alpar@100
  1133
    void process(const Node& node) {}
alpar@100
  1134
  };
alpar@100
  1135
#else
alpar@100
  1136
  template <typename _Digraph>
alpar@100
  1137
  struct BfsVisitor {
alpar@100
  1138
    typedef _Digraph Digraph;
alpar@100
  1139
    typedef typename Digraph::Arc Arc;
alpar@100
  1140
    typedef typename Digraph::Node Node;
alpar@100
  1141
    void discover(const Arc&) {}
alpar@100
  1142
    void reach(const Node&) {}
alpar@100
  1143
    void examine(const Arc&) {}
alpar@100
  1144
    void start(const Node&) {}
alpar@100
  1145
    void process(const Node&) {}
alpar@100
  1146
alpar@100
  1147
    template <typename _Visitor>
alpar@100
  1148
    struct Constraints {
alpar@100
  1149
      void constraints() {
alpar@100
  1150
	Arc arc;
alpar@100
  1151
	Node node;
alpar@100
  1152
	visitor.discover(arc);
alpar@100
  1153
	visitor.reach(node);
alpar@100
  1154
	visitor.examine(arc);
alpar@100
  1155
	visitor.start(node);
alpar@100
  1156
        visitor.process(node);
alpar@100
  1157
      }
alpar@100
  1158
      _Visitor& visitor;
alpar@100
  1159
    };
alpar@100
  1160
  };
alpar@100
  1161
#endif
alpar@100
  1162
alpar@100
  1163
  /// \brief Default traits class of BfsVisit class.
alpar@100
  1164
  ///
alpar@100
  1165
  /// Default traits class of BfsVisit class.
kpeter@157
  1166
  /// \tparam _Digraph Digraph type.
alpar@100
  1167
  template<class _Digraph>
alpar@100
  1168
  struct BfsVisitDefaultTraits {
alpar@100
  1169
alpar@100
  1170
    /// \brief The digraph type the algorithm runs on. 
alpar@100
  1171
    typedef _Digraph Digraph;
alpar@100
  1172
alpar@100
  1173
    /// \brief The type of the map that indicates which nodes are reached.
alpar@100
  1174
    /// 
alpar@100
  1175
    /// The type of the map that indicates which nodes are reached.
alpar@100
  1176
    /// It must meet the \ref concepts::WriteMap "WriteMap" concept.
alpar@100
  1177
    /// \todo named parameter to set this type, function to read and write.
alpar@100
  1178
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
alpar@100
  1179
alpar@100
  1180
    /// \brief Instantiates a ReachedMap.
alpar@100
  1181
    ///
alpar@100
  1182
    /// This function instantiates a \ref ReachedMap. 
alpar@100
  1183
    /// \param digraph is the digraph, to which
alpar@100
  1184
    /// we would like to define the \ref ReachedMap.
alpar@100
  1185
    static ReachedMap *createReachedMap(const Digraph &digraph) {
alpar@100
  1186
      return new ReachedMap(digraph);
alpar@100
  1187
    }
alpar@100
  1188
alpar@100
  1189
  };
alpar@100
  1190
alpar@100
  1191
  /// \ingroup search
alpar@100
  1192
  ///  
alpar@100
  1193
  /// \brief %BFS Visit algorithm class.
alpar@100
  1194
  ///  
alpar@100
  1195
  /// This class provides an efficient implementation of the %BFS algorithm
alpar@100
  1196
  /// with visitor interface.
alpar@100
  1197
  ///
alpar@100
  1198
  /// The %BfsVisit class provides an alternative interface to the Bfs
alpar@100
  1199
  /// class. It works with callback mechanism, the BfsVisit object calls
alpar@100
  1200
  /// on every bfs event the \c Visitor class member functions. 
alpar@100
  1201
  ///
kpeter@157
  1202
  /// \tparam _Digraph The digraph type the algorithm runs on. The default value is
alpar@100
  1203
  /// \ref ListDigraph. The value of _Digraph is not used directly by Bfs, it
alpar@100
  1204
  /// is only passed to \ref BfsDefaultTraits.
kpeter@157
  1205
  /// \tparam _Visitor The Visitor object for the algorithm. The 
alpar@100
  1206
  /// \ref BfsVisitor "BfsVisitor<_Digraph>" is an empty Visitor which
alpar@100
  1207
  /// does not observe the Bfs events. If you want to observe the bfs
alpar@100
  1208
  /// events you should implement your own Visitor class.
kpeter@157
  1209
  /// \tparam _Traits Traits class to set various data types used by the 
alpar@100
  1210
  /// algorithm. The default traits class is
alpar@100
  1211
  /// \ref BfsVisitDefaultTraits "BfsVisitDefaultTraits<_Digraph>".
alpar@100
  1212
  /// See \ref BfsVisitDefaultTraits for the documentation of
alpar@100
  1213
  /// a Bfs visit traits class.
alpar@100
  1214
#ifdef DOXYGEN
alpar@100
  1215
  template <typename _Digraph, typename _Visitor, typename _Traits>
alpar@100
  1216
#else
alpar@100
  1217
  template <typename _Digraph = ListDigraph,
alpar@100
  1218
	    typename _Visitor = BfsVisitor<_Digraph>,
alpar@100
  1219
	    typename _Traits = BfsDefaultTraits<_Digraph> >
alpar@100
  1220
#endif
alpar@100
  1221
  class BfsVisit {
alpar@100
  1222
  public:
alpar@100
  1223
    
alpar@100
  1224
    /// \brief \ref Exception for uninitialized parameters.
alpar@100
  1225
    ///
alpar@100
  1226
    /// This error represents problems in the initialization
alpar@100
  1227
    /// of the parameters of the algorithms.
alpar@100
  1228
    class UninitializedParameter : public lemon::UninitializedParameter {
alpar@100
  1229
    public:
alpar@100
  1230
      virtual const char* what() const throw() 
alpar@100
  1231
      {
alpar@100
  1232
	return "lemon::BfsVisit::UninitializedParameter";
alpar@100
  1233
      }
alpar@100
  1234
    };
alpar@100
  1235
alpar@100
  1236
    typedef _Traits Traits;
alpar@100
  1237
alpar@100
  1238
    typedef typename Traits::Digraph Digraph;
alpar@100
  1239
alpar@100
  1240
    typedef _Visitor Visitor;
alpar@100
  1241
alpar@100
  1242
    ///The type of the map indicating which nodes are reached.
alpar@100
  1243
    typedef typename Traits::ReachedMap ReachedMap;
alpar@100
  1244
alpar@100
  1245
  private:
alpar@100
  1246
alpar@100
  1247
    typedef typename Digraph::Node Node;
alpar@100
  1248
    typedef typename Digraph::NodeIt NodeIt;
alpar@100
  1249
    typedef typename Digraph::Arc Arc;
alpar@100
  1250
    typedef typename Digraph::OutArcIt OutArcIt;
alpar@100
  1251
alpar@100
  1252
    /// Pointer to the underlying digraph.
alpar@100
  1253
    const Digraph *_digraph;
alpar@100
  1254
    /// Pointer to the visitor object.
alpar@100
  1255
    Visitor *_visitor;
alpar@100
  1256
    ///Pointer to the map of reached status of the nodes.
alpar@100
  1257
    ReachedMap *_reached;
alpar@100
  1258
    ///Indicates if \ref _reached is locally allocated (\c true) or not.
alpar@100
  1259
    bool local_reached;
alpar@100
  1260
alpar@100
  1261
    std::vector<typename Digraph::Node> _list;
alpar@100
  1262
    int _list_front, _list_back;
alpar@100
  1263
alpar@100
  1264
    /// \brief Creates the maps if necessary.
alpar@100
  1265
    ///
alpar@100
  1266
    /// Creates the maps if necessary.
alpar@100
  1267
    void create_maps() {
alpar@100
  1268
      if(!_reached) {
alpar@100
  1269
	local_reached = true;
alpar@100
  1270
	_reached = Traits::createReachedMap(*_digraph);
alpar@100
  1271
      }
alpar@100
  1272
    }
alpar@100
  1273
alpar@100
  1274
  protected:
alpar@100
  1275
alpar@100
  1276
    BfsVisit() {}
alpar@100
  1277
    
alpar@100
  1278
  public:
alpar@100
  1279
alpar@100
  1280
    typedef BfsVisit Create;
alpar@100
  1281
alpar@100
  1282
    /// \name Named template parameters
alpar@100
  1283
alpar@100
  1284
    ///@{
alpar@100
  1285
    template <class T>
alpar@100
  1286
    struct DefReachedMapTraits : public Traits {
alpar@100
  1287
      typedef T ReachedMap;
alpar@100
  1288
      static ReachedMap *createReachedMap(const Digraph &digraph) {
alpar@100
  1289
	throw UninitializedParameter();
alpar@100
  1290
      }
alpar@100
  1291
    };
alpar@100
  1292
    /// \brief \ref named-templ-param "Named parameter" for setting 
alpar@100
  1293
    /// ReachedMap type
alpar@100
  1294
    ///
alpar@100
  1295
    /// \ref named-templ-param "Named parameter" for setting ReachedMap type
alpar@100
  1296
    template <class T>
alpar@100
  1297
    struct DefReachedMap : public BfsVisit< Digraph, Visitor,
alpar@100
  1298
					    DefReachedMapTraits<T> > {
alpar@100
  1299
      typedef BfsVisit< Digraph, Visitor, DefReachedMapTraits<T> > Create;
alpar@100
  1300
    };
alpar@100
  1301
    ///@}
alpar@100
  1302
alpar@100
  1303
  public:      
alpar@100
  1304
    
alpar@100
  1305
    /// \brief Constructor.
alpar@100
  1306
    ///
alpar@100
  1307
    /// Constructor.
alpar@100
  1308
    ///
alpar@100
  1309
    /// \param digraph the digraph the algorithm will run on.
alpar@100
  1310
    /// \param visitor The visitor of the algorithm.
alpar@100
  1311
    ///
alpar@100
  1312
    BfsVisit(const Digraph& digraph, Visitor& visitor) 
alpar@100
  1313
      : _digraph(&digraph), _visitor(&visitor),
alpar@100
  1314
	_reached(0), local_reached(false) {}
alpar@100
  1315
    
alpar@100
  1316
    /// \brief Destructor.
alpar@100
  1317
    ///
alpar@100
  1318
    /// Destructor.
alpar@100
  1319
    ~BfsVisit() {
alpar@100
  1320
      if(local_reached) delete _reached;
alpar@100
  1321
    }
alpar@100
  1322
alpar@100
  1323
    /// \brief Sets the map indicating if a node is reached.
alpar@100
  1324
    ///
alpar@100
  1325
    /// Sets the map indicating if a node is reached.
alpar@100
  1326
    /// If you don't use this function before calling \ref run(),
alpar@100
  1327
    /// it will allocate one. The destuctor deallocates this
alpar@100
  1328
    /// automatically allocated map, of course.
alpar@100
  1329
    /// \return <tt> (*this) </tt>
alpar@100
  1330
    BfsVisit &reachedMap(ReachedMap &m) {
alpar@100
  1331
      if(local_reached) {
alpar@100
  1332
	delete _reached;
alpar@100
  1333
	local_reached = false;
alpar@100
  1334
      }
alpar@100
  1335
      _reached = &m;
alpar@100
  1336
      return *this;
alpar@100
  1337
    }
alpar@100
  1338
alpar@100
  1339
  public:
alpar@100
  1340
    /// \name Execution control
alpar@100
  1341
    /// The simplest way to execute the algorithm is to use
alpar@100
  1342
    /// one of the member functions called \c run(...).
alpar@100
  1343
    /// \n
alpar@100
  1344
    /// If you need more control on the execution,
alpar@100
  1345
    /// first you must call \ref init(), then you can adda source node
alpar@100
  1346
    /// with \ref addSource().
alpar@100
  1347
    /// Finally \ref start() will perform the actual path
alpar@100
  1348
    /// computation.
alpar@100
  1349
alpar@100
  1350
    /// @{
alpar@100
  1351
    /// \brief Initializes the internal data structures.
alpar@100
  1352
    ///
alpar@100
  1353
    /// Initializes the internal data structures.
alpar@100
  1354
    ///
alpar@100
  1355
    void init() {
alpar@100
  1356
      create_maps();
alpar@100
  1357
      _list.resize(countNodes(*_digraph));
alpar@100
  1358
      _list_front = _list_back = -1;
alpar@100
  1359
      for (NodeIt u(*_digraph) ; u != INVALID ; ++u) {
alpar@100
  1360
	_reached->set(u, false);
alpar@100
  1361
      }
alpar@100
  1362
    }
alpar@100
  1363
    
alpar@100
  1364
    /// \brief Adds a new source node.
alpar@100
  1365
    ///
alpar@100
  1366
    /// Adds a new source node to the set of nodes to be processed.
alpar@100
  1367
    void addSource(Node s) {
alpar@100
  1368
      if(!(*_reached)[s]) {
alpar@100
  1369
	  _reached->set(s,true);
alpar@100
  1370
	  _visitor->start(s);
alpar@100
  1371
	  _visitor->reach(s);
alpar@100
  1372
          _list[++_list_back] = s;
alpar@100
  1373
	}
alpar@100
  1374
    }
alpar@100
  1375
    
alpar@100
  1376
    /// \brief Processes the next node.
alpar@100
  1377
    ///
alpar@100
  1378
    /// Processes the next node.
alpar@100
  1379
    ///
alpar@100
  1380
    /// \return The processed node.
alpar@100
  1381
    ///
alpar@100
  1382
    /// \pre The queue must not be empty!
alpar@100
  1383
    Node processNextNode() { 
alpar@100
  1384
      Node n = _list[++_list_front];
alpar@100
  1385
      _visitor->process(n);
alpar@100
  1386
      Arc e;
alpar@100
  1387
      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
alpar@100
  1388
        Node m = _digraph->target(e);
alpar@100
  1389
        if (!(*_reached)[m]) {
alpar@100
  1390
          _visitor->discover(e);
alpar@100
  1391
          _visitor->reach(m);
alpar@100
  1392
          _reached->set(m, true);
alpar@100
  1393
          _list[++_list_back] = m;
alpar@100
  1394
        } else {
alpar@100
  1395
          _visitor->examine(e);
alpar@100
  1396
        }
alpar@100
  1397
      }
alpar@100
  1398
      return n;
alpar@100
  1399
    }
alpar@100
  1400
alpar@100
  1401
    /// \brief Processes the next node.
alpar@100
  1402
    ///
alpar@100
  1403
    /// Processes the next node. And checks that the given target node
alpar@100
  1404
    /// is reached. If the target node is reachable from the processed
alpar@100
  1405
    /// node then the reached parameter will be set true. The reached
alpar@100
  1406
    /// parameter should be initially false.
alpar@100
  1407
    ///
alpar@100
  1408
    /// \param target The target node.
alpar@100
  1409
    /// \retval reach Indicates that the target node is reached.
alpar@100
  1410
    /// \return The processed node.
alpar@100
  1411
    ///
alpar@100
  1412
    /// \warning The queue must not be empty!
alpar@100
  1413
    Node processNextNode(Node target, bool& reach) {
alpar@100
  1414
      Node n = _list[++_list_front];
alpar@100
  1415
      _visitor->process(n);
alpar@100
  1416
      Arc e;
alpar@100
  1417
      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
alpar@100
  1418
        Node m = _digraph->target(e);
alpar@100
  1419
        if (!(*_reached)[m]) {
alpar@100
  1420
          _visitor->discover(e);
alpar@100
  1421
          _visitor->reach(m);
alpar@100
  1422
          _reached->set(m, true);
alpar@100
  1423
          _list[++_list_back] = m;
alpar@100
  1424
          reach = reach || (target == m);
alpar@100
  1425
        } else {
alpar@100
  1426
          _visitor->examine(e);
alpar@100
  1427
        }
alpar@100
  1428
      }
alpar@100
  1429
      return n;
alpar@100
  1430
    }
alpar@100
  1431
alpar@100
  1432
    /// \brief Processes the next node.
alpar@100
  1433
    ///
alpar@100
  1434
    /// Processes the next node. And checks that at least one of
alpar@100
  1435
    /// reached node has true value in the \c nm node map. If one node
alpar@100
  1436
    /// with true value is reachable from the processed node then the
alpar@100
  1437
    /// rnode parameter will be set to the first of such nodes.
alpar@100
  1438
    ///
alpar@100
  1439
    /// \param nm The node map of possible targets.
alpar@100
  1440
    /// \retval rnode The reached target node.
alpar@100
  1441
    /// \return The processed node.
alpar@100
  1442
    ///
alpar@100
  1443
    /// \warning The queue must not be empty!
alpar@100
  1444
    template <typename NM>
alpar@100
  1445
    Node processNextNode(const NM& nm, Node& rnode) {
alpar@100
  1446
      Node n = _list[++_list_front];
alpar@100
  1447
      _visitor->process(n);
alpar@100
  1448
      Arc e;
alpar@100
  1449
      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
alpar@100
  1450
        Node m = _digraph->target(e);
alpar@100
  1451
        if (!(*_reached)[m]) {
alpar@100
  1452
          _visitor->discover(e);
alpar@100
  1453
          _visitor->reach(m);
alpar@100
  1454
          _reached->set(m, true);
alpar@100
  1455
          _list[++_list_back] = m;
alpar@100
  1456
          if (nm[m] && rnode == INVALID) rnode = m;
alpar@100
  1457
        } else {
alpar@100
  1458
          _visitor->examine(e);
alpar@100
  1459
        }
alpar@100
  1460
      }
alpar@100
  1461
      return n;
alpar@100
  1462
    }
alpar@100
  1463
alpar@100
  1464
    /// \brief Next node to be processed.
alpar@100
  1465
    ///
alpar@100
  1466
    /// Next node to be processed.
alpar@100
  1467
    ///
alpar@100
  1468
    /// \return The next node to be processed or INVALID if the stack is
alpar@100
  1469
    /// empty.
alpar@100
  1470
    Node nextNode() { 
alpar@100
  1471
      return _list_front != _list_back ? _list[_list_front + 1] : INVALID;
alpar@100
  1472
    }
alpar@100
  1473
alpar@100
  1474
    /// \brief Returns \c false if there are nodes
alpar@100
  1475
    /// to be processed in the queue
alpar@100
  1476
    ///
alpar@100
  1477
    /// Returns \c false if there are nodes
alpar@100
  1478
    /// to be processed in the queue
alpar@100
  1479
    bool emptyQueue() { return _list_front == _list_back; }
alpar@100
  1480
alpar@100
  1481
    /// \brief Returns the number of the nodes to be processed.
alpar@100
  1482
    ///
alpar@100
  1483
    /// Returns the number of the nodes to be processed in the queue.
alpar@100
  1484
    int queueSize() { return _list_back - _list_front; }
alpar@100
  1485
    
alpar@100
  1486
    /// \brief Executes the algorithm.
alpar@100
  1487
    ///
alpar@100
  1488
    /// Executes the algorithm.
alpar@100
  1489
    ///
alpar@100
  1490
    /// \pre init() must be called and at least one node should be added
alpar@100
  1491
    /// with addSource() before using this function.
alpar@100
  1492
    void start() {
alpar@100
  1493
      while ( !emptyQueue() ) processNextNode();
alpar@100
  1494
    }
alpar@100
  1495
    
alpar@100
  1496
    /// \brief Executes the algorithm until \c dest is reached.
alpar@100
  1497
    ///
alpar@100
  1498
    /// Executes the algorithm until \c dest is reached.
alpar@100
  1499
    ///
alpar@100
  1500
    /// \pre init() must be called and at least one node should be added
alpar@100
  1501
    /// with addSource() before using this function.
alpar@100
  1502
    void start(Node dest) {
alpar@100
  1503
      bool reach = false;
alpar@100
  1504
      while ( !emptyQueue() && !reach ) processNextNode(dest, reach);
alpar@100
  1505
    }
alpar@100
  1506
    
alpar@100
  1507
    /// \brief Executes the algorithm until a condition is met.
alpar@100
  1508
    ///
alpar@100
  1509
    /// Executes the algorithm until a condition is met.
alpar@100
  1510
    ///
alpar@100
  1511
    /// \pre init() must be called and at least one node should be added
alpar@100
  1512
    /// with addSource() before using this function.
alpar@100
  1513
    ///
alpar@100
  1514
    ///\param nm must be a bool (or convertible) node map. The
alpar@100
  1515
    ///algorithm will stop when it reaches a node \c v with
alpar@100
  1516
    /// <tt>nm[v]</tt> true.
alpar@100
  1517
    ///
alpar@100
  1518
    ///\return The reached node \c v with <tt>nm[v]</tt> true or
alpar@100
  1519
    ///\c INVALID if no such node was found.
alpar@100
  1520
    template <typename NM>
alpar@100
  1521
    Node start(const NM &nm) {
alpar@100
  1522
      Node rnode = INVALID;
alpar@100
  1523
      while ( !emptyQueue() && rnode == INVALID ) {
alpar@100
  1524
	processNextNode(nm, rnode);
alpar@100
  1525
      }
alpar@100
  1526
      return rnode;
alpar@100
  1527
    }
alpar@100
  1528
alpar@100
  1529
    /// \brief Runs %BFSVisit algorithm from node \c s.
alpar@100
  1530
    ///
alpar@100
  1531
    /// This method runs the %BFS algorithm from a root node \c s.
alpar@100
  1532
    /// \note b.run(s) is just a shortcut of the following code.
alpar@100
  1533
    ///\code
alpar@100
  1534
    ///   b.init();
alpar@100
  1535
    ///   b.addSource(s);
alpar@100
  1536
    ///   b.start();
alpar@100
  1537
    ///\endcode
alpar@100
  1538
    void run(Node s) {
alpar@100
  1539
      init();
alpar@100
  1540
      addSource(s);
alpar@100
  1541
      start();
alpar@100
  1542
    }
alpar@100
  1543
alpar@100
  1544
    /// \brief Runs %BFSVisit algorithm to visit all nodes in the digraph.
alpar@100
  1545
    ///    
alpar@100
  1546
    /// This method runs the %BFS algorithm in order to
alpar@100
  1547
    /// compute the %BFS path to each node. The algorithm computes
alpar@100
  1548
    /// - The %BFS tree.
alpar@100
  1549
    /// - The distance of each node from the root in the %BFS tree.
alpar@100
  1550
    ///
alpar@100
  1551
    ///\note b.run() is just a shortcut of the following code.
alpar@100
  1552
    ///\code
alpar@100
  1553
    ///  b.init();
alpar@100
  1554
    ///  for (NodeIt it(digraph); it != INVALID; ++it) {
alpar@100
  1555
    ///    if (!b.reached(it)) {
alpar@100
  1556
    ///      b.addSource(it);
alpar@100
  1557
    ///      b.start();
alpar@100
  1558
    ///    }
alpar@100
  1559
    ///  }
alpar@100
  1560
    ///\endcode
alpar@100
  1561
    void run() {
alpar@100
  1562
      init();
alpar@100
  1563
      for (NodeIt it(*_digraph); it != INVALID; ++it) {
alpar@100
  1564
        if (!reached(it)) {
alpar@100
  1565
          addSource(it);
alpar@100
  1566
          start();
alpar@100
  1567
        }
alpar@100
  1568
      }
alpar@100
  1569
    }
alpar@100
  1570
    ///@}
alpar@100
  1571
alpar@100
  1572
    /// \name Query Functions
alpar@100
  1573
    /// The result of the %BFS algorithm can be obtained using these
alpar@100
  1574
    /// functions.\n
alpar@100
  1575
    /// Before the use of these functions,
alpar@100
  1576
    /// either run() or start() must be called.
alpar@100
  1577
    ///@{
alpar@100
  1578
alpar@100
  1579
    /// \brief Checks if a node is reachable from the root.
alpar@100
  1580
    ///
alpar@100
  1581
    /// Returns \c true if \c v is reachable from the root(s).
alpar@100
  1582
    /// \warning The source nodes are inditated as unreachable.
alpar@100
  1583
    /// \pre Either \ref run() or \ref start()
alpar@100
  1584
    /// must be called before using this function.
alpar@100
  1585
    ///
alpar@100
  1586
    bool reached(Node v) { return (*_reached)[v]; }
alpar@100
  1587
    ///@}
alpar@100
  1588
  };
alpar@100
  1589
alpar@100
  1590
} //END OF NAMESPACE LEMON
alpar@100
  1591
alpar@100
  1592
#endif
alpar@100
  1593