alpar@209: /* -*- mode: C++; indent-tabs-mode: nil; -*-
alpar@100:  *
alpar@209:  * This file is a part of LEMON, a generic C++ optimization library.
alpar@100:  *
alpar@100:  * Copyright (C) 2003-2008
alpar@100:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@100:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
alpar@100:  *
alpar@100:  * Permission to use, modify and distribute this software is granted
alpar@100:  * provided that this copyright notice appears in all copies. For
alpar@100:  * precise terms see the accompanying LICENSE file.
alpar@100:  *
alpar@100:  * This software is provided "AS IS" with no warranty of any kind,
alpar@100:  * express or implied, and with no claim as to its suitability for any
alpar@100:  * purpose.
alpar@100:  *
alpar@100:  */
alpar@100: 
alpar@100: #ifndef LEMON_BFS_H
alpar@100: #define LEMON_BFS_H
alpar@100: 
alpar@100: ///\ingroup search
alpar@100: ///\file
kpeter@244: ///\brief BFS algorithm.
alpar@100: 
alpar@100: #include <lemon/list_graph.h>
alpar@100: #include <lemon/bits/path_dump.h>
deba@220: #include <lemon/core.h>
alpar@100: #include <lemon/error.h>
alpar@100: #include <lemon/maps.h>
kpeter@278: #include <lemon/path.h>
alpar@100: 
alpar@100: namespace lemon {
alpar@100: 
alpar@100:   ///Default traits class of Bfs class.
alpar@100: 
alpar@100:   ///Default traits class of Bfs class.
kpeter@157:   ///\tparam GR Digraph type.
alpar@100:   template<class GR>
alpar@100:   struct BfsDefaultTraits
alpar@100:   {
kpeter@244:     ///The type of the digraph the algorithm runs on.
alpar@100:     typedef GR Digraph;
kpeter@244: 
kpeter@244:     ///\brief The type of the map that stores the predecessor
alpar@100:     ///arcs of the shortest paths.
alpar@209:     ///
kpeter@244:     ///The type of the map that stores the predecessor
alpar@100:     ///arcs of the shortest paths.
alpar@100:     ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@244:     typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
kpeter@244:     ///Instantiates a \ref PredMap.
alpar@209: 
alpar@209:     ///This function instantiates a \ref PredMap.
kpeter@244:     ///\param g is the digraph, to which we would like to define the
kpeter@244:     ///\ref PredMap.
kpeter@244:     static PredMap *createPredMap(const Digraph &g)
alpar@100:     {
kpeter@244:       return new PredMap(g);
alpar@100:     }
kpeter@244: 
alpar@100:     ///The type of the map that indicates which nodes are processed.
alpar@209: 
alpar@100:     ///The type of the map that indicates which nodes are processed.
alpar@100:     ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
alpar@100:     typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
kpeter@244:     ///Instantiates a \ref ProcessedMap.
alpar@209: 
alpar@209:     ///This function instantiates a \ref ProcessedMap.
alpar@100:     ///\param g is the digraph, to which
alpar@100:     ///we would like to define the \ref ProcessedMap
alpar@100: #ifdef DOXYGEN
kpeter@244:     static ProcessedMap *createProcessedMap(const Digraph &g)
alpar@100: #else
kpeter@244:     static ProcessedMap *createProcessedMap(const Digraph &)
alpar@100: #endif
alpar@100:     {
alpar@100:       return new ProcessedMap();
alpar@100:     }
kpeter@244: 
alpar@100:     ///The type of the map that indicates which nodes are reached.
alpar@209: 
alpar@100:     ///The type of the map that indicates which nodes are reached.
kpeter@244:     ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
alpar@100:     typedef typename Digraph::template NodeMap<bool> ReachedMap;
kpeter@244:     ///Instantiates a \ref ReachedMap.
alpar@209: 
alpar@209:     ///This function instantiates a \ref ReachedMap.
kpeter@244:     ///\param g is the digraph, to which
alpar@100:     ///we would like to define the \ref ReachedMap.
kpeter@244:     static ReachedMap *createReachedMap(const Digraph &g)
alpar@100:     {
kpeter@244:       return new ReachedMap(g);
alpar@100:     }
alpar@209: 
kpeter@244:     ///The type of the map that stores the distances of the nodes.
kpeter@244: 
kpeter@244:     ///The type of the map that stores the distances of the nodes.
alpar@100:     ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
alpar@100:     typedef typename Digraph::template NodeMap<int> DistMap;
kpeter@244:     ///Instantiates a \ref DistMap.
alpar@209: 
alpar@209:     ///This function instantiates a \ref DistMap.
kpeter@244:     ///\param g is the digraph, to which we would like to define the
kpeter@244:     ///\ref DistMap.
kpeter@244:     static DistMap *createDistMap(const Digraph &g)
alpar@100:     {
kpeter@244:       return new DistMap(g);
alpar@100:     }
alpar@100:   };
alpar@209: 
alpar@100:   ///%BFS algorithm class.
alpar@209: 
alpar@100:   ///\ingroup search
alpar@100:   ///This class provides an efficient implementation of the %BFS algorithm.
alpar@100:   ///
kpeter@278:   ///There is also a \ref bfs() "function-type interface" for the BFS
kpeter@244:   ///algorithm, which is convenient in the simplier cases and it can be
kpeter@244:   ///used easier.
kpeter@244:   ///
kpeter@244:   ///\tparam GR The type of the digraph the algorithm runs on.
kpeter@244:   ///The default value is \ref ListDigraph. The value of GR is not used
kpeter@244:   ///directly by \ref Bfs, it is only passed to \ref BfsDefaultTraits.
kpeter@157:   ///\tparam TR Traits class to set various data types used by the algorithm.
alpar@100:   ///The default traits class is
alpar@100:   ///\ref BfsDefaultTraits "BfsDefaultTraits<GR>".
alpar@100:   ///See \ref BfsDefaultTraits for the documentation of
alpar@100:   ///a Bfs traits class.
alpar@100: #ifdef DOXYGEN
alpar@100:   template <typename GR,
alpar@209:             typename TR>
alpar@100: #else
alpar@100:   template <typename GR=ListDigraph,
alpar@209:             typename TR=BfsDefaultTraits<GR> >
alpar@100: #endif
alpar@100:   class Bfs {
alpar@100:   public:
kpeter@244:     ///\ref Exception for uninitialized parameters.
kpeter@244: 
kpeter@244:     ///This error represents problems in the initialization of the
kpeter@244:     ///parameters of the algorithm.
alpar@100:     class UninitializedParameter : public lemon::UninitializedParameter {
alpar@100:     public:
alpar@100:       virtual const char* what() const throw() {
alpar@209:         return "lemon::Bfs::UninitializedParameter";
alpar@100:       }
alpar@100:     };
alpar@100: 
kpeter@244:     ///The type of the digraph the algorithm runs on.
alpar@100:     typedef typename TR::Digraph Digraph;
alpar@209: 
kpeter@244:     ///\brief The type of the map that stores the predecessor arcs of the
kpeter@244:     ///shortest paths.
alpar@100:     typedef typename TR::PredMap PredMap;
kpeter@244:     ///The type of the map that stores the distances of the nodes.
kpeter@244:     typedef typename TR::DistMap DistMap;
kpeter@244:     ///The type of the map that indicates which nodes are reached.
alpar@100:     typedef typename TR::ReachedMap ReachedMap;
kpeter@244:     ///The type of the map that indicates which nodes are processed.
alpar@100:     typedef typename TR::ProcessedMap ProcessedMap;
kpeter@244:     ///The type of the paths.
kpeter@244:     typedef PredMapPath<Digraph, PredMap> Path;
kpeter@244: 
kpeter@244:     ///The traits class.
kpeter@244:     typedef TR Traits;
kpeter@244: 
alpar@100:   private:
alpar@100: 
alpar@100:     typedef typename Digraph::Node Node;
alpar@100:     typedef typename Digraph::NodeIt NodeIt;
alpar@100:     typedef typename Digraph::Arc Arc;
alpar@100:     typedef typename Digraph::OutArcIt OutArcIt;
alpar@100: 
kpeter@244:     //Pointer to the underlying digraph.
alpar@100:     const Digraph *G;
kpeter@244:     //Pointer to the map of predecessor arcs.
alpar@100:     PredMap *_pred;
kpeter@244:     //Indicates if _pred is locally allocated (true) or not.
alpar@100:     bool local_pred;
kpeter@244:     //Pointer to the map of distances.
alpar@100:     DistMap *_dist;
kpeter@244:     //Indicates if _dist is locally allocated (true) or not.
alpar@100:     bool local_dist;
kpeter@244:     //Pointer to the map of reached status of the nodes.
alpar@100:     ReachedMap *_reached;
kpeter@244:     //Indicates if _reached is locally allocated (true) or not.
alpar@100:     bool local_reached;
kpeter@244:     //Pointer to the map of processed status of the nodes.
alpar@100:     ProcessedMap *_processed;
kpeter@244:     //Indicates if _processed is locally allocated (true) or not.
alpar@100:     bool local_processed;
alpar@100: 
alpar@100:     std::vector<typename Digraph::Node> _queue;
alpar@100:     int _queue_head,_queue_tail,_queue_next_dist;
alpar@100:     int _curr_dist;
alpar@100: 
alpar@280:     //Creates the maps if necessary.
alpar@209:     void create_maps()
alpar@100:     {
alpar@100:       if(!_pred) {
alpar@209:         local_pred = true;
alpar@209:         _pred = Traits::createPredMap(*G);
alpar@100:       }
alpar@100:       if(!_dist) {
alpar@209:         local_dist = true;
alpar@209:         _dist = Traits::createDistMap(*G);
alpar@100:       }
alpar@100:       if(!_reached) {
alpar@209:         local_reached = true;
alpar@209:         _reached = Traits::createReachedMap(*G);
alpar@100:       }
alpar@100:       if(!_processed) {
alpar@209:         local_processed = true;
alpar@209:         _processed = Traits::createProcessedMap(*G);
alpar@100:       }
alpar@100:     }
alpar@100: 
alpar@100:   protected:
alpar@209: 
alpar@100:     Bfs() {}
alpar@209: 
alpar@100:   public:
alpar@209: 
alpar@100:     typedef Bfs Create;
alpar@100: 
alpar@100:     ///\name Named template parameters
alpar@100: 
alpar@100:     ///@{
alpar@100: 
alpar@100:     template <class T>
kpeter@257:     struct SetPredMapTraits : public Traits {
alpar@100:       typedef T PredMap;
alpar@209:       static PredMap *createPredMap(const Digraph &)
alpar@100:       {
alpar@209:         throw UninitializedParameter();
alpar@100:       }
alpar@100:     };
alpar@100:     ///\brief \ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref PredMap type.
alpar@100:     ///
kpeter@244:     ///\ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref PredMap type.
alpar@100:     template <class T>
kpeter@257:     struct SetPredMap : public Bfs< Digraph, SetPredMapTraits<T> > {
kpeter@257:       typedef Bfs< Digraph, SetPredMapTraits<T> > Create;
alpar@100:     };
alpar@209: 
alpar@100:     template <class T>
kpeter@257:     struct SetDistMapTraits : public Traits {
alpar@100:       typedef T DistMap;
alpar@209:       static DistMap *createDistMap(const Digraph &)
alpar@100:       {
alpar@209:         throw UninitializedParameter();
alpar@100:       }
alpar@100:     };
alpar@100:     ///\brief \ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref DistMap type.
alpar@100:     ///
kpeter@244:     ///\ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref DistMap type.
alpar@100:     template <class T>
kpeter@257:     struct SetDistMap : public Bfs< Digraph, SetDistMapTraits<T> > {
kpeter@257:       typedef Bfs< Digraph, SetDistMapTraits<T> > Create;
alpar@100:     };
alpar@209: 
alpar@100:     template <class T>
kpeter@257:     struct SetReachedMapTraits : public Traits {
alpar@100:       typedef T ReachedMap;
alpar@209:       static ReachedMap *createReachedMap(const Digraph &)
alpar@100:       {
alpar@209:         throw UninitializedParameter();
alpar@100:       }
alpar@100:     };
alpar@100:     ///\brief \ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref ReachedMap type.
alpar@100:     ///
kpeter@244:     ///\ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref ReachedMap type.
alpar@100:     template <class T>
kpeter@257:     struct SetReachedMap : public Bfs< Digraph, SetReachedMapTraits<T> > {
kpeter@257:       typedef Bfs< Digraph, SetReachedMapTraits<T> > Create;
alpar@100:     };
alpar@209: 
alpar@100:     template <class T>
kpeter@257:     struct SetProcessedMapTraits : public Traits {
alpar@100:       typedef T ProcessedMap;
alpar@209:       static ProcessedMap *createProcessedMap(const Digraph &)
alpar@100:       {
alpar@209:         throw UninitializedParameter();
alpar@100:       }
alpar@100:     };
alpar@100:     ///\brief \ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref ProcessedMap type.
alpar@100:     ///
kpeter@244:     ///\ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref ProcessedMap type.
alpar@100:     template <class T>
kpeter@257:     struct SetProcessedMap : public Bfs< Digraph, SetProcessedMapTraits<T> > {
kpeter@257:       typedef Bfs< Digraph, SetProcessedMapTraits<T> > Create;
alpar@100:     };
alpar@209: 
kpeter@257:     struct SetStandardProcessedMapTraits : public Traits {
alpar@100:       typedef typename Digraph::template NodeMap<bool> ProcessedMap;
kpeter@244:       static ProcessedMap *createProcessedMap(const Digraph &g)
alpar@100:       {
kpeter@244:         return new ProcessedMap(g);
alpar@100:       }
alpar@100:     };
kpeter@244:     ///\brief \ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
alpar@100:     ///
kpeter@244:     ///\ref named-templ-param "Named parameter" for setting
kpeter@244:     ///\ref ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
alpar@100:     ///If you don't set it explicitly, it will be automatically allocated.
kpeter@257:     struct SetStandardProcessedMap :
kpeter@257:       public Bfs< Digraph, SetStandardProcessedMapTraits > {
kpeter@257:       typedef Bfs< Digraph, SetStandardProcessedMapTraits > Create;
alpar@100:     };
alpar@209: 
alpar@100:     ///@}
alpar@100: 
alpar@209:   public:
alpar@209: 
alpar@100:     ///Constructor.
alpar@209: 
kpeter@244:     ///Constructor.
kpeter@244:     ///\param g The digraph the algorithm runs on.
kpeter@244:     Bfs(const Digraph &g) :
kpeter@244:       G(&g),
alpar@100:       _pred(NULL), local_pred(false),
alpar@100:       _dist(NULL), local_dist(false),
alpar@100:       _reached(NULL), local_reached(false),
alpar@100:       _processed(NULL), local_processed(false)
alpar@100:     { }
alpar@209: 
alpar@100:     ///Destructor.
alpar@209:     ~Bfs()
alpar@100:     {
alpar@100:       if(local_pred) delete _pred;
alpar@100:       if(local_dist) delete _dist;
alpar@100:       if(local_reached) delete _reached;
alpar@100:       if(local_processed) delete _processed;
alpar@100:     }
alpar@100: 
kpeter@244:     ///Sets the map that stores the predecessor arcs.
alpar@100: 
kpeter@244:     ///Sets the map that stores the predecessor arcs.
alpar@100:     ///If you don't use this function before calling \ref run(),
alpar@100:     ///it will allocate one. The destructor deallocates this
alpar@100:     ///automatically allocated map, of course.
alpar@100:     ///\return <tt> (*this) </tt>
alpar@209:     Bfs &predMap(PredMap &m)
alpar@100:     {
alpar@100:       if(local_pred) {
alpar@209:         delete _pred;
alpar@209:         local_pred=false;
alpar@100:       }
alpar@100:       _pred = &m;
alpar@100:       return *this;
alpar@100:     }
alpar@100: 
kpeter@244:     ///Sets the map that indicates which nodes are reached.
alpar@100: 
kpeter@244:     ///Sets the map that indicates which nodes are reached.
alpar@100:     ///If you don't use this function before calling \ref run(),
alpar@100:     ///it will allocate one. The destructor deallocates this
alpar@100:     ///automatically allocated map, of course.
alpar@100:     ///\return <tt> (*this) </tt>
alpar@209:     Bfs &reachedMap(ReachedMap &m)
alpar@100:     {
alpar@100:       if(local_reached) {
alpar@209:         delete _reached;
alpar@209:         local_reached=false;
alpar@100:       }
alpar@100:       _reached = &m;
alpar@100:       return *this;
alpar@100:     }
alpar@100: 
kpeter@244:     ///Sets the map that indicates which nodes are processed.
alpar@100: 
kpeter@244:     ///Sets the map that indicates which nodes are processed.
alpar@100:     ///If you don't use this function before calling \ref run(),
alpar@100:     ///it will allocate one. The destructor deallocates this
alpar@100:     ///automatically allocated map, of course.
alpar@100:     ///\return <tt> (*this) </tt>
alpar@209:     Bfs &processedMap(ProcessedMap &m)
alpar@100:     {
alpar@100:       if(local_processed) {
alpar@209:         delete _processed;
alpar@209:         local_processed=false;
alpar@100:       }
alpar@100:       _processed = &m;
alpar@100:       return *this;
alpar@100:     }
alpar@100: 
kpeter@244:     ///Sets the map that stores the distances of the nodes.
alpar@100: 
kpeter@244:     ///Sets the map that stores the distances of the nodes calculated by
kpeter@244:     ///the algorithm.
alpar@100:     ///If you don't use this function before calling \ref run(),
alpar@100:     ///it will allocate one. The destructor deallocates this
alpar@100:     ///automatically allocated map, of course.
alpar@100:     ///\return <tt> (*this) </tt>
alpar@209:     Bfs &distMap(DistMap &m)
alpar@100:     {
alpar@100:       if(local_dist) {
alpar@209:         delete _dist;
alpar@209:         local_dist=false;
alpar@100:       }
alpar@100:       _dist = &m;
alpar@100:       return *this;
alpar@100:     }
alpar@100: 
alpar@100:   public:
kpeter@244: 
alpar@100:     ///\name Execution control
alpar@100:     ///The simplest way to execute the algorithm is to use
kpeter@244:     ///one of the member functions called \ref lemon::Bfs::run() "run()".
alpar@100:     ///\n
kpeter@244:     ///If you need more control on the execution, first you must call
kpeter@244:     ///\ref lemon::Bfs::init() "init()", then you can add several source
kpeter@244:     ///nodes with \ref lemon::Bfs::addSource() "addSource()".
kpeter@244:     ///Finally \ref lemon::Bfs::start() "start()" will perform the
kpeter@244:     ///actual path computation.
alpar@100: 
alpar@100:     ///@{
alpar@100: 
kpeter@244:     ///Initializes the internal data structures.
kpeter@244: 
alpar@100:     ///Initializes the internal data structures.
alpar@100:     ///
alpar@100:     void init()
alpar@100:     {
alpar@100:       create_maps();
alpar@100:       _queue.resize(countNodes(*G));
alpar@100:       _queue_head=_queue_tail=0;
alpar@100:       _curr_dist=1;
alpar@100:       for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
alpar@209:         _pred->set(u,INVALID);
alpar@209:         _reached->set(u,false);
alpar@209:         _processed->set(u,false);
alpar@100:       }
alpar@100:     }
alpar@209: 
alpar@100:     ///Adds a new source node.
alpar@100: 
alpar@100:     ///Adds a new source node to the set of nodes to be processed.
alpar@100:     ///
alpar@100:     void addSource(Node s)
alpar@100:     {
alpar@100:       if(!(*_reached)[s])
alpar@209:         {
alpar@209:           _reached->set(s,true);
alpar@209:           _pred->set(s,INVALID);
alpar@209:           _dist->set(s,0);
alpar@209:           _queue[_queue_head++]=s;
alpar@209:           _queue_next_dist=_queue_head;
alpar@209:         }
alpar@100:     }
alpar@209: 
alpar@100:     ///Processes the next node.
alpar@100: 
alpar@100:     ///Processes the next node.
alpar@100:     ///
alpar@100:     ///\return The processed node.
alpar@100:     ///
kpeter@244:     ///\pre The queue must not be empty.
alpar@100:     Node processNextNode()
alpar@100:     {
alpar@100:       if(_queue_tail==_queue_next_dist) {
alpar@209:         _curr_dist++;
alpar@209:         _queue_next_dist=_queue_head;
alpar@100:       }
alpar@100:       Node n=_queue[_queue_tail++];
alpar@100:       _processed->set(n,true);
alpar@100:       Node m;
alpar@100:       for(OutArcIt e(*G,n);e!=INVALID;++e)
alpar@209:         if(!(*_reached)[m=G->target(e)]) {
alpar@209:           _queue[_queue_head++]=m;
alpar@209:           _reached->set(m,true);
alpar@209:           _pred->set(m,e);
alpar@209:           _dist->set(m,_curr_dist);
alpar@209:         }
alpar@100:       return n;
alpar@100:     }
alpar@100: 
alpar@100:     ///Processes the next node.
alpar@100: 
kpeter@244:     ///Processes the next node and checks if the given target node
alpar@100:     ///is reached. If the target node is reachable from the processed
kpeter@244:     ///node, then the \c reach parameter will be set to \c true.
alpar@100:     ///
alpar@100:     ///\param target The target node.
kpeter@244:     ///\retval reach Indicates if the target node is reached.
kpeter@244:     ///It should be initially \c false.
kpeter@244:     ///
alpar@100:     ///\return The processed node.
alpar@100:     ///
kpeter@244:     ///\pre The queue must not be empty.
alpar@100:     Node processNextNode(Node target, bool& reach)
alpar@100:     {
alpar@100:       if(_queue_tail==_queue_next_dist) {
alpar@209:         _curr_dist++;
alpar@209:         _queue_next_dist=_queue_head;
alpar@100:       }
alpar@100:       Node n=_queue[_queue_tail++];
alpar@100:       _processed->set(n,true);
alpar@100:       Node m;
alpar@100:       for(OutArcIt e(*G,n);e!=INVALID;++e)
alpar@209:         if(!(*_reached)[m=G->target(e)]) {
alpar@209:           _queue[_queue_head++]=m;
alpar@209:           _reached->set(m,true);
alpar@209:           _pred->set(m,e);
alpar@209:           _dist->set(m,_curr_dist);
alpar@100:           reach = reach || (target == m);
alpar@209:         }
alpar@100:       return n;
alpar@100:     }
alpar@100: 
alpar@100:     ///Processes the next node.
alpar@100: 
kpeter@244:     ///Processes the next node and checks if at least one of reached
kpeter@244:     ///nodes has \c true value in the \c nm node map. If one node
kpeter@244:     ///with \c true value is reachable from the processed node, then the
kpeter@244:     ///\c rnode parameter will be set to the first of such nodes.
alpar@100:     ///
kpeter@244:     ///\param nm A \c bool (or convertible) node map that indicates the
kpeter@244:     ///possible targets.
alpar@100:     ///\retval rnode The reached target node.
kpeter@244:     ///It should be initially \c INVALID.
kpeter@244:     ///
alpar@100:     ///\return The processed node.
alpar@100:     ///
kpeter@244:     ///\pre The queue must not be empty.
alpar@100:     template<class NM>
alpar@100:     Node processNextNode(const NM& nm, Node& rnode)
alpar@100:     {
alpar@100:       if(_queue_tail==_queue_next_dist) {
alpar@209:         _curr_dist++;
alpar@209:         _queue_next_dist=_queue_head;
alpar@100:       }
alpar@100:       Node n=_queue[_queue_tail++];
alpar@100:       _processed->set(n,true);
alpar@100:       Node m;
alpar@100:       for(OutArcIt e(*G,n);e!=INVALID;++e)
alpar@209:         if(!(*_reached)[m=G->target(e)]) {
alpar@209:           _queue[_queue_head++]=m;
alpar@209:           _reached->set(m,true);
alpar@209:           _pred->set(m,e);
alpar@209:           _dist->set(m,_curr_dist);
alpar@209:           if (nm[m] && rnode == INVALID) rnode = m;
alpar@209:         }
alpar@100:       return n;
alpar@100:     }
alpar@209: 
kpeter@244:     ///The next node to be processed.
alpar@100: 
kpeter@244:     ///Returns the next node to be processed or \c INVALID if the queue
kpeter@244:     ///is empty.
kpeter@244:     Node nextNode() const
alpar@209:     {
alpar@100:       return _queue_tail<_queue_head?_queue[_queue_tail]:INVALID;
alpar@100:     }
alpar@209: 
alpar@100:     ///\brief Returns \c false if there are nodes
kpeter@244:     ///to be processed.
alpar@100:     ///
alpar@100:     ///Returns \c false if there are nodes
kpeter@244:     ///to be processed in the queue.
kpeter@244:     bool emptyQueue() const { return _queue_tail==_queue_head; }
kpeter@244: 
alpar@100:     ///Returns the number of the nodes to be processed.
alpar@209: 
alpar@100:     ///Returns the number of the nodes to be processed in the queue.
kpeter@244:     int queueSize() const { return _queue_head-_queue_tail; }
alpar@209: 
alpar@100:     ///Executes the algorithm.
alpar@100: 
alpar@100:     ///Executes the algorithm.
alpar@100:     ///
kpeter@244:     ///This method runs the %BFS algorithm from the root node(s)
kpeter@244:     ///in order to compute the shortest path to each node.
alpar@100:     ///
kpeter@244:     ///The algorithm computes
kpeter@244:     ///- the shortest path tree (forest),
kpeter@244:     ///- the distance of each node from the root(s).
kpeter@244:     ///
kpeter@244:     ///\pre init() must be called and at least one root node should be
kpeter@244:     ///added with addSource() before using this function.
kpeter@244:     ///
kpeter@244:     ///\note <tt>b.start()</tt> is just a shortcut of the following code.
kpeter@244:     ///\code
kpeter@244:     ///  while ( !b.emptyQueue() ) {
kpeter@244:     ///    b.processNextNode();
kpeter@244:     ///  }
kpeter@244:     ///\endcode
alpar@100:     void start()
alpar@100:     {
alpar@100:       while ( !emptyQueue() ) processNextNode();
alpar@100:     }
alpar@209: 
kpeter@244:     ///Executes the algorithm until the given target node is reached.
alpar@100: 
kpeter@244:     ///Executes the algorithm until the given target node is reached.
alpar@100:     ///
alpar@100:     ///This method runs the %BFS algorithm from the root node(s)
kpeter@286:     ///in order to compute the shortest path to \c t.
kpeter@244:     ///
alpar@100:     ///The algorithm computes
kpeter@286:     ///- the shortest path to \c t,
kpeter@286:     ///- the distance of \c t from the root(s).
kpeter@244:     ///
kpeter@244:     ///\pre init() must be called and at least one root node should be
kpeter@244:     ///added with addSource() before using this function.
kpeter@244:     ///
kpeter@244:     ///\note <tt>b.start(t)</tt> is just a shortcut of the following code.
kpeter@244:     ///\code
kpeter@244:     ///  bool reach = false;
kpeter@244:     ///  while ( !b.emptyQueue() && !reach ) {
kpeter@244:     ///    b.processNextNode(t, reach);
kpeter@244:     ///  }
kpeter@244:     ///\endcode
kpeter@286:     void start(Node t)
alpar@100:     {
alpar@100:       bool reach = false;
kpeter@286:       while ( !emptyQueue() && !reach ) processNextNode(t, reach);
alpar@100:     }
alpar@209: 
alpar@100:     ///Executes the algorithm until a condition is met.
alpar@100: 
alpar@100:     ///Executes the algorithm until a condition is met.
alpar@100:     ///
kpeter@244:     ///This method runs the %BFS algorithm from the root node(s) in
kpeter@244:     ///order to compute the shortest path to a node \c v with
kpeter@244:     /// <tt>nm[v]</tt> true, if such a node can be found.
alpar@100:     ///
kpeter@244:     ///\param nm A \c bool (or convertible) node map. The algorithm
kpeter@244:     ///will stop when it reaches a node \c v with <tt>nm[v]</tt> true.
alpar@100:     ///
alpar@100:     ///\return The reached node \c v with <tt>nm[v]</tt> true or
alpar@100:     ///\c INVALID if no such node was found.
kpeter@244:     ///
kpeter@244:     ///\pre init() must be called and at least one root node should be
kpeter@244:     ///added with addSource() before using this function.
kpeter@244:     ///
kpeter@244:     ///\note <tt>b.start(nm)</tt> is just a shortcut of the following code.
kpeter@244:     ///\code
kpeter@244:     ///  Node rnode = INVALID;
kpeter@244:     ///  while ( !b.emptyQueue() && rnode == INVALID ) {
kpeter@244:     ///    b.processNextNode(nm, rnode);
kpeter@244:     ///  }
kpeter@244:     ///  return rnode;
kpeter@244:     ///\endcode
kpeter@244:     template<class NodeBoolMap>
kpeter@244:     Node start(const NodeBoolMap &nm)
alpar@100:     {
alpar@100:       Node rnode = INVALID;
alpar@100:       while ( !emptyQueue() && rnode == INVALID ) {
alpar@209:         processNextNode(nm, rnode);
alpar@100:       }
alpar@100:       return rnode;
alpar@100:     }
alpar@209: 
kpeter@286:     ///Runs the algorithm from the given source node.
alpar@209: 
kpeter@244:     ///This method runs the %BFS algorithm from node \c s
kpeter@244:     ///in order to compute the shortest path to each node.
alpar@100:     ///
kpeter@244:     ///The algorithm computes
kpeter@244:     ///- the shortest path tree,
kpeter@244:     ///- the distance of each node from the root.
kpeter@244:     ///
kpeter@244:     ///\note <tt>b.run(s)</tt> is just a shortcut of the following code.
alpar@100:     ///\code
alpar@100:     ///  b.init();
alpar@100:     ///  b.addSource(s);
alpar@100:     ///  b.start();
alpar@100:     ///\endcode
alpar@100:     void run(Node s) {
alpar@100:       init();
alpar@100:       addSource(s);
alpar@100:       start();
alpar@100:     }
alpar@209: 
alpar@100:     ///Finds the shortest path between \c s and \c t.
alpar@209: 
kpeter@244:     ///This method runs the %BFS algorithm from node \c s
kpeter@286:     ///in order to compute the shortest path to node \c t
kpeter@286:     ///(it stops searching when \c t is processed).
alpar@100:     ///
kpeter@286:     ///\return \c true if \c t is reachable form \c s.
kpeter@244:     ///
kpeter@244:     ///\note Apart from the return value, <tt>b.run(s,t)</tt> is just a
kpeter@244:     ///shortcut of the following code.
alpar@100:     ///\code
alpar@100:     ///  b.init();
alpar@100:     ///  b.addSource(s);
alpar@100:     ///  b.start(t);
alpar@100:     ///\endcode
kpeter@286:     bool run(Node s,Node t) {
alpar@100:       init();
alpar@100:       addSource(s);
alpar@100:       start(t);
kpeter@286:       return reached(t);
alpar@100:     }
alpar@209: 
kpeter@244:     ///Runs the algorithm to visit all nodes in the digraph.
kpeter@244: 
kpeter@244:     ///This method runs the %BFS algorithm in order to
kpeter@244:     ///compute the shortest path to each node.
kpeter@244:     ///
kpeter@244:     ///The algorithm computes
kpeter@244:     ///- the shortest path tree (forest),
kpeter@244:     ///- the distance of each node from the root(s).
kpeter@244:     ///
kpeter@244:     ///\note <tt>b.run(s)</tt> is just a shortcut of the following code.
kpeter@244:     ///\code
kpeter@244:     ///  b.init();
kpeter@244:     ///  for (NodeIt n(gr); n != INVALID; ++n) {
kpeter@244:     ///    if (!b.reached(n)) {
kpeter@244:     ///      b.addSource(n);
kpeter@244:     ///      b.start();
kpeter@244:     ///    }
kpeter@244:     ///  }
kpeter@244:     ///\endcode
kpeter@244:     void run() {
kpeter@244:       init();
kpeter@244:       for (NodeIt n(*G); n != INVALID; ++n) {
kpeter@244:         if (!reached(n)) {
kpeter@244:           addSource(n);
kpeter@244:           start();
kpeter@244:         }
kpeter@244:       }
kpeter@244:     }
kpeter@244: 
alpar@100:     ///@}
alpar@100: 
alpar@100:     ///\name Query Functions
alpar@100:     ///The result of the %BFS algorithm can be obtained using these
alpar@100:     ///functions.\n
kpeter@244:     ///Either \ref lemon::Bfs::run() "run()" or \ref lemon::Bfs::start()
kpeter@244:     ///"start()" must be called before using them.
alpar@209: 
alpar@100:     ///@{
alpar@100: 
kpeter@244:     ///The shortest path to a node.
alpar@100: 
kpeter@244:     ///Returns the shortest path to a node.
kpeter@244:     ///
kpeter@244:     ///\warning \c t should be reachable from the root(s).
kpeter@244:     ///
kpeter@244:     ///\pre Either \ref run() or \ref start() must be called before
kpeter@244:     ///using this function.
kpeter@244:     Path path(Node t) const { return Path(*G, *_pred, t); }
alpar@100: 
alpar@100:     ///The distance of a node from the root(s).
alpar@100: 
alpar@100:     ///Returns the distance of a node from the root(s).
kpeter@244:     ///
kpeter@244:     ///\warning If node \c v is not reachable from the root(s), then
kpeter@244:     ///the return value of this function is undefined.
kpeter@244:     ///
kpeter@244:     ///\pre Either \ref run() or \ref start() must be called before
kpeter@244:     ///using this function.
alpar@100:     int dist(Node v) const { return (*_dist)[v]; }
alpar@100: 
kpeter@244:     ///Returns the 'previous arc' of the shortest path tree for a node.
alpar@100: 
kpeter@244:     ///This function returns the 'previous arc' of the shortest path
kpeter@244:     ///tree for the node \c v, i.e. it returns the last arc of a
kpeter@244:     ///shortest path from the root(s) to \c v. It is \c INVALID if \c v
kpeter@244:     ///is not reachable from the root(s) or if \c v is a root.
kpeter@244:     ///
kpeter@244:     ///The shortest path tree used here is equal to the shortest path
kpeter@244:     ///tree used in \ref predNode().
kpeter@244:     ///
kpeter@244:     ///\pre Either \ref run() or \ref start() must be called before
kpeter@244:     ///using this function.
alpar@100:     Arc predArc(Node v) const { return (*_pred)[v];}
alpar@100: 
kpeter@244:     ///Returns the 'previous node' of the shortest path tree for a node.
alpar@100: 
kpeter@244:     ///This function returns the 'previous node' of the shortest path
kpeter@244:     ///tree for the node \c v, i.e. it returns the last but one node
kpeter@244:     ///from a shortest path from the root(s) to \c v. It is \c INVALID
kpeter@244:     ///if \c v is not reachable from the root(s) or if \c v is a root.
kpeter@244:     ///
alpar@100:     ///The shortest path tree used here is equal to the shortest path
alpar@100:     ///tree used in \ref predArc().
kpeter@244:     ///
alpar@100:     ///\pre Either \ref run() or \ref start() must be called before
alpar@100:     ///using this function.
alpar@100:     Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
alpar@209:                                   G->source((*_pred)[v]); }
alpar@209: 
kpeter@244:     ///\brief Returns a const reference to the node map that stores the
kpeter@244:     /// distances of the nodes.
kpeter@244:     ///
kpeter@244:     ///Returns a const reference to the node map that stores the distances
kpeter@244:     ///of the nodes calculated by the algorithm.
kpeter@244:     ///
kpeter@244:     ///\pre Either \ref run() or \ref init()
kpeter@244:     ///must be called before using this function.
alpar@100:     const DistMap &distMap() const { return *_dist;}
alpar@209: 
kpeter@244:     ///\brief Returns a const reference to the node map that stores the
kpeter@244:     ///predecessor arcs.
kpeter@244:     ///
kpeter@244:     ///Returns a const reference to the node map that stores the predecessor
kpeter@244:     ///arcs, which form the shortest path tree.
kpeter@244:     ///
alpar@100:     ///\pre Either \ref run() or \ref init()
alpar@100:     ///must be called before using this function.
alpar@100:     const PredMap &predMap() const { return *_pred;}
alpar@209: 
kpeter@244:     ///Checks if a node is reachable from the root(s).
alpar@100: 
kpeter@244:     ///Returns \c true if \c v is reachable from the root(s).
alpar@100:     ///\pre Either \ref run() or \ref start()
alpar@100:     ///must be called before using this function.
kpeter@244:     bool reached(Node v) const { return (*_reached)[v]; }
alpar@209: 
alpar@100:     ///@}
alpar@100:   };
alpar@100: 
kpeter@244:   ///Default traits class of bfs() function.
alpar@100: 
kpeter@244:   ///Default traits class of bfs() function.
kpeter@157:   ///\tparam GR Digraph type.
alpar@100:   template<class GR>
alpar@100:   struct BfsWizardDefaultTraits
alpar@100:   {
kpeter@244:     ///The type of the digraph the algorithm runs on.
alpar@100:     typedef GR Digraph;
kpeter@244: 
kpeter@244:     ///\brief The type of the map that stores the predecessor
alpar@100:     ///arcs of the shortest paths.
alpar@209:     ///
kpeter@244:     ///The type of the map that stores the predecessor
alpar@100:     ///arcs of the shortest paths.
alpar@100:     ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@278:     typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
kpeter@244:     ///Instantiates a \ref PredMap.
alpar@209: 
alpar@209:     ///This function instantiates a \ref PredMap.
kpeter@244:     ///\param g is the digraph, to which we would like to define the
kpeter@244:     ///\ref PredMap.
kpeter@244:     static PredMap *createPredMap(const Digraph &g)
alpar@100:     {
kpeter@278:       return new PredMap(g);
alpar@100:     }
alpar@100: 
alpar@100:     ///The type of the map that indicates which nodes are processed.
alpar@209: 
alpar@100:     ///The type of the map that indicates which nodes are processed.
alpar@100:     ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@278:     ///By default it is a NullMap.
alpar@100:     typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
kpeter@244:     ///Instantiates a \ref ProcessedMap.
alpar@209: 
alpar@209:     ///This function instantiates a \ref ProcessedMap.
alpar@100:     ///\param g is the digraph, to which
kpeter@244:     ///we would like to define the \ref ProcessedMap.
alpar@100: #ifdef DOXYGEN
kpeter@244:     static ProcessedMap *createProcessedMap(const Digraph &g)
alpar@100: #else
kpeter@244:     static ProcessedMap *createProcessedMap(const Digraph &)
alpar@100: #endif
alpar@100:     {
alpar@100:       return new ProcessedMap();
alpar@100:     }
kpeter@244: 
alpar@100:     ///The type of the map that indicates which nodes are reached.
alpar@209: 
alpar@100:     ///The type of the map that indicates which nodes are reached.
kpeter@244:     ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
alpar@100:     typedef typename Digraph::template NodeMap<bool> ReachedMap;
kpeter@244:     ///Instantiates a \ref ReachedMap.
alpar@209: 
alpar@209:     ///This function instantiates a \ref ReachedMap.
kpeter@244:     ///\param g is the digraph, to which
alpar@100:     ///we would like to define the \ref ReachedMap.
kpeter@244:     static ReachedMap *createReachedMap(const Digraph &g)
alpar@100:     {
kpeter@244:       return new ReachedMap(g);
alpar@100:     }
alpar@209: 
kpeter@244:     ///The type of the map that stores the distances of the nodes.
kpeter@244: 
kpeter@244:     ///The type of the map that stores the distances of the nodes.
alpar@100:     ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@278:     typedef typename Digraph::template NodeMap<int> DistMap;
kpeter@244:     ///Instantiates a \ref DistMap.
alpar@209: 
alpar@209:     ///This function instantiates a \ref DistMap.
alpar@210:     ///\param g is the digraph, to which we would like to define
alpar@210:     ///the \ref DistMap
kpeter@244:     static DistMap *createDistMap(const Digraph &g)
alpar@100:     {
kpeter@278:       return new DistMap(g);
alpar@100:     }
kpeter@278: 
kpeter@278:     ///The type of the shortest paths.
kpeter@278: 
kpeter@278:     ///The type of the shortest paths.
kpeter@278:     ///It must meet the \ref concepts::Path "Path" concept.
kpeter@278:     typedef lemon::Path<Digraph> Path;
alpar@100:   };
alpar@209: 
kpeter@244:   /// Default traits class used by \ref BfsWizard
alpar@100: 
alpar@100:   /// To make it easier to use Bfs algorithm
kpeter@244:   /// we have created a wizard class.
alpar@100:   /// This \ref BfsWizard class needs default traits,
kpeter@244:   /// as well as the \ref Bfs class.
alpar@100:   /// The \ref BfsWizardBase is a class to be the default traits of the
alpar@100:   /// \ref BfsWizard class.
alpar@100:   template<class GR>
alpar@100:   class BfsWizardBase : public BfsWizardDefaultTraits<GR>
alpar@100:   {
alpar@100: 
alpar@100:     typedef BfsWizardDefaultTraits<GR> Base;
alpar@100:   protected:
kpeter@244:     //The type of the nodes in the digraph.
alpar@100:     typedef typename Base::Digraph::Node Node;
alpar@100: 
kpeter@244:     //Pointer to the digraph the algorithm runs on.
alpar@100:     void *_g;
kpeter@244:     //Pointer to the map of reached nodes.
alpar@100:     void *_reached;
kpeter@244:     //Pointer to the map of processed nodes.
alpar@100:     void *_processed;
kpeter@244:     //Pointer to the map of predecessors arcs.
alpar@100:     void *_pred;
kpeter@244:     //Pointer to the map of distances.
alpar@100:     void *_dist;
kpeter@278:     //Pointer to the shortest path to the target node.
kpeter@278:     void *_path;
kpeter@278:     //Pointer to the distance of the target node.
kpeter@278:     int *_di;
alpar@209: 
alpar@100:     public:
alpar@100:     /// Constructor.
alpar@209: 
alpar@100:     /// This constructor does not require parameters, therefore it initiates
kpeter@278:     /// all of the attributes to \c 0.
alpar@100:     BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0),
kpeter@278:                       _dist(0), _path(0), _di(0) {}
alpar@100: 
alpar@100:     /// Constructor.
alpar@209: 
kpeter@278:     /// This constructor requires one parameter,
kpeter@278:     /// others are initiated to \c 0.
kpeter@244:     /// \param g The digraph the algorithm runs on.
kpeter@278:     BfsWizardBase(const GR &g) :
alpar@209:       _g(reinterpret_cast<void*>(const_cast<GR*>(&g))),
kpeter@278:       _reached(0), _processed(0), _pred(0), _dist(0),  _path(0), _di(0) {}
alpar@100: 
alpar@100:   };
alpar@209: 
kpeter@278:   /// Auxiliary class for the function-type interface of BFS algorithm.
alpar@100: 
kpeter@278:   /// This auxiliary class is created to implement the
kpeter@278:   /// \ref bfs() "function-type interface" of \ref Bfs algorithm.
kpeter@278:   /// It does not have own \ref run() method, it uses the functions
kpeter@278:   /// and features of the plain \ref Bfs.
alpar@100:   ///
kpeter@278:   /// This class should only be used through the \ref bfs() function,
kpeter@278:   /// which makes it easier to use the algorithm.
alpar@100:   template<class TR>
alpar@100:   class BfsWizard : public TR
alpar@100:   {
alpar@100:     typedef TR Base;
alpar@100: 
kpeter@244:     ///The type of the digraph the algorithm runs on.
alpar@100:     typedef typename TR::Digraph Digraph;
kpeter@244: 
alpar@100:     typedef typename Digraph::Node Node;
alpar@100:     typedef typename Digraph::NodeIt NodeIt;
alpar@100:     typedef typename Digraph::Arc Arc;
alpar@100:     typedef typename Digraph::OutArcIt OutArcIt;
alpar@209: 
kpeter@244:     ///\brief The type of the map that stores the predecessor
alpar@100:     ///arcs of the shortest paths.
alpar@100:     typedef typename TR::PredMap PredMap;
kpeter@244:     ///\brief The type of the map that stores the distances of the nodes.
alpar@100:     typedef typename TR::DistMap DistMap;
kpeter@244:     ///\brief The type of the map that indicates which nodes are reached.
kpeter@244:     typedef typename TR::ReachedMap ReachedMap;
kpeter@244:     ///\brief The type of the map that indicates which nodes are processed.
kpeter@244:     typedef typename TR::ProcessedMap ProcessedMap;
kpeter@278:     ///The type of the shortest paths
kpeter@278:     typedef typename TR::Path Path;
alpar@100: 
alpar@100:   public:
kpeter@244: 
alpar@100:     /// Constructor.
alpar@100:     BfsWizard() : TR() {}
alpar@100: 
alpar@100:     /// Constructor that requires parameters.
alpar@100: 
alpar@100:     /// Constructor that requires parameters.
alpar@100:     /// These parameters will be the default values for the traits class.
kpeter@278:     /// \param g The digraph the algorithm runs on.
kpeter@278:     BfsWizard(const Digraph &g) :
kpeter@278:       TR(g) {}
alpar@100: 
alpar@100:     ///Copy constructor
alpar@100:     BfsWizard(const TR &b) : TR(b) {}
alpar@100: 
alpar@100:     ~BfsWizard() {}
alpar@100: 
kpeter@278:     ///Runs BFS algorithm from the given source node.
alpar@209: 
kpeter@278:     ///This method runs BFS algorithm from node \c s
kpeter@278:     ///in order to compute the shortest path to each node.
kpeter@278:     void run(Node s)
kpeter@278:     {
kpeter@278:       Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
kpeter@278:       if (Base::_pred)
kpeter@278:         alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@278:       if (Base::_dist)
kpeter@278:         alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@278:       if (Base::_reached)
kpeter@278:         alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
kpeter@278:       if (Base::_processed)
kpeter@278:         alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
kpeter@278:       if (s!=INVALID)
kpeter@278:         alg.run(s);
kpeter@278:       else
kpeter@278:         alg.run();
kpeter@278:     }
kpeter@278: 
kpeter@278:     ///Finds the shortest path between \c s and \c t.
kpeter@278: 
kpeter@278:     ///This method runs BFS algorithm from node \c s
kpeter@278:     ///in order to compute the shortest path to node \c t
kpeter@278:     ///(it stops searching when \c t is processed).
kpeter@278:     ///
kpeter@278:     ///\return \c true if \c t is reachable form \c s.
kpeter@278:     bool run(Node s, Node t)
kpeter@278:     {
kpeter@278:       if (s==INVALID || t==INVALID) throw UninitializedParameter();
kpeter@278:       Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
kpeter@278:       if (Base::_pred)
kpeter@278:         alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@278:       if (Base::_dist)
kpeter@278:         alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@278:       if (Base::_reached)
kpeter@278:         alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
kpeter@278:       if (Base::_processed)
kpeter@278:         alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
kpeter@278:       alg.run(s,t);
kpeter@278:       if (Base::_path)
kpeter@278:         *reinterpret_cast<Path*>(Base::_path) = alg.path(t);
kpeter@278:       if (Base::_di)
kpeter@278:         *Base::_di = alg.dist(t);
kpeter@278:       return alg.reached(t);
kpeter@278:     }
kpeter@278: 
kpeter@278:     ///Runs BFS algorithm to visit all nodes in the digraph.
kpeter@278: 
kpeter@278:     ///This method runs BFS algorithm in order to compute
kpeter@278:     ///the shortest path to each node.
alpar@100:     void run()
alpar@100:     {
kpeter@278:       run(INVALID);
alpar@100:     }
alpar@209: 
kpeter@244:     template<class T>
kpeter@257:     struct SetPredMapBase : public Base {
kpeter@244:       typedef T PredMap;
kpeter@244:       static PredMap *createPredMap(const Digraph &) { return 0; };
kpeter@257:       SetPredMapBase(const TR &b) : TR(b) {}
kpeter@244:     };
kpeter@278:     ///\brief \ref named-func-param "Named parameter"
kpeter@244:     ///for setting \ref PredMap object.
kpeter@244:     ///
kpeter@278:     ///\ref named-func-param "Named parameter"
kpeter@244:     ///for setting \ref PredMap object.
kpeter@244:     template<class T>
kpeter@257:     BfsWizard<SetPredMapBase<T> > predMap(const T &t)
kpeter@244:     {
kpeter@244:       Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@257:       return BfsWizard<SetPredMapBase<T> >(*this);
kpeter@244:     }
kpeter@244: 
kpeter@244:     template<class T>
kpeter@257:     struct SetReachedMapBase : public Base {
kpeter@244:       typedef T ReachedMap;
kpeter@244:       static ReachedMap *createReachedMap(const Digraph &) { return 0; };
kpeter@257:       SetReachedMapBase(const TR &b) : TR(b) {}
kpeter@244:     };
kpeter@278:     ///\brief \ref named-func-param "Named parameter"
kpeter@244:     ///for setting \ref ReachedMap object.
kpeter@244:     ///
kpeter@278:     /// \ref named-func-param "Named parameter"
kpeter@244:     ///for setting \ref ReachedMap object.
kpeter@244:     template<class T>
kpeter@257:     BfsWizard<SetReachedMapBase<T> > reachedMap(const T &t)
kpeter@244:     {
kpeter@244:       Base::_reached=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@257:       return BfsWizard<SetReachedMapBase<T> >(*this);
kpeter@244:     }
kpeter@244: 
kpeter@244:     template<class T>
kpeter@278:     struct SetDistMapBase : public Base {
kpeter@278:       typedef T DistMap;
kpeter@278:       static DistMap *createDistMap(const Digraph &) { return 0; };
kpeter@278:       SetDistMapBase(const TR &b) : TR(b) {}
kpeter@278:     };
kpeter@278:     ///\brief \ref named-func-param "Named parameter"
kpeter@278:     ///for setting \ref DistMap object.
kpeter@278:     ///
kpeter@278:     /// \ref named-func-param "Named parameter"
kpeter@278:     ///for setting \ref DistMap object.
kpeter@278:     template<class T>
kpeter@278:     BfsWizard<SetDistMapBase<T> > distMap(const T &t)
kpeter@278:     {
kpeter@278:       Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@278:       return BfsWizard<SetDistMapBase<T> >(*this);
kpeter@278:     }
kpeter@278: 
kpeter@278:     template<class T>
kpeter@257:     struct SetProcessedMapBase : public Base {
kpeter@244:       typedef T ProcessedMap;
kpeter@244:       static ProcessedMap *createProcessedMap(const Digraph &) { return 0; };
kpeter@257:       SetProcessedMapBase(const TR &b) : TR(b) {}
kpeter@244:     };
kpeter@278:     ///\brief \ref named-func-param "Named parameter"
kpeter@244:     ///for setting \ref ProcessedMap object.
kpeter@244:     ///
kpeter@278:     /// \ref named-func-param "Named parameter"
kpeter@244:     ///for setting \ref ProcessedMap object.
kpeter@244:     template<class T>
kpeter@257:     BfsWizard<SetProcessedMapBase<T> > processedMap(const T &t)
kpeter@244:     {
kpeter@244:       Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@257:       return BfsWizard<SetProcessedMapBase<T> >(*this);
kpeter@244:     }
kpeter@244: 
kpeter@244:     template<class T>
kpeter@278:     struct SetPathBase : public Base {
kpeter@278:       typedef T Path;
kpeter@278:       SetPathBase(const TR &b) : TR(b) {}
kpeter@244:     };
kpeter@278:     ///\brief \ref named-func-param "Named parameter"
kpeter@278:     ///for getting the shortest path to the target node.
kpeter@244:     ///
kpeter@278:     ///\ref named-func-param "Named parameter"
kpeter@278:     ///for getting the shortest path to the target node.
kpeter@244:     template<class T>
kpeter@278:     BfsWizard<SetPathBase<T> > path(const T &t)
kpeter@244:     {
kpeter@278:       Base::_path=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@278:       return BfsWizard<SetPathBase<T> >(*this);
kpeter@278:     }
kpeter@278: 
kpeter@278:     ///\brief \ref named-func-param "Named parameter"
kpeter@278:     ///for getting the distance of the target node.
kpeter@278:     ///
kpeter@278:     ///\ref named-func-param "Named parameter"
kpeter@278:     ///for getting the distance of the target node.
kpeter@278:     BfsWizard dist(const int &d)
kpeter@278:     {
kpeter@278:       Base::_di=const_cast<int*>(&d);
kpeter@278:       return *this;
kpeter@244:     }
kpeter@244: 
alpar@100:   };
alpar@209: 
kpeter@278:   ///Function-type interface for BFS algorithm.
alpar@100: 
alpar@100:   /// \ingroup search
kpeter@278:   ///Function-type interface for BFS algorithm.
alpar@100:   ///
kpeter@278:   ///This function also has several \ref named-func-param "named parameters",
alpar@100:   ///they are declared as the members of class \ref BfsWizard.
kpeter@278:   ///The following examples show how to use these parameters.
alpar@100:   ///\code
kpeter@278:   ///  // Compute shortest path from node s to each node
kpeter@278:   ///  bfs(g).predMap(preds).distMap(dists).run(s);
kpeter@278:   ///
kpeter@278:   ///  // Compute shortest path from s to t
kpeter@278:   ///  bool reached = bfs(g).path(p).dist(d).run(s,t);
alpar@100:   ///\endcode
alpar@100:   ///\warning Don't forget to put the \ref BfsWizard::run() "run()"
alpar@100:   ///to the end of the parameter list.
alpar@100:   ///\sa BfsWizard
alpar@100:   ///\sa Bfs
alpar@100:   template<class GR>
alpar@100:   BfsWizard<BfsWizardBase<GR> >
kpeter@278:   bfs(const GR &digraph)
alpar@100:   {
kpeter@278:     return BfsWizard<BfsWizardBase<GR> >(digraph);
alpar@100:   }
alpar@100: 
alpar@100: #ifdef DOXYGEN
kpeter@244:   /// \brief Visitor class for BFS.
alpar@209:   ///
alpar@100:   /// This class defines the interface of the BfsVisit events, and
kpeter@244:   /// it could be the base of a real visitor class.
alpar@100:   template <typename _Digraph>
alpar@100:   struct BfsVisitor {
alpar@100:     typedef _Digraph Digraph;
alpar@100:     typedef typename Digraph::Arc Arc;
alpar@100:     typedef typename Digraph::Node Node;
kpeter@244:     /// \brief Called for the source node(s) of the BFS.
alpar@209:     ///
kpeter@244:     /// This function is called for the source node(s) of the BFS.
kpeter@244:     void start(const Node& node) {}
kpeter@244:     /// \brief Called when a node is reached first time.
kpeter@244:     ///
kpeter@244:     /// This function is called when a node is reached first time.
kpeter@244:     void reach(const Node& node) {}
kpeter@244:     /// \brief Called when a node is processed.
kpeter@244:     ///
kpeter@244:     /// This function is called when a node is processed.
kpeter@244:     void process(const Node& node) {}
kpeter@244:     /// \brief Called when an arc reaches a new node.
kpeter@244:     ///
kpeter@244:     /// This function is called when the BFS finds an arc whose target node
kpeter@244:     /// is not reached yet.
alpar@100:     void discover(const Arc& arc) {}
kpeter@244:     /// \brief Called when an arc is examined but its target node is
alpar@100:     /// already discovered.
alpar@209:     ///
kpeter@244:     /// This function is called when an arc is examined but its target node is
alpar@100:     /// already discovered.
alpar@100:     void examine(const Arc& arc) {}
alpar@100:   };
alpar@100: #else
alpar@100:   template <typename _Digraph>
alpar@100:   struct BfsVisitor {
alpar@100:     typedef _Digraph Digraph;
alpar@100:     typedef typename Digraph::Arc Arc;
alpar@100:     typedef typename Digraph::Node Node;
kpeter@244:     void start(const Node&) {}
kpeter@244:     void reach(const Node&) {}
kpeter@244:     void process(const Node&) {}
alpar@100:     void discover(const Arc&) {}
alpar@100:     void examine(const Arc&) {}
alpar@100: 
alpar@100:     template <typename _Visitor>
alpar@100:     struct Constraints {
alpar@100:       void constraints() {
alpar@209:         Arc arc;
alpar@209:         Node node;
kpeter@244:         visitor.start(node);
kpeter@244:         visitor.reach(node);
kpeter@244:         visitor.process(node);
alpar@209:         visitor.discover(arc);
alpar@209:         visitor.examine(arc);
alpar@100:       }
alpar@100:       _Visitor& visitor;
alpar@100:     };
alpar@100:   };
alpar@100: #endif
alpar@100: 
alpar@100:   /// \brief Default traits class of BfsVisit class.
alpar@100:   ///
alpar@100:   /// Default traits class of BfsVisit class.
kpeter@244:   /// \tparam _Digraph The type of the digraph the algorithm runs on.
alpar@100:   template<class _Digraph>
alpar@100:   struct BfsVisitDefaultTraits {
alpar@100: 
kpeter@244:     /// \brief The type of the digraph the algorithm runs on.
alpar@100:     typedef _Digraph Digraph;
alpar@100: 
alpar@100:     /// \brief The type of the map that indicates which nodes are reached.
alpar@209:     ///
alpar@100:     /// The type of the map that indicates which nodes are reached.
kpeter@244:     /// It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
alpar@100:     typedef typename Digraph::template NodeMap<bool> ReachedMap;
alpar@100: 
kpeter@244:     /// \brief Instantiates a \ref ReachedMap.
alpar@100:     ///
alpar@209:     /// This function instantiates a \ref ReachedMap.
alpar@100:     /// \param digraph is the digraph, to which
alpar@100:     /// we would like to define the \ref ReachedMap.
alpar@100:     static ReachedMap *createReachedMap(const Digraph &digraph) {
alpar@100:       return new ReachedMap(digraph);
alpar@100:     }
alpar@100: 
alpar@100:   };
alpar@100: 
alpar@100:   /// \ingroup search
alpar@209:   ///
kpeter@244:   /// \brief %BFS algorithm class with visitor interface.
alpar@209:   ///
alpar@100:   /// This class provides an efficient implementation of the %BFS algorithm
alpar@100:   /// with visitor interface.
alpar@100:   ///
alpar@100:   /// The %BfsVisit class provides an alternative interface to the Bfs
alpar@100:   /// class. It works with callback mechanism, the BfsVisit object calls
kpeter@244:   /// the member functions of the \c Visitor class on every BFS event.
alpar@100:   ///
kpeter@252:   /// This interface of the BFS algorithm should be used in special cases
kpeter@252:   /// when extra actions have to be performed in connection with certain
kpeter@252:   /// events of the BFS algorithm. Otherwise consider to use Bfs or bfs()
kpeter@252:   /// instead.
kpeter@252:   ///
kpeter@244:   /// \tparam _Digraph The type of the digraph the algorithm runs on.
alpar@210:   /// The default value is
kpeter@244:   /// \ref ListDigraph. The value of _Digraph is not used directly by
kpeter@244:   /// \ref BfsVisit, it is only passed to \ref BfsVisitDefaultTraits.
kpeter@244:   /// \tparam _Visitor The Visitor type that is used by the algorithm.
kpeter@244:   /// \ref BfsVisitor "BfsVisitor<_Digraph>" is an empty visitor, which
kpeter@244:   /// does not observe the BFS events. If you want to observe the BFS
kpeter@244:   /// events, you should implement your own visitor class.
alpar@209:   /// \tparam _Traits Traits class to set various data types used by the
alpar@100:   /// algorithm. The default traits class is
alpar@100:   /// \ref BfsVisitDefaultTraits "BfsVisitDefaultTraits<_Digraph>".
alpar@100:   /// See \ref BfsVisitDefaultTraits for the documentation of
kpeter@244:   /// a BFS visit traits class.
alpar@100: #ifdef DOXYGEN
alpar@100:   template <typename _Digraph, typename _Visitor, typename _Traits>
alpar@100: #else
alpar@100:   template <typename _Digraph = ListDigraph,
alpar@209:             typename _Visitor = BfsVisitor<_Digraph>,
deba@288:             typename _Traits = BfsVisitDefaultTraits<_Digraph> >
alpar@100: #endif
alpar@100:   class BfsVisit {
alpar@100:   public:
alpar@209: 
alpar@100:     /// \brief \ref Exception for uninitialized parameters.
alpar@100:     ///
alpar@100:     /// This error represents problems in the initialization
kpeter@244:     /// of the parameters of the algorithm.
alpar@100:     class UninitializedParameter : public lemon::UninitializedParameter {
alpar@100:     public:
alpar@209:       virtual const char* what() const throw()
alpar@100:       {
alpar@209:         return "lemon::BfsVisit::UninitializedParameter";
alpar@100:       }
alpar@100:     };
alpar@100: 
kpeter@244:     ///The traits class.
alpar@100:     typedef _Traits Traits;
alpar@100: 
kpeter@244:     ///The type of the digraph the algorithm runs on.
alpar@100:     typedef typename Traits::Digraph Digraph;
alpar@100: 
kpeter@244:     ///The visitor type used by the algorithm.
alpar@100:     typedef _Visitor Visitor;
alpar@100: 
kpeter@244:     ///The type of the map that indicates which nodes are reached.
alpar@100:     typedef typename Traits::ReachedMap ReachedMap;
alpar@100: 
alpar@100:   private:
alpar@100: 
alpar@100:     typedef typename Digraph::Node Node;
alpar@100:     typedef typename Digraph::NodeIt NodeIt;
alpar@100:     typedef typename Digraph::Arc Arc;
alpar@100:     typedef typename Digraph::OutArcIt OutArcIt;
alpar@100: 
kpeter@244:     //Pointer to the underlying digraph.
alpar@100:     const Digraph *_digraph;
kpeter@244:     //Pointer to the visitor object.
alpar@100:     Visitor *_visitor;
kpeter@244:     //Pointer to the map of reached status of the nodes.
alpar@100:     ReachedMap *_reached;
kpeter@244:     //Indicates if _reached is locally allocated (true) or not.
alpar@100:     bool local_reached;
alpar@100: 
alpar@100:     std::vector<typename Digraph::Node> _list;
alpar@100:     int _list_front, _list_back;
alpar@100: 
alpar@280:     //Creates the maps if necessary.
alpar@100:     void create_maps() {
alpar@100:       if(!_reached) {
alpar@209:         local_reached = true;
alpar@209:         _reached = Traits::createReachedMap(*_digraph);
alpar@100:       }
alpar@100:     }
alpar@100: 
alpar@100:   protected:
alpar@100: 
alpar@100:     BfsVisit() {}
alpar@209: 
alpar@100:   public:
alpar@100: 
alpar@100:     typedef BfsVisit Create;
alpar@100: 
alpar@100:     /// \name Named template parameters
alpar@100: 
alpar@100:     ///@{
alpar@100:     template <class T>
kpeter@257:     struct SetReachedMapTraits : public Traits {
alpar@100:       typedef T ReachedMap;
alpar@100:       static ReachedMap *createReachedMap(const Digraph &digraph) {
alpar@209:         throw UninitializedParameter();
alpar@100:       }
alpar@100:     };
alpar@209:     /// \brief \ref named-templ-param "Named parameter" for setting
kpeter@244:     /// ReachedMap type.
alpar@100:     ///
kpeter@244:     /// \ref named-templ-param "Named parameter" for setting ReachedMap type.
alpar@100:     template <class T>
kpeter@257:     struct SetReachedMap : public BfsVisit< Digraph, Visitor,
kpeter@257:                                             SetReachedMapTraits<T> > {
kpeter@257:       typedef BfsVisit< Digraph, Visitor, SetReachedMapTraits<T> > Create;
alpar@100:     };
alpar@100:     ///@}
alpar@100: 
alpar@209:   public:
alpar@209: 
alpar@100:     /// \brief Constructor.
alpar@100:     ///
alpar@100:     /// Constructor.
alpar@100:     ///
kpeter@244:     /// \param digraph The digraph the algorithm runs on.
kpeter@244:     /// \param visitor The visitor object of the algorithm.
alpar@209:     BfsVisit(const Digraph& digraph, Visitor& visitor)
alpar@100:       : _digraph(&digraph), _visitor(&visitor),
alpar@209:         _reached(0), local_reached(false) {}
alpar@209: 
alpar@100:     /// \brief Destructor.
alpar@100:     ~BfsVisit() {
alpar@100:       if(local_reached) delete _reached;
alpar@100:     }
alpar@100: 
kpeter@244:     /// \brief Sets the map that indicates which nodes are reached.
alpar@100:     ///
kpeter@244:     /// Sets the map that indicates which nodes are reached.
alpar@100:     /// If you don't use this function before calling \ref run(),
kpeter@244:     /// it will allocate one. The destructor deallocates this
alpar@100:     /// automatically allocated map, of course.
alpar@100:     /// \return <tt> (*this) </tt>
alpar@100:     BfsVisit &reachedMap(ReachedMap &m) {
alpar@100:       if(local_reached) {
alpar@209:         delete _reached;
alpar@209:         local_reached = false;
alpar@100:       }
alpar@100:       _reached = &m;
alpar@100:       return *this;
alpar@100:     }
alpar@100: 
alpar@100:   public:
kpeter@244: 
alpar@100:     /// \name Execution control
alpar@100:     /// The simplest way to execute the algorithm is to use
kpeter@244:     /// one of the member functions called \ref lemon::BfsVisit::run()
kpeter@244:     /// "run()".
alpar@100:     /// \n
kpeter@244:     /// If you need more control on the execution, first you must call
kpeter@244:     /// \ref lemon::BfsVisit::init() "init()", then you can add several
kpeter@244:     /// source nodes with \ref lemon::BfsVisit::addSource() "addSource()".
kpeter@244:     /// Finally \ref lemon::BfsVisit::start() "start()" will perform the
kpeter@244:     /// actual path computation.
alpar@100: 
alpar@100:     /// @{
kpeter@244: 
alpar@100:     /// \brief Initializes the internal data structures.
alpar@100:     ///
alpar@100:     /// Initializes the internal data structures.
alpar@100:     void init() {
alpar@100:       create_maps();
alpar@100:       _list.resize(countNodes(*_digraph));
alpar@100:       _list_front = _list_back = -1;
alpar@100:       for (NodeIt u(*_digraph) ; u != INVALID ; ++u) {
alpar@209:         _reached->set(u, false);
alpar@100:       }
alpar@100:     }
alpar@209: 
alpar@100:     /// \brief Adds a new source node.
alpar@100:     ///
alpar@100:     /// Adds a new source node to the set of nodes to be processed.
alpar@100:     void addSource(Node s) {
alpar@100:       if(!(*_reached)[s]) {
alpar@209:           _reached->set(s,true);
alpar@209:           _visitor->start(s);
alpar@209:           _visitor->reach(s);
alpar@100:           _list[++_list_back] = s;
alpar@209:         }
alpar@100:     }
alpar@209: 
alpar@100:     /// \brief Processes the next node.
alpar@100:     ///
alpar@100:     /// Processes the next node.
alpar@100:     ///
alpar@100:     /// \return The processed node.
alpar@100:     ///
kpeter@244:     /// \pre The queue must not be empty.
alpar@209:     Node processNextNode() {
alpar@100:       Node n = _list[++_list_front];
alpar@100:       _visitor->process(n);
alpar@100:       Arc e;
alpar@100:       for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
alpar@100:         Node m = _digraph->target(e);
alpar@100:         if (!(*_reached)[m]) {
alpar@100:           _visitor->discover(e);
alpar@100:           _visitor->reach(m);
alpar@100:           _reached->set(m, true);
alpar@100:           _list[++_list_back] = m;
alpar@100:         } else {
alpar@100:           _visitor->examine(e);
alpar@100:         }
alpar@100:       }
alpar@100:       return n;
alpar@100:     }
alpar@100: 
alpar@100:     /// \brief Processes the next node.
alpar@100:     ///
kpeter@244:     /// Processes the next node and checks if the given target node
alpar@100:     /// is reached. If the target node is reachable from the processed
kpeter@244:     /// node, then the \c reach parameter will be set to \c true.
alpar@100:     ///
alpar@100:     /// \param target The target node.
kpeter@244:     /// \retval reach Indicates if the target node is reached.
kpeter@244:     /// It should be initially \c false.
kpeter@244:     ///
alpar@100:     /// \return The processed node.
alpar@100:     ///
kpeter@244:     /// \pre The queue must not be empty.
alpar@100:     Node processNextNode(Node target, bool& reach) {
alpar@100:       Node n = _list[++_list_front];
alpar@100:       _visitor->process(n);
alpar@100:       Arc e;
alpar@100:       for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
alpar@100:         Node m = _digraph->target(e);
alpar@100:         if (!(*_reached)[m]) {
alpar@100:           _visitor->discover(e);
alpar@100:           _visitor->reach(m);
alpar@100:           _reached->set(m, true);
alpar@100:           _list[++_list_back] = m;
alpar@100:           reach = reach || (target == m);
alpar@100:         } else {
alpar@100:           _visitor->examine(e);
alpar@100:         }
alpar@100:       }
alpar@100:       return n;
alpar@100:     }
alpar@100: 
alpar@100:     /// \brief Processes the next node.
alpar@100:     ///
kpeter@244:     /// Processes the next node and checks if at least one of reached
kpeter@244:     /// nodes has \c true value in the \c nm node map. If one node
kpeter@244:     /// with \c true value is reachable from the processed node, then the
kpeter@244:     /// \c rnode parameter will be set to the first of such nodes.
alpar@100:     ///
kpeter@244:     /// \param nm A \c bool (or convertible) node map that indicates the
kpeter@244:     /// possible targets.
alpar@100:     /// \retval rnode The reached target node.
kpeter@244:     /// It should be initially \c INVALID.
kpeter@244:     ///
alpar@100:     /// \return The processed node.
alpar@100:     ///
kpeter@244:     /// \pre The queue must not be empty.
alpar@100:     template <typename NM>
alpar@100:     Node processNextNode(const NM& nm, Node& rnode) {
alpar@100:       Node n = _list[++_list_front];
alpar@100:       _visitor->process(n);
alpar@100:       Arc e;
alpar@100:       for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
alpar@100:         Node m = _digraph->target(e);
alpar@100:         if (!(*_reached)[m]) {
alpar@100:           _visitor->discover(e);
alpar@100:           _visitor->reach(m);
alpar@100:           _reached->set(m, true);
alpar@100:           _list[++_list_back] = m;
alpar@100:           if (nm[m] && rnode == INVALID) rnode = m;
alpar@100:         } else {
alpar@100:           _visitor->examine(e);
alpar@100:         }
alpar@100:       }
alpar@100:       return n;
alpar@100:     }
alpar@100: 
kpeter@244:     /// \brief The next node to be processed.
alpar@100:     ///
kpeter@244:     /// Returns the next node to be processed or \c INVALID if the queue
kpeter@244:     /// is empty.
kpeter@244:     Node nextNode() const {
alpar@100:       return _list_front != _list_back ? _list[_list_front + 1] : INVALID;
alpar@100:     }
alpar@100: 
alpar@100:     /// \brief Returns \c false if there are nodes
kpeter@244:     /// to be processed.
alpar@100:     ///
alpar@100:     /// Returns \c false if there are nodes
kpeter@244:     /// to be processed in the queue.
kpeter@244:     bool emptyQueue() const { return _list_front == _list_back; }
alpar@100: 
alpar@100:     /// \brief Returns the number of the nodes to be processed.
alpar@100:     ///
alpar@100:     /// Returns the number of the nodes to be processed in the queue.
kpeter@244:     int queueSize() const { return _list_back - _list_front; }
alpar@209: 
alpar@100:     /// \brief Executes the algorithm.
alpar@100:     ///
alpar@100:     /// Executes the algorithm.
alpar@100:     ///
kpeter@244:     /// This method runs the %BFS algorithm from the root node(s)
kpeter@244:     /// in order to compute the shortest path to each node.
kpeter@244:     ///
kpeter@244:     /// The algorithm computes
kpeter@244:     /// - the shortest path tree (forest),
kpeter@244:     /// - the distance of each node from the root(s).
kpeter@244:     ///
kpeter@244:     /// \pre init() must be called and at least one root node should be added
alpar@100:     /// with addSource() before using this function.
kpeter@244:     ///
kpeter@244:     /// \note <tt>b.start()</tt> is just a shortcut of the following code.
kpeter@244:     /// \code
kpeter@244:     ///   while ( !b.emptyQueue() ) {
kpeter@244:     ///     b.processNextNode();
kpeter@244:     ///   }
kpeter@244:     /// \endcode
alpar@100:     void start() {
alpar@100:       while ( !emptyQueue() ) processNextNode();
alpar@100:     }
alpar@209: 
kpeter@244:     /// \brief Executes the algorithm until the given target node is reached.
alpar@100:     ///
kpeter@244:     /// Executes the algorithm until the given target node is reached.
alpar@100:     ///
kpeter@244:     /// This method runs the %BFS algorithm from the root node(s)
kpeter@286:     /// in order to compute the shortest path to \c t.
kpeter@244:     ///
kpeter@244:     /// The algorithm computes
kpeter@286:     /// - the shortest path to \c t,
kpeter@286:     /// - the distance of \c t from the root(s).
kpeter@244:     ///
kpeter@244:     /// \pre init() must be called and at least one root node should be
kpeter@244:     /// added with addSource() before using this function.
kpeter@244:     ///
kpeter@244:     /// \note <tt>b.start(t)</tt> is just a shortcut of the following code.
kpeter@244:     /// \code
kpeter@244:     ///   bool reach = false;
kpeter@244:     ///   while ( !b.emptyQueue() && !reach ) {
kpeter@244:     ///     b.processNextNode(t, reach);
kpeter@244:     ///   }
kpeter@244:     /// \endcode
kpeter@286:     void start(Node t) {
alpar@100:       bool reach = false;
kpeter@286:       while ( !emptyQueue() && !reach ) processNextNode(t, reach);
alpar@100:     }
alpar@209: 
alpar@100:     /// \brief Executes the algorithm until a condition is met.
alpar@100:     ///
alpar@100:     /// Executes the algorithm until a condition is met.
alpar@100:     ///
kpeter@244:     /// This method runs the %BFS algorithm from the root node(s) in
kpeter@244:     /// order to compute the shortest path to a node \c v with
kpeter@244:     /// <tt>nm[v]</tt> true, if such a node can be found.
alpar@100:     ///
kpeter@244:     /// \param nm must be a bool (or convertible) node map. The
kpeter@244:     /// algorithm will stop when it reaches a node \c v with
alpar@100:     /// <tt>nm[v]</tt> true.
alpar@100:     ///
kpeter@244:     /// \return The reached node \c v with <tt>nm[v]</tt> true or
kpeter@244:     /// \c INVALID if no such node was found.
kpeter@244:     ///
kpeter@244:     /// \pre init() must be called and at least one root node should be
kpeter@244:     /// added with addSource() before using this function.
kpeter@244:     ///
kpeter@244:     /// \note <tt>b.start(nm)</tt> is just a shortcut of the following code.
kpeter@244:     /// \code
kpeter@244:     ///   Node rnode = INVALID;
kpeter@244:     ///   while ( !b.emptyQueue() && rnode == INVALID ) {
kpeter@244:     ///     b.processNextNode(nm, rnode);
kpeter@244:     ///   }
kpeter@244:     ///   return rnode;
kpeter@244:     /// \endcode
alpar@100:     template <typename NM>
alpar@100:     Node start(const NM &nm) {
alpar@100:       Node rnode = INVALID;
alpar@100:       while ( !emptyQueue() && rnode == INVALID ) {
alpar@209:         processNextNode(nm, rnode);
alpar@100:       }
alpar@100:       return rnode;
alpar@100:     }
alpar@100: 
kpeter@286:     /// \brief Runs the algorithm from the given source node.
alpar@100:     ///
kpeter@244:     /// This method runs the %BFS algorithm from node \c s
kpeter@244:     /// in order to compute the shortest path to each node.
kpeter@244:     ///
kpeter@244:     /// The algorithm computes
kpeter@244:     /// - the shortest path tree,
kpeter@244:     /// - the distance of each node from the root.
kpeter@244:     ///
kpeter@244:     /// \note <tt>b.run(s)</tt> is just a shortcut of the following code.
alpar@100:     ///\code
alpar@100:     ///   b.init();
alpar@100:     ///   b.addSource(s);
alpar@100:     ///   b.start();
alpar@100:     ///\endcode
alpar@100:     void run(Node s) {
alpar@100:       init();
alpar@100:       addSource(s);
alpar@100:       start();
alpar@100:     }
alpar@100: 
kpeter@286:     /// \brief Finds the shortest path between \c s and \c t.
kpeter@286:     ///
kpeter@286:     /// This method runs the %BFS algorithm from node \c s
kpeter@286:     /// in order to compute the shortest path to node \c t
kpeter@286:     /// (it stops searching when \c t is processed).
kpeter@286:     ///
kpeter@286:     /// \return \c true if \c t is reachable form \c s.
kpeter@286:     ///
kpeter@286:     /// \note Apart from the return value, <tt>b.run(s,t)</tt> is just a
kpeter@286:     /// shortcut of the following code.
kpeter@286:     ///\code
kpeter@286:     ///   b.init();
kpeter@286:     ///   b.addSource(s);
kpeter@286:     ///   b.start(t);
kpeter@286:     ///\endcode
kpeter@286:     bool run(Node s,Node t) {
kpeter@286:       init();
kpeter@286:       addSource(s);
kpeter@286:       start(t);
kpeter@286:       return reached(t);
kpeter@286:     }
kpeter@286: 
kpeter@244:     /// \brief Runs the algorithm to visit all nodes in the digraph.
alpar@209:     ///
alpar@100:     /// This method runs the %BFS algorithm in order to
kpeter@244:     /// compute the shortest path to each node.
alpar@100:     ///
kpeter@244:     /// The algorithm computes
kpeter@244:     /// - the shortest path tree (forest),
kpeter@244:     /// - the distance of each node from the root(s).
kpeter@244:     ///
kpeter@244:     /// \note <tt>b.run(s)</tt> is just a shortcut of the following code.
alpar@100:     ///\code
alpar@100:     ///  b.init();
kpeter@244:     ///  for (NodeIt n(gr); n != INVALID; ++n) {
kpeter@244:     ///    if (!b.reached(n)) {
kpeter@244:     ///      b.addSource(n);
alpar@100:     ///      b.start();
alpar@100:     ///    }
alpar@100:     ///  }
alpar@100:     ///\endcode
alpar@100:     void run() {
alpar@100:       init();
alpar@100:       for (NodeIt it(*_digraph); it != INVALID; ++it) {
alpar@100:         if (!reached(it)) {
alpar@100:           addSource(it);
alpar@100:           start();
alpar@100:         }
alpar@100:       }
alpar@100:     }
kpeter@244: 
alpar@100:     ///@}
alpar@100: 
alpar@100:     /// \name Query Functions
alpar@100:     /// The result of the %BFS algorithm can be obtained using these
alpar@100:     /// functions.\n
kpeter@244:     /// Either \ref lemon::BfsVisit::run() "run()" or
kpeter@244:     /// \ref lemon::BfsVisit::start() "start()" must be called before
kpeter@244:     /// using them.
alpar@100:     ///@{
alpar@100: 
kpeter@244:     /// \brief Checks if a node is reachable from the root(s).
alpar@100:     ///
alpar@100:     /// Returns \c true if \c v is reachable from the root(s).
alpar@100:     /// \pre Either \ref run() or \ref start()
alpar@100:     /// must be called before using this function.
alpar@100:     bool reached(Node v) { return (*_reached)[v]; }
kpeter@244: 
alpar@100:     ///@}
kpeter@244: 
alpar@100:   };
alpar@100: 
alpar@100: } //END OF NAMESPACE LEMON
alpar@100: 
alpar@100: #endif