COIN-OR::LEMON - Graph Library

source: lemon-0.x/lemon/dfs.h @ 1665:fdeb961110ac

Last change on this file since 1665:fdeb961110ac was 1665:fdeb961110ac, checked in by Alpar Juttner, 14 years ago

Functions to query the next node/edge to be processed.

File size: 35.8 KB
Line 
1/* -*- C++ -*-
2 * lemon/dfs.h - Part of LEMON, a generic C++ optimization library
3 *
4 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
5 * (Egervary Research Group on Combinatorial Optimization, EGRES).
6 *
7 * Permission to use, modify and distribute this software is granted
8 * provided that this copyright notice appears in all copies. For
9 * precise terms see the accompanying LICENSE file.
10 *
11 * This software is provided "AS IS" with no warranty of any kind,
12 * express or implied, and with no claim as to its suitability for any
13 * purpose.
14 *
15 */
16
17#ifndef LEMON_DFS_H
18#define LEMON_DFS_H
19
20///\ingroup flowalgs
21///\file
22///\brief Dfs algorithm.
23
24#include <lemon/list_graph.h>
25#include <lemon/graph_utils.h>
26#include <lemon/invalid.h>
27#include <lemon/error.h>
28#include <lemon/maps.h>
29
30namespace lemon {
31
32
33 
34  ///Default traits class of Dfs class.
35
36  ///Default traits class of Dfs class.
37  ///\param GR Graph type.
38  template<class GR>
39  struct DfsDefaultTraits
40  {
41    ///The graph type the algorithm runs on.
42    typedef GR Graph;
43    ///\brief The type of the map that stores the last
44    ///edges of the %DFS paths.
45    ///
46    ///The type of the map that stores the last
47    ///edges of the %DFS paths.
48    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
49    ///
50    typedef typename Graph::template NodeMap<typename GR::Edge> PredMap;
51    ///Instantiates a PredMap.
52 
53    ///This function instantiates a \ref PredMap.
54    ///\param G is the graph, to which we would like to define the PredMap.
55    ///\todo The graph alone may be insufficient to initialize
56    static PredMap *createPredMap(const GR &G)
57    {
58      return new PredMap(G);
59    }
60//     ///\brief The type of the map that stores the last but one
61//     ///nodes of the %DFS paths.
62//     ///
63//     ///The type of the map that stores the last but one
64//     ///nodes of the %DFS paths.
65//     ///It must meet the \ref concept::WriteMap "WriteMap" concept.
66//     ///
67//     typedef NullMap<typename Graph::Node,typename Graph::Node> PredNodeMap;
68//     ///Instantiates a PredNodeMap.
69   
70//     ///This function instantiates a \ref PredNodeMap.
71//     ///\param G is the graph, to which
72//     ///we would like to define the \ref PredNodeMap
73//     static PredNodeMap *createPredNodeMap(const GR &G)
74//     {
75//       return new PredNodeMap();
76//     }
77
78    ///The type of the map that indicates which nodes are processed.
79 
80    ///The type of the map that indicates which nodes are processed.
81    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
82    ///\todo named parameter to set this type, function to read and write.
83    typedef NullMap<typename Graph::Node,bool> ProcessedMap;
84    ///Instantiates a ProcessedMap.
85 
86    ///This function instantiates a \ref ProcessedMap.
87    ///\param g is the graph, to which
88    ///we would like to define the \ref ProcessedMap
89#ifdef DOXYGEN
90    static ProcessedMap *createProcessedMap(const GR &g)
91#else
92    static ProcessedMap *createProcessedMap(const GR &)
93#endif
94    {
95      return new ProcessedMap();
96    }
97    ///The type of the map that indicates which nodes are reached.
98 
99    ///The type of the map that indicates which nodes are reached.
100    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
101    ///\todo named parameter to set this type, function to read and write.
102    typedef typename Graph::template NodeMap<bool> ReachedMap;
103    ///Instantiates a ReachedMap.
104 
105    ///This function instantiates a \ref ReachedMap.
106    ///\param G is the graph, to which
107    ///we would like to define the \ref ReachedMap.
108    static ReachedMap *createReachedMap(const GR &G)
109    {
110      return new ReachedMap(G);
111    }
112    ///The type of the map that stores the dists of the nodes.
113 
114    ///The type of the map that stores the dists of the nodes.
115    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
116    ///
117    typedef typename Graph::template NodeMap<int> DistMap;
118    ///Instantiates a DistMap.
119 
120    ///This function instantiates a \ref DistMap.
121    ///\param G is the graph, to which we would like to define the \ref DistMap
122    static DistMap *createDistMap(const GR &G)
123    {
124      return new DistMap(G);
125    }
126  };
127 
128  ///%DFS algorithm class.
129 
130  ///\ingroup flowalgs
131  ///This class provides an efficient implementation of the %DFS algorithm.
132  ///
133  ///\param GR The graph type the algorithm runs on. The default value is
134  ///\ref ListGraph. The value of GR is not used directly by Dfs, it
135  ///is only passed to \ref DfsDefaultTraits.
136  ///\param TR Traits class to set various data types used by the algorithm.
137  ///The default traits class is
138  ///\ref DfsDefaultTraits "DfsDefaultTraits<GR>".
139  ///See \ref DfsDefaultTraits for the documentation of
140  ///a Dfs traits class.
141  ///
142  ///\author Jacint Szabo and Alpar Juttner
143  ///\todo A compare object would be nice.
144
145#ifdef DOXYGEN
146  template <typename GR,
147            typename TR>
148#else
149  template <typename GR=ListGraph,
150            typename TR=DfsDefaultTraits<GR> >
151#endif
152  class Dfs {
153  public:
154    /**
155     * \brief \ref Exception for uninitialized parameters.
156     *
157     * This error represents problems in the initialization
158     * of the parameters of the algorithms.
159     */
160    class UninitializedParameter : public lemon::UninitializedParameter {
161    public:
162      virtual const char* exceptionName() const {
163        return "lemon::Dfs::UninitializedParameter";
164      }
165    };
166
167    typedef TR Traits;
168    ///The type of the underlying graph.
169    typedef typename TR::Graph Graph;
170    ///\e
171    typedef typename Graph::Node Node;
172    ///\e
173    typedef typename Graph::NodeIt NodeIt;
174    ///\e
175    typedef typename Graph::Edge Edge;
176    ///\e
177    typedef typename Graph::OutEdgeIt OutEdgeIt;
178   
179    ///\brief The type of the map that stores the last
180    ///edges of the %DFS paths.
181    typedef typename TR::PredMap PredMap;
182//     ///\brief The type of the map that stores the last but one
183//     ///nodes of the %DFS paths.
184//     typedef typename TR::PredNodeMap PredNodeMap;
185    ///The type of the map indicating which nodes are reached.
186    typedef typename TR::ReachedMap ReachedMap;
187    ///The type of the map indicating which nodes are processed.
188    typedef typename TR::ProcessedMap ProcessedMap;
189    ///The type of the map that stores the dists of the nodes.
190    typedef typename TR::DistMap DistMap;
191  private:
192    /// Pointer to the underlying graph.
193    const Graph *G;
194    ///Pointer to the map of predecessors edges.
195    PredMap *_pred;
196    ///Indicates if \ref _pred is locally allocated (\c true) or not.
197    bool local_pred;
198//     ///Pointer to the map of predecessors nodes.
199//     PredNodeMap *_predNode;
200//     ///Indicates if \ref _predNode is locally allocated (\c true) or not.
201//     bool local_predNode;
202    ///Pointer to the map of distances.
203    DistMap *_dist;
204    ///Indicates if \ref _dist is locally allocated (\c true) or not.
205    bool local_dist;
206    ///Pointer to the map of reached status of the nodes.
207    ReachedMap *_reached;
208    ///Indicates if \ref _reached is locally allocated (\c true) or not.
209    bool local_reached;
210    ///Pointer to the map of processed status of the nodes.
211    ProcessedMap *_processed;
212    ///Indicates if \ref _processed is locally allocated (\c true) or not.
213    bool local_processed;
214
215    std::vector<typename Graph::OutEdgeIt> _stack;
216    int _stack_head;
217//     ///The source node of the last execution.
218//     Node source;
219
220    ///Creates the maps if necessary.
221   
222    ///\todo Error if \c G are \c NULL.
223    ///\todo Better memory allocation (instead of new).
224    void create_maps()
225    {
226      if(!_pred) {
227        local_pred = true;
228        _pred = Traits::createPredMap(*G);
229      }
230//       if(!_predNode) {
231//      local_predNode = true;
232//      _predNode = Traits::createPredNodeMap(*G);
233//       }
234      if(!_dist) {
235        local_dist = true;
236        _dist = Traits::createDistMap(*G);
237      }
238      if(!_reached) {
239        local_reached = true;
240        _reached = Traits::createReachedMap(*G);
241      }
242      if(!_processed) {
243        local_processed = true;
244        _processed = Traits::createProcessedMap(*G);
245      }
246    }
247   
248  public :
249 
250    ///\name Named template parameters
251
252    ///@{
253
254    template <class T>
255    struct DefPredMapTraits : public Traits {
256      typedef T PredMap;
257      static PredMap *createPredMap(const Graph &G)
258      {
259        throw UninitializedParameter();
260      }
261    };
262    ///\ref named-templ-param "Named parameter" for setting PredMap type
263
264    ///\ref named-templ-param "Named parameter" for setting PredMap type
265    ///
266    template <class T>
267    class DefPredMap : public Dfs< Graph,
268                                        DefPredMapTraits<T> > { };
269   
270//     template <class T>
271//     struct DefPredNodeMapTraits : public Traits {
272//       typedef T PredNodeMap;
273//       static PredNodeMap *createPredNodeMap(const Graph &G)
274//       {
275//      throw UninitializedParameter();
276//       }
277//     };
278//     ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
279
280//     ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
281//     ///
282//     template <class T>
283//     class DefPredNodeMap : public Dfs< Graph,
284//                                          LengthMap,
285//                                          DefPredNodeMapTraits<T> > { };
286   
287    template <class T>
288    struct DefDistMapTraits : public Traits {
289      typedef T DistMap;
290      static DistMap *createDistMap(const Graph &G)
291      {
292        throw UninitializedParameter();
293      }
294    };
295    ///\ref named-templ-param "Named parameter" for setting DistMap type
296
297    ///\ref named-templ-param "Named parameter" for setting DistMap type
298    ///
299    template <class T>
300    class DefDistMap : public Dfs< Graph,
301                                   DefDistMapTraits<T> > { };
302   
303    template <class T>
304    struct DefReachedMapTraits : public Traits {
305      typedef T ReachedMap;
306      static ReachedMap *createReachedMap(const Graph &G)
307      {
308        throw UninitializedParameter();
309      }
310    };
311    ///\ref named-templ-param "Named parameter" for setting ReachedMap type
312
313    ///\ref named-templ-param "Named parameter" for setting ReachedMap type
314    ///
315    template <class T>
316    class DefReachedMap : public Dfs< Graph,
317                                      DefReachedMapTraits<T> > { };
318   
319    struct DefGraphReachedMapTraits : public Traits {
320      typedef typename Graph::template NodeMap<bool> ReachedMap;
321      static ReachedMap *createReachedMap(const Graph &G)
322      {
323        return new ReachedMap(G);
324      }
325    };
326    template <class T>
327    struct DefProcessedMapTraits : public Traits {
328      typedef T ProcessedMap;
329      static ProcessedMap *createProcessedMap(const Graph &G)
330      {
331        throw UninitializedParameter();
332      }
333    };
334    ///\ref named-templ-param "Named parameter" for setting ProcessedMap type
335
336    ///\ref named-templ-param "Named parameter" for setting ProcessedMap type
337    ///
338    template <class T>
339    class DefProcessedMap : public Dfs< Graph,
340                                        DefProcessedMapTraits<T> > { };
341   
342    struct DefGraphProcessedMapTraits : public Traits {
343      typedef typename Graph::template NodeMap<bool> ProcessedMap;
344      static ProcessedMap *createProcessedMap(const Graph &G)
345      {
346        return new ProcessedMap(G);
347      }
348    };
349    ///\brief \ref named-templ-param "Named parameter"
350    ///for setting the ProcessedMap type to be Graph::NodeMap<bool>.
351    ///
352    ///\ref named-templ-param "Named parameter"
353    ///for setting the ProcessedMap type to be Graph::NodeMap<bool>.
354    ///If you don't set it explicitely, it will be automatically allocated.
355    template <class T>
356    class DefProcessedMapToBeDefaultMap :
357      public Dfs< Graph,
358                  DefGraphProcessedMapTraits> { };
359   
360    ///@}
361
362  public:     
363   
364    ///Constructor.
365   
366    ///\param _G the graph the algorithm will run on.
367    ///
368    Dfs(const Graph& _G) :
369      G(&_G),
370      _pred(NULL), local_pred(false),
371//       _predNode(NULL), local_predNode(false),
372      _dist(NULL), local_dist(false),
373      _reached(NULL), local_reached(false),
374      _processed(NULL), local_processed(false)
375    { }
376   
377    ///Destructor.
378    ~Dfs()
379    {
380      if(local_pred) delete _pred;
381//       if(local_predNode) delete _predNode;
382      if(local_dist) delete _dist;
383      if(local_reached) delete _reached;
384      if(local_processed) delete _processed;
385    }
386
387    ///Sets the map storing the predecessor edges.
388
389    ///Sets the map storing the predecessor edges.
390    ///If you don't use this function before calling \ref run(),
391    ///it will allocate one. The destuctor deallocates this
392    ///automatically allocated map, of course.
393    ///\return <tt> (*this) </tt>
394    Dfs &predMap(PredMap &m)
395    {
396      if(local_pred) {
397        delete _pred;
398        local_pred=false;
399      }
400      _pred = &m;
401      return *this;
402    }
403
404//     ///Sets the map storing the predecessor nodes.
405
406//     ///Sets the map storing the predecessor nodes.
407//     ///If you don't use this function before calling \ref run(),
408//     ///it will allocate one. The destuctor deallocates this
409//     ///automatically allocated map, of course.
410//     ///\return <tt> (*this) </tt>
411//     Dfs &predNodeMap(PredNodeMap &m)
412//     {
413//       if(local_predNode) {
414//      delete _predNode;
415//      local_predNode=false;
416//       }
417//       _predNode = &m;
418//       return *this;
419//     }
420
421    ///Sets the map storing the distances calculated by the algorithm.
422
423    ///Sets the map storing the distances calculated by the algorithm.
424    ///If you don't use this function before calling \ref run(),
425    ///it will allocate one. The destuctor deallocates this
426    ///automatically allocated map, of course.
427    ///\return <tt> (*this) </tt>
428    Dfs &distMap(DistMap &m)
429    {
430      if(local_dist) {
431        delete _dist;
432        local_dist=false;
433      }
434      _dist = &m;
435      return *this;
436    }
437
438    ///Sets the map indicating if a node is reached.
439
440    ///Sets the map indicating if a node is reached.
441    ///If you don't use this function before calling \ref run(),
442    ///it will allocate one. The destuctor deallocates this
443    ///automatically allocated map, of course.
444    ///\return <tt> (*this) </tt>
445    Dfs &reachedMap(ReachedMap &m)
446    {
447      if(local_reached) {
448        delete _reached;
449        local_reached=false;
450      }
451      _reached = &m;
452      return *this;
453    }
454
455    ///Sets the map indicating if a node is processed.
456
457    ///Sets the map indicating if a node is processed.
458    ///If you don't use this function before calling \ref run(),
459    ///it will allocate one. The destuctor deallocates this
460    ///automatically allocated map, of course.
461    ///\return <tt> (*this) </tt>
462    Dfs &processedMap(ProcessedMap &m)
463    {
464      if(local_processed) {
465        delete _processed;
466        local_processed=false;
467      }
468      _processed = &m;
469      return *this;
470    }
471
472  public:
473    ///\name Execution control
474    ///The simplest way to execute the algorithm is to use
475    ///one of the member functions called \c run(...).
476    ///\n
477    ///If you need more control on the execution,
478    ///first you must call \ref init(), then you can add several source nodes
479    ///with \ref addSource().
480    ///Finally \ref start() will perform the actual path
481    ///computation.
482
483    ///@{
484
485    ///Initializes the internal data structures.
486
487    ///Initializes the internal data structures.
488    ///
489    void init()
490    {
491      create_maps();
492      _stack.resize(countNodes(*G));
493      _stack_head=-1;
494      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
495        _pred->set(u,INVALID);
496        // _predNode->set(u,INVALID);
497        _reached->set(u,false);
498        _processed->set(u,false);
499      }
500    }
501   
502    ///Adds a new source node.
503
504    ///Adds a new source node to the set of nodes to be processed.
505    ///
506    ///\bug dists are wrong (or at least strange) in case of multiple sources.
507    void addSource(Node s)
508    {
509      if(!(*_reached)[s])
510        {
511          _reached->set(s,true);
512          _pred->set(s,INVALID);
513          // _predNode->set(u,INVALID);
514          OutEdgeIt e(*G,s);
515          if(e!=INVALID) _stack[++_stack_head]=e;
516          else _processed->set(s,true);
517          _dist->set(s,_stack_head);
518        }
519    }
520   
521    ///Processes the next edge.
522
523    ///Processes the next edge.
524    ///
525    ///\return The processed edge.
526    ///
527    ///\pre The stack must not be empty!
528    Edge processNextEdge()
529    {
530      Node m;
531      Edge e=_stack[_stack_head];
532      if(!(*_reached)[m=G->target(e)]) {
533        _pred->set(m,e);
534        _reached->set(m,true);
535        //        _pred_node->set(m,G->source(e));
536        ++_stack_head;
537        _stack[_stack_head] = OutEdgeIt(*G, m);
538        _dist->set(m,_stack_head);
539      }
540      else {
541        m=G->source(e);
542        ++_stack[_stack_head];
543      }
544      //'m' is now the (original) source of the _stack[_stack_head]
545      while(_stack_head>=0 && _stack[_stack_head]==INVALID) {
546        _processed->set(m,true);
547        --_stack_head;
548        if(_stack_head>=0) {
549          m=G->source(_stack[_stack_head]);
550          ++_stack[_stack_head];
551        }
552      }
553      return e;
554    }
555    ///Next edge to be processed.
556
557    ///Next edge to be processed.
558    ///
559    ///\return The next edge to be processed or INVALID if the stack is
560    /// empty.
561    OutEdgeIt NextEdge()
562    {
563      return _stack_head>=0?_stack[_stack_head]:INVALID;
564    }
565     
566    ///\brief Returns \c false if there are nodes
567    ///to be processed in the queue
568    ///
569    ///Returns \c false if there are nodes
570    ///to be processed in the queue
571    ///
572    ///\todo This should be called emptyStack() or some "neutral" name.
573    bool emptyQueue() { return _stack_head<0; }
574    ///Returns the number of the nodes to be processed.
575   
576    ///Returns the number of the nodes to be processed in the queue.
577    ///
578    ///\todo This should be called stackSize() or some "neutral" name.
579    int queueSize() { return _stack_head+1; }
580   
581    ///Executes the algorithm.
582
583    ///Executes the algorithm.
584    ///
585    ///\pre init() must be called and at least one node should be added
586    ///with addSource() before using this function.
587    ///
588    ///This method runs the %DFS algorithm from the root node(s)
589    ///in order to
590    ///compute the
591    ///%DFS path to each node. The algorithm computes
592    ///- The %DFS tree.
593    ///- The distance of each node from the root(s) in the %DFS tree.
594    ///
595    void start()
596    {
597      while ( !emptyQueue() ) processNextEdge();
598    }
599   
600    ///Executes the algorithm until \c dest is reached.
601
602    ///Executes the algorithm until \c dest is reached.
603    ///
604    ///\pre init() must be called and at least one node should be added
605    ///with addSource() before using this function.
606    ///
607    ///This method runs the %DFS algorithm from the root node(s)
608    ///in order to
609    ///compute the
610    ///%DFS path to \c dest. The algorithm computes
611    ///- The %DFS path to \c  dest.
612    ///- The distance of \c dest from the root(s) in the %DFS tree.
613    ///
614    void start(Node dest)
615    {
616      while ( !emptyQueue() && G->target(_stack[_stack_head])!=dest )
617        processNextEdge();
618    }
619   
620    ///Executes the algorithm until a condition is met.
621
622    ///Executes the algorithm until a condition is met.
623    ///
624    ///\pre init() must be called and at least one node should be added
625    ///with addSource() before using this function.
626    ///
627    ///\param nm must be a bool (or convertible) edge map. The algorithm
628    ///will stop when it reaches an edge \c e with <tt>nm[e]==true</tt>.
629    ///
630    ///\warning Contrary to \ref Dfs and \ref Dijkstra, \c nm is an edge map,
631    ///not a node map.
632    template<class NM>
633      void start(const NM &nm)
634      {
635        while ( !emptyQueue() && !nm[_stack[_stack_head]] ) processNextEdge();
636      }
637   
638    ///Runs %DFS algorithm from node \c s.
639   
640    ///This method runs the %DFS algorithm from a root node \c s
641    ///in order to
642    ///compute the
643    ///%DFS path to each node. The algorithm computes
644    ///- The %DFS tree.
645    ///- The distance of each node from the root in the %DFS tree.
646    ///
647    ///\note d.run(s) is just a shortcut of the following code.
648    ///\code
649    ///  d.init();
650    ///  d.addSource(s);
651    ///  d.start();
652    ///\endcode
653    void run(Node s) {
654      init();
655      addSource(s);
656      start();
657    }
658   
659    ///Finds the %DFS path between \c s and \c t.
660   
661    ///Finds the %DFS path between \c s and \c t.
662    ///
663    ///\return The length of the %DFS s---t path if there exists one,
664    ///0 otherwise.
665    ///\note Apart from the return value, d.run(s,t) is
666    ///just a shortcut of the following code.
667    ///\code
668    ///  d.init();
669    ///  d.addSource(s);
670    ///  d.start(t);
671    ///\endcode
672    int run(Node s,Node t) {
673      init();
674      addSource(s);
675      start(t);
676      return reached(t)?_stack_head+1:0;
677    }
678   
679    ///@}
680
681    ///\name Query Functions
682    ///The result of the %DFS algorithm can be obtained using these
683    ///functions.\n
684    ///Before the use of these functions,
685    ///either run() or start() must be called.
686   
687    ///@{
688
689    ///Copies the path to \c t on the DFS tree into \c p
690   
691    ///This function copies the path to \c t on the DFS tree  into \c p.
692    ///If \c t is a source itself or unreachable, then it does not
693    ///alter \c p.
694    ///\todo Is this the right way to handle unreachable nodes?
695    ///
696    ///\return Returns \c true if a path to \c t was actually copied to \c p,
697    ///\c false otherwise.
698    ///\sa DirPath
699    template<class P>
700    bool getPath(P &p,Node t)
701    {
702      if(reached(t)) {
703        p.clear();
704        typename P::Builder b(p);
705        for(b.setStartNode(t);pred(t)!=INVALID;t=predNode(t))
706          b.pushFront(pred(t));
707        b.commit();
708        return true;
709      }
710      return false;
711    }
712
713    ///The distance of a node from the root(s).
714
715    ///Returns the distance of a node from the root(s).
716    ///\pre \ref run() must be called before using this function.
717    ///\warning If node \c v is unreachable from the root(s) then the return value
718    ///of this funcion is undefined.
719    int dist(Node v) const { return (*_dist)[v]; }
720
721    ///Returns the 'previous edge' of the %DFS tree.
722
723    ///For a node \c v it returns the 'previous edge'
724    ///of the %DFS path,
725    ///i.e. it returns the last edge of a %DFS path from the root(s) to \c
726    ///v. It is \ref INVALID
727    ///if \c v is unreachable from the root(s) or \c v is a root. The
728    ///%DFS tree used here is equal to the %DFS tree used in
729    ///\ref predNode().
730    ///\pre Either \ref run() or \ref start() must be called before using
731    ///this function.
732    ///\todo predEdge could be a better name.
733    Edge pred(Node v) const { return (*_pred)[v];}
734
735    ///Returns the 'previous node' of the %DFS tree.
736
737    ///For a node \c v it returns the 'previous node'
738    ///of the %DFS tree,
739    ///i.e. it returns the last but one node from a %DFS path from the
740    ///root(a) to \c /v.
741    ///It is INVALID if \c v is unreachable from the root(s) or
742    ///if \c v itself a root.
743    ///The %DFS tree used here is equal to the %DFS
744    ///tree used in \ref pred().
745    ///\pre Either \ref run() or \ref start() must be called before
746    ///using this function.
747    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
748                                  G->source((*_pred)[v]); }
749   
750    ///Returns a reference to the NodeMap of distances.
751
752    ///Returns a reference to the NodeMap of distances.
753    ///\pre Either \ref run() or \ref init() must
754    ///be called before using this function.
755    const DistMap &distMap() const { return *_dist;}
756 
757    ///Returns a reference to the %DFS edge-tree map.
758
759    ///Returns a reference to the NodeMap of the edges of the
760    ///%DFS tree.
761    ///\pre Either \ref run() or \ref init()
762    ///must be called before using this function.
763    const PredMap &predMap() const { return *_pred;}
764 
765//     ///Returns a reference to the map of nodes of %DFS paths.
766
767//     ///Returns a reference to the NodeMap of the last but one nodes of the
768//     ///%DFS tree.
769//     ///\pre \ref run() must be called before using this function.
770//     const PredNodeMap &predNodeMap() const { return *_predNode;}
771
772    ///Checks if a node is reachable from the root.
773
774    ///Returns \c true if \c v is reachable from the root(s).
775    ///\warning The source nodes are inditated as unreachable.
776    ///\pre Either \ref run() or \ref start()
777    ///must be called before using this function.
778    ///
779    bool reached(Node v) { return (*_reached)[v]; }
780   
781    ///@}
782  };
783
784  ///Default traits class of Dfs function.
785
786  ///Default traits class of Dfs function.
787  ///\param GR Graph type.
788  template<class GR>
789  struct DfsWizardDefaultTraits
790  {
791    ///The graph type the algorithm runs on.
792    typedef GR Graph;
793    ///\brief The type of the map that stores the last
794    ///edges of the %DFS paths.
795    ///
796    ///The type of the map that stores the last
797    ///edges of the %DFS paths.
798    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
799    ///
800    typedef NullMap<typename Graph::Node,typename GR::Edge> PredMap;
801    ///Instantiates a PredMap.
802 
803    ///This function instantiates a \ref PredMap.
804    ///\param g is the graph, to which we would like to define the PredMap.
805    ///\todo The graph alone may be insufficient to initialize
806#ifdef DOXYGEN
807    static PredMap *createPredMap(const GR &g)
808#else
809    static PredMap *createPredMap(const GR &)
810#endif
811    {
812      return new PredMap();
813    }
814//     ///\brief The type of the map that stores the last but one
815//     ///nodes of the %DFS paths.
816//     ///
817//     ///The type of the map that stores the last but one
818//     ///nodes of the %DFS paths.
819//     ///It must meet the \ref concept::WriteMap "WriteMap" concept.
820//     ///
821//     typedef NullMap<typename Graph::Node,typename Graph::Node> PredNodeMap;
822//     ///Instantiates a PredNodeMap.
823   
824//     ///This function instantiates a \ref PredNodeMap.
825//     ///\param G is the graph, to which
826//     ///we would like to define the \ref PredNodeMap
827//     static PredNodeMap *createPredNodeMap(const GR &G)
828//     {
829//       return new PredNodeMap();
830//     }
831
832    ///The type of the map that indicates which nodes are processed.
833 
834    ///The type of the map that indicates which nodes are processed.
835    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
836    ///\todo named parameter to set this type, function to read and write.
837    typedef NullMap<typename Graph::Node,bool> ProcessedMap;
838    ///Instantiates a ProcessedMap.
839 
840    ///This function instantiates a \ref ProcessedMap.
841    ///\param g is the graph, to which
842    ///we would like to define the \ref ProcessedMap
843#ifdef DOXYGEN
844    static ProcessedMap *createProcessedMap(const GR &g)
845#else
846    static ProcessedMap *createProcessedMap(const GR &)
847#endif
848    {
849      return new ProcessedMap();
850    }
851    ///The type of the map that indicates which nodes are reached.
852 
853    ///The type of the map that indicates which nodes are reached.
854    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
855    ///\todo named parameter to set this type, function to read and write.
856    typedef typename Graph::template NodeMap<bool> ReachedMap;
857    ///Instantiates a ReachedMap.
858 
859    ///This function instantiates a \ref ReachedMap.
860    ///\param G is the graph, to which
861    ///we would like to define the \ref ReachedMap.
862    static ReachedMap *createReachedMap(const GR &G)
863    {
864      return new ReachedMap(G);
865    }
866    ///The type of the map that stores the dists of the nodes.
867 
868    ///The type of the map that stores the dists of the nodes.
869    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
870    ///
871    typedef NullMap<typename Graph::Node,int> DistMap;
872    ///Instantiates a DistMap.
873 
874    ///This function instantiates a \ref DistMap.
875    ///\param g is the graph, to which we would like to define the \ref DistMap
876#ifdef DOXYGEN
877    static DistMap *createDistMap(const GR &g)
878#else
879    static DistMap *createDistMap(const GR &)
880#endif
881    {
882      return new DistMap();
883    }
884  };
885 
886  /// Default traits used by \ref DfsWizard
887
888  /// To make it easier to use Dfs algorithm
889  ///we have created a wizard class.
890  /// This \ref DfsWizard class needs default traits,
891  ///as well as the \ref Dfs class.
892  /// The \ref DfsWizardBase is a class to be the default traits of the
893  /// \ref DfsWizard class.
894  template<class GR>
895  class DfsWizardBase : public DfsWizardDefaultTraits<GR>
896  {
897
898    typedef DfsWizardDefaultTraits<GR> Base;
899  protected:
900    /// Type of the nodes in the graph.
901    typedef typename Base::Graph::Node Node;
902
903    /// Pointer to the underlying graph.
904    void *_g;
905    ///Pointer to the map of reached nodes.
906    void *_reached;
907    ///Pointer to the map of processed nodes.
908    void *_processed;
909    ///Pointer to the map of predecessors edges.
910    void *_pred;
911//     ///Pointer to the map of predecessors nodes.
912//     void *_predNode;
913    ///Pointer to the map of distances.
914    void *_dist;
915    ///Pointer to the source node.
916    Node _source;
917   
918    public:
919    /// Constructor.
920   
921    /// This constructor does not require parameters, therefore it initiates
922    /// all of the attributes to default values (0, INVALID).
923    DfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0),
924//                         _predNode(0),
925                           _dist(0), _source(INVALID) {}
926
927    /// Constructor.
928   
929    /// This constructor requires some parameters,
930    /// listed in the parameters list.
931    /// Others are initiated to 0.
932    /// \param g is the initial value of  \ref _g
933    /// \param s is the initial value of  \ref _source
934    DfsWizardBase(const GR &g, Node s=INVALID) :
935      _g((void *)&g), _reached(0), _processed(0), _pred(0),
936//       _predNode(0),
937      _dist(0), _source(s) {}
938
939  };
940 
941  /// A class to make the usage of the Dfs algorithm easier
942
943  /// This class is created to make it easier to use the Dfs algorithm.
944  /// It uses the functions and features of the plain \ref Dfs,
945  /// but it is much simpler to use it.
946  ///
947  /// Simplicity means that the way to change the types defined
948  /// in the traits class is based on functions that returns the new class
949  /// and not on templatable built-in classes.
950  /// When using the plain \ref Dfs
951  /// the new class with the modified type comes from
952  /// the original class by using the ::
953  /// operator. In the case of \ref DfsWizard only
954  /// a function have to be called and it will
955  /// return the needed class.
956  ///
957  /// It does not have own \ref run method. When its \ref run method is called
958  /// it initiates a plain \ref Dfs object, and calls the \ref Dfs::run
959  /// method of it.
960  template<class TR>
961  class DfsWizard : public TR
962  {
963    typedef TR Base;
964
965    ///The type of the underlying graph.
966    typedef typename TR::Graph Graph;
967    //\e
968    typedef typename Graph::Node Node;
969    //\e
970    typedef typename Graph::NodeIt NodeIt;
971    //\e
972    typedef typename Graph::Edge Edge;
973    //\e
974    typedef typename Graph::OutEdgeIt OutEdgeIt;
975   
976    ///\brief The type of the map that stores
977    ///the reached nodes
978    typedef typename TR::ReachedMap ReachedMap;
979    ///\brief The type of the map that stores
980    ///the processed nodes
981    typedef typename TR::ProcessedMap ProcessedMap;
982    ///\brief The type of the map that stores the last
983    ///edges of the %DFS paths.
984    typedef typename TR::PredMap PredMap;
985//     ///\brief The type of the map that stores the last but one
986//     ///nodes of the %DFS paths.
987//     typedef typename TR::PredNodeMap PredNodeMap;
988    ///The type of the map that stores the distances of the nodes.
989    typedef typename TR::DistMap DistMap;
990
991public:
992    /// Constructor.
993    DfsWizard() : TR() {}
994
995    /// Constructor that requires parameters.
996
997    /// Constructor that requires parameters.
998    /// These parameters will be the default values for the traits class.
999    DfsWizard(const Graph &g, Node s=INVALID) :
1000      TR(g,s) {}
1001
1002    ///Copy constructor
1003    DfsWizard(const TR &b) : TR(b) {}
1004
1005    ~DfsWizard() {}
1006
1007    ///Runs Dfs algorithm from a given node.
1008   
1009    ///Runs Dfs algorithm from a given node.
1010    ///The node can be given by the \ref source function.
1011    void run()
1012    {
1013      if(Base::_source==INVALID) throw UninitializedParameter();
1014      Dfs<Graph,TR> alg(*(Graph*)Base::_g);
1015      if(Base::_reached) alg.reachedMap(*(ReachedMap*)Base::_reached);
1016      if(Base::_processed) alg.processedMap(*(ProcessedMap*)Base::_processed);
1017      if(Base::_pred) alg.predMap(*(PredMap*)Base::_pred);
1018//       if(Base::_predNode) alg.predNodeMap(*(PredNodeMap*)Base::_predNode);
1019      if(Base::_dist) alg.distMap(*(DistMap*)Base::_dist);
1020      alg.run(Base::_source);
1021    }
1022
1023    ///Runs Dfs algorithm from the given node.
1024
1025    ///Runs Dfs algorithm from the given node.
1026    ///\param s is the given source.
1027    void run(Node s)
1028    {
1029      Base::_source=s;
1030      run();
1031    }
1032
1033    template<class T>
1034    struct DefPredMapBase : public Base {
1035      typedef T PredMap;
1036      static PredMap *createPredMap(const Graph &) { return 0; };
1037      DefPredMapBase(const TR &b) : TR(b) {}
1038    };
1039   
1040    ///\brief \ref named-templ-param "Named parameter"
1041    ///function for setting PredMap type
1042    ///
1043    /// \ref named-templ-param "Named parameter"
1044    ///function for setting PredMap type
1045    ///
1046    template<class T>
1047    DfsWizard<DefPredMapBase<T> > predMap(const T &t)
1048    {
1049      Base::_pred=(void *)&t;
1050      return DfsWizard<DefPredMapBase<T> >(*this);
1051    }
1052   
1053 
1054    template<class T>
1055    struct DefReachedMapBase : public Base {
1056      typedef T ReachedMap;
1057      static ReachedMap *createReachedMap(const Graph &) { return 0; };
1058      DefReachedMapBase(const TR &b) : TR(b) {}
1059    };
1060   
1061    ///\brief \ref named-templ-param "Named parameter"
1062    ///function for setting ReachedMap
1063    ///
1064    /// \ref named-templ-param "Named parameter"
1065    ///function for setting ReachedMap
1066    ///
1067    template<class T>
1068    DfsWizard<DefReachedMapBase<T> > reachedMap(const T &t)
1069    {
1070      Base::_pred=(void *)&t;
1071      return DfsWizard<DefReachedMapBase<T> >(*this);
1072    }
1073   
1074
1075    template<class T>
1076    struct DefProcessedMapBase : public Base {
1077      typedef T ProcessedMap;
1078      static ProcessedMap *createProcessedMap(const Graph &) { return 0; };
1079      DefProcessedMapBase(const TR &b) : TR(b) {}
1080    };
1081   
1082    ///\brief \ref named-templ-param "Named parameter"
1083    ///function for setting ProcessedMap
1084    ///
1085    /// \ref named-templ-param "Named parameter"
1086    ///function for setting ProcessedMap
1087    ///
1088    template<class T>
1089    DfsWizard<DefProcessedMapBase<T> > processedMap(const T &t)
1090    {
1091      Base::_pred=(void *)&t;
1092      return DfsWizard<DefProcessedMapBase<T> >(*this);
1093    }
1094   
1095
1096//     template<class T>
1097//     struct DefPredNodeMapBase : public Base {
1098//       typedef T PredNodeMap;
1099//       static PredNodeMap *createPredNodeMap(const Graph &G) { return 0; };
1100//       DefPredNodeMapBase(const TR &b) : TR(b) {}
1101//     };
1102   
1103//     ///\brief \ref named-templ-param "Named parameter"
1104//     ///function for setting PredNodeMap type
1105//     ///
1106//     /// \ref named-templ-param "Named parameter"
1107//     ///function for setting PredNodeMap type
1108//     ///
1109//     template<class T>
1110//     DfsWizard<DefPredNodeMapBase<T> > predNodeMap(const T &t)
1111//     {
1112//       Base::_predNode=(void *)&t;
1113//       return DfsWizard<DefPredNodeMapBase<T> >(*this);
1114//     }
1115   
1116    template<class T>
1117    struct DefDistMapBase : public Base {
1118      typedef T DistMap;
1119      static DistMap *createDistMap(const Graph &) { return 0; };
1120      DefDistMapBase(const TR &b) : TR(b) {}
1121    };
1122   
1123    ///\brief \ref named-templ-param "Named parameter"
1124    ///function for setting DistMap type
1125    ///
1126    /// \ref named-templ-param "Named parameter"
1127    ///function for setting DistMap type
1128    ///
1129    template<class T>
1130    DfsWizard<DefDistMapBase<T> > distMap(const T &t)
1131    {
1132      Base::_dist=(void *)&t;
1133      return DfsWizard<DefDistMapBase<T> >(*this);
1134    }
1135   
1136    /// Sets the source node, from which the Dfs algorithm runs.
1137
1138    /// Sets the source node, from which the Dfs algorithm runs.
1139    /// \param s is the source node.
1140    DfsWizard<TR> &source(Node s)
1141    {
1142      Base::_source=s;
1143      return *this;
1144    }
1145   
1146  };
1147 
1148  ///Function type interface for Dfs algorithm.
1149
1150  /// \ingroup flowalgs
1151  ///Function type interface for Dfs algorithm.
1152  ///
1153  ///This function also has several
1154  ///\ref named-templ-func-param "named parameters",
1155  ///they are declared as the members of class \ref DfsWizard.
1156  ///The following
1157  ///example shows how to use these parameters.
1158  ///\code
1159  ///  dfs(g,source).predMap(preds).run();
1160  ///\endcode
1161  ///\warning Don't forget to put the \ref DfsWizard::run() "run()"
1162  ///to the end of the parameter list.
1163  ///\sa DfsWizard
1164  ///\sa Dfs
1165  template<class GR>
1166  DfsWizard<DfsWizardBase<GR> >
1167  dfs(const GR &g,typename GR::Node s=INVALID)
1168  {
1169    return DfsWizard<DfsWizardBase<GR> >(g,s);
1170  }
1171
1172} //END OF NAMESPACE LEMON
1173
1174#endif
1175
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