COIN-OR::LEMON - Graph Library

source: lemon/lemon/bfs.h @ 1127:be7dd3a8d6a3

1.2
Last change on this file since 1127:be7dd3a8d6a3 was 1127:be7dd3a8d6a3, checked in by Alpar Juttner <alpar@…>, 12 years ago

Merge Intel C++ compatibility fixes to branch 1.2

File size: 54.3 KB
RevLine 
[209]1/* -*- mode: C++; indent-tabs-mode: nil; -*-
[100]2 *
[209]3 * This file is a part of LEMON, a generic C++ optimization library.
[100]4 *
[956]5 * Copyright (C) 2003-2010
[100]6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#ifndef LEMON_BFS_H
20#define LEMON_BFS_H
21
22///\ingroup search
23///\file
[244]24///\brief BFS algorithm.
[100]25
26#include <lemon/list_graph.h>
27#include <lemon/bits/path_dump.h>
[220]28#include <lemon/core.h>
[100]29#include <lemon/error.h>
30#include <lemon/maps.h>
[278]31#include <lemon/path.h>
[100]32
33namespace lemon {
34
35  ///Default traits class of Bfs class.
36
37  ///Default traits class of Bfs class.
[157]38  ///\tparam GR Digraph type.
[100]39  template<class GR>
40  struct BfsDefaultTraits
41  {
[244]42    ///The type of the digraph the algorithm runs on.
[100]43    typedef GR Digraph;
[244]44
45    ///\brief The type of the map that stores the predecessor
[100]46    ///arcs of the shortest paths.
[209]47    ///
[244]48    ///The type of the map that stores the predecessor
[100]49    ///arcs of the shortest paths.
[763]50    ///It must conform to the \ref concepts::WriteMap "WriteMap" concept.
[244]51    typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
[525]52    ///Instantiates a \c PredMap.
[209]53
[525]54    ///This function instantiates a \ref PredMap.
[244]55    ///\param g is the digraph, to which we would like to define the
[525]56    ///\ref PredMap.
[244]57    static PredMap *createPredMap(const Digraph &g)
[100]58    {
[244]59      return new PredMap(g);
[100]60    }
[244]61
[100]62    ///The type of the map that indicates which nodes are processed.
[209]63
[100]64    ///The type of the map that indicates which nodes are processed.
[763]65    ///It must conform to the \ref concepts::WriteMap "WriteMap" concept.
[833]66    ///By default, it is a NullMap.
[100]67    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
[525]68    ///Instantiates a \c ProcessedMap.
[209]69
[525]70    ///This function instantiates a \ref ProcessedMap.
[100]71    ///\param g is the digraph, to which
[525]72    ///we would like to define the \ref ProcessedMap
[100]73#ifdef DOXYGEN
[244]74    static ProcessedMap *createProcessedMap(const Digraph &g)
[100]75#else
[244]76    static ProcessedMap *createProcessedMap(const Digraph &)
[100]77#endif
78    {
79      return new ProcessedMap();
80    }
[244]81
[100]82    ///The type of the map that indicates which nodes are reached.
[209]83
[421]84    ///The type of the map that indicates which nodes are reached.
[956]85    ///It must conform to
86    ///the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
[100]87    typedef typename Digraph::template NodeMap<bool> ReachedMap;
[525]88    ///Instantiates a \c ReachedMap.
[209]89
[525]90    ///This function instantiates a \ref ReachedMap.
[244]91    ///\param g is the digraph, to which
[525]92    ///we would like to define the \ref ReachedMap.
[244]93    static ReachedMap *createReachedMap(const Digraph &g)
[100]94    {
[244]95      return new ReachedMap(g);
[100]96    }
[209]97
[244]98    ///The type of the map that stores the distances of the nodes.
99
100    ///The type of the map that stores the distances of the nodes.
[763]101    ///It must conform to the \ref concepts::WriteMap "WriteMap" concept.
[100]102    typedef typename Digraph::template NodeMap<int> DistMap;
[525]103    ///Instantiates a \c DistMap.
[209]104
[525]105    ///This function instantiates a \ref DistMap.
[244]106    ///\param g is the digraph, to which we would like to define the
[525]107    ///\ref DistMap.
[244]108    static DistMap *createDistMap(const Digraph &g)
[100]109    {
[244]110      return new DistMap(g);
[100]111    }
112  };
[209]113
[100]114  ///%BFS algorithm class.
[209]115
[100]116  ///\ingroup search
117  ///This class provides an efficient implementation of the %BFS algorithm.
118  ///
[278]119  ///There is also a \ref bfs() "function-type interface" for the BFS
[244]120  ///algorithm, which is convenient in the simplier cases and it can be
121  ///used easier.
122  ///
123  ///\tparam GR The type of the digraph the algorithm runs on.
[421]124  ///The default type is \ref ListDigraph.
[891]125  ///\tparam TR The traits class that defines various types used by the
126  ///algorithm. By default, it is \ref BfsDefaultTraits
127  ///"BfsDefaultTraits<GR>".
128  ///In most cases, this parameter should not be set directly,
129  ///consider to use the named template parameters instead.
[100]130#ifdef DOXYGEN
131  template <typename GR,
[209]132            typename TR>
[100]133#else
134  template <typename GR=ListDigraph,
[209]135            typename TR=BfsDefaultTraits<GR> >
[100]136#endif
137  class Bfs {
138  public:
139
[244]140    ///The type of the digraph the algorithm runs on.
[100]141    typedef typename TR::Digraph Digraph;
[209]142
[244]143    ///\brief The type of the map that stores the predecessor arcs of the
144    ///shortest paths.
[100]145    typedef typename TR::PredMap PredMap;
[244]146    ///The type of the map that stores the distances of the nodes.
147    typedef typename TR::DistMap DistMap;
148    ///The type of the map that indicates which nodes are reached.
[100]149    typedef typename TR::ReachedMap ReachedMap;
[244]150    ///The type of the map that indicates which nodes are processed.
[100]151    typedef typename TR::ProcessedMap ProcessedMap;
[244]152    ///The type of the paths.
153    typedef PredMapPath<Digraph, PredMap> Path;
154
[421]155    ///The \ref BfsDefaultTraits "traits class" of the algorithm.
[244]156    typedef TR Traits;
157
[100]158  private:
159
160    typedef typename Digraph::Node Node;
161    typedef typename Digraph::NodeIt NodeIt;
162    typedef typename Digraph::Arc Arc;
163    typedef typename Digraph::OutArcIt OutArcIt;
164
[244]165    //Pointer to the underlying digraph.
[100]166    const Digraph *G;
[244]167    //Pointer to the map of predecessor arcs.
[100]168    PredMap *_pred;
[244]169    //Indicates if _pred is locally allocated (true) or not.
[100]170    bool local_pred;
[244]171    //Pointer to the map of distances.
[100]172    DistMap *_dist;
[244]173    //Indicates if _dist is locally allocated (true) or not.
[100]174    bool local_dist;
[244]175    //Pointer to the map of reached status of the nodes.
[100]176    ReachedMap *_reached;
[244]177    //Indicates if _reached is locally allocated (true) or not.
[100]178    bool local_reached;
[244]179    //Pointer to the map of processed status of the nodes.
[100]180    ProcessedMap *_processed;
[244]181    //Indicates if _processed is locally allocated (true) or not.
[100]182    bool local_processed;
183
184    std::vector<typename Digraph::Node> _queue;
185    int _queue_head,_queue_tail,_queue_next_dist;
186    int _curr_dist;
187
[280]188    //Creates the maps if necessary.
[209]189    void create_maps()
[100]190    {
191      if(!_pred) {
[209]192        local_pred = true;
193        _pred = Traits::createPredMap(*G);
[100]194      }
195      if(!_dist) {
[209]196        local_dist = true;
197        _dist = Traits::createDistMap(*G);
[100]198      }
199      if(!_reached) {
[209]200        local_reached = true;
201        _reached = Traits::createReachedMap(*G);
[100]202      }
203      if(!_processed) {
[209]204        local_processed = true;
205        _processed = Traits::createProcessedMap(*G);
[100]206      }
207    }
208
209  protected:
[209]210
[100]211    Bfs() {}
[209]212
[100]213  public:
[209]214
[100]215    typedef Bfs Create;
216
[421]217    ///\name Named Template Parameters
[100]218
219    ///@{
220
221    template <class T>
[257]222    struct SetPredMapTraits : public Traits {
[100]223      typedef T PredMap;
[209]224      static PredMap *createPredMap(const Digraph &)
[100]225      {
[290]226        LEMON_ASSERT(false, "PredMap is not initialized");
227        return 0; // ignore warnings
[100]228      }
229    };
230    ///\brief \ref named-templ-param "Named parameter" for setting
[525]231    ///\c PredMap type.
[100]232    ///
[244]233    ///\ref named-templ-param "Named parameter" for setting
[525]234    ///\c PredMap type.
[763]235    ///It must conform to the \ref concepts::WriteMap "WriteMap" concept.
[100]236    template <class T>
[257]237    struct SetPredMap : public Bfs< Digraph, SetPredMapTraits<T> > {
238      typedef Bfs< Digraph, SetPredMapTraits<T> > Create;
[100]239    };
[209]240
[100]241    template <class T>
[257]242    struct SetDistMapTraits : public Traits {
[100]243      typedef T DistMap;
[209]244      static DistMap *createDistMap(const Digraph &)
[100]245      {
[290]246        LEMON_ASSERT(false, "DistMap is not initialized");
247        return 0; // ignore warnings
[100]248      }
249    };
250    ///\brief \ref named-templ-param "Named parameter" for setting
[525]251    ///\c DistMap type.
[100]252    ///
[244]253    ///\ref named-templ-param "Named parameter" for setting
[525]254    ///\c DistMap type.
[763]255    ///It must conform to the \ref concepts::WriteMap "WriteMap" concept.
[100]256    template <class T>
[257]257    struct SetDistMap : public Bfs< Digraph, SetDistMapTraits<T> > {
258      typedef Bfs< Digraph, SetDistMapTraits<T> > Create;
[100]259    };
[209]260
[100]261    template <class T>
[257]262    struct SetReachedMapTraits : public Traits {
[100]263      typedef T ReachedMap;
[209]264      static ReachedMap *createReachedMap(const Digraph &)
[100]265      {
[290]266        LEMON_ASSERT(false, "ReachedMap is not initialized");
267        return 0; // ignore warnings
[100]268      }
269    };
270    ///\brief \ref named-templ-param "Named parameter" for setting
[525]271    ///\c ReachedMap type.
[100]272    ///
[244]273    ///\ref named-templ-param "Named parameter" for setting
[525]274    ///\c ReachedMap type.
[956]275    ///It must conform to
276    ///the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
[100]277    template <class T>
[257]278    struct SetReachedMap : public Bfs< Digraph, SetReachedMapTraits<T> > {
279      typedef Bfs< Digraph, SetReachedMapTraits<T> > Create;
[100]280    };
[209]281
[100]282    template <class T>
[257]283    struct SetProcessedMapTraits : public Traits {
[100]284      typedef T ProcessedMap;
[209]285      static ProcessedMap *createProcessedMap(const Digraph &)
[100]286      {
[290]287        LEMON_ASSERT(false, "ProcessedMap is not initialized");
288        return 0; // ignore warnings
[100]289      }
290    };
291    ///\brief \ref named-templ-param "Named parameter" for setting
[525]292    ///\c ProcessedMap type.
[100]293    ///
[244]294    ///\ref named-templ-param "Named parameter" for setting
[525]295    ///\c ProcessedMap type.
[763]296    ///It must conform to the \ref concepts::WriteMap "WriteMap" concept.
[100]297    template <class T>
[257]298    struct SetProcessedMap : public Bfs< Digraph, SetProcessedMapTraits<T> > {
299      typedef Bfs< Digraph, SetProcessedMapTraits<T> > Create;
[100]300    };
[209]301
[257]302    struct SetStandardProcessedMapTraits : public Traits {
[100]303      typedef typename Digraph::template NodeMap<bool> ProcessedMap;
[244]304      static ProcessedMap *createProcessedMap(const Digraph &g)
[100]305      {
[244]306        return new ProcessedMap(g);
[290]307        return 0; // ignore warnings
[100]308      }
309    };
[244]310    ///\brief \ref named-templ-param "Named parameter" for setting
[525]311    ///\c ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
[100]312    ///
[244]313    ///\ref named-templ-param "Named parameter" for setting
[525]314    ///\c ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
[100]315    ///If you don't set it explicitly, it will be automatically allocated.
[257]316    struct SetStandardProcessedMap :
317      public Bfs< Digraph, SetStandardProcessedMapTraits > {
318      typedef Bfs< Digraph, SetStandardProcessedMapTraits > Create;
[100]319    };
[209]320
[100]321    ///@}
322
[209]323  public:
324
[100]325    ///Constructor.
[209]326
[244]327    ///Constructor.
328    ///\param g The digraph the algorithm runs on.
329    Bfs(const Digraph &g) :
330      G(&g),
[100]331      _pred(NULL), local_pred(false),
332      _dist(NULL), local_dist(false),
333      _reached(NULL), local_reached(false),
334      _processed(NULL), local_processed(false)
335    { }
[209]336
[100]337    ///Destructor.
[209]338    ~Bfs()
[100]339    {
340      if(local_pred) delete _pred;
341      if(local_dist) delete _dist;
342      if(local_reached) delete _reached;
343      if(local_processed) delete _processed;
344    }
345
[244]346    ///Sets the map that stores the predecessor arcs.
[100]347
[244]348    ///Sets the map that stores the predecessor arcs.
[421]349    ///If you don't use this function before calling \ref run(Node) "run()"
350    ///or \ref init(), an instance will be allocated automatically.
351    ///The destructor deallocates this automatically allocated map,
352    ///of course.
[100]353    ///\return <tt> (*this) </tt>
[209]354    Bfs &predMap(PredMap &m)
[100]355    {
356      if(local_pred) {
[209]357        delete _pred;
358        local_pred=false;
[100]359      }
360      _pred = &m;
361      return *this;
362    }
363
[244]364    ///Sets the map that indicates which nodes are reached.
[100]365
[244]366    ///Sets the map that indicates which nodes are reached.
[421]367    ///If you don't use this function before calling \ref run(Node) "run()"
368    ///or \ref init(), an instance will be allocated automatically.
369    ///The destructor deallocates this automatically allocated map,
370    ///of course.
[100]371    ///\return <tt> (*this) </tt>
[209]372    Bfs &reachedMap(ReachedMap &m)
[100]373    {
374      if(local_reached) {
[209]375        delete _reached;
376        local_reached=false;
[100]377      }
378      _reached = &m;
379      return *this;
380    }
381
[244]382    ///Sets the map that indicates which nodes are processed.
[100]383
[244]384    ///Sets the map that indicates which nodes are processed.
[421]385    ///If you don't use this function before calling \ref run(Node) "run()"
386    ///or \ref init(), an instance will be allocated automatically.
387    ///The destructor deallocates this automatically allocated map,
388    ///of course.
[100]389    ///\return <tt> (*this) </tt>
[209]390    Bfs &processedMap(ProcessedMap &m)
[100]391    {
392      if(local_processed) {
[209]393        delete _processed;
394        local_processed=false;
[100]395      }
396      _processed = &m;
397      return *this;
398    }
399
[244]400    ///Sets the map that stores the distances of the nodes.
[100]401
[244]402    ///Sets the map that stores the distances of the nodes calculated by
403    ///the algorithm.
[421]404    ///If you don't use this function before calling \ref run(Node) "run()"
405    ///or \ref init(), an instance will be allocated automatically.
406    ///The destructor deallocates this automatically allocated map,
407    ///of course.
[100]408    ///\return <tt> (*this) </tt>
[209]409    Bfs &distMap(DistMap &m)
[100]410    {
411      if(local_dist) {
[209]412        delete _dist;
413        local_dist=false;
[100]414      }
415      _dist = &m;
416      return *this;
417    }
418
419  public:
[244]420
[421]421    ///\name Execution Control
422    ///The simplest way to execute the BFS algorithm is to use one of the
423    ///member functions called \ref run(Node) "run()".\n
[760]424    ///If you need better control on the execution, you have to call
425    ///\ref init() first, then you can add several source nodes with
[421]426    ///\ref addSource(). Finally the actual path computation can be
427    ///performed with one of the \ref start() functions.
[100]428
429    ///@{
430
[421]431    ///\brief Initializes the internal data structures.
432    ///
[244]433    ///Initializes the internal data structures.
[100]434    void init()
435    {
436      create_maps();
437      _queue.resize(countNodes(*G));
438      _queue_head=_queue_tail=0;
439      _curr_dist=1;
440      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
[209]441        _pred->set(u,INVALID);
442        _reached->set(u,false);
443        _processed->set(u,false);
[100]444      }
445    }
[209]446
[100]447    ///Adds a new source node.
448
449    ///Adds a new source node to the set of nodes to be processed.
450    ///
451    void addSource(Node s)
452    {
453      if(!(*_reached)[s])
[209]454        {
455          _reached->set(s,true);
456          _pred->set(s,INVALID);
457          _dist->set(s,0);
458          _queue[_queue_head++]=s;
459          _queue_next_dist=_queue_head;
460        }
[100]461    }
[209]462
[100]463    ///Processes the next node.
464
465    ///Processes the next node.
466    ///
467    ///\return The processed node.
468    ///
[244]469    ///\pre The queue must not be empty.
[100]470    Node processNextNode()
471    {
472      if(_queue_tail==_queue_next_dist) {
[209]473        _curr_dist++;
474        _queue_next_dist=_queue_head;
[100]475      }
476      Node n=_queue[_queue_tail++];
477      _processed->set(n,true);
478      Node m;
479      for(OutArcIt e(*G,n);e!=INVALID;++e)
[209]480        if(!(*_reached)[m=G->target(e)]) {
481          _queue[_queue_head++]=m;
482          _reached->set(m,true);
483          _pred->set(m,e);
484          _dist->set(m,_curr_dist);
485        }
[100]486      return n;
487    }
488
489    ///Processes the next node.
490
[244]491    ///Processes the next node and checks if the given target node
[100]492    ///is reached. If the target node is reachable from the processed
[244]493    ///node, then the \c reach parameter will be set to \c true.
[100]494    ///
495    ///\param target The target node.
[244]496    ///\retval reach Indicates if the target node is reached.
497    ///It should be initially \c false.
498    ///
[100]499    ///\return The processed node.
500    ///
[244]501    ///\pre The queue must not be empty.
[100]502    Node processNextNode(Node target, bool& reach)
503    {
504      if(_queue_tail==_queue_next_dist) {
[209]505        _curr_dist++;
506        _queue_next_dist=_queue_head;
[100]507      }
508      Node n=_queue[_queue_tail++];
509      _processed->set(n,true);
510      Node m;
511      for(OutArcIt e(*G,n);e!=INVALID;++e)
[209]512        if(!(*_reached)[m=G->target(e)]) {
513          _queue[_queue_head++]=m;
514          _reached->set(m,true);
515          _pred->set(m,e);
516          _dist->set(m,_curr_dist);
[100]517          reach = reach || (target == m);
[209]518        }
[100]519      return n;
520    }
521
522    ///Processes the next node.
523
[244]524    ///Processes the next node and checks if at least one of reached
525    ///nodes has \c true value in the \c nm node map. If one node
526    ///with \c true value is reachable from the processed node, then the
527    ///\c rnode parameter will be set to the first of such nodes.
[100]528    ///
[244]529    ///\param nm A \c bool (or convertible) node map that indicates the
530    ///possible targets.
[100]531    ///\retval rnode The reached target node.
[244]532    ///It should be initially \c INVALID.
533    ///
[100]534    ///\return The processed node.
535    ///
[244]536    ///\pre The queue must not be empty.
[100]537    template<class NM>
538    Node processNextNode(const NM& nm, Node& rnode)
539    {
540      if(_queue_tail==_queue_next_dist) {
[209]541        _curr_dist++;
542        _queue_next_dist=_queue_head;
[100]543      }
544      Node n=_queue[_queue_tail++];
545      _processed->set(n,true);
546      Node m;
547      for(OutArcIt e(*G,n);e!=INVALID;++e)
[209]548        if(!(*_reached)[m=G->target(e)]) {
549          _queue[_queue_head++]=m;
550          _reached->set(m,true);
551          _pred->set(m,e);
552          _dist->set(m,_curr_dist);
553          if (nm[m] && rnode == INVALID) rnode = m;
554        }
[100]555      return n;
556    }
[209]557
[244]558    ///The next node to be processed.
[100]559
[244]560    ///Returns the next node to be processed or \c INVALID if the queue
561    ///is empty.
562    Node nextNode() const
[209]563    {
[100]564      return _queue_tail<_queue_head?_queue[_queue_tail]:INVALID;
565    }
[209]566
[421]567    ///Returns \c false if there are nodes to be processed.
568
569    ///Returns \c false if there are nodes to be processed
570    ///in the queue.
[244]571    bool emptyQueue() const { return _queue_tail==_queue_head; }
572
[100]573    ///Returns the number of the nodes to be processed.
[209]574
[421]575    ///Returns the number of the nodes to be processed
576    ///in the queue.
[244]577    int queueSize() const { return _queue_head-_queue_tail; }
[209]578
[100]579    ///Executes the algorithm.
580
581    ///Executes the algorithm.
582    ///
[244]583    ///This method runs the %BFS algorithm from the root node(s)
584    ///in order to compute the shortest path to each node.
[100]585    ///
[244]586    ///The algorithm computes
587    ///- the shortest path tree (forest),
588    ///- the distance of each node from the root(s).
589    ///
590    ///\pre init() must be called and at least one root node should be
591    ///added with addSource() before using this function.
592    ///
593    ///\note <tt>b.start()</tt> is just a shortcut of the following code.
594    ///\code
595    ///  while ( !b.emptyQueue() ) {
596    ///    b.processNextNode();
597    ///  }
598    ///\endcode
[100]599    void start()
600    {
601      while ( !emptyQueue() ) processNextNode();
602    }
[209]603
[244]604    ///Executes the algorithm until the given target node is reached.
[100]605
[244]606    ///Executes the algorithm until the given target node is reached.
[100]607    ///
608    ///This method runs the %BFS algorithm from the root node(s)
[286]609    ///in order to compute the shortest path to \c t.
[244]610    ///
[100]611    ///The algorithm computes
[286]612    ///- the shortest path to \c t,
613    ///- the distance of \c t from the root(s).
[244]614    ///
615    ///\pre init() must be called and at least one root node should be
616    ///added with addSource() before using this function.
617    ///
618    ///\note <tt>b.start(t)</tt> is just a shortcut of the following code.
619    ///\code
620    ///  bool reach = false;
621    ///  while ( !b.emptyQueue() && !reach ) {
622    ///    b.processNextNode(t, reach);
623    ///  }
624    ///\endcode
[286]625    void start(Node t)
[100]626    {
627      bool reach = false;
[286]628      while ( !emptyQueue() && !reach ) processNextNode(t, reach);
[100]629    }
[209]630
[100]631    ///Executes the algorithm until a condition is met.
632
633    ///Executes the algorithm until a condition is met.
634    ///
[244]635    ///This method runs the %BFS algorithm from the root node(s) in
636    ///order to compute the shortest path to a node \c v with
637    /// <tt>nm[v]</tt> true, if such a node can be found.
[100]638    ///
[244]639    ///\param nm A \c bool (or convertible) node map. The algorithm
640    ///will stop when it reaches a node \c v with <tt>nm[v]</tt> true.
[100]641    ///
642    ///\return The reached node \c v with <tt>nm[v]</tt> true or
643    ///\c INVALID if no such node was found.
[244]644    ///
645    ///\pre init() must be called and at least one root node should be
646    ///added with addSource() before using this function.
647    ///
648    ///\note <tt>b.start(nm)</tt> is just a shortcut of the following code.
649    ///\code
650    ///  Node rnode = INVALID;
651    ///  while ( !b.emptyQueue() && rnode == INVALID ) {
652    ///    b.processNextNode(nm, rnode);
653    ///  }
654    ///  return rnode;
655    ///\endcode
656    template<class NodeBoolMap>
657    Node start(const NodeBoolMap &nm)
[100]658    {
659      Node rnode = INVALID;
660      while ( !emptyQueue() && rnode == INVALID ) {
[209]661        processNextNode(nm, rnode);
[100]662      }
663      return rnode;
664    }
[209]665
[286]666    ///Runs the algorithm from the given source node.
[209]667
[244]668    ///This method runs the %BFS algorithm from node \c s
669    ///in order to compute the shortest path to each node.
[100]670    ///
[244]671    ///The algorithm computes
672    ///- the shortest path tree,
673    ///- the distance of each node from the root.
674    ///
675    ///\note <tt>b.run(s)</tt> is just a shortcut of the following code.
[100]676    ///\code
677    ///  b.init();
678    ///  b.addSource(s);
679    ///  b.start();
680    ///\endcode
681    void run(Node s) {
682      init();
683      addSource(s);
684      start();
685    }
[209]686
[100]687    ///Finds the shortest path between \c s and \c t.
[209]688
[244]689    ///This method runs the %BFS algorithm from node \c s
[286]690    ///in order to compute the shortest path to node \c t
691    ///(it stops searching when \c t is processed).
[100]692    ///
[286]693    ///\return \c true if \c t is reachable form \c s.
[244]694    ///
695    ///\note Apart from the return value, <tt>b.run(s,t)</tt> is just a
696    ///shortcut of the following code.
[100]697    ///\code
698    ///  b.init();
699    ///  b.addSource(s);
700    ///  b.start(t);
701    ///\endcode
[286]702    bool run(Node s,Node t) {
[100]703      init();
704      addSource(s);
705      start(t);
[286]706      return reached(t);
[100]707    }
[209]708
[244]709    ///Runs the algorithm to visit all nodes in the digraph.
710
[834]711    ///This method runs the %BFS algorithm in order to visit all nodes
712    ///in the digraph.
[244]713    ///
714    ///\note <tt>b.run(s)</tt> is just a shortcut of the following code.
715    ///\code
716    ///  b.init();
717    ///  for (NodeIt n(gr); n != INVALID; ++n) {
718    ///    if (!b.reached(n)) {
719    ///      b.addSource(n);
720    ///      b.start();
721    ///    }
722    ///  }
723    ///\endcode
724    void run() {
725      init();
726      for (NodeIt n(*G); n != INVALID; ++n) {
727        if (!reached(n)) {
728          addSource(n);
729          start();
730        }
731      }
732    }
733
[100]734    ///@}
735
736    ///\name Query Functions
[421]737    ///The results of the BFS algorithm can be obtained using these
[100]738    ///functions.\n
[421]739    ///Either \ref run(Node) "run()" or \ref start() should be called
740    ///before using them.
[209]741
[100]742    ///@{
743
[763]744    ///The shortest path to the given node.
[100]745
[763]746    ///Returns the shortest path to the given node from the root(s).
[244]747    ///
[421]748    ///\warning \c t should be reached from the root(s).
[244]749    ///
[421]750    ///\pre Either \ref run(Node) "run()" or \ref init()
751    ///must be called before using this function.
[244]752    Path path(Node t) const { return Path(*G, *_pred, t); }
[100]753
[763]754    ///The distance of the given node from the root(s).
[100]755
[763]756    ///Returns the distance of the given node from the root(s).
[244]757    ///
[421]758    ///\warning If node \c v is not reached from the root(s), then
[244]759    ///the return value of this function is undefined.
760    ///
[421]761    ///\pre Either \ref run(Node) "run()" or \ref init()
762    ///must be called before using this function.
[100]763    int dist(Node v) const { return (*_dist)[v]; }
764
[763]765    ///\brief Returns the 'previous arc' of the shortest path tree for
766    ///the given node.
767    ///
[244]768    ///This function returns the 'previous arc' of the shortest path
769    ///tree for the node \c v, i.e. it returns the last arc of a
[421]770    ///shortest path from a root to \c v. It is \c INVALID if \c v
771    ///is not reached from the root(s) or if \c v is a root.
[244]772    ///
773    ///The shortest path tree used here is equal to the shortest path
[763]774    ///tree used in \ref predNode() and \ref predMap().
[244]775    ///
[421]776    ///\pre Either \ref run(Node) "run()" or \ref init()
777    ///must be called before using this function.
[100]778    Arc predArc(Node v) const { return (*_pred)[v];}
779
[763]780    ///\brief Returns the 'previous node' of the shortest path tree for
781    ///the given node.
782    ///
[244]783    ///This function returns the 'previous node' of the shortest path
784    ///tree for the node \c v, i.e. it returns the last but one node
[763]785    ///of a shortest path from a root to \c v. It is \c INVALID
[421]786    ///if \c v is not reached from the root(s) or if \c v is a root.
[244]787    ///
[100]788    ///The shortest path tree used here is equal to the shortest path
[763]789    ///tree used in \ref predArc() and \ref predMap().
[244]790    ///
[421]791    ///\pre Either \ref run(Node) "run()" or \ref init()
792    ///must be called before using this function.
[100]793    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
[209]794                                  G->source((*_pred)[v]); }
795
[244]796    ///\brief Returns a const reference to the node map that stores the
797    /// distances of the nodes.
798    ///
799    ///Returns a const reference to the node map that stores the distances
800    ///of the nodes calculated by the algorithm.
801    ///
[421]802    ///\pre Either \ref run(Node) "run()" or \ref init()
[244]803    ///must be called before using this function.
[100]804    const DistMap &distMap() const { return *_dist;}
[209]805
[244]806    ///\brief Returns a const reference to the node map that stores the
807    ///predecessor arcs.
808    ///
809    ///Returns a const reference to the node map that stores the predecessor
[763]810    ///arcs, which form the shortest path tree (forest).
[244]811    ///
[421]812    ///\pre Either \ref run(Node) "run()" or \ref init()
[100]813    ///must be called before using this function.
814    const PredMap &predMap() const { return *_pred;}
[209]815
[763]816    ///Checks if the given node is reached from the root(s).
[100]817
[421]818    ///Returns \c true if \c v is reached from the root(s).
819    ///
820    ///\pre Either \ref run(Node) "run()" or \ref init()
[100]821    ///must be called before using this function.
[244]822    bool reached(Node v) const { return (*_reached)[v]; }
[209]823
[100]824    ///@}
825  };
826
[244]827  ///Default traits class of bfs() function.
[100]828
[244]829  ///Default traits class of bfs() function.
[157]830  ///\tparam GR Digraph type.
[100]831  template<class GR>
832  struct BfsWizardDefaultTraits
833  {
[244]834    ///The type of the digraph the algorithm runs on.
[100]835    typedef GR Digraph;
[244]836
837    ///\brief The type of the map that stores the predecessor
[100]838    ///arcs of the shortest paths.
[209]839    ///
[244]840    ///The type of the map that stores the predecessor
[100]841    ///arcs of the shortest paths.
[763]842    ///It must conform to the \ref concepts::WriteMap "WriteMap" concept.
[278]843    typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
[301]844    ///Instantiates a PredMap.
[209]845
[301]846    ///This function instantiates a PredMap.
[244]847    ///\param g is the digraph, to which we would like to define the
[301]848    ///PredMap.
[244]849    static PredMap *createPredMap(const Digraph &g)
[100]850    {
[278]851      return new PredMap(g);
[100]852    }
853
854    ///The type of the map that indicates which nodes are processed.
[209]855
[100]856    ///The type of the map that indicates which nodes are processed.
[763]857    ///It must conform to the \ref concepts::WriteMap "WriteMap" concept.
[833]858    ///By default, it is a NullMap.
[100]859    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
[301]860    ///Instantiates a ProcessedMap.
[209]861
[301]862    ///This function instantiates a ProcessedMap.
[100]863    ///\param g is the digraph, to which
[301]864    ///we would like to define the ProcessedMap.
[100]865#ifdef DOXYGEN
[244]866    static ProcessedMap *createProcessedMap(const Digraph &g)
[100]867#else
[244]868    static ProcessedMap *createProcessedMap(const Digraph &)
[100]869#endif
870    {
871      return new ProcessedMap();
872    }
[244]873
[100]874    ///The type of the map that indicates which nodes are reached.
[209]875
[100]876    ///The type of the map that indicates which nodes are reached.
[956]877    ///It must conform to
878    ///the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
[100]879    typedef typename Digraph::template NodeMap<bool> ReachedMap;
[301]880    ///Instantiates a ReachedMap.
[209]881
[301]882    ///This function instantiates a ReachedMap.
[244]883    ///\param g is the digraph, to which
[301]884    ///we would like to define the ReachedMap.
[244]885    static ReachedMap *createReachedMap(const Digraph &g)
[100]886    {
[244]887      return new ReachedMap(g);
[100]888    }
[209]889
[244]890    ///The type of the map that stores the distances of the nodes.
891
892    ///The type of the map that stores the distances of the nodes.
[763]893    ///It must conform to the \ref concepts::WriteMap "WriteMap" concept.
[278]894    typedef typename Digraph::template NodeMap<int> DistMap;
[301]895    ///Instantiates a DistMap.
[209]896
[301]897    ///This function instantiates a DistMap.
[210]898    ///\param g is the digraph, to which we would like to define
[301]899    ///the DistMap
[244]900    static DistMap *createDistMap(const Digraph &g)
[100]901    {
[278]902      return new DistMap(g);
[100]903    }
[278]904
905    ///The type of the shortest paths.
906
907    ///The type of the shortest paths.
[763]908    ///It must conform to the \ref concepts::Path "Path" concept.
[278]909    typedef lemon::Path<Digraph> Path;
[100]910  };
[209]911
[301]912  /// Default traits class used by BfsWizard
[100]913
[763]914  /// Default traits class used by BfsWizard.
915  /// \tparam GR The type of the digraph.
[100]916  template<class GR>
917  class BfsWizardBase : public BfsWizardDefaultTraits<GR>
918  {
919
920    typedef BfsWizardDefaultTraits<GR> Base;
921  protected:
[244]922    //The type of the nodes in the digraph.
[100]923    typedef typename Base::Digraph::Node Node;
924
[244]925    //Pointer to the digraph the algorithm runs on.
[100]926    void *_g;
[244]927    //Pointer to the map of reached nodes.
[100]928    void *_reached;
[244]929    //Pointer to the map of processed nodes.
[100]930    void *_processed;
[244]931    //Pointer to the map of predecessors arcs.
[100]932    void *_pred;
[244]933    //Pointer to the map of distances.
[100]934    void *_dist;
[278]935    //Pointer to the shortest path to the target node.
936    void *_path;
937    //Pointer to the distance of the target node.
938    int *_di;
[209]939
[100]940    public:
941    /// Constructor.
[209]942
[763]943    /// This constructor does not require parameters, it initiates
[278]944    /// all of the attributes to \c 0.
[100]945    BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0),
[278]946                      _dist(0), _path(0), _di(0) {}
[100]947
948    /// Constructor.
[209]949
[278]950    /// This constructor requires one parameter,
951    /// others are initiated to \c 0.
[244]952    /// \param g The digraph the algorithm runs on.
[278]953    BfsWizardBase(const GR &g) :
[209]954      _g(reinterpret_cast<void*>(const_cast<GR*>(&g))),
[278]955      _reached(0), _processed(0), _pred(0), _dist(0),  _path(0), _di(0) {}
[100]956
957  };
[209]958
[278]959  /// Auxiliary class for the function-type interface of BFS algorithm.
[100]960
[278]961  /// This auxiliary class is created to implement the
962  /// \ref bfs() "function-type interface" of \ref Bfs algorithm.
[421]963  /// It does not have own \ref run(Node) "run()" method, it uses the
964  /// functions and features of the plain \ref Bfs.
[100]965  ///
[278]966  /// This class should only be used through the \ref bfs() function,
967  /// which makes it easier to use the algorithm.
[891]968  ///
969  /// \tparam TR The traits class that defines various types used by the
970  /// algorithm.
[100]971  template<class TR>
972  class BfsWizard : public TR
973  {
974    typedef TR Base;
975
976    typedef typename TR::Digraph Digraph;
[244]977
[100]978    typedef typename Digraph::Node Node;
979    typedef typename Digraph::NodeIt NodeIt;
980    typedef typename Digraph::Arc Arc;
981    typedef typename Digraph::OutArcIt OutArcIt;
[209]982
[100]983    typedef typename TR::PredMap PredMap;
984    typedef typename TR::DistMap DistMap;
[244]985    typedef typename TR::ReachedMap ReachedMap;
986    typedef typename TR::ProcessedMap ProcessedMap;
[278]987    typedef typename TR::Path Path;
[100]988
989  public:
[244]990
[100]991    /// Constructor.
992    BfsWizard() : TR() {}
993
994    /// Constructor that requires parameters.
995
996    /// Constructor that requires parameters.
997    /// These parameters will be the default values for the traits class.
[278]998    /// \param g The digraph the algorithm runs on.
999    BfsWizard(const Digraph &g) :
1000      TR(g) {}
[100]1001
1002    ///Copy constructor
1003    BfsWizard(const TR &b) : TR(b) {}
1004
1005    ~BfsWizard() {}
1006
[278]1007    ///Runs BFS algorithm from the given source node.
[209]1008
[278]1009    ///This method runs BFS algorithm from node \c s
1010    ///in order to compute the shortest path to each node.
1011    void run(Node s)
1012    {
1013      Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
1014      if (Base::_pred)
1015        alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
1016      if (Base::_dist)
1017        alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
1018      if (Base::_reached)
1019        alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
1020      if (Base::_processed)
1021        alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
1022      if (s!=INVALID)
1023        alg.run(s);
1024      else
1025        alg.run();
1026    }
1027
1028    ///Finds the shortest path between \c s and \c t.
1029
1030    ///This method runs BFS algorithm from node \c s
1031    ///in order to compute the shortest path to node \c t
1032    ///(it stops searching when \c t is processed).
1033    ///
1034    ///\return \c true if \c t is reachable form \c s.
1035    bool run(Node s, Node t)
1036    {
1037      Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
1038      if (Base::_pred)
1039        alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
1040      if (Base::_dist)
1041        alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
1042      if (Base::_reached)
1043        alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
1044      if (Base::_processed)
1045        alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
1046      alg.run(s,t);
1047      if (Base::_path)
1048        *reinterpret_cast<Path*>(Base::_path) = alg.path(t);
1049      if (Base::_di)
1050        *Base::_di = alg.dist(t);
1051      return alg.reached(t);
1052    }
1053
1054    ///Runs BFS algorithm to visit all nodes in the digraph.
1055
[834]1056    ///This method runs BFS algorithm in order to visit all nodes
1057    ///in the digraph.
[100]1058    void run()
1059    {
[278]1060      run(INVALID);
[100]1061    }
[209]1062
[244]1063    template<class T>
[257]1064    struct SetPredMapBase : public Base {
[244]1065      typedef T PredMap;
1066      static PredMap *createPredMap(const Digraph &) { return 0; };
[257]1067      SetPredMapBase(const TR &b) : TR(b) {}
[244]1068    };
[763]1069
1070    ///\brief \ref named-templ-param "Named parameter" for setting
1071    ///the predecessor map.
[244]1072    ///
[763]1073    ///\ref named-templ-param "Named parameter" function for setting
1074    ///the map that stores the predecessor arcs of the nodes.
[244]1075    template<class T>
[257]1076    BfsWizard<SetPredMapBase<T> > predMap(const T &t)
[244]1077    {
1078      Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
[257]1079      return BfsWizard<SetPredMapBase<T> >(*this);
[244]1080    }
1081
1082    template<class T>
[257]1083    struct SetReachedMapBase : public Base {
[244]1084      typedef T ReachedMap;
1085      static ReachedMap *createReachedMap(const Digraph &) { return 0; };
[257]1086      SetReachedMapBase(const TR &b) : TR(b) {}
[244]1087    };
[763]1088
1089    ///\brief \ref named-templ-param "Named parameter" for setting
1090    ///the reached map.
[244]1091    ///
[763]1092    ///\ref named-templ-param "Named parameter" function for setting
1093    ///the map that indicates which nodes are reached.
[244]1094    template<class T>
[257]1095    BfsWizard<SetReachedMapBase<T> > reachedMap(const T &t)
[244]1096    {
1097      Base::_reached=reinterpret_cast<void*>(const_cast<T*>(&t));
[257]1098      return BfsWizard<SetReachedMapBase<T> >(*this);
[244]1099    }
1100
1101    template<class T>
[278]1102    struct SetDistMapBase : public Base {
1103      typedef T DistMap;
1104      static DistMap *createDistMap(const Digraph &) { return 0; };
1105      SetDistMapBase(const TR &b) : TR(b) {}
1106    };
[763]1107
1108    ///\brief \ref named-templ-param "Named parameter" for setting
1109    ///the distance map.
[278]1110    ///
[763]1111    ///\ref named-templ-param "Named parameter" function for setting
1112    ///the map that stores the distances of the nodes calculated
1113    ///by the algorithm.
[278]1114    template<class T>
1115    BfsWizard<SetDistMapBase<T> > distMap(const T &t)
1116    {
1117      Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
1118      return BfsWizard<SetDistMapBase<T> >(*this);
1119    }
1120
1121    template<class T>
[257]1122    struct SetProcessedMapBase : public Base {
[244]1123      typedef T ProcessedMap;
1124      static ProcessedMap *createProcessedMap(const Digraph &) { return 0; };
[257]1125      SetProcessedMapBase(const TR &b) : TR(b) {}
[244]1126    };
[763]1127
1128    ///\brief \ref named-func-param "Named parameter" for setting
1129    ///the processed map.
[244]1130    ///
[763]1131    ///\ref named-templ-param "Named parameter" function for setting
1132    ///the map that indicates which nodes are processed.
[244]1133    template<class T>
[257]1134    BfsWizard<SetProcessedMapBase<T> > processedMap(const T &t)
[244]1135    {
1136      Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t));
[257]1137      return BfsWizard<SetProcessedMapBase<T> >(*this);
[244]1138    }
1139
1140    template<class T>
[278]1141    struct SetPathBase : public Base {
1142      typedef T Path;
1143      SetPathBase(const TR &b) : TR(b) {}
[244]1144    };
[278]1145    ///\brief \ref named-func-param "Named parameter"
1146    ///for getting the shortest path to the target node.
[244]1147    ///
[278]1148    ///\ref named-func-param "Named parameter"
1149    ///for getting the shortest path to the target node.
[244]1150    template<class T>
[278]1151    BfsWizard<SetPathBase<T> > path(const T &t)
[244]1152    {
[278]1153      Base::_path=reinterpret_cast<void*>(const_cast<T*>(&t));
1154      return BfsWizard<SetPathBase<T> >(*this);
1155    }
1156
1157    ///\brief \ref named-func-param "Named parameter"
1158    ///for getting the distance of the target node.
1159    ///
1160    ///\ref named-func-param "Named parameter"
1161    ///for getting the distance of the target node.
1162    BfsWizard dist(const int &d)
1163    {
1164      Base::_di=const_cast<int*>(&d);
1165      return *this;
[244]1166    }
1167
[100]1168  };
[209]1169
[278]1170  ///Function-type interface for BFS algorithm.
[100]1171
1172  /// \ingroup search
[278]1173  ///Function-type interface for BFS algorithm.
[100]1174  ///
[278]1175  ///This function also has several \ref named-func-param "named parameters",
[100]1176  ///they are declared as the members of class \ref BfsWizard.
[278]1177  ///The following examples show how to use these parameters.
[100]1178  ///\code
[278]1179  ///  // Compute shortest path from node s to each node
1180  ///  bfs(g).predMap(preds).distMap(dists).run(s);
1181  ///
1182  ///  // Compute shortest path from s to t
1183  ///  bool reached = bfs(g).path(p).dist(d).run(s,t);
[100]1184  ///\endcode
[421]1185  ///\warning Don't forget to put the \ref BfsWizard::run(Node) "run()"
[100]1186  ///to the end of the parameter list.
1187  ///\sa BfsWizard
1188  ///\sa Bfs
1189  template<class GR>
1190  BfsWizard<BfsWizardBase<GR> >
[278]1191  bfs(const GR &digraph)
[100]1192  {
[278]1193    return BfsWizard<BfsWizardBase<GR> >(digraph);
[100]1194  }
1195
1196#ifdef DOXYGEN
[244]1197  /// \brief Visitor class for BFS.
[209]1198  ///
[100]1199  /// This class defines the interface of the BfsVisit events, and
[244]1200  /// it could be the base of a real visitor class.
[525]1201  template <typename GR>
[100]1202  struct BfsVisitor {
[525]1203    typedef GR Digraph;
[100]1204    typedef typename Digraph::Arc Arc;
1205    typedef typename Digraph::Node Node;
[244]1206    /// \brief Called for the source node(s) of the BFS.
[209]1207    ///
[244]1208    /// This function is called for the source node(s) of the BFS.
1209    void start(const Node& node) {}
1210    /// \brief Called when a node is reached first time.
1211    ///
1212    /// This function is called when a node is reached first time.
1213    void reach(const Node& node) {}
1214    /// \brief Called when a node is processed.
1215    ///
1216    /// This function is called when a node is processed.
1217    void process(const Node& node) {}
1218    /// \brief Called when an arc reaches a new node.
1219    ///
1220    /// This function is called when the BFS finds an arc whose target node
1221    /// is not reached yet.
[100]1222    void discover(const Arc& arc) {}
[244]1223    /// \brief Called when an arc is examined but its target node is
[100]1224    /// already discovered.
[209]1225    ///
[244]1226    /// This function is called when an arc is examined but its target node is
[100]1227    /// already discovered.
1228    void examine(const Arc& arc) {}
1229  };
1230#else
[525]1231  template <typename GR>
[100]1232  struct BfsVisitor {
[525]1233    typedef GR Digraph;
[100]1234    typedef typename Digraph::Arc Arc;
1235    typedef typename Digraph::Node Node;
[244]1236    void start(const Node&) {}
1237    void reach(const Node&) {}
1238    void process(const Node&) {}
[100]1239    void discover(const Arc&) {}
1240    void examine(const Arc&) {}
1241
1242    template <typename _Visitor>
1243    struct Constraints {
1244      void constraints() {
[209]1245        Arc arc;
1246        Node node;
[244]1247        visitor.start(node);
1248        visitor.reach(node);
1249        visitor.process(node);
[209]1250        visitor.discover(arc);
1251        visitor.examine(arc);
[100]1252      }
1253      _Visitor& visitor;
[1125]1254      Constraints() {}
[100]1255    };
1256  };
1257#endif
1258
1259  /// \brief Default traits class of BfsVisit class.
1260  ///
1261  /// Default traits class of BfsVisit class.
[525]1262  /// \tparam GR The type of the digraph the algorithm runs on.
1263  template<class GR>
[100]1264  struct BfsVisitDefaultTraits {
1265
[244]1266    /// \brief The type of the digraph the algorithm runs on.
[525]1267    typedef GR Digraph;
[100]1268
1269    /// \brief The type of the map that indicates which nodes are reached.
[209]1270    ///
[100]1271    /// The type of the map that indicates which nodes are reached.
[956]1272    /// It must conform to
1273    ///the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
[100]1274    typedef typename Digraph::template NodeMap<bool> ReachedMap;
1275
[301]1276    /// \brief Instantiates a ReachedMap.
[100]1277    ///
[301]1278    /// This function instantiates a ReachedMap.
[100]1279    /// \param digraph is the digraph, to which
[301]1280    /// we would like to define the ReachedMap.
[100]1281    static ReachedMap *createReachedMap(const Digraph &digraph) {
1282      return new ReachedMap(digraph);
1283    }
1284
1285  };
1286
1287  /// \ingroup search
[209]1288  ///
[525]1289  /// \brief BFS algorithm class with visitor interface.
[209]1290  ///
[525]1291  /// This class provides an efficient implementation of the BFS algorithm
[100]1292  /// with visitor interface.
1293  ///
[525]1294  /// The BfsVisit class provides an alternative interface to the Bfs
[100]1295  /// class. It works with callback mechanism, the BfsVisit object calls
[244]1296  /// the member functions of the \c Visitor class on every BFS event.
[100]1297  ///
[252]1298  /// This interface of the BFS algorithm should be used in special cases
1299  /// when extra actions have to be performed in connection with certain
1300  /// events of the BFS algorithm. Otherwise consider to use Bfs or bfs()
1301  /// instead.
1302  ///
[525]1303  /// \tparam GR The type of the digraph the algorithm runs on.
1304  /// The default type is \ref ListDigraph.
1305  /// The value of GR is not used directly by \ref BfsVisit,
1306  /// it is only passed to \ref BfsVisitDefaultTraits.
1307  /// \tparam VS The Visitor type that is used by the algorithm.
1308  /// \ref BfsVisitor "BfsVisitor<GR>" is an empty visitor, which
[244]1309  /// does not observe the BFS events. If you want to observe the BFS
1310  /// events, you should implement your own visitor class.
[891]1311  /// \tparam TR The traits class that defines various types used by the
1312  /// algorithm. By default, it is \ref BfsVisitDefaultTraits
1313  /// "BfsVisitDefaultTraits<GR>".
1314  /// In most cases, this parameter should not be set directly,
1315  /// consider to use the named template parameters instead.
[100]1316#ifdef DOXYGEN
[525]1317  template <typename GR, typename VS, typename TR>
[100]1318#else
[525]1319  template <typename GR = ListDigraph,
1320            typename VS = BfsVisitor<GR>,
1321            typename TR = BfsVisitDefaultTraits<GR> >
[100]1322#endif
1323  class BfsVisit {
1324  public:
[209]1325
[244]1326    ///The traits class.
[525]1327    typedef TR Traits;
[100]1328
[244]1329    ///The type of the digraph the algorithm runs on.
[100]1330    typedef typename Traits::Digraph Digraph;
1331
[244]1332    ///The visitor type used by the algorithm.
[525]1333    typedef VS Visitor;
[100]1334
[244]1335    ///The type of the map that indicates which nodes are reached.
[100]1336    typedef typename Traits::ReachedMap ReachedMap;
1337
1338  private:
1339
1340    typedef typename Digraph::Node Node;
1341    typedef typename Digraph::NodeIt NodeIt;
1342    typedef typename Digraph::Arc Arc;
1343    typedef typename Digraph::OutArcIt OutArcIt;
1344
[244]1345    //Pointer to the underlying digraph.
[100]1346    const Digraph *_digraph;
[244]1347    //Pointer to the visitor object.
[100]1348    Visitor *_visitor;
[244]1349    //Pointer to the map of reached status of the nodes.
[100]1350    ReachedMap *_reached;
[244]1351    //Indicates if _reached is locally allocated (true) or not.
[100]1352    bool local_reached;
1353
1354    std::vector<typename Digraph::Node> _list;
1355    int _list_front, _list_back;
1356
[280]1357    //Creates the maps if necessary.
[100]1358    void create_maps() {
1359      if(!_reached) {
[209]1360        local_reached = true;
1361        _reached = Traits::createReachedMap(*_digraph);
[100]1362      }
1363    }
1364
1365  protected:
1366
1367    BfsVisit() {}
[209]1368
[100]1369  public:
1370
1371    typedef BfsVisit Create;
1372
[421]1373    /// \name Named Template Parameters
[100]1374
1375    ///@{
1376    template <class T>
[257]1377    struct SetReachedMapTraits : public Traits {
[100]1378      typedef T ReachedMap;
1379      static ReachedMap *createReachedMap(const Digraph &digraph) {
[290]1380        LEMON_ASSERT(false, "ReachedMap is not initialized");
1381        return 0; // ignore warnings
[100]1382      }
1383    };
[209]1384    /// \brief \ref named-templ-param "Named parameter" for setting
[244]1385    /// ReachedMap type.
[100]1386    ///
[244]1387    /// \ref named-templ-param "Named parameter" for setting ReachedMap type.
[100]1388    template <class T>
[257]1389    struct SetReachedMap : public BfsVisit< Digraph, Visitor,
1390                                            SetReachedMapTraits<T> > {
1391      typedef BfsVisit< Digraph, Visitor, SetReachedMapTraits<T> > Create;
[100]1392    };
1393    ///@}
1394
[209]1395  public:
1396
[100]1397    /// \brief Constructor.
1398    ///
1399    /// Constructor.
1400    ///
[244]1401    /// \param digraph The digraph the algorithm runs on.
1402    /// \param visitor The visitor object of the algorithm.
[209]1403    BfsVisit(const Digraph& digraph, Visitor& visitor)
[100]1404      : _digraph(&digraph), _visitor(&visitor),
[209]1405        _reached(0), local_reached(false) {}
1406
[100]1407    /// \brief Destructor.
1408    ~BfsVisit() {
1409      if(local_reached) delete _reached;
1410    }
1411
[244]1412    /// \brief Sets the map that indicates which nodes are reached.
[100]1413    ///
[244]1414    /// Sets the map that indicates which nodes are reached.
[421]1415    /// If you don't use this function before calling \ref run(Node) "run()"
1416    /// or \ref init(), an instance will be allocated automatically.
1417    /// The destructor deallocates this automatically allocated map,
1418    /// of course.
[100]1419    /// \return <tt> (*this) </tt>
1420    BfsVisit &reachedMap(ReachedMap &m) {
1421      if(local_reached) {
[209]1422        delete _reached;
1423        local_reached = false;
[100]1424      }
1425      _reached = &m;
1426      return *this;
1427    }
1428
1429  public:
[244]1430
[421]1431    /// \name Execution Control
1432    /// The simplest way to execute the BFS algorithm is to use one of the
1433    /// member functions called \ref run(Node) "run()".\n
[760]1434    /// If you need better control on the execution, you have to call
1435    /// \ref init() first, then you can add several source nodes with
[421]1436    /// \ref addSource(). Finally the actual path computation can be
1437    /// performed with one of the \ref start() functions.
[100]1438
1439    /// @{
[244]1440
[100]1441    /// \brief Initializes the internal data structures.
1442    ///
1443    /// Initializes the internal data structures.
1444    void init() {
1445      create_maps();
1446      _list.resize(countNodes(*_digraph));
1447      _list_front = _list_back = -1;
1448      for (NodeIt u(*_digraph) ; u != INVALID ; ++u) {
[209]1449        _reached->set(u, false);
[100]1450      }
1451    }
[209]1452
[100]1453    /// \brief Adds a new source node.
1454    ///
1455    /// Adds a new source node to the set of nodes to be processed.
1456    void addSource(Node s) {
1457      if(!(*_reached)[s]) {
[209]1458          _reached->set(s,true);
1459          _visitor->start(s);
1460          _visitor->reach(s);
[100]1461          _list[++_list_back] = s;
[209]1462        }
[100]1463    }
[209]1464
[100]1465    /// \brief Processes the next node.
1466    ///
1467    /// Processes the next node.
1468    ///
1469    /// \return The processed node.
1470    ///
[244]1471    /// \pre The queue must not be empty.
[209]1472    Node processNextNode() {
[100]1473      Node n = _list[++_list_front];
1474      _visitor->process(n);
1475      Arc e;
1476      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
1477        Node m = _digraph->target(e);
1478        if (!(*_reached)[m]) {
1479          _visitor->discover(e);
1480          _visitor->reach(m);
1481          _reached->set(m, true);
1482          _list[++_list_back] = m;
1483        } else {
1484          _visitor->examine(e);
1485        }
1486      }
1487      return n;
1488    }
1489
1490    /// \brief Processes the next node.
1491    ///
[244]1492    /// Processes the next node and checks if the given target node
[100]1493    /// is reached. If the target node is reachable from the processed
[244]1494    /// node, then the \c reach parameter will be set to \c true.
[100]1495    ///
1496    /// \param target The target node.
[244]1497    /// \retval reach Indicates if the target node is reached.
1498    /// It should be initially \c false.
1499    ///
[100]1500    /// \return The processed node.
1501    ///
[244]1502    /// \pre The queue must not be empty.
[100]1503    Node processNextNode(Node target, bool& reach) {
1504      Node n = _list[++_list_front];
1505      _visitor->process(n);
1506      Arc e;
1507      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
1508        Node m = _digraph->target(e);
1509        if (!(*_reached)[m]) {
1510          _visitor->discover(e);
1511          _visitor->reach(m);
1512          _reached->set(m, true);
1513          _list[++_list_back] = m;
1514          reach = reach || (target == m);
1515        } else {
1516          _visitor->examine(e);
1517        }
1518      }
1519      return n;
1520    }
1521
1522    /// \brief Processes the next node.
1523    ///
[244]1524    /// Processes the next node and checks if at least one of reached
1525    /// nodes has \c true value in the \c nm node map. If one node
1526    /// with \c true value is reachable from the processed node, then the
1527    /// \c rnode parameter will be set to the first of such nodes.
[100]1528    ///
[244]1529    /// \param nm A \c bool (or convertible) node map that indicates the
1530    /// possible targets.
[100]1531    /// \retval rnode The reached target node.
[244]1532    /// It should be initially \c INVALID.
1533    ///
[100]1534    /// \return The processed node.
1535    ///
[244]1536    /// \pre The queue must not be empty.
[100]1537    template <typename NM>
1538    Node processNextNode(const NM& nm, Node& rnode) {
1539      Node n = _list[++_list_front];
1540      _visitor->process(n);
1541      Arc e;
1542      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
1543        Node m = _digraph->target(e);
1544        if (!(*_reached)[m]) {
1545          _visitor->discover(e);
1546          _visitor->reach(m);
1547          _reached->set(m, true);
1548          _list[++_list_back] = m;
1549          if (nm[m] && rnode == INVALID) rnode = m;
1550        } else {
1551          _visitor->examine(e);
1552        }
1553      }
1554      return n;
1555    }
1556
[244]1557    /// \brief The next node to be processed.
[100]1558    ///
[244]1559    /// Returns the next node to be processed or \c INVALID if the queue
1560    /// is empty.
1561    Node nextNode() const {
[100]1562      return _list_front != _list_back ? _list[_list_front + 1] : INVALID;
1563    }
1564
1565    /// \brief Returns \c false if there are nodes
[244]1566    /// to be processed.
[100]1567    ///
1568    /// Returns \c false if there are nodes
[244]1569    /// to be processed in the queue.
1570    bool emptyQueue() const { return _list_front == _list_back; }
[100]1571
1572    /// \brief Returns the number of the nodes to be processed.
1573    ///
1574    /// Returns the number of the nodes to be processed in the queue.
[244]1575    int queueSize() const { return _list_back - _list_front; }
[209]1576
[100]1577    /// \brief Executes the algorithm.
1578    ///
1579    /// Executes the algorithm.
1580    ///
[244]1581    /// This method runs the %BFS algorithm from the root node(s)
1582    /// in order to compute the shortest path to each node.
1583    ///
1584    /// The algorithm computes
1585    /// - the shortest path tree (forest),
1586    /// - the distance of each node from the root(s).
1587    ///
1588    /// \pre init() must be called and at least one root node should be added
[100]1589    /// with addSource() before using this function.
[244]1590    ///
1591    /// \note <tt>b.start()</tt> is just a shortcut of the following code.
1592    /// \code
1593    ///   while ( !b.emptyQueue() ) {
1594    ///     b.processNextNode();
1595    ///   }
1596    /// \endcode
[100]1597    void start() {
1598      while ( !emptyQueue() ) processNextNode();
1599    }
[209]1600
[244]1601    /// \brief Executes the algorithm until the given target node is reached.
[100]1602    ///
[244]1603    /// Executes the algorithm until the given target node is reached.
[100]1604    ///
[244]1605    /// This method runs the %BFS algorithm from the root node(s)
[286]1606    /// in order to compute the shortest path to \c t.
[244]1607    ///
1608    /// The algorithm computes
[286]1609    /// - the shortest path to \c t,
1610    /// - the distance of \c t from the root(s).
[244]1611    ///
1612    /// \pre init() must be called and at least one root node should be
1613    /// added with addSource() before using this function.
1614    ///
1615    /// \note <tt>b.start(t)</tt> is just a shortcut of the following code.
1616    /// \code
1617    ///   bool reach = false;
1618    ///   while ( !b.emptyQueue() && !reach ) {
1619    ///     b.processNextNode(t, reach);
1620    ///   }
1621    /// \endcode
[286]1622    void start(Node t) {
[100]1623      bool reach = false;
[286]1624      while ( !emptyQueue() && !reach ) processNextNode(t, reach);
[100]1625    }
[209]1626
[100]1627    /// \brief Executes the algorithm until a condition is met.
1628    ///
1629    /// Executes the algorithm until a condition is met.
1630    ///
[244]1631    /// This method runs the %BFS algorithm from the root node(s) in
1632    /// order to compute the shortest path to a node \c v with
1633    /// <tt>nm[v]</tt> true, if such a node can be found.
[100]1634    ///
[244]1635    /// \param nm must be a bool (or convertible) node map. The
1636    /// algorithm will stop when it reaches a node \c v with
[100]1637    /// <tt>nm[v]</tt> true.
1638    ///
[244]1639    /// \return The reached node \c v with <tt>nm[v]</tt> true or
1640    /// \c INVALID if no such node was found.
1641    ///
1642    /// \pre init() must be called and at least one root node should be
1643    /// added with addSource() before using this function.
1644    ///
1645    /// \note <tt>b.start(nm)</tt> is just a shortcut of the following code.
1646    /// \code
1647    ///   Node rnode = INVALID;
1648    ///   while ( !b.emptyQueue() && rnode == INVALID ) {
1649    ///     b.processNextNode(nm, rnode);
1650    ///   }
1651    ///   return rnode;
1652    /// \endcode
[100]1653    template <typename NM>
1654    Node start(const NM &nm) {
1655      Node rnode = INVALID;
1656      while ( !emptyQueue() && rnode == INVALID ) {
[209]1657        processNextNode(nm, rnode);
[100]1658      }
1659      return rnode;
1660    }
1661
[286]1662    /// \brief Runs the algorithm from the given source node.
[100]1663    ///
[244]1664    /// This method runs the %BFS algorithm from node \c s
1665    /// in order to compute the shortest path to each node.
1666    ///
1667    /// The algorithm computes
1668    /// - the shortest path tree,
1669    /// - the distance of each node from the root.
1670    ///
1671    /// \note <tt>b.run(s)</tt> is just a shortcut of the following code.
[100]1672    ///\code
1673    ///   b.init();
1674    ///   b.addSource(s);
1675    ///   b.start();
1676    ///\endcode
1677    void run(Node s) {
1678      init();
1679      addSource(s);
1680      start();
1681    }
1682
[286]1683    /// \brief Finds the shortest path between \c s and \c t.
1684    ///
1685    /// This method runs the %BFS algorithm from node \c s
1686    /// in order to compute the shortest path to node \c t
1687    /// (it stops searching when \c t is processed).
1688    ///
1689    /// \return \c true if \c t is reachable form \c s.
1690    ///
1691    /// \note Apart from the return value, <tt>b.run(s,t)</tt> is just a
1692    /// shortcut of the following code.
1693    ///\code
1694    ///   b.init();
1695    ///   b.addSource(s);
1696    ///   b.start(t);
1697    ///\endcode
1698    bool run(Node s,Node t) {
1699      init();
1700      addSource(s);
1701      start(t);
1702      return reached(t);
1703    }
1704
[244]1705    /// \brief Runs the algorithm to visit all nodes in the digraph.
[209]1706    ///
[834]1707    /// This method runs the %BFS algorithm in order to visit all nodes
1708    /// in the digraph.
[244]1709    ///
1710    /// \note <tt>b.run(s)</tt> is just a shortcut of the following code.
[100]1711    ///\code
1712    ///  b.init();
[244]1713    ///  for (NodeIt n(gr); n != INVALID; ++n) {
1714    ///    if (!b.reached(n)) {
1715    ///      b.addSource(n);
[100]1716    ///      b.start();
1717    ///    }
1718    ///  }
1719    ///\endcode
1720    void run() {
1721      init();
1722      for (NodeIt it(*_digraph); it != INVALID; ++it) {
1723        if (!reached(it)) {
1724          addSource(it);
1725          start();
1726        }
1727      }
1728    }
[244]1729
[100]1730    ///@}
1731
1732    /// \name Query Functions
[421]1733    /// The results of the BFS algorithm can be obtained using these
[100]1734    /// functions.\n
[421]1735    /// Either \ref run(Node) "run()" or \ref start() should be called
1736    /// before using them.
1737
[100]1738    ///@{
1739
[763]1740    /// \brief Checks if the given node is reached from the root(s).
[100]1741    ///
[421]1742    /// Returns \c true if \c v is reached from the root(s).
1743    ///
1744    /// \pre Either \ref run(Node) "run()" or \ref init()
[100]1745    /// must be called before using this function.
[437]1746    bool reached(Node v) const { return (*_reached)[v]; }
[244]1747
[100]1748    ///@}
[244]1749
[100]1750  };
1751
1752} //END OF NAMESPACE LEMON
1753
1754#endif
Note: See TracBrowser for help on using the repository browser.