COIN-OR::LEMON - Graph Library

source: lemon-0.x/lemon/dijkstra.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: 34.5 KB
Line 
1/* -*- C++ -*-
2 * lemon/dijkstra.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_DIJKSTRA_H
18#define LEMON_DIJKSTRA_H
19
20///\ingroup flowalgs
21///\file
22///\brief Dijkstra algorithm.
23///
24///\todo getPath() should be implemented! (also for BFS and DFS)
25
26#include <lemon/list_graph.h>
27#include <lemon/bin_heap.h>
28#include <lemon/invalid.h>
29#include <lemon/error.h>
30#include <lemon/maps.h>
31
32namespace lemon {
33
34
35 
36  ///Default traits class of Dijkstra class.
37
38  ///Default traits class of Dijkstra class.
39  ///\param GR Graph type.
40  ///\param LM Type of length map.
41  template<class GR, class LM>
42  struct DijkstraDefaultTraits
43  {
44    ///The graph type the algorithm runs on.
45    typedef GR Graph;
46    ///The type of the map that stores the edge lengths.
47
48    ///The type of the map that stores the edge lengths.
49    ///It must meet the \ref concept::ReadMap "ReadMap" concept.
50    typedef LM LengthMap;
51    //The type of the length of the edges.
52    typedef typename LM::Value Value;
53    ///The heap type used by Dijkstra algorithm.
54
55    ///The heap type used by Dijkstra algorithm.
56    ///
57    ///\sa BinHeap
58    ///\sa Dijkstra
59    typedef BinHeap<typename Graph::Node,
60                    typename LM::Value,
61                    typename GR::template NodeMap<int>,
62                    std::less<Value> > Heap;
63
64    ///\brief The type of the map that stores the last
65    ///edges of the shortest paths.
66    ///
67    ///The type of the map that stores the last
68    ///edges of the shortest paths.
69    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
70    ///
71    typedef typename Graph::template NodeMap<typename GR::Edge> PredMap;
72    ///Instantiates a PredMap.
73 
74    ///This function instantiates a \ref PredMap.
75    ///\param G is the graph, to which we would like to define the PredMap.
76    ///\todo The graph alone may be insufficient for the initialization
77    static PredMap *createPredMap(const GR &G)
78    {
79      return new PredMap(G);
80    }
81//     ///\brief The type of the map that stores the last but one
82//     ///nodes of the shortest paths.
83//     ///
84//     ///The type of the map that stores the last but one
85//     ///nodes of the shortest paths.
86//     ///It must meet the \ref concept::WriteMap "WriteMap" concept.
87//     ///
88//     typedef NullMap<typename Graph::Node,typename Graph::Node> PredNodeMap;
89//     ///Instantiates a PredNodeMap.
90   
91//     ///This function instantiates a \ref PredNodeMap.
92//     ///\param G is the graph, to which
93//     ///we would like to define the \ref PredNodeMap
94//     static PredNodeMap *createPredNodeMap(const GR &G)
95//     {
96//       return new PredNodeMap();
97//     }
98
99    ///The type of the map that stores whether a nodes is processed.
100 
101    ///The type of the map that stores whether a nodes is processed.
102    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
103    ///By default it is a NullMap.
104    ///\todo If it is set to a real map,
105    ///Dijkstra::processed() should read this.
106    ///\todo named parameter to set this type, function to read and write.
107    typedef NullMap<typename Graph::Node,bool> ProcessedMap;
108    ///Instantiates a ProcessedMap.
109 
110    ///This function instantiates a \ref ProcessedMap.
111    ///\param g is the graph, to which
112    ///we would like to define the \ref ProcessedMap
113#ifdef DOXYGEN
114    static ProcessedMap *createProcessedMap(const GR &g)
115#else
116    static ProcessedMap *createProcessedMap(const GR &)
117#endif
118    {
119      return new ProcessedMap();
120    }
121    ///The type of the map that stores the dists of the nodes.
122 
123    ///The type of the map that stores the dists of the nodes.
124    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
125    ///
126    typedef typename Graph::template NodeMap<typename LM::Value> DistMap;
127    ///Instantiates a DistMap.
128 
129    ///This function instantiates a \ref DistMap.
130    ///\param G is the graph, to which we would like to define the \ref DistMap
131    static DistMap *createDistMap(const GR &G)
132    {
133      return new DistMap(G);
134    }
135  };
136 
137  ///%Dijkstra algorithm class.
138 
139  /// \ingroup flowalgs
140  ///This class provides an efficient implementation of %Dijkstra algorithm.
141  ///The edge lengths are passed to the algorithm using a
142  ///\ref concept::ReadMap "ReadMap",
143  ///so it is easy to change it to any kind of length.
144  ///
145  ///The type of the length is determined by the
146  ///\ref concept::ReadMap::Value "Value" of the length map.
147  ///
148  ///It is also possible to change the underlying priority heap.
149  ///
150  ///\param GR The graph type the algorithm runs on. The default value
151  ///is \ref ListGraph. The value of GR is not used directly by
152  ///Dijkstra, it is only passed to \ref DijkstraDefaultTraits.
153  ///\param LM This read-only EdgeMap determines the lengths of the
154  ///edges. It is read once for each edge, so the map may involve in
155  ///relatively time consuming process to compute the edge length if
156  ///it is necessary. The default map type is \ref
157  ///concept::StaticGraph::EdgeMap "Graph::EdgeMap<int>".  The value
158  ///of LM is not used directly by Dijkstra, it is only passed to \ref
159  ///DijkstraDefaultTraits.  \param TR Traits class to set
160  ///various data types used by the algorithm.  The default traits
161  ///class is \ref DijkstraDefaultTraits
162  ///"DijkstraDefaultTraits<GR,LM>".  See \ref
163  ///DijkstraDefaultTraits for the documentation of a Dijkstra traits
164  ///class.
165  ///
166  ///\author Jacint Szabo and Alpar Juttner
167  ///\todo A compare object would be nice.
168
169#ifdef DOXYGEN
170  template <typename GR,
171            typename LM,
172            typename TR>
173#else
174  template <typename GR=ListGraph,
175            typename LM=typename GR::template EdgeMap<int>,
176            typename TR=DijkstraDefaultTraits<GR,LM> >
177#endif
178  class Dijkstra {
179  public:
180    /**
181     * \brief \ref Exception for uninitialized parameters.
182     *
183     * This error represents problems in the initialization
184     * of the parameters of the algorithms.
185     */
186    class UninitializedParameter : public lemon::UninitializedParameter {
187    public:
188      virtual const char* exceptionName() const {
189        return "lemon::Dijkstra::UninitializedParameter";
190      }
191    };
192
193    typedef TR Traits;
194    ///The type of the underlying graph.
195    typedef typename TR::Graph Graph;
196    ///\e
197    typedef typename Graph::Node Node;
198    ///\e
199    typedef typename Graph::NodeIt NodeIt;
200    ///\e
201    typedef typename Graph::Edge Edge;
202    ///\e
203    typedef typename Graph::OutEdgeIt OutEdgeIt;
204   
205    ///The type of the length of the edges.
206    typedef typename TR::LengthMap::Value Value;
207    ///The type of the map that stores the edge lengths.
208    typedef typename TR::LengthMap LengthMap;
209    ///\brief The type of the map that stores the last
210    ///edges of the shortest paths.
211    typedef typename TR::PredMap PredMap;
212//     ///\brief The type of the map that stores the last but one
213//     ///nodes of the shortest paths.
214//     typedef typename TR::PredNodeMap PredNodeMap;
215    ///The type of the map indicating if a node is processed.
216    typedef typename TR::ProcessedMap ProcessedMap;
217    ///The type of the map that stores the dists of the nodes.
218    typedef typename TR::DistMap DistMap;
219    ///The heap type used by the dijkstra algorithm.
220    typedef typename TR::Heap Heap;
221  private:
222    /// Pointer to the underlying graph.
223    const Graph *G;
224    /// Pointer to the length map
225    const LengthMap *length;
226    ///Pointer to the map of predecessors edges.
227    PredMap *_pred;
228    ///Indicates if \ref _pred is locally allocated (\c true) or not.
229    bool local_pred;
230//     ///Pointer to the map of predecessors nodes.
231//     PredNodeMap *_predNode;
232//     ///Indicates if \ref _predNode is locally allocated (\c true) or not.
233//     bool local_predNode;
234    ///Pointer to the map of distances.
235    DistMap *_dist;
236    ///Indicates if \ref _dist is locally allocated (\c true) or not.
237    bool local_dist;
238    ///Pointer to the map of processed status of the nodes.
239    ProcessedMap *_processed;
240    ///Indicates if \ref _processed is locally allocated (\c true) or not.
241    bool local_processed;
242
243//     ///The source node of the last execution.
244//     Node source;
245
246    ///Creates the maps if necessary.
247   
248    ///\todo Error if \c G or are \c NULL. What about \c length?
249    ///\todo Better memory allocation (instead of new).
250    void create_maps()
251    {
252      if(!_pred) {
253        local_pred = true;
254        _pred = Traits::createPredMap(*G);
255      }
256//       if(!_predNode) {
257//      local_predNode = true;
258//      _predNode = Traits::createPredNodeMap(*G);
259//       }
260      if(!_dist) {
261        local_dist = true;
262        _dist = Traits::createDistMap(*G);
263      }
264      if(!_processed) {
265        local_processed = true;
266        _processed = Traits::createProcessedMap(*G);
267      }
268    }
269   
270  public :
271 
272    ///\name Named template parameters
273
274    ///@{
275
276    template <class T>
277    struct DefPredMapTraits : public Traits {
278      typedef T PredMap;
279      static PredMap *createPredMap(const Graph &G)
280      {
281        throw UninitializedParameter();
282      }
283    };
284    ///\ref named-templ-param "Named parameter" for setting PredMap type
285
286    ///\ref named-templ-param "Named parameter" for setting PredMap type
287    ///
288    template <class T>
289    class DefPredMap : public Dijkstra< Graph,
290                                        LengthMap,
291                                        DefPredMapTraits<T> > { };
292   
293//     template <class T>
294//     struct DefPredNodeMapTraits : public Traits {
295//       typedef T PredNodeMap;
296//       static PredNodeMap *createPredNodeMap(const Graph &G)
297//       {
298//      throw UninitializedParameter();
299//       }
300//     };
301//     ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
302
303//     ///\ref named-templ-param "Named parameter" for setting PredNodeMap type
304//     ///
305//     template <class T>
306//     class DefPredNodeMap : public Dijkstra< Graph,
307//                                          LengthMap,
308//                                          DefPredNodeMapTraits<T> > { };
309   
310    template <class T>
311    struct DefDistMapTraits : public Traits {
312      typedef T DistMap;
313      static DistMap *createDistMap(const Graph &G)
314      {
315        throw UninitializedParameter();
316      }
317    };
318    ///\ref named-templ-param "Named parameter" for setting DistMap type
319
320    ///\ref named-templ-param "Named parameter" for setting DistMap type
321    ///
322    template <class T>
323    class DefDistMap : public Dijkstra< Graph,
324                                        LengthMap,
325                                        DefDistMapTraits<T> > { };
326   
327    template <class T>
328    struct DefProcessedMapTraits : public Traits {
329      typedef T ProcessedMap;
330      static ProcessedMap *createProcessedMap(const Graph &G)
331      {
332        throw UninitializedParameter();
333      }
334    };
335    ///\ref named-templ-param "Named parameter" for setting ProcessedMap type
336
337    ///\ref named-templ-param "Named parameter" for setting ProcessedMap type
338    ///
339    template <class T>
340    class DefProcessedMap : public Dijkstra< Graph,
341                                        LengthMap,
342                                        DefProcessedMapTraits<T> > { };
343   
344    struct DefGraphProcessedMapTraits : public Traits {
345      typedef typename Graph::template NodeMap<bool> ProcessedMap;
346      static ProcessedMap *createProcessedMap(const Graph &G)
347      {
348        return new ProcessedMap(G);
349      }
350    };
351    ///\brief \ref named-templ-param "Named parameter"
352    ///for setting the ProcessedMap type to be Graph::NodeMap<bool>.
353    ///
354    ///\ref named-templ-param "Named parameter"
355    ///for setting the ProcessedMap type to be Graph::NodeMap<bool>.
356    ///If you don't set it explicitely, it will be automatically allocated.
357    template <class T>
358    class DefProcessedMapToBeDefaultMap :
359      public Dijkstra< Graph,
360                       LengthMap,
361                       DefGraphProcessedMapTraits> { };
362   
363    ///@}
364
365
366  private:
367    typename Graph::template NodeMap<int> _heap_map;
368    Heap _heap;
369  public:     
370   
371    ///Constructor.
372   
373    ///\param _G the graph the algorithm will run on.
374    ///\param _length the length map used by the algorithm.
375    Dijkstra(const Graph& _G, const LengthMap& _length) :
376      G(&_G), length(&_length),
377      _pred(NULL), local_pred(false),
378//       _predNode(NULL), local_predNode(false),
379      _dist(NULL), local_dist(false),
380      _processed(NULL), local_processed(false),
381      _heap_map(*G,-1),_heap(_heap_map)
382    { }
383   
384    ///Destructor.
385    ~Dijkstra()
386    {
387      if(local_pred) delete _pred;
388//       if(local_predNode) delete _predNode;
389      if(local_dist) delete _dist;
390      if(local_processed) delete _processed;
391    }
392
393    ///Sets the length map.
394
395    ///Sets the length map.
396    ///\return <tt> (*this) </tt>
397    Dijkstra &lengthMap(const LengthMap &m)
398    {
399      length = &m;
400      return *this;
401    }
402
403    ///Sets the map storing the predecessor edges.
404
405    ///Sets the map storing the predecessor edges.
406    ///If you don't use this function before calling \ref run(),
407    ///it will allocate one. The destuctor deallocates this
408    ///automatically allocated map, of course.
409    ///\return <tt> (*this) </tt>
410    Dijkstra &predMap(PredMap &m)
411    {
412      if(local_pred) {
413        delete _pred;
414        local_pred=false;
415      }
416      _pred = &m;
417      return *this;
418    }
419
420//     ///Sets the map storing the predecessor nodes.
421
422//     ///Sets the map storing the predecessor nodes.
423//     ///If you don't use this function before calling \ref run(),
424//     ///it will allocate one. The destuctor deallocates this
425//     ///automatically allocated map, of course.
426//     ///\return <tt> (*this) </tt>
427//     Dijkstra &predNodeMap(PredNodeMap &m)
428//     {
429//       if(local_predNode) {
430//      delete _predNode;
431//      local_predNode=false;
432//       }
433//       _predNode = &m;
434//       return *this;
435//     }
436
437    ///Sets the map storing the distances calculated by the algorithm.
438
439    ///Sets the map storing the distances calculated by the algorithm.
440    ///If you don't use this function before calling \ref run(),
441    ///it will allocate one. The destuctor deallocates this
442    ///automatically allocated map, of course.
443    ///\return <tt> (*this) </tt>
444    Dijkstra &distMap(DistMap &m)
445    {
446      if(local_dist) {
447        delete _dist;
448        local_dist=false;
449      }
450      _dist = &m;
451      return *this;
452    }
453
454  private:
455    void finalizeNodeData(Node v,Value dst)
456    {
457      _processed->set(v,true);
458      _dist->set(v, dst);
459//       if((*_pred)[v]!=INVALID)
460//       _predNode->set(v,G->source((*_pred)[v])); ///\todo What to do?
461    }
462
463  public:
464    ///\name Execution control
465    ///The simplest way to execute the algorithm is to use
466    ///one of the member functions called \c run(...).
467    ///\n
468    ///If you need more control on the execution,
469    ///first you must call \ref init(), then you can add several source nodes
470    ///with \ref addSource().
471    ///Finally \ref start() will perform the actual path
472    ///computation.
473
474    ///@{
475
476    ///Initializes the internal data structures.
477
478    ///Initializes the internal data structures.
479    ///
480    ///\todo _heap_map's type could also be in the traits class.
481    ///\todo The heaps should be able to make themselves empty directly.
482    void init()
483    {
484      create_maps();
485      while(!_heap.empty()) _heap.pop();
486      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
487        _pred->set(u,INVALID);
488//      _predNode->set(u,INVALID);
489        _processed->set(u,false);
490        _heap_map.set(u,Heap::PRE_HEAP);
491      }
492    }
493   
494    ///Adds a new source node.
495
496    ///Adds a new source node to the priority heap.
497    ///
498    ///The optional second parameter is the initial distance of the node.
499    ///
500    ///It checks if the node has already been added to the heap and
501    ///It is pushed to the heap only if either it was not in the heap
502    ///or the shortest path found till then is longer then \c dst.
503    void addSource(Node s,Value dst=0)
504    {
505//       source = s;
506      if(_heap.state(s) != Heap::IN_HEAP) _heap.push(s,dst);
507      else if(_heap[s]<dst) {
508        _heap.push(s,dst);
509        _pred->set(s,INVALID);
510      }
511    }
512   
513    ///Processes the next node in the priority heap
514
515    ///Processes the next node in the priority heap.
516    ///
517    ///\return The processed node.
518    ///
519    ///\warning The priority heap must not be empty!
520    Node processNextNode()
521    {
522      Node v=_heap.top();
523      Value oldvalue=_heap[v];
524      _heap.pop();
525      finalizeNodeData(v,oldvalue);
526     
527      for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {
528        Node w=G->target(e);
529        switch(_heap.state(w)) {
530        case Heap::PRE_HEAP:
531          _heap.push(w,oldvalue+(*length)[e]);
532          _pred->set(w,e);
533//        _predNode->set(w,v);
534          break;
535        case Heap::IN_HEAP:
536          if ( oldvalue+(*length)[e] < _heap[w] ) {
537            _heap.decrease(w, oldvalue+(*length)[e]);
538            _pred->set(w,e);
539//          _predNode->set(w,v);
540          }
541          break;
542        case Heap::POST_HEAP:
543          break;
544        }
545      }
546      return v;
547    }
548
549    ///Next node to be processed.
550   
551    ///Next node to be processed.
552    ///
553    ///\return The next node to be processed or INVALID if the priority heap
554    /// is empty.
555    Node NextNode()
556    {
557      return _heap.empty()?_heap.top():INVALID;
558    }
559 
560    ///\brief Returns \c false if there are nodes
561    ///to be processed in the priority heap
562    ///
563    ///Returns \c false if there are nodes
564    ///to be processed in the priority heap
565    bool emptyQueue() { return _heap.empty(); }
566    ///Returns the number of the nodes to be processed in the priority heap
567
568    ///Returns the number of the nodes to be processed in the priority heap
569    ///
570    int queueSize() { return _heap.size(); }
571   
572    ///Executes the algorithm.
573
574    ///Executes the algorithm.
575    ///
576    ///\pre init() must be called and at least one node should be added
577    ///with addSource() before using this function.
578    ///
579    ///This method runs the %Dijkstra algorithm from the root node(s)
580    ///in order to
581    ///compute the
582    ///shortest path to each node. The algorithm computes
583    ///- The shortest path tree.
584    ///- The distance of each node from the root(s).
585    ///
586    void start()
587    {
588      while ( !_heap.empty() ) processNextNode();
589    }
590   
591    ///Executes the algorithm until \c dest is reached.
592
593    ///Executes the algorithm until \c dest is reached.
594    ///
595    ///\pre init() must be called and at least one node should be added
596    ///with addSource() before using this function.
597    ///
598    ///This method runs the %Dijkstra algorithm from the root node(s)
599    ///in order to
600    ///compute the
601    ///shortest path to \c dest. The algorithm computes
602    ///- The shortest path to \c  dest.
603    ///- The distance of \c dest from the root(s).
604    ///
605    void start(Node dest)
606    {
607      while ( !_heap.empty() && _heap.top()!=dest ) processNextNode();
608      if ( !_heap.empty() ) finalizeNodeData(_heap.top(),_heap.prio());
609    }
610   
611    ///Executes the algorithm until a condition is met.
612
613    ///Executes the algorithm until a condition is met.
614    ///
615    ///\pre init() must be called and at least one node should be added
616    ///with addSource() before using this function.
617    ///
618    ///\param nm must be a bool (or convertible) node map. The algorithm
619    ///will stop when it reaches a node \c v with <tt>nm[v]==true</tt>.
620    template<class NodeBoolMap>
621    void start(const NodeBoolMap &nm)
622    {
623      while ( !_heap.empty() && !nm[_heap.top()] ) processNextNode();
624      if ( !_heap.empty() ) finalizeNodeData(_heap.top(),_heap.prio());
625    }
626   
627    ///Runs %Dijkstra algorithm from node \c s.
628   
629    ///This method runs the %Dijkstra algorithm from a root node \c s
630    ///in order to
631    ///compute the
632    ///shortest path to each node. The algorithm computes
633    ///- The shortest path tree.
634    ///- The distance of each node from the root.
635    ///
636    ///\note d.run(s) is just a shortcut of the following code.
637    ///\code
638    ///  d.init();
639    ///  d.addSource(s);
640    ///  d.start();
641    ///\endcode
642    void run(Node s) {
643      init();
644      addSource(s);
645      start();
646    }
647   
648    ///Finds the shortest path between \c s and \c t.
649   
650    ///Finds the shortest path between \c s and \c t.
651    ///
652    ///\return The length of the shortest s---t path if there exists one,
653    ///0 otherwise.
654    ///\note Apart from the return value, d.run(s) is
655    ///just a shortcut of the following code.
656    ///\code
657    ///  d.init();
658    ///  d.addSource(s);
659    ///  d.start(t);
660    ///\endcode
661    Value run(Node s,Node t) {
662      init();
663      addSource(s);
664      start(t);
665      return (*_pred)[t]==INVALID?0:(*_dist)[t];
666    }
667   
668    ///@}
669
670    ///\name Query Functions
671    ///The result of the %Dijkstra algorithm can be obtained using these
672    ///functions.\n
673    ///Before the use of these functions,
674    ///either run() or start() must be called.
675   
676    ///@{
677
678    ///Copies the shortest path to \c t into \c p
679   
680    ///This function copies the shortest path to \c t into \c p.
681    ///If it \c t is a source itself or unreachable, then it does not
682    ///alter \c p.
683    ///\todo Is it the right way to handle unreachable nodes?
684    ///\return Returns \c true if a path to \c t was actually copied to \c p,
685    ///\c false otherwise.
686    ///\sa DirPath
687    template<class P>
688    bool getPath(P &p,Node t)
689    {
690      if(reached(t)) {
691        p.clear();
692        typename P::Builder b(p);
693        for(b.setStartNode(t);pred(t)!=INVALID;t=predNode(t))
694          b.pushFront(pred(t));
695        b.commit();
696        return true;
697      }
698      return false;
699    }
700         
701    ///The distance of a node from the root.
702
703    ///Returns the distance of a node from the root.
704    ///\pre \ref run() must be called before using this function.
705    ///\warning If node \c v in unreachable from the root the return value
706    ///of this funcion is undefined.
707    Value dist(Node v) const { return (*_dist)[v]; }
708
709    ///Returns the 'previous edge' of the shortest path tree.
710
711    ///For a node \c v it returns the 'previous edge' of the shortest path tree,
712    ///i.e. it returns the last edge of a shortest path from the root to \c
713    ///v. It is \ref INVALID
714    ///if \c v is unreachable from the root or if \c v=s. The
715    ///shortest path tree used here is equal to the shortest path tree used in
716    ///\ref predNode().  \pre \ref run() must be called before using
717    ///this function.
718    ///\todo predEdge could be a better name.
719    Edge pred(Node v) const { return (*_pred)[v]; }
720
721    ///Returns the 'previous node' of the shortest path tree.
722
723    ///For a node \c v it returns the 'previous node' of the shortest path tree,
724    ///i.e. it returns the last but one node from a shortest path from the
725    ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
726    ///\c v=s. The shortest path tree used here is equal to the shortest path
727    ///tree used in \ref pred().  \pre \ref run() must be called before
728    ///using this function.
729    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
730                                  G->source((*_pred)[v]); }
731   
732    ///Returns a reference to the NodeMap of distances.
733
734    ///Returns a reference to the NodeMap of distances. \pre \ref run() must
735    ///be called before using this function.
736    const DistMap &distMap() const { return *_dist;}
737 
738    ///Returns a reference to the shortest path tree map.
739
740    ///Returns a reference to the NodeMap of the edges of the
741    ///shortest path tree.
742    ///\pre \ref run() must be called before using this function.
743    const PredMap &predMap() const { return *_pred;}
744 
745//     ///Returns a reference to the map of nodes of shortest paths.
746
747//     ///Returns a reference to the NodeMap of the last but one nodes of the
748//     ///shortest path tree.
749//     ///\pre \ref run() must be called before using this function.
750//     const PredNodeMap &predNodeMap() const { return *_predNode;}
751
752    ///Checks if a node is reachable from the root.
753
754    ///Returns \c true if \c v is reachable from the root.
755    ///\warning The source nodes are inditated as unreached.
756    ///\pre \ref run() must be called before using this function.
757    ///
758    bool reached(Node v) { return _heap_map[v]!=Heap::PRE_HEAP; }
759   
760    ///@}
761  };
762
763
764
765
766 
767  ///Default traits class of Dijkstra function.
768
769  ///Default traits class of Dijkstra function.
770  ///\param GR Graph type.
771  ///\param LM Type of length map.
772  template<class GR, class LM>
773  struct DijkstraWizardDefaultTraits
774  {
775    ///The graph type the algorithm runs on.
776    typedef GR Graph;
777    ///The type of the map that stores the edge lengths.
778
779    ///The type of the map that stores the edge lengths.
780    ///It must meet the \ref concept::ReadMap "ReadMap" concept.
781    typedef LM LengthMap;
782    //The type of the length of the edges.
783    typedef typename LM::Value Value;
784    ///The heap type used by Dijkstra algorithm.
785
786    ///The heap type used by Dijkstra algorithm.
787    ///
788    ///\sa BinHeap
789    ///\sa Dijkstra
790    typedef BinHeap<typename Graph::Node,
791                    typename LM::Value,
792                    typename GR::template NodeMap<int>,
793                    std::less<Value> > Heap;
794
795    ///\brief The type of the map that stores the last
796    ///edges of the shortest paths.
797    ///
798    ///The type of the map that stores the last
799    ///edges of the shortest paths.
800    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
801    ///
802    typedef NullMap <typename GR::Node,typename GR::Edge> PredMap;
803    ///Instantiates a PredMap.
804 
805    ///This function instantiates a \ref PredMap.
806    ///\param g is the graph, to which we would like to define the PredMap.
807    ///\todo The graph alone may be insufficient for the initialization
808#ifdef DOXYGEN
809    static PredMap *createPredMap(const GR &g)
810#else
811    static PredMap *createPredMap(const GR &)
812#endif
813    {
814      return new PredMap();
815    }
816    ///The type of the map that stores whether a nodes is processed.
817 
818    ///The type of the map that stores whether a nodes is processed.
819    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
820    ///By default it is a NullMap.
821    ///\todo If it is set to a real map,
822    ///Dijkstra::processed() should read this.
823    ///\todo named parameter to set this type, function to read and write.
824    typedef NullMap<typename Graph::Node,bool> ProcessedMap;
825    ///Instantiates a ProcessedMap.
826 
827    ///This function instantiates a \ref ProcessedMap.
828    ///\param g is the graph, to which
829    ///we would like to define the \ref ProcessedMap
830#ifdef DOXYGEN
831    static ProcessedMap *createProcessedMap(const GR &g)
832#else
833    static ProcessedMap *createProcessedMap(const GR &)
834#endif
835    {
836      return new ProcessedMap();
837    }
838    ///The type of the map that stores the dists of the nodes.
839 
840    ///The type of the map that stores the dists of the nodes.
841    ///It must meet the \ref concept::WriteMap "WriteMap" concept.
842    ///
843    typedef NullMap<typename Graph::Node,typename LM::Value> DistMap;
844    ///Instantiates a DistMap.
845 
846    ///This function instantiates a \ref DistMap.
847    ///\param g is the graph, to which we would like to define the \ref DistMap
848#ifdef DOXYGEN
849    static DistMap *createDistMap(const GR &g)
850#else
851    static DistMap *createDistMap(const GR &)
852#endif
853    {
854      return new DistMap();
855    }
856  };
857 
858  /// Default traits used by \ref DijkstraWizard
859
860  /// To make it easier to use Dijkstra algorithm
861  ///we have created a wizard class.
862  /// This \ref DijkstraWizard class needs default traits,
863  ///as well as the \ref Dijkstra class.
864  /// The \ref DijkstraWizardBase is a class to be the default traits of the
865  /// \ref DijkstraWizard class.
866  /// \todo More named parameters are required...
867  template<class GR,class LM>
868  class DijkstraWizardBase : public DijkstraWizardDefaultTraits<GR,LM>
869  {
870
871    typedef DijkstraWizardDefaultTraits<GR,LM> Base;
872  protected:
873    /// Type of the nodes in the graph.
874    typedef typename Base::Graph::Node Node;
875
876    /// Pointer to the underlying graph.
877    void *_g;
878    /// Pointer to the length map
879    void *_length;
880    ///Pointer to the map of predecessors edges.
881    void *_pred;
882//     ///Pointer to the map of predecessors nodes.
883//     void *_predNode;
884    ///Pointer to the map of distances.
885    void *_dist;
886    ///Pointer to the source node.
887    Node _source;
888
889    public:
890    /// Constructor.
891   
892    /// This constructor does not require parameters, therefore it initiates
893    /// all of the attributes to default values (0, INVALID).
894    DijkstraWizardBase() : _g(0), _length(0), _pred(0),
895//                         _predNode(0),
896                           _dist(0), _source(INVALID) {}
897
898    /// Constructor.
899   
900    /// This constructor requires some parameters,
901    /// listed in the parameters list.
902    /// Others are initiated to 0.
903    /// \param g is the initial value of  \ref _g
904    /// \param l is the initial value of  \ref _length
905    /// \param s is the initial value of  \ref _source
906    DijkstraWizardBase(const GR &g,const LM &l, Node s=INVALID) :
907      _g((void *)&g), _length((void *)&l), _pred(0),
908//       _predNode(0),
909      _dist(0), _source(s) {}
910
911  };
912 
913  /// A class to make the usage of Dijkstra algorithm easier
914
915  /// This class is created to make it easier to use Dijkstra algorithm.
916  /// It uses the functions and features of the plain \ref Dijkstra,
917  /// but it is much simpler to use it.
918  ///
919  /// Simplicity means that the way to change the types defined
920  /// in the traits class is based on functions that returns the new class
921  /// and not on templatable built-in classes.
922  /// When using the plain \ref Dijkstra
923  /// the new class with the modified type comes from
924  /// the original class by using the ::
925  /// operator. In the case of \ref DijkstraWizard only
926  /// a function have to be called and it will
927  /// return the needed class.
928  ///
929  /// It does not have own \ref run method. When its \ref run method is called
930  /// it initiates a plain \ref Dijkstra class, and calls the \ref Dijkstra::run
931  /// method of it.
932  template<class TR>
933  class DijkstraWizard : public TR
934  {
935    typedef TR Base;
936
937    ///The type of the underlying graph.
938    typedef typename TR::Graph Graph;
939    //\e
940    typedef typename Graph::Node Node;
941    //\e
942    typedef typename Graph::NodeIt NodeIt;
943    //\e
944    typedef typename Graph::Edge Edge;
945    //\e
946    typedef typename Graph::OutEdgeIt OutEdgeIt;
947   
948    ///The type of the map that stores the edge lengths.
949    typedef typename TR::LengthMap LengthMap;
950    ///The type of the length of the edges.
951    typedef typename LengthMap::Value Value;
952    ///\brief The type of the map that stores the last
953    ///edges of the shortest paths.
954    typedef typename TR::PredMap PredMap;
955//     ///\brief The type of the map that stores the last but one
956//     ///nodes of the shortest paths.
957//     typedef typename TR::PredNodeMap PredNodeMap;
958    ///The type of the map that stores the dists of the nodes.
959    typedef typename TR::DistMap DistMap;
960
961    ///The heap type used by the dijkstra algorithm.
962    typedef typename TR::Heap Heap;
963public:
964    /// Constructor.
965    DijkstraWizard() : TR() {}
966
967    /// Constructor that requires parameters.
968
969    /// Constructor that requires parameters.
970    /// These parameters will be the default values for the traits class.
971    DijkstraWizard(const Graph &g,const LengthMap &l, Node s=INVALID) :
972      TR(g,l,s) {}
973
974    ///Copy constructor
975    DijkstraWizard(const TR &b) : TR(b) {}
976
977    ~DijkstraWizard() {}
978
979    ///Runs Dijkstra algorithm from a given node.
980   
981    ///Runs Dijkstra algorithm from a given node.
982    ///The node can be given by the \ref source function.
983    void run()
984    {
985      if(Base::_source==INVALID) throw UninitializedParameter();
986      Dijkstra<Graph,LengthMap,TR>
987        dij(*(Graph*)Base::_g,*(LengthMap*)Base::_length);
988      if(Base::_pred) dij.predMap(*(PredMap*)Base::_pred);
989//       if(Base::_predNode) Dij.predNodeMap(*(PredNodeMap*)Base::_predNode);
990      if(Base::_dist) dij.distMap(*(DistMap*)Base::_dist);
991      dij.run(Base::_source);
992    }
993
994    ///Runs Dijkstra algorithm from the given node.
995
996    ///Runs Dijkstra algorithm from the given node.
997    ///\param s is the given source.
998    void run(Node s)
999    {
1000      Base::_source=s;
1001      run();
1002    }
1003
1004    template<class T>
1005    struct DefPredMapBase : public Base {
1006      typedef T PredMap;
1007      static PredMap *createPredMap(const Graph &) { return 0; };
1008      DefPredMapBase(const TR &b) : TR(b) {}
1009    };
1010   
1011    ///\brief \ref named-templ-param "Named parameter"
1012    ///function for setting PredMap type
1013    ///
1014    /// \ref named-templ-param "Named parameter"
1015    ///function for setting PredMap type
1016    ///
1017    template<class T>
1018    DijkstraWizard<DefPredMapBase<T> > predMap(const T &t)
1019    {
1020      Base::_pred=(void *)&t;
1021      return DijkstraWizard<DefPredMapBase<T> >(*this);
1022    }
1023   
1024
1025//     template<class T>
1026//     struct DefPredNodeMapBase : public Base {
1027//       typedef T PredNodeMap;
1028//       static PredNodeMap *createPredNodeMap(const Graph &G) { return 0; };
1029//       DefPredNodeMapBase(const TR &b) : TR(b) {}
1030//     };
1031   
1032//     ///\brief \ref named-templ-param "Named parameter"
1033//     ///function for setting PredNodeMap type
1034//     ///
1035//     /// \ref named-templ-param "Named parameter"
1036//     ///function for setting PredNodeMap type
1037//     ///
1038//     template<class T>
1039//     DijkstraWizard<DefPredNodeMapBase<T> > predNodeMap(const T &t)
1040//     {
1041//       Base::_predNode=(void *)&t;
1042//       return DijkstraWizard<DefPredNodeMapBase<T> >(*this);
1043//     }
1044   
1045    template<class T>
1046    struct DefDistMapBase : public Base {
1047      typedef T DistMap;
1048      static DistMap *createDistMap(const Graph &) { return 0; };
1049      DefDistMapBase(const TR &b) : TR(b) {}
1050    };
1051   
1052    ///\brief \ref named-templ-param "Named parameter"
1053    ///function for setting DistMap type
1054    ///
1055    /// \ref named-templ-param "Named parameter"
1056    ///function for setting DistMap type
1057    ///
1058    template<class T>
1059    DijkstraWizard<DefDistMapBase<T> > distMap(const T &t)
1060    {
1061      Base::_dist=(void *)&t;
1062      return DijkstraWizard<DefDistMapBase<T> >(*this);
1063    }
1064   
1065    /// Sets the source node, from which the Dijkstra algorithm runs.
1066
1067    /// Sets the source node, from which the Dijkstra algorithm runs.
1068    /// \param s is the source node.
1069    DijkstraWizard<TR> &source(Node s)
1070    {
1071      Base::_source=s;
1072      return *this;
1073    }
1074   
1075  };
1076 
1077  ///Function type interface for Dijkstra algorithm.
1078
1079  /// \ingroup flowalgs
1080  ///Function type interface for Dijkstra algorithm.
1081  ///
1082  ///This function also has several
1083  ///\ref named-templ-func-param "named parameters",
1084  ///they are declared as the members of class \ref DijkstraWizard.
1085  ///The following
1086  ///example shows how to use these parameters.
1087  ///\code
1088  ///  dijkstra(g,length,source).predMap(preds).run();
1089  ///\endcode
1090  ///\warning Don't forget to put the \ref DijkstraWizard::run() "run()"
1091  ///to the end of the parameter list.
1092  ///\sa DijkstraWizard
1093  ///\sa Dijkstra
1094  template<class GR, class LM>
1095  DijkstraWizard<DijkstraWizardBase<GR,LM> >
1096  dijkstra(const GR &g,const LM &l,typename GR::Node s=INVALID)
1097  {
1098    return DijkstraWizard<DijkstraWizardBase<GR,LM> >(g,l,s);
1099  }
1100
1101} //END OF NAMESPACE LEMON
1102
1103#endif
1104
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