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alpar (Alpar Juttner)
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1 1
/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 2
 *
3 3
 * This file is a part of LEMON, a generic C++ optimization library.
4 4
 *
5 5
 * Copyright (C) 2003-2008
6 6
 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 7
 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 8
 *
9 9
 * Permission to use, modify and distribute this software is granted
10 10
 * provided that this copyright notice appears in all copies. For
11 11
 * precise terms see the accompanying LICENSE file.
12 12
 *
13 13
 * This software is provided "AS IS" with no warranty of any kind,
14 14
 * express or implied, and with no claim as to its suitability for any
15 15
 * purpose.
16 16
 *
17 17
 */
18 18

	
19 19
#ifndef LEMON_BFS_H
20 20
#define LEMON_BFS_H
21 21

	
22 22
///\ingroup search
23 23
///\file
24 24
///\brief BFS algorithm.
25 25

	
26 26
#include <lemon/list_graph.h>
27 27
#include <lemon/bits/path_dump.h>
28 28
#include <lemon/core.h>
29 29
#include <lemon/error.h>
30 30
#include <lemon/maps.h>
31 31

	
32 32
namespace lemon {
33 33

	
34 34
  ///Default traits class of Bfs class.
35 35

	
36 36
  ///Default traits class of Bfs class.
37 37
  ///\tparam GR Digraph type.
38 38
  template<class GR>
39 39
  struct BfsDefaultTraits
40 40
  {
41 41
    ///The type of the digraph the algorithm runs on.
42 42
    typedef GR Digraph;
43 43

	
44 44
    ///\brief The type of the map that stores the predecessor
45 45
    ///arcs of the shortest paths.
46 46
    ///
47 47
    ///The type of the map that stores the predecessor
48 48
    ///arcs of the shortest paths.
49 49
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
50 50
    typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
51 51
    ///Instantiates a \ref PredMap.
52 52

	
53 53
    ///This function instantiates a \ref PredMap.
54 54
    ///\param g is the digraph, to which we would like to define the
55 55
    ///\ref PredMap.
56 56
    ///\todo The digraph alone may be insufficient to initialize
57 57
    static PredMap *createPredMap(const Digraph &g)
58 58
    {
59 59
      return new PredMap(g);
60 60
    }
61 61

	
62 62
    ///The type of the map that indicates which nodes are processed.
63 63

	
64 64
    ///The type of the map that indicates which nodes are processed.
65 65
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
66 66
    ///By default it is a NullMap.
67 67
    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
68 68
    ///Instantiates a \ref ProcessedMap.
69 69

	
70 70
    ///This function instantiates a \ref ProcessedMap.
71 71
    ///\param g is the digraph, to which
72 72
    ///we would like to define the \ref ProcessedMap
73 73
#ifdef DOXYGEN
74 74
    static ProcessedMap *createProcessedMap(const Digraph &g)
75 75
#else
76 76
    static ProcessedMap *createProcessedMap(const Digraph &)
77 77
#endif
78 78
    {
79 79
      return new ProcessedMap();
80 80
    }
81 81

	
82 82
    ///The type of the map that indicates which nodes are reached.
83 83

	
84 84
    ///The type of the map that indicates which nodes are reached.
85 85
    ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
86 86
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
87 87
    ///Instantiates a \ref ReachedMap.
88 88

	
89 89
    ///This function instantiates a \ref ReachedMap.
90 90
    ///\param g is the digraph, to which
91 91
    ///we would like to define the \ref ReachedMap.
92 92
    static ReachedMap *createReachedMap(const Digraph &g)
93 93
    {
94 94
      return new ReachedMap(g);
95 95
    }
96 96

	
97 97
    ///The type of the map that stores the distances of the nodes.
98 98

	
99 99
    ///The type of the map that stores the distances of the nodes.
100 100
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
101 101
    typedef typename Digraph::template NodeMap<int> DistMap;
102 102
    ///Instantiates a \ref DistMap.
103 103

	
104 104
    ///This function instantiates a \ref DistMap.
105 105
    ///\param g is the digraph, to which we would like to define the
106 106
    ///\ref DistMap.
107 107
    static DistMap *createDistMap(const Digraph &g)
108 108
    {
109 109
      return new DistMap(g);
110 110
    }
111 111
  };
112 112

	
113 113
  ///%BFS algorithm class.
114 114

	
115 115
  ///\ingroup search
116 116
  ///This class provides an efficient implementation of the %BFS algorithm.
117 117
  ///
118 118
  ///There is also a \ref bfs() "function type interface" for the BFS
119 119
  ///algorithm, which is convenient in the simplier cases and it can be
120 120
  ///used easier.
121 121
  ///
122 122
  ///\tparam GR The type of the digraph the algorithm runs on.
123 123
  ///The default value is \ref ListDigraph. The value of GR is not used
124 124
  ///directly by \ref Bfs, it is only passed to \ref BfsDefaultTraits.
125 125
  ///\tparam TR Traits class to set various data types used by the algorithm.
126 126
  ///The default traits class is
127 127
  ///\ref BfsDefaultTraits "BfsDefaultTraits<GR>".
128 128
  ///See \ref BfsDefaultTraits for the documentation of
129 129
  ///a Bfs traits class.
130 130
#ifdef DOXYGEN
131 131
  template <typename GR,
132 132
            typename TR>
133 133
#else
134 134
  template <typename GR=ListDigraph,
135 135
            typename TR=BfsDefaultTraits<GR> >
136 136
#endif
137 137
  class Bfs {
138 138
  public:
139 139
    ///\ref Exception for uninitialized parameters.
140 140

	
141 141
    ///This error represents problems in the initialization of the
142 142
    ///parameters of the algorithm.
143 143
    class UninitializedParameter : public lemon::UninitializedParameter {
144 144
    public:
145 145
      virtual const char* what() const throw() {
146 146
        return "lemon::Bfs::UninitializedParameter";
147 147
      }
148 148
    };
149 149

	
150 150
    ///The type of the digraph the algorithm runs on.
151 151
    typedef typename TR::Digraph Digraph;
152 152

	
153 153
    ///\brief The type of the map that stores the predecessor arcs of the
154 154
    ///shortest paths.
155 155
    typedef typename TR::PredMap PredMap;
156 156
    ///The type of the map that stores the distances of the nodes.
157 157
    typedef typename TR::DistMap DistMap;
158 158
    ///The type of the map that indicates which nodes are reached.
159 159
    typedef typename TR::ReachedMap ReachedMap;
160 160
    ///The type of the map that indicates which nodes are processed.
161 161
    typedef typename TR::ProcessedMap ProcessedMap;
162 162
    ///The type of the paths.
163 163
    typedef PredMapPath<Digraph, PredMap> Path;
164 164

	
165 165
    ///The traits class.
166 166
    typedef TR Traits;
167 167

	
168 168
  private:
169 169

	
170 170
    typedef typename Digraph::Node Node;
171 171
    typedef typename Digraph::NodeIt NodeIt;
172 172
    typedef typename Digraph::Arc Arc;
173 173
    typedef typename Digraph::OutArcIt OutArcIt;
174 174

	
175 175
    //Pointer to the underlying digraph.
176 176
    const Digraph *G;
177 177
    //Pointer to the map of predecessor arcs.
178 178
    PredMap *_pred;
179 179
    //Indicates if _pred is locally allocated (true) or not.
180 180
    bool local_pred;
181 181
    //Pointer to the map of distances.
182 182
    DistMap *_dist;
183 183
    //Indicates if _dist is locally allocated (true) or not.
184 184
    bool local_dist;
185 185
    //Pointer to the map of reached status of the nodes.
186 186
    ReachedMap *_reached;
187 187
    //Indicates if _reached is locally allocated (true) or not.
188 188
    bool local_reached;
189 189
    //Pointer to the map of processed status of the nodes.
190 190
    ProcessedMap *_processed;
191 191
    //Indicates if _processed is locally allocated (true) or not.
192 192
    bool local_processed;
193 193

	
194 194
    std::vector<typename Digraph::Node> _queue;
195 195
    int _queue_head,_queue_tail,_queue_next_dist;
196 196
    int _curr_dist;
197 197

	
198 198
    ///Creates the maps if necessary.
199 199
    ///\todo Better memory allocation (instead of new).
200 200
    void create_maps()
201 201
    {
202 202
      if(!_pred) {
203 203
        local_pred = true;
204 204
        _pred = Traits::createPredMap(*G);
205 205
      }
206 206
      if(!_dist) {
207 207
        local_dist = true;
208 208
        _dist = Traits::createDistMap(*G);
209 209
      }
210 210
      if(!_reached) {
211 211
        local_reached = true;
212 212
        _reached = Traits::createReachedMap(*G);
213 213
      }
214 214
      if(!_processed) {
215 215
        local_processed = true;
216 216
        _processed = Traits::createProcessedMap(*G);
217 217
      }
218 218
    }
219 219

	
220 220
  protected:
221 221

	
222 222
    Bfs() {}
223 223

	
224 224
  public:
225 225

	
226 226
    typedef Bfs Create;
227 227

	
228 228
    ///\name Named template parameters
229 229

	
230 230
    ///@{
231 231

	
232 232
    template <class T>
233 233
    struct DefPredMapTraits : public Traits {
234 234
      typedef T PredMap;
235 235
      static PredMap *createPredMap(const Digraph &)
236 236
      {
237 237
        throw UninitializedParameter();
238 238
      }
239 239
    };
240 240
    ///\brief \ref named-templ-param "Named parameter" for setting
241 241
    ///\ref PredMap type.
242 242
    ///
243 243
    ///\ref named-templ-param "Named parameter" for setting
244 244
    ///\ref PredMap type.
245 245
    template <class T>
246 246
    struct DefPredMap : public Bfs< Digraph, DefPredMapTraits<T> > {
247 247
      typedef Bfs< Digraph, DefPredMapTraits<T> > Create;
248 248
    };
249 249

	
250 250
    template <class T>
251 251
    struct DefDistMapTraits : public Traits {
252 252
      typedef T DistMap;
253 253
      static DistMap *createDistMap(const Digraph &)
254 254
      {
255 255
        throw UninitializedParameter();
256 256
      }
257 257
    };
258 258
    ///\brief \ref named-templ-param "Named parameter" for setting
259 259
    ///\ref DistMap type.
260 260
    ///
261 261
    ///\ref named-templ-param "Named parameter" for setting
262 262
    ///\ref DistMap type.
263 263
    template <class T>
264 264
    struct DefDistMap : public Bfs< Digraph, DefDistMapTraits<T> > {
265 265
      typedef Bfs< Digraph, DefDistMapTraits<T> > Create;
266 266
    };
267 267

	
268 268
    template <class T>
269 269
    struct DefReachedMapTraits : public Traits {
270 270
      typedef T ReachedMap;
271 271
      static ReachedMap *createReachedMap(const Digraph &)
272 272
      {
273 273
        throw UninitializedParameter();
274 274
      }
275 275
    };
276 276
    ///\brief \ref named-templ-param "Named parameter" for setting
277 277
    ///\ref ReachedMap type.
278 278
    ///
279 279
    ///\ref named-templ-param "Named parameter" for setting
280 280
    ///\ref ReachedMap type.
281 281
    template <class T>
282 282
    struct DefReachedMap : public Bfs< Digraph, DefReachedMapTraits<T> > {
283 283
      typedef Bfs< Digraph, DefReachedMapTraits<T> > Create;
284 284
    };
285 285

	
286 286
    template <class T>
287 287
    struct DefProcessedMapTraits : public Traits {
288 288
      typedef T ProcessedMap;
289 289
      static ProcessedMap *createProcessedMap(const Digraph &)
290 290
      {
291 291
        throw UninitializedParameter();
292 292
      }
293 293
    };
294 294
    ///\brief \ref named-templ-param "Named parameter" for setting
295 295
    ///\ref ProcessedMap type.
296 296
    ///
297 297
    ///\ref named-templ-param "Named parameter" for setting
298 298
    ///\ref ProcessedMap type.
299 299
    template <class T>
300 300
    struct DefProcessedMap : public Bfs< Digraph, DefProcessedMapTraits<T> > {
301 301
      typedef Bfs< Digraph, DefProcessedMapTraits<T> > Create;
302 302
    };
303 303

	
304 304
    struct DefDigraphProcessedMapTraits : public Traits {
305 305
      typedef typename Digraph::template NodeMap<bool> ProcessedMap;
306 306
      static ProcessedMap *createProcessedMap(const Digraph &g)
307 307
      {
308 308
        return new ProcessedMap(g);
309 309
      }
310 310
    };
311 311
    ///\brief \ref named-templ-param "Named parameter" for setting
312 312
    ///\ref ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
313 313
    ///
314 314
    ///\ref named-templ-param "Named parameter" for setting
315 315
    ///\ref ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
316 316
    ///If you don't set it explicitly, it will be automatically allocated.
317 317
    template <class T>
318 318
    struct DefProcessedMapToBeDefaultMap :
319 319
      public Bfs< Digraph, DefDigraphProcessedMapTraits> {
320 320
      typedef Bfs< Digraph, DefDigraphProcessedMapTraits> Create;
321 321
    };
322 322

	
323 323
    ///@}
324 324

	
325 325
  public:
326 326

	
327 327
    ///Constructor.
328 328

	
329 329
    ///Constructor.
330 330
    ///\param g The digraph the algorithm runs on.
331 331
    Bfs(const Digraph &g) :
332 332
      G(&g),
333 333
      _pred(NULL), local_pred(false),
334 334
      _dist(NULL), local_dist(false),
335 335
      _reached(NULL), local_reached(false),
336 336
      _processed(NULL), local_processed(false)
337 337
    { }
338 338

	
339 339
    ///Destructor.
340 340
    ~Bfs()
341 341
    {
342 342
      if(local_pred) delete _pred;
343 343
      if(local_dist) delete _dist;
344 344
      if(local_reached) delete _reached;
345 345
      if(local_processed) delete _processed;
346 346
    }
347 347

	
348 348
    ///Sets the map that stores the predecessor arcs.
349 349

	
350 350
    ///Sets the map that stores the predecessor arcs.
351 351
    ///If you don't use this function before calling \ref run(),
352 352
    ///it will allocate one. The destructor deallocates this
353 353
    ///automatically allocated map, of course.
354 354
    ///\return <tt> (*this) </tt>
355 355
    Bfs &predMap(PredMap &m)
356 356
    {
357 357
      if(local_pred) {
358 358
        delete _pred;
359 359
        local_pred=false;
360 360
      }
361 361
      _pred = &m;
362 362
      return *this;
363 363
    }
364 364

	
365 365
    ///Sets the map that indicates which nodes are reached.
366 366

	
367 367
    ///Sets the map that indicates which nodes are reached.
368 368
    ///If you don't use this function before calling \ref run(),
369 369
    ///it will allocate one. The destructor deallocates this
370 370
    ///automatically allocated map, of course.
371 371
    ///\return <tt> (*this) </tt>
372 372
    Bfs &reachedMap(ReachedMap &m)
373 373
    {
374 374
      if(local_reached) {
375 375
        delete _reached;
376 376
        local_reached=false;
377 377
      }
378 378
      _reached = &m;
379 379
      return *this;
380 380
    }
381 381

	
382 382
    ///Sets the map that indicates which nodes are processed.
383 383

	
384 384
    ///Sets the map that indicates which nodes are processed.
385 385
    ///If you don't use this function before calling \ref run(),
386 386
    ///it will allocate one. The destructor deallocates this
387 387
    ///automatically allocated map, of course.
388 388
    ///\return <tt> (*this) </tt>
389 389
    Bfs &processedMap(ProcessedMap &m)
390 390
    {
391 391
      if(local_processed) {
392 392
        delete _processed;
393 393
        local_processed=false;
394 394
      }
395 395
      _processed = &m;
396 396
      return *this;
397 397
    }
398 398

	
399 399
    ///Sets the map that stores the distances of the nodes.
400 400

	
401 401
    ///Sets the map that stores the distances of the nodes calculated by
402 402
    ///the algorithm.
403 403
    ///If you don't use this function before calling \ref run(),
404 404
    ///it will allocate one. The destructor deallocates this
405 405
    ///automatically allocated map, of course.
406 406
    ///\return <tt> (*this) </tt>
407 407
    Bfs &distMap(DistMap &m)
408 408
    {
409 409
      if(local_dist) {
410 410
        delete _dist;
411 411
        local_dist=false;
412 412
      }
413 413
      _dist = &m;
414 414
      return *this;
415 415
    }
416 416

	
417 417
  public:
418 418

	
419 419
    ///\name Execution control
420 420
    ///The simplest way to execute the algorithm is to use
421 421
    ///one of the member functions called \ref lemon::Bfs::run() "run()".
422 422
    ///\n
423 423
    ///If you need more control on the execution, first you must call
424 424
    ///\ref lemon::Bfs::init() "init()", then you can add several source
425 425
    ///nodes with \ref lemon::Bfs::addSource() "addSource()".
426 426
    ///Finally \ref lemon::Bfs::start() "start()" will perform the
427 427
    ///actual path computation.
428 428

	
429 429
    ///@{
430 430

	
431 431
    ///Initializes the internal data structures.
432 432

	
433 433
    ///Initializes the internal data structures.
434 434
    ///
435 435
    void init()
436 436
    {
437 437
      create_maps();
438 438
      _queue.resize(countNodes(*G));
439 439
      _queue_head=_queue_tail=0;
440 440
      _curr_dist=1;
441 441
      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
442 442
        _pred->set(u,INVALID);
443 443
        _reached->set(u,false);
444 444
        _processed->set(u,false);
445 445
      }
446 446
    }
447 447

	
448 448
    ///Adds a new source node.
449 449

	
450 450
    ///Adds a new source node to the set of nodes to be processed.
451 451
    ///
452 452
    void addSource(Node s)
453 453
    {
454 454
      if(!(*_reached)[s])
455 455
        {
456 456
          _reached->set(s,true);
457 457
          _pred->set(s,INVALID);
458 458
          _dist->set(s,0);
459 459
          _queue[_queue_head++]=s;
460 460
          _queue_next_dist=_queue_head;
461 461
        }
462 462
    }
463 463

	
464 464
    ///Processes the next node.
465 465

	
466 466
    ///Processes the next node.
467 467
    ///
468 468
    ///\return The processed node.
469 469
    ///
470 470
    ///\pre The queue must not be empty.
471 471
    Node processNextNode()
472 472
    {
473 473
      if(_queue_tail==_queue_next_dist) {
474 474
        _curr_dist++;
475 475
        _queue_next_dist=_queue_head;
476 476
      }
477 477
      Node n=_queue[_queue_tail++];
478 478
      _processed->set(n,true);
479 479
      Node m;
480 480
      for(OutArcIt e(*G,n);e!=INVALID;++e)
481 481
        if(!(*_reached)[m=G->target(e)]) {
482 482
          _queue[_queue_head++]=m;
483 483
          _reached->set(m,true);
484 484
          _pred->set(m,e);
485 485
          _dist->set(m,_curr_dist);
486 486
        }
487 487
      return n;
488 488
    }
489 489

	
490 490
    ///Processes the next node.
491 491

	
492 492
    ///Processes the next node and checks if the given target node
493 493
    ///is reached. If the target node is reachable from the processed
494 494
    ///node, then the \c reach parameter will be set to \c true.
495 495
    ///
496 496
    ///\param target The target node.
497 497
    ///\retval reach Indicates if the target node is reached.
498 498
    ///It should be initially \c false.
499 499
    ///
500 500
    ///\return The processed node.
501 501
    ///
502 502
    ///\pre The queue must not be empty.
503 503
    Node processNextNode(Node target, bool& reach)
504 504
    {
505 505
      if(_queue_tail==_queue_next_dist) {
506 506
        _curr_dist++;
507 507
        _queue_next_dist=_queue_head;
508 508
      }
509 509
      Node n=_queue[_queue_tail++];
510 510
      _processed->set(n,true);
511 511
      Node m;
512 512
      for(OutArcIt e(*G,n);e!=INVALID;++e)
513 513
        if(!(*_reached)[m=G->target(e)]) {
514 514
          _queue[_queue_head++]=m;
515 515
          _reached->set(m,true);
516 516
          _pred->set(m,e);
517 517
          _dist->set(m,_curr_dist);
518 518
          reach = reach || (target == m);
519 519
        }
520 520
      return n;
521 521
    }
522 522

	
523 523
    ///Processes the next node.
524 524

	
525 525
    ///Processes the next node and checks if at least one of reached
526 526
    ///nodes has \c true value in the \c nm node map. If one node
527 527
    ///with \c true value is reachable from the processed node, then the
528 528
    ///\c rnode parameter will be set to the first of such nodes.
529 529
    ///
530 530
    ///\param nm A \c bool (or convertible) node map that indicates the
531 531
    ///possible targets.
532 532
    ///\retval rnode The reached target node.
533 533
    ///It should be initially \c INVALID.
534 534
    ///
535 535
    ///\return The processed node.
536 536
    ///
537 537
    ///\pre The queue must not be empty.
538 538
    template<class NM>
539 539
    Node processNextNode(const NM& nm, Node& rnode)
540 540
    {
541 541
      if(_queue_tail==_queue_next_dist) {
542 542
        _curr_dist++;
543 543
        _queue_next_dist=_queue_head;
544 544
      }
545 545
      Node n=_queue[_queue_tail++];
546 546
      _processed->set(n,true);
547 547
      Node m;
548 548
      for(OutArcIt e(*G,n);e!=INVALID;++e)
549 549
        if(!(*_reached)[m=G->target(e)]) {
550 550
          _queue[_queue_head++]=m;
551 551
          _reached->set(m,true);
552 552
          _pred->set(m,e);
553 553
          _dist->set(m,_curr_dist);
554 554
          if (nm[m] && rnode == INVALID) rnode = m;
555 555
        }
556 556
      return n;
557 557
    }
558 558

	
559 559
    ///The next node to be processed.
560 560

	
561 561
    ///Returns the next node to be processed or \c INVALID if the queue
562 562
    ///is empty.
563 563
    Node nextNode() const
564 564
    {
565 565
      return _queue_tail<_queue_head?_queue[_queue_tail]:INVALID;
566 566
    }
567 567

	
568 568
    ///\brief Returns \c false if there are nodes
569 569
    ///to be processed.
570 570
    ///
571 571
    ///Returns \c false if there are nodes
572 572
    ///to be processed in the queue.
573 573
    bool emptyQueue() const { return _queue_tail==_queue_head; }
574 574

	
575 575
    ///Returns the number of the nodes to be processed.
576 576

	
577 577
    ///Returns the number of the nodes to be processed in the queue.
578 578
    int queueSize() const { return _queue_head-_queue_tail; }
579 579

	
580 580
    ///Executes the algorithm.
581 581

	
582 582
    ///Executes the algorithm.
583 583
    ///
584 584
    ///This method runs the %BFS algorithm from the root node(s)
585 585
    ///in order to compute the shortest path to each node.
586 586
    ///
587 587
    ///The algorithm computes
588 588
    ///- the shortest path tree (forest),
589 589
    ///- the distance of each node from the root(s).
590 590
    ///
591 591
    ///\pre init() must be called and at least one root node should be
592 592
    ///added with addSource() before using this function.
593 593
    ///
594 594
    ///\note <tt>b.start()</tt> is just a shortcut of the following code.
595 595
    ///\code
596 596
    ///  while ( !b.emptyQueue() ) {
597 597
    ///    b.processNextNode();
598 598
    ///  }
599 599
    ///\endcode
600 600
    void start()
601 601
    {
602 602
      while ( !emptyQueue() ) processNextNode();
603 603
    }
604 604

	
605 605
    ///Executes the algorithm until the given target node is reached.
606 606

	
607 607
    ///Executes the algorithm until the given target node is reached.
608 608
    ///
609 609
    ///This method runs the %BFS algorithm from the root node(s)
610 610
    ///in order to compute the shortest path to \c dest.
611 611
    ///
612 612
    ///The algorithm computes
613 613
    ///- the shortest path to \c dest,
614 614
    ///- the distance of \c dest from the root(s).
615 615
    ///
616 616
    ///\pre init() must be called and at least one root node should be
617 617
    ///added with addSource() before using this function.
618 618
    ///
619 619
    ///\note <tt>b.start(t)</tt> is just a shortcut of the following code.
620 620
    ///\code
621 621
    ///  bool reach = false;
622 622
    ///  while ( !b.emptyQueue() && !reach ) {
623 623
    ///    b.processNextNode(t, reach);
624 624
    ///  }
625 625
    ///\endcode
626 626
    void start(Node dest)
627 627
    {
628 628
      bool reach = false;
629 629
      while ( !emptyQueue() && !reach ) processNextNode(dest, reach);
630 630
    }
631 631

	
632 632
    ///Executes the algorithm until a condition is met.
633 633

	
634 634
    ///Executes the algorithm until a condition is met.
635 635
    ///
636 636
    ///This method runs the %BFS algorithm from the root node(s) in
637 637
    ///order to compute the shortest path to a node \c v with
638 638
    /// <tt>nm[v]</tt> true, if such a node can be found.
639 639
    ///
640 640
    ///\param nm A \c bool (or convertible) node map. The algorithm
641 641
    ///will stop when it reaches a node \c v with <tt>nm[v]</tt> true.
642 642
    ///
643 643
    ///\return The reached node \c v with <tt>nm[v]</tt> true or
644 644
    ///\c INVALID if no such node was found.
645 645
    ///
646 646
    ///\pre init() must be called and at least one root node should be
647 647
    ///added with addSource() before using this function.
648 648
    ///
649 649
    ///\note <tt>b.start(nm)</tt> is just a shortcut of the following code.
650 650
    ///\code
651 651
    ///  Node rnode = INVALID;
652 652
    ///  while ( !b.emptyQueue() && rnode == INVALID ) {
653 653
    ///    b.processNextNode(nm, rnode);
654 654
    ///  }
655 655
    ///  return rnode;
656 656
    ///\endcode
657 657
    template<class NodeBoolMap>
658 658
    Node start(const NodeBoolMap &nm)
659 659
    {
660 660
      Node rnode = INVALID;
661 661
      while ( !emptyQueue() && rnode == INVALID ) {
662 662
        processNextNode(nm, rnode);
663 663
      }
664 664
      return rnode;
665 665
    }
666 666

	
667 667
    ///Runs the algorithm from the given node.
668 668

	
669 669
    ///This method runs the %BFS algorithm from node \c s
670 670
    ///in order to compute the shortest path to each node.
671 671
    ///
672 672
    ///The algorithm computes
673 673
    ///- the shortest path tree,
674 674
    ///- the distance of each node from the root.
675 675
    ///
676 676
    ///\note <tt>b.run(s)</tt> is just a shortcut of the following code.
677 677
    ///\code
678 678
    ///  b.init();
679 679
    ///  b.addSource(s);
680 680
    ///  b.start();
681 681
    ///\endcode
682 682
    void run(Node s) {
683 683
      init();
684 684
      addSource(s);
685 685
      start();
686 686
    }
687 687

	
688 688
    ///Finds the shortest path between \c s and \c t.
689 689

	
690 690
    ///This method runs the %BFS algorithm from node \c s
691 691
    ///in order to compute the shortest path to \c t.
692 692
    ///
693 693
    ///\return The length of the shortest <tt>s</tt>--<tt>t</tt> path,
694 694
    ///if \c t is reachable form \c s, \c 0 otherwise.
695 695
    ///
696 696
    ///\note Apart from the return value, <tt>b.run(s,t)</tt> is just a
697 697
    ///shortcut of the following code.
698 698
    ///\code
699 699
    ///  b.init();
700 700
    ///  b.addSource(s);
701 701
    ///  b.start(t);
702 702
    ///\endcode
703 703
    int run(Node s,Node t) {
704 704
      init();
705 705
      addSource(s);
706 706
      start(t);
707 707
      return reached(t) ? _curr_dist : 0;
708 708
    }
709 709

	
710 710
    ///Runs the algorithm to visit all nodes in the digraph.
711 711

	
712 712
    ///This method runs the %BFS algorithm in order to
713 713
    ///compute the shortest path to each node.
714 714
    ///
715 715
    ///The algorithm computes
716 716
    ///- the shortest path tree (forest),
717 717
    ///- the distance of each node from the root(s).
718 718
    ///
719 719
    ///\note <tt>b.run(s)</tt> is just a shortcut of the following code.
720 720
    ///\code
721 721
    ///  b.init();
722 722
    ///  for (NodeIt n(gr); n != INVALID; ++n) {
723 723
    ///    if (!b.reached(n)) {
724 724
    ///      b.addSource(n);
725 725
    ///      b.start();
726 726
    ///    }
727 727
    ///  }
728 728
    ///\endcode
729 729
    void run() {
730 730
      init();
731 731
      for (NodeIt n(*G); n != INVALID; ++n) {
732 732
        if (!reached(n)) {
733 733
          addSource(n);
734 734
          start();
735 735
        }
736 736
      }
737 737
    }
738 738

	
739 739
    ///@}
740 740

	
741 741
    ///\name Query Functions
742 742
    ///The result of the %BFS algorithm can be obtained using these
743 743
    ///functions.\n
744 744
    ///Either \ref lemon::Bfs::run() "run()" or \ref lemon::Bfs::start()
745 745
    ///"start()" must be called before using them.
746 746

	
747 747
    ///@{
748 748

	
749 749
    ///The shortest path to a node.
750 750

	
751 751
    ///Returns the shortest path to a node.
752 752
    ///
753 753
    ///\warning \c t should be reachable from the root(s).
754 754
    ///
755 755
    ///\pre Either \ref run() or \ref start() must be called before
756 756
    ///using this function.
757 757
    Path path(Node t) const { return Path(*G, *_pred, t); }
758 758

	
759 759
    ///The distance of a node from the root(s).
760 760

	
761 761
    ///Returns the distance of a node from the root(s).
762 762
    ///
763 763
    ///\warning If node \c v is not reachable from the root(s), then
764 764
    ///the return value of this function is undefined.
765 765
    ///
766 766
    ///\pre Either \ref run() or \ref start() must be called before
767 767
    ///using this function.
768 768
    int dist(Node v) const { return (*_dist)[v]; }
769 769

	
770 770
    ///Returns the 'previous arc' of the shortest path tree for a node.
771 771

	
772 772
    ///This function returns the 'previous arc' of the shortest path
773 773
    ///tree for the node \c v, i.e. it returns the last arc of a
774 774
    ///shortest path from the root(s) to \c v. It is \c INVALID if \c v
775 775
    ///is not reachable from the root(s) or if \c v is a root.
776 776
    ///
777 777
    ///The shortest path tree used here is equal to the shortest path
778 778
    ///tree used in \ref predNode().
779 779
    ///
780 780
    ///\pre Either \ref run() or \ref start() must be called before
781 781
    ///using this function.
782 782
    Arc predArc(Node v) const { return (*_pred)[v];}
783 783

	
784 784
    ///Returns the 'previous node' of the shortest path tree for a node.
785 785

	
786 786
    ///This function returns the 'previous node' of the shortest path
787 787
    ///tree for the node \c v, i.e. it returns the last but one node
788 788
    ///from a shortest path from the root(s) to \c v. It is \c INVALID
789 789
    ///if \c v is not reachable from the root(s) or if \c v is a root.
790 790
    ///
791 791
    ///The shortest path tree used here is equal to the shortest path
792 792
    ///tree used in \ref predArc().
793 793
    ///
794 794
    ///\pre Either \ref run() or \ref start() must be called before
795 795
    ///using this function.
796 796
    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
797 797
                                  G->source((*_pred)[v]); }
798 798

	
799 799
    ///\brief Returns a const reference to the node map that stores the
800 800
    /// distances of the nodes.
801 801
    ///
802 802
    ///Returns a const reference to the node map that stores the distances
803 803
    ///of the nodes calculated by the algorithm.
804 804
    ///
805 805
    ///\pre Either \ref run() or \ref init()
806 806
    ///must be called before using this function.
807 807
    const DistMap &distMap() const { return *_dist;}
808 808

	
809 809
    ///\brief Returns a const reference to the node map that stores the
810 810
    ///predecessor arcs.
811 811
    ///
812 812
    ///Returns a const reference to the node map that stores the predecessor
813 813
    ///arcs, which form the shortest path tree.
814 814
    ///
815 815
    ///\pre Either \ref run() or \ref init()
816 816
    ///must be called before using this function.
817 817
    const PredMap &predMap() const { return *_pred;}
818 818

	
819 819
    ///Checks if a node is reachable from the root(s).
820 820

	
821 821
    ///Returns \c true if \c v is reachable from the root(s).
822 822
    ///\pre Either \ref run() or \ref start()
823 823
    ///must be called before using this function.
824 824
    bool reached(Node v) const { return (*_reached)[v]; }
825 825

	
826 826
    ///@}
827 827
  };
828 828

	
829 829
  ///Default traits class of bfs() function.
830 830

	
831 831
  ///Default traits class of bfs() function.
832 832
  ///\tparam GR Digraph type.
833 833
  template<class GR>
834 834
  struct BfsWizardDefaultTraits
835 835
  {
836 836
    ///The type of the digraph the algorithm runs on.
837 837
    typedef GR Digraph;
838 838

	
839 839
    ///\brief The type of the map that stores the predecessor
840 840
    ///arcs of the shortest paths.
841 841
    ///
842 842
    ///The type of the map that stores the predecessor
843 843
    ///arcs of the shortest paths.
844 844
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
845 845
    typedef NullMap<typename Digraph::Node,typename Digraph::Arc> PredMap;
846 846
    ///Instantiates a \ref PredMap.
847 847

	
848 848
    ///This function instantiates a \ref PredMap.
849 849
    ///\param g is the digraph, to which we would like to define the
850 850
    ///\ref PredMap.
851 851
    ///\todo The digraph alone may be insufficient to initialize
852 852
#ifdef DOXYGEN
853 853
    static PredMap *createPredMap(const Digraph &g)
854 854
#else
855 855
    static PredMap *createPredMap(const Digraph &)
856 856
#endif
857 857
    {
858 858
      return new PredMap();
859 859
    }
860 860

	
861 861
    ///The type of the map that indicates which nodes are processed.
862 862

	
863 863
    ///The type of the map that indicates which nodes are processed.
864 864
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
865 865
    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
866 866
    ///Instantiates a \ref ProcessedMap.
867 867

	
868 868
    ///This function instantiates a \ref ProcessedMap.
869 869
    ///\param g is the digraph, to which
870 870
    ///we would like to define the \ref ProcessedMap.
871 871
#ifdef DOXYGEN
872 872
    static ProcessedMap *createProcessedMap(const Digraph &g)
873 873
#else
874 874
    static ProcessedMap *createProcessedMap(const Digraph &)
875 875
#endif
876 876
    {
877 877
      return new ProcessedMap();
878 878
    }
879 879

	
880 880
    ///The type of the map that indicates which nodes are reached.
881 881

	
882 882
    ///The type of the map that indicates which nodes are reached.
883 883
    ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
884 884
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
885 885
    ///Instantiates a \ref ReachedMap.
886 886

	
887 887
    ///This function instantiates a \ref ReachedMap.
888 888
    ///\param g is the digraph, to which
889 889
    ///we would like to define the \ref ReachedMap.
890 890
    static ReachedMap *createReachedMap(const Digraph &g)
891 891
    {
892 892
      return new ReachedMap(g);
893 893
    }
894 894

	
895 895
    ///The type of the map that stores the distances of the nodes.
896 896

	
897 897
    ///The type of the map that stores the distances of the nodes.
898 898
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
899 899
    ///
900 900
    typedef NullMap<typename Digraph::Node,int> DistMap;
901 901
    ///Instantiates a \ref DistMap.
902 902

	
903 903
    ///This function instantiates a \ref DistMap.
904 904
    ///\param g is the digraph, to which we would like to define
905 905
    ///the \ref DistMap
906 906
#ifdef DOXYGEN
907 907
    static DistMap *createDistMap(const Digraph &g)
908 908
#else
909 909
    static DistMap *createDistMap(const Digraph &)
910 910
#endif
911 911
    {
912 912
      return new DistMap();
913 913
    }
914 914
  };
915 915

	
916 916
  /// Default traits class used by \ref BfsWizard
917 917

	
918 918
  /// To make it easier to use Bfs algorithm
919 919
  /// we have created a wizard class.
920 920
  /// This \ref BfsWizard class needs default traits,
921 921
  /// as well as the \ref Bfs class.
922 922
  /// The \ref BfsWizardBase is a class to be the default traits of the
923 923
  /// \ref BfsWizard class.
924 924
  template<class GR>
925 925
  class BfsWizardBase : public BfsWizardDefaultTraits<GR>
926 926
  {
927 927

	
928 928
    typedef BfsWizardDefaultTraits<GR> Base;
929 929
  protected:
930 930
    //The type of the nodes in the digraph.
931 931
    typedef typename Base::Digraph::Node Node;
932 932

	
933 933
    //Pointer to the digraph the algorithm runs on.
934 934
    void *_g;
935 935
    //Pointer to the map of reached nodes.
936 936
    void *_reached;
937 937
    //Pointer to the map of processed nodes.
938 938
    void *_processed;
939 939
    //Pointer to the map of predecessors arcs.
940 940
    void *_pred;
941 941
    //Pointer to the map of distances.
942 942
    void *_dist;
943 943
    //Pointer to the source node.
944 944
    Node _source;
945 945

	
946 946
    public:
947 947
    /// Constructor.
948 948

	
949 949
    /// This constructor does not require parameters, therefore it initiates
950 950
    /// all of the attributes to default values (0, INVALID).
951 951
    BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0),
952 952
                      _dist(0), _source(INVALID) {}
953 953

	
954 954
    /// Constructor.
955 955

	
956 956
    /// This constructor requires some parameters,
957 957
    /// listed in the parameters list.
958 958
    /// Others are initiated to 0.
959 959
    /// \param g The digraph the algorithm runs on.
960 960
    /// \param s The source node.
961 961
    BfsWizardBase(const GR &g, Node s=INVALID) :
962 962
      _g(reinterpret_cast<void*>(const_cast<GR*>(&g))),
963 963
      _reached(0), _processed(0), _pred(0), _dist(0), _source(s) {}
964 964

	
965 965
  };
966 966

	
967 967
  /// Auxiliary class for the function type interface of BFS algorithm.
968 968

	
969 969
  /// This auxiliary class is created to implement the function type
970 970
  /// interface of \ref Bfs algorithm. It uses the functions and features
971 971
  /// of the plain \ref Bfs, but it is much simpler to use it.
972 972
  /// It should only be used through the \ref bfs() function, which makes
973 973
  /// it easier to use the algorithm.
974 974
  ///
975 975
  /// Simplicity means that the way to change the types defined
976 976
  /// in the traits class is based on functions that returns the new class
977 977
  /// and not on templatable built-in classes.
978 978
  /// When using the plain \ref Bfs
979 979
  /// the new class with the modified type comes from
980 980
  /// the original class by using the ::
981 981
  /// operator. In the case of \ref BfsWizard only
982 982
  /// a function have to be called, and it will
983 983
  /// return the needed class.
984 984
  ///
985 985
  /// It does not have own \ref run() method. When its \ref run() method
986 986
  /// is called, it initiates a plain \ref Bfs object, and calls the
987 987
  /// \ref Bfs::run() method of it.
988 988
  template<class TR>
989 989
  class BfsWizard : public TR
990 990
  {
991 991
    typedef TR Base;
992 992

	
993 993
    ///The type of the digraph the algorithm runs on.
994 994
    typedef typename TR::Digraph Digraph;
995 995

	
996 996
    typedef typename Digraph::Node Node;
997 997
    typedef typename Digraph::NodeIt NodeIt;
998 998
    typedef typename Digraph::Arc Arc;
999 999
    typedef typename Digraph::OutArcIt OutArcIt;
1000 1000

	
1001 1001
    ///\brief The type of the map that stores the predecessor
1002 1002
    ///arcs of the shortest paths.
1003 1003
    typedef typename TR::PredMap PredMap;
1004 1004
    ///\brief The type of the map that stores the distances of the nodes.
1005 1005
    typedef typename TR::DistMap DistMap;
1006 1006
    ///\brief The type of the map that indicates which nodes are reached.
1007 1007
    typedef typename TR::ReachedMap ReachedMap;
1008 1008
    ///\brief The type of the map that indicates which nodes are processed.
1009 1009
    typedef typename TR::ProcessedMap ProcessedMap;
1010 1010

	
1011 1011
  public:
1012 1012

	
1013 1013
    /// Constructor.
1014 1014
    BfsWizard() : TR() {}
1015 1015

	
1016 1016
    /// Constructor that requires parameters.
1017 1017

	
1018 1018
    /// Constructor that requires parameters.
1019 1019
    /// These parameters will be the default values for the traits class.
1020 1020
    BfsWizard(const Digraph &g, Node s=INVALID) :
1021 1021
      TR(g,s) {}
1022 1022

	
1023 1023
    ///Copy constructor
1024 1024
    BfsWizard(const TR &b) : TR(b) {}
1025 1025

	
1026 1026
    ~BfsWizard() {}
1027 1027

	
1028 1028
    ///Runs BFS algorithm from a source node.
1029 1029

	
1030 1030
    ///Runs BFS algorithm from a source node.
1031 1031
    ///The node can be given with the \ref source() function.
1032 1032
    void run()
1033 1033
    {
1034 1034
      if(Base::_source==INVALID) throw UninitializedParameter();
1035 1035
      Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
1036 1036
      if(Base::_reached)
1037 1037
        alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
1038 1038
      if(Base::_processed)
1039 1039
        alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
1040 1040
      if(Base::_pred)
1041 1041
        alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
1042 1042
      if(Base::_dist)
1043 1043
        alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
1044 1044
      alg.run(Base::_source);
1045 1045
    }
1046 1046

	
1047 1047
    ///Runs BFS algorithm from the given node.
1048 1048

	
1049 1049
    ///Runs BFS algorithm from the given node.
1050 1050
    ///\param s is the given source.
1051 1051
    void run(Node s)
1052 1052
    {
1053 1053
      Base::_source=s;
1054 1054
      run();
1055 1055
    }
1056 1056

	
1057 1057
    /// Sets the source node, from which the Bfs algorithm runs.
1058 1058

	
1059 1059
    /// Sets the source node, from which the Bfs algorithm runs.
1060 1060
    /// \param s is the source node.
1061 1061
    BfsWizard<TR> &source(Node s)
1062 1062
    {
1063 1063
      Base::_source=s;
1064 1064
      return *this;
1065 1065
    }
1066 1066

	
1067 1067
    template<class T>
1068 1068
    struct DefPredMapBase : public Base {
1069 1069
      typedef T PredMap;
1070 1070
      static PredMap *createPredMap(const Digraph &) { return 0; };
1071 1071
      DefPredMapBase(const TR &b) : TR(b) {}
1072 1072
    };
1073 1073
    ///\brief \ref named-templ-param "Named parameter"
1074 1074
    ///for setting \ref PredMap object.
1075 1075
    ///
1076 1076
    /// \ref named-templ-param "Named parameter"
1077 1077
    ///for setting \ref PredMap object.
1078 1078
    template<class T>
1079 1079
    BfsWizard<DefPredMapBase<T> > predMap(const T &t)
1080 1080
    {
1081 1081
      Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
1082 1082
      return BfsWizard<DefPredMapBase<T> >(*this);
1083 1083
    }
1084 1084

	
1085 1085
    template<class T>
1086 1086
    struct DefReachedMapBase : public Base {
1087 1087
      typedef T ReachedMap;
1088 1088
      static ReachedMap *createReachedMap(const Digraph &) { return 0; };
1089 1089
      DefReachedMapBase(const TR &b) : TR(b) {}
1090 1090
    };
1091 1091
    ///\brief \ref named-templ-param "Named parameter"
1092 1092
    ///for setting \ref ReachedMap object.
1093 1093
    ///
1094 1094
    /// \ref named-templ-param "Named parameter"
1095 1095
    ///for setting \ref ReachedMap object.
1096 1096
    template<class T>
1097 1097
    BfsWizard<DefReachedMapBase<T> > reachedMap(const T &t)
1098 1098
    {
1099 1099
      Base::_reached=reinterpret_cast<void*>(const_cast<T*>(&t));
1100 1100
      return BfsWizard<DefReachedMapBase<T> >(*this);
1101 1101
    }
1102 1102

	
1103 1103
    template<class T>
1104 1104
    struct DefProcessedMapBase : public Base {
1105 1105
      typedef T ProcessedMap;
1106 1106
      static ProcessedMap *createProcessedMap(const Digraph &) { return 0; };
1107 1107
      DefProcessedMapBase(const TR &b) : TR(b) {}
1108 1108
    };
1109 1109
    ///\brief \ref named-templ-param "Named parameter"
1110 1110
    ///for setting \ref ProcessedMap object.
1111 1111
    ///
1112 1112
    /// \ref named-templ-param "Named parameter"
1113 1113
    ///for setting \ref ProcessedMap object.
1114 1114
    template<class T>
1115 1115
    BfsWizard<DefProcessedMapBase<T> > processedMap(const T &t)
1116 1116
    {
1117 1117
      Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t));
1118 1118
      return BfsWizard<DefProcessedMapBase<T> >(*this);
1119 1119
    }
1120 1120

	
1121 1121
    template<class T>
1122 1122
    struct DefDistMapBase : public Base {
1123 1123
      typedef T DistMap;
1124 1124
      static DistMap *createDistMap(const Digraph &) { return 0; };
1125 1125
      DefDistMapBase(const TR &b) : TR(b) {}
1126 1126
    };
1127 1127
    ///\brief \ref named-templ-param "Named parameter"
1128 1128
    ///for setting \ref DistMap object.
1129 1129
    ///
1130 1130
    /// \ref named-templ-param "Named parameter"
1131 1131
    ///for setting \ref DistMap object.
1132 1132
    template<class T>
1133 1133
    BfsWizard<DefDistMapBase<T> > distMap(const T &t)
1134 1134
    {
1135 1135
      Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
1136 1136
      return BfsWizard<DefDistMapBase<T> >(*this);
1137 1137
    }
1138 1138

	
1139 1139
  };
1140 1140

	
1141 1141
  ///Function type interface for Bfs algorithm.
1142 1142

	
1143 1143
  /// \ingroup search
1144 1144
  ///Function type interface for Bfs algorithm.
1145 1145
  ///
1146 1146
  ///This function also has several
1147 1147
  ///\ref named-templ-func-param "named parameters",
1148 1148
  ///they are declared as the members of class \ref BfsWizard.
1149 1149
  ///The following
1150 1150
  ///example shows how to use these parameters.
1151 1151
  ///\code
1152 1152
  ///  bfs(g,source).predMap(preds).run();
1153 1153
  ///\endcode
1154 1154
  ///\warning Don't forget to put the \ref BfsWizard::run() "run()"
1155 1155
  ///to the end of the parameter list.
1156 1156
  ///\sa BfsWizard
1157 1157
  ///\sa Bfs
1158 1158
  template<class GR>
1159 1159
  BfsWizard<BfsWizardBase<GR> >
1160 1160
  bfs(const GR &g,typename GR::Node s=INVALID)
1161 1161
  {
1162 1162
    return BfsWizard<BfsWizardBase<GR> >(g,s);
1163 1163
  }
1164 1164

	
1165 1165
#ifdef DOXYGEN
1166 1166
  /// \brief Visitor class for BFS.
1167 1167
  ///
1168 1168
  /// This class defines the interface of the BfsVisit events, and
1169 1169
  /// it could be the base of a real visitor class.
1170 1170
  template <typename _Digraph>
1171 1171
  struct BfsVisitor {
1172 1172
    typedef _Digraph Digraph;
1173 1173
    typedef typename Digraph::Arc Arc;
1174 1174
    typedef typename Digraph::Node Node;
1175 1175
    /// \brief Called for the source node(s) of the BFS.
1176 1176
    ///
1177 1177
    /// This function is called for the source node(s) of the BFS.
1178 1178
    void start(const Node& node) {}
1179 1179
    /// \brief Called when a node is reached first time.
1180 1180
    ///
1181 1181
    /// This function is called when a node is reached first time.
1182 1182
    void reach(const Node& node) {}
1183 1183
    /// \brief Called when a node is processed.
1184 1184
    ///
1185 1185
    /// This function is called when a node is processed.
1186 1186
    void process(const Node& node) {}
1187 1187
    /// \brief Called when an arc reaches a new node.
1188 1188
    ///
1189 1189
    /// This function is called when the BFS finds an arc whose target node
1190 1190
    /// is not reached yet.
1191 1191
    void discover(const Arc& arc) {}
1192 1192
    /// \brief Called when an arc is examined but its target node is
1193 1193
    /// already discovered.
1194 1194
    ///
1195 1195
    /// This function is called when an arc is examined but its target node is
1196 1196
    /// already discovered.
1197 1197
    void examine(const Arc& arc) {}
1198 1198
  };
1199 1199
#else
1200 1200
  template <typename _Digraph>
1201 1201
  struct BfsVisitor {
1202 1202
    typedef _Digraph Digraph;
1203 1203
    typedef typename Digraph::Arc Arc;
1204 1204
    typedef typename Digraph::Node Node;
1205 1205
    void start(const Node&) {}
1206 1206
    void reach(const Node&) {}
1207 1207
    void process(const Node&) {}
1208 1208
    void discover(const Arc&) {}
1209 1209
    void examine(const Arc&) {}
1210 1210

	
1211 1211
    template <typename _Visitor>
1212 1212
    struct Constraints {
1213 1213
      void constraints() {
1214 1214
        Arc arc;
1215 1215
        Node node;
1216 1216
        visitor.start(node);
1217 1217
        visitor.reach(node);
1218 1218
        visitor.process(node);
1219 1219
        visitor.discover(arc);
1220 1220
        visitor.examine(arc);
1221 1221
      }
1222 1222
      _Visitor& visitor;
1223 1223
    };
1224 1224
  };
1225 1225
#endif
1226 1226

	
1227 1227
  /// \brief Default traits class of BfsVisit class.
1228 1228
  ///
1229 1229
  /// Default traits class of BfsVisit class.
1230 1230
  /// \tparam _Digraph The type of the digraph the algorithm runs on.
1231 1231
  template<class _Digraph>
1232 1232
  struct BfsVisitDefaultTraits {
1233 1233

	
1234 1234
    /// \brief The type of the digraph the algorithm runs on.
1235 1235
    typedef _Digraph Digraph;
1236 1236

	
1237 1237
    /// \brief The type of the map that indicates which nodes are reached.
1238 1238
    ///
1239 1239
    /// The type of the map that indicates which nodes are reached.
1240 1240
    /// It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
1241 1241
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
1242 1242

	
1243 1243
    /// \brief Instantiates a \ref ReachedMap.
1244 1244
    ///
1245 1245
    /// This function instantiates a \ref ReachedMap.
1246 1246
    /// \param digraph is the digraph, to which
1247 1247
    /// we would like to define the \ref ReachedMap.
1248 1248
    static ReachedMap *createReachedMap(const Digraph &digraph) {
1249 1249
      return new ReachedMap(digraph);
1250 1250
    }
1251 1251

	
1252 1252
  };
1253 1253

	
1254 1254
  /// \ingroup search
1255 1255
  ///
1256 1256
  /// \brief %BFS algorithm class with visitor interface.
1257 1257
  ///
1258 1258
  /// This class provides an efficient implementation of the %BFS algorithm
1259 1259
  /// with visitor interface.
1260 1260
  ///
1261 1261
  /// The %BfsVisit class provides an alternative interface to the Bfs
1262 1262
  /// class. It works with callback mechanism, the BfsVisit object calls
1263 1263
  /// the member functions of the \c Visitor class on every BFS event.
1264 1264
  ///
1265
  /// This interface of the BFS algorithm should be used in special cases
1266
  /// when extra actions have to be performed in connection with certain
1267
  /// events of the BFS algorithm. Otherwise consider to use Bfs or bfs()
1268
  /// instead.
1269
  ///
1265 1270
  /// \tparam _Digraph The type of the digraph the algorithm runs on.
1266 1271
  /// The default value is
1267 1272
  /// \ref ListDigraph. The value of _Digraph is not used directly by
1268 1273
  /// \ref BfsVisit, it is only passed to \ref BfsVisitDefaultTraits.
1269 1274
  /// \tparam _Visitor The Visitor type that is used by the algorithm.
1270 1275
  /// \ref BfsVisitor "BfsVisitor<_Digraph>" is an empty visitor, which
1271 1276
  /// does not observe the BFS events. If you want to observe the BFS
1272 1277
  /// events, you should implement your own visitor class.
1273 1278
  /// \tparam _Traits Traits class to set various data types used by the
1274 1279
  /// algorithm. The default traits class is
1275 1280
  /// \ref BfsVisitDefaultTraits "BfsVisitDefaultTraits<_Digraph>".
1276 1281
  /// See \ref BfsVisitDefaultTraits for the documentation of
1277 1282
  /// a BFS visit traits class.
1278 1283
#ifdef DOXYGEN
1279 1284
  template <typename _Digraph, typename _Visitor, typename _Traits>
1280 1285
#else
1281 1286
  template <typename _Digraph = ListDigraph,
1282 1287
            typename _Visitor = BfsVisitor<_Digraph>,
1283 1288
            typename _Traits = BfsDefaultTraits<_Digraph> >
1284 1289
#endif
1285 1290
  class BfsVisit {
1286 1291
  public:
1287 1292

	
1288 1293
    /// \brief \ref Exception for uninitialized parameters.
1289 1294
    ///
1290 1295
    /// This error represents problems in the initialization
1291 1296
    /// of the parameters of the algorithm.
1292 1297
    class UninitializedParameter : public lemon::UninitializedParameter {
1293 1298
    public:
1294 1299
      virtual const char* what() const throw()
1295 1300
      {
1296 1301
        return "lemon::BfsVisit::UninitializedParameter";
1297 1302
      }
1298 1303
    };
1299 1304

	
1300 1305
    ///The traits class.
1301 1306
    typedef _Traits Traits;
1302 1307

	
1303 1308
    ///The type of the digraph the algorithm runs on.
1304 1309
    typedef typename Traits::Digraph Digraph;
1305 1310

	
1306 1311
    ///The visitor type used by the algorithm.
1307 1312
    typedef _Visitor Visitor;
1308 1313

	
1309 1314
    ///The type of the map that indicates which nodes are reached.
1310 1315
    typedef typename Traits::ReachedMap ReachedMap;
1311 1316

	
1312 1317
  private:
1313 1318

	
1314 1319
    typedef typename Digraph::Node Node;
1315 1320
    typedef typename Digraph::NodeIt NodeIt;
1316 1321
    typedef typename Digraph::Arc Arc;
1317 1322
    typedef typename Digraph::OutArcIt OutArcIt;
1318 1323

	
1319 1324
    //Pointer to the underlying digraph.
1320 1325
    const Digraph *_digraph;
1321 1326
    //Pointer to the visitor object.
1322 1327
    Visitor *_visitor;
1323 1328
    //Pointer to the map of reached status of the nodes.
1324 1329
    ReachedMap *_reached;
1325 1330
    //Indicates if _reached is locally allocated (true) or not.
1326 1331
    bool local_reached;
1327 1332

	
1328 1333
    std::vector<typename Digraph::Node> _list;
1329 1334
    int _list_front, _list_back;
1330 1335

	
1331 1336
    ///Creates the maps if necessary.
1332 1337
    ///\todo Better memory allocation (instead of new).
1333 1338
    void create_maps() {
1334 1339
      if(!_reached) {
1335 1340
        local_reached = true;
1336 1341
        _reached = Traits::createReachedMap(*_digraph);
1337 1342
      }
1338 1343
    }
1339 1344

	
1340 1345
  protected:
1341 1346

	
1342 1347
    BfsVisit() {}
1343 1348

	
1344 1349
  public:
1345 1350

	
1346 1351
    typedef BfsVisit Create;
1347 1352

	
1348 1353
    /// \name Named template parameters
1349 1354

	
1350 1355
    ///@{
1351 1356
    template <class T>
1352 1357
    struct DefReachedMapTraits : public Traits {
1353 1358
      typedef T ReachedMap;
1354 1359
      static ReachedMap *createReachedMap(const Digraph &digraph) {
1355 1360
        throw UninitializedParameter();
1356 1361
      }
1357 1362
    };
1358 1363
    /// \brief \ref named-templ-param "Named parameter" for setting
1359 1364
    /// ReachedMap type.
1360 1365
    ///
1361 1366
    /// \ref named-templ-param "Named parameter" for setting ReachedMap type.
1362 1367
    template <class T>
1363 1368
    struct DefReachedMap : public BfsVisit< Digraph, Visitor,
1364 1369
                                            DefReachedMapTraits<T> > {
1365 1370
      typedef BfsVisit< Digraph, Visitor, DefReachedMapTraits<T> > Create;
1366 1371
    };
1367 1372
    ///@}
1368 1373

	
1369 1374
  public:
1370 1375

	
1371 1376
    /// \brief Constructor.
1372 1377
    ///
1373 1378
    /// Constructor.
1374 1379
    ///
1375 1380
    /// \param digraph The digraph the algorithm runs on.
1376 1381
    /// \param visitor The visitor object of the algorithm.
1377 1382
    BfsVisit(const Digraph& digraph, Visitor& visitor)
1378 1383
      : _digraph(&digraph), _visitor(&visitor),
1379 1384
        _reached(0), local_reached(false) {}
1380 1385

	
1381 1386
    /// \brief Destructor.
1382 1387
    ~BfsVisit() {
1383 1388
      if(local_reached) delete _reached;
1384 1389
    }
1385 1390

	
1386 1391
    /// \brief Sets the map that indicates which nodes are reached.
1387 1392
    ///
1388 1393
    /// Sets the map that indicates which nodes are reached.
1389 1394
    /// If you don't use this function before calling \ref run(),
1390 1395
    /// it will allocate one. The destructor deallocates this
1391 1396
    /// automatically allocated map, of course.
1392 1397
    /// \return <tt> (*this) </tt>
1393 1398
    BfsVisit &reachedMap(ReachedMap &m) {
1394 1399
      if(local_reached) {
1395 1400
        delete _reached;
1396 1401
        local_reached = false;
1397 1402
      }
1398 1403
      _reached = &m;
1399 1404
      return *this;
1400 1405
    }
1401 1406

	
1402 1407
  public:
1403 1408

	
1404 1409
    /// \name Execution control
1405 1410
    /// The simplest way to execute the algorithm is to use
1406 1411
    /// one of the member functions called \ref lemon::BfsVisit::run()
1407 1412
    /// "run()".
1408 1413
    /// \n
1409 1414
    /// If you need more control on the execution, first you must call
1410 1415
    /// \ref lemon::BfsVisit::init() "init()", then you can add several
1411 1416
    /// source nodes with \ref lemon::BfsVisit::addSource() "addSource()".
1412 1417
    /// Finally \ref lemon::BfsVisit::start() "start()" will perform the
1413 1418
    /// actual path computation.
1414 1419

	
1415 1420
    /// @{
1416 1421

	
1417 1422
    /// \brief Initializes the internal data structures.
1418 1423
    ///
1419 1424
    /// Initializes the internal data structures.
1420 1425
    void init() {
1421 1426
      create_maps();
1422 1427
      _list.resize(countNodes(*_digraph));
1423 1428
      _list_front = _list_back = -1;
1424 1429
      for (NodeIt u(*_digraph) ; u != INVALID ; ++u) {
1425 1430
        _reached->set(u, false);
1426 1431
      }
1427 1432
    }
1428 1433

	
1429 1434
    /// \brief Adds a new source node.
1430 1435
    ///
1431 1436
    /// Adds a new source node to the set of nodes to be processed.
1432 1437
    void addSource(Node s) {
1433 1438
      if(!(*_reached)[s]) {
1434 1439
          _reached->set(s,true);
1435 1440
          _visitor->start(s);
1436 1441
          _visitor->reach(s);
1437 1442
          _list[++_list_back] = s;
1438 1443
        }
1439 1444
    }
1440 1445

	
1441 1446
    /// \brief Processes the next node.
1442 1447
    ///
1443 1448
    /// Processes the next node.
1444 1449
    ///
1445 1450
    /// \return The processed node.
1446 1451
    ///
1447 1452
    /// \pre The queue must not be empty.
1448 1453
    Node processNextNode() {
1449 1454
      Node n = _list[++_list_front];
1450 1455
      _visitor->process(n);
1451 1456
      Arc e;
1452 1457
      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
1453 1458
        Node m = _digraph->target(e);
1454 1459
        if (!(*_reached)[m]) {
1455 1460
          _visitor->discover(e);
1456 1461
          _visitor->reach(m);
1457 1462
          _reached->set(m, true);
1458 1463
          _list[++_list_back] = m;
1459 1464
        } else {
1460 1465
          _visitor->examine(e);
1461 1466
        }
1462 1467
      }
1463 1468
      return n;
1464 1469
    }
1465 1470

	
1466 1471
    /// \brief Processes the next node.
1467 1472
    ///
1468 1473
    /// Processes the next node and checks if the given target node
1469 1474
    /// is reached. If the target node is reachable from the processed
1470 1475
    /// node, then the \c reach parameter will be set to \c true.
1471 1476
    ///
1472 1477
    /// \param target The target node.
1473 1478
    /// \retval reach Indicates if the target node is reached.
1474 1479
    /// It should be initially \c false.
1475 1480
    ///
1476 1481
    /// \return The processed node.
1477 1482
    ///
1478 1483
    /// \pre The queue must not be empty.
1479 1484
    Node processNextNode(Node target, bool& reach) {
1480 1485
      Node n = _list[++_list_front];
1481 1486
      _visitor->process(n);
1482 1487
      Arc e;
1483 1488
      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
1484 1489
        Node m = _digraph->target(e);
1485 1490
        if (!(*_reached)[m]) {
1486 1491
          _visitor->discover(e);
1487 1492
          _visitor->reach(m);
1488 1493
          _reached->set(m, true);
1489 1494
          _list[++_list_back] = m;
1490 1495
          reach = reach || (target == m);
1491 1496
        } else {
1492 1497
          _visitor->examine(e);
1493 1498
        }
1494 1499
      }
1495 1500
      return n;
1496 1501
    }
1497 1502

	
1498 1503
    /// \brief Processes the next node.
1499 1504
    ///
1500 1505
    /// Processes the next node and checks if at least one of reached
1501 1506
    /// nodes has \c true value in the \c nm node map. If one node
1502 1507
    /// with \c true value is reachable from the processed node, then the
1503 1508
    /// \c rnode parameter will be set to the first of such nodes.
1504 1509
    ///
1505 1510
    /// \param nm A \c bool (or convertible) node map that indicates the
1506 1511
    /// possible targets.
1507 1512
    /// \retval rnode The reached target node.
1508 1513
    /// It should be initially \c INVALID.
1509 1514
    ///
1510 1515
    /// \return The processed node.
1511 1516
    ///
1512 1517
    /// \pre The queue must not be empty.
1513 1518
    template <typename NM>
1514 1519
    Node processNextNode(const NM& nm, Node& rnode) {
1515 1520
      Node n = _list[++_list_front];
1516 1521
      _visitor->process(n);
1517 1522
      Arc e;
1518 1523
      for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) {
1519 1524
        Node m = _digraph->target(e);
1520 1525
        if (!(*_reached)[m]) {
1521 1526
          _visitor->discover(e);
1522 1527
          _visitor->reach(m);
1523 1528
          _reached->set(m, true);
1524 1529
          _list[++_list_back] = m;
1525 1530
          if (nm[m] && rnode == INVALID) rnode = m;
1526 1531
        } else {
1527 1532
          _visitor->examine(e);
1528 1533
        }
1529 1534
      }
1530 1535
      return n;
1531 1536
    }
1532 1537

	
1533 1538
    /// \brief The next node to be processed.
1534 1539
    ///
1535 1540
    /// Returns the next node to be processed or \c INVALID if the queue
1536 1541
    /// is empty.
1537 1542
    Node nextNode() const {
1538 1543
      return _list_front != _list_back ? _list[_list_front + 1] : INVALID;
1539 1544
    }
1540 1545

	
1541 1546
    /// \brief Returns \c false if there are nodes
1542 1547
    /// to be processed.
1543 1548
    ///
1544 1549
    /// Returns \c false if there are nodes
1545 1550
    /// to be processed in the queue.
1546 1551
    bool emptyQueue() const { return _list_front == _list_back; }
1547 1552

	
1548 1553
    /// \brief Returns the number of the nodes to be processed.
1549 1554
    ///
1550 1555
    /// Returns the number of the nodes to be processed in the queue.
1551 1556
    int queueSize() const { return _list_back - _list_front; }
1552 1557

	
1553 1558
    /// \brief Executes the algorithm.
1554 1559
    ///
1555 1560
    /// Executes the algorithm.
1556 1561
    ///
1557 1562
    /// This method runs the %BFS algorithm from the root node(s)
1558 1563
    /// in order to compute the shortest path to each node.
1559 1564
    ///
1560 1565
    /// The algorithm computes
1561 1566
    /// - the shortest path tree (forest),
1562 1567
    /// - the distance of each node from the root(s).
1563 1568
    ///
1564 1569
    /// \pre init() must be called and at least one root node should be added
1565 1570
    /// with addSource() before using this function.
1566 1571
    ///
1567 1572
    /// \note <tt>b.start()</tt> is just a shortcut of the following code.
1568 1573
    /// \code
1569 1574
    ///   while ( !b.emptyQueue() ) {
1570 1575
    ///     b.processNextNode();
1571 1576
    ///   }
1572 1577
    /// \endcode
1573 1578
    void start() {
1574 1579
      while ( !emptyQueue() ) processNextNode();
1575 1580
    }
1576 1581

	
1577 1582
    /// \brief Executes the algorithm until the given target node is reached.
1578 1583
    ///
1579 1584
    /// Executes the algorithm until the given target node is reached.
1580 1585
    ///
1581 1586
    /// This method runs the %BFS algorithm from the root node(s)
1582 1587
    /// in order to compute the shortest path to \c dest.
1583 1588
    ///
1584 1589
    /// The algorithm computes
1585 1590
    /// - the shortest path to \c dest,
1586 1591
    /// - the distance of \c dest from the root(s).
1587 1592
    ///
1588 1593
    /// \pre init() must be called and at least one root node should be
1589 1594
    /// added with addSource() before using this function.
1590 1595
    ///
1591 1596
    /// \note <tt>b.start(t)</tt> is just a shortcut of the following code.
1592 1597
    /// \code
1593 1598
    ///   bool reach = false;
1594 1599
    ///   while ( !b.emptyQueue() && !reach ) {
1595 1600
    ///     b.processNextNode(t, reach);
1596 1601
    ///   }
1597 1602
    /// \endcode
1598 1603
    void start(Node dest) {
1599 1604
      bool reach = false;
1600 1605
      while ( !emptyQueue() && !reach ) processNextNode(dest, reach);
1601 1606
    }
1602 1607

	
1603 1608
    /// \brief Executes the algorithm until a condition is met.
1604 1609
    ///
1605 1610
    /// Executes the algorithm until a condition is met.
1606 1611
    ///
1607 1612
    /// This method runs the %BFS algorithm from the root node(s) in
1608 1613
    /// order to compute the shortest path to a node \c v with
1609 1614
    /// <tt>nm[v]</tt> true, if such a node can be found.
1610 1615
    ///
1611 1616
    /// \param nm must be a bool (or convertible) node map. The
1612 1617
    /// algorithm will stop when it reaches a node \c v with
1613 1618
    /// <tt>nm[v]</tt> true.
1614 1619
    ///
1615 1620
    /// \return The reached node \c v with <tt>nm[v]</tt> true or
1616 1621
    /// \c INVALID if no such node was found.
1617 1622
    ///
1618 1623
    /// \pre init() must be called and at least one root node should be
1619 1624
    /// added with addSource() before using this function.
1620 1625
    ///
1621 1626
    /// \note <tt>b.start(nm)</tt> is just a shortcut of the following code.
1622 1627
    /// \code
1623 1628
    ///   Node rnode = INVALID;
1624 1629
    ///   while ( !b.emptyQueue() && rnode == INVALID ) {
1625 1630
    ///     b.processNextNode(nm, rnode);
1626 1631
    ///   }
1627 1632
    ///   return rnode;
1628 1633
    /// \endcode
1629 1634
    template <typename NM>
1630 1635
    Node start(const NM &nm) {
1631 1636
      Node rnode = INVALID;
1632 1637
      while ( !emptyQueue() && rnode == INVALID ) {
1633 1638
        processNextNode(nm, rnode);
1634 1639
      }
1635 1640
      return rnode;
1636 1641
    }
1637 1642

	
1638 1643
    /// \brief Runs the algorithm from the given node.
1639 1644
    ///
1640 1645
    /// This method runs the %BFS algorithm from node \c s
1641 1646
    /// in order to compute the shortest path to each node.
1642 1647
    ///
1643 1648
    /// The algorithm computes
1644 1649
    /// - the shortest path tree,
1645 1650
    /// - the distance of each node from the root.
1646 1651
    ///
1647 1652
    /// \note <tt>b.run(s)</tt> is just a shortcut of the following code.
1648 1653
    ///\code
1649 1654
    ///   b.init();
1650 1655
    ///   b.addSource(s);
1651 1656
    ///   b.start();
1652 1657
    ///\endcode
1653 1658
    void run(Node s) {
1654 1659
      init();
1655 1660
      addSource(s);
1656 1661
      start();
1657 1662
    }
1658 1663

	
1659 1664
    /// \brief Runs the algorithm to visit all nodes in the digraph.
1660 1665
    ///
1661 1666
    /// This method runs the %BFS algorithm in order to
1662 1667
    /// compute the shortest path to each node.
1663 1668
    ///
1664 1669
    /// The algorithm computes
1665 1670
    /// - the shortest path tree (forest),
1666 1671
    /// - the distance of each node from the root(s).
1667 1672
    ///
1668 1673
    /// \note <tt>b.run(s)</tt> is just a shortcut of the following code.
1669 1674
    ///\code
1670 1675
    ///  b.init();
1671 1676
    ///  for (NodeIt n(gr); n != INVALID; ++n) {
1672 1677
    ///    if (!b.reached(n)) {
1673 1678
    ///      b.addSource(n);
1674 1679
    ///      b.start();
1675 1680
    ///    }
1676 1681
    ///  }
1677 1682
    ///\endcode
1678 1683
    void run() {
1679 1684
      init();
1680 1685
      for (NodeIt it(*_digraph); it != INVALID; ++it) {
1681 1686
        if (!reached(it)) {
1682 1687
          addSource(it);
1683 1688
          start();
1684 1689
        }
1685 1690
      }
1686 1691
    }
1687 1692

	
1688 1693
    ///@}
1689 1694

	
1690 1695
    /// \name Query Functions
1691 1696
    /// The result of the %BFS algorithm can be obtained using these
1692 1697
    /// functions.\n
1693 1698
    /// Either \ref lemon::BfsVisit::run() "run()" or
1694 1699
    /// \ref lemon::BfsVisit::start() "start()" must be called before
1695 1700
    /// using them.
1696 1701
    ///@{
1697 1702

	
1698 1703
    /// \brief Checks if a node is reachable from the root(s).
1699 1704
    ///
1700 1705
    /// Returns \c true if \c v is reachable from the root(s).
1701 1706
    /// \pre Either \ref run() or \ref start()
1702 1707
    /// must be called before using this function.
1703 1708
    bool reached(Node v) { return (*_reached)[v]; }
1704 1709

	
1705 1710
    ///@}
1706 1711

	
1707 1712
  };
1708 1713

	
1709 1714
} //END OF NAMESPACE LEMON
1710 1715

	
1711 1716
#endif
Ignore white space 6 line context
1 1
/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 2
 *
3 3
 * This file is a part of LEMON, a generic C++ optimization library.
4 4
 *
5 5
 * Copyright (C) 2003-2008
6 6
 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 7
 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 8
 *
9 9
 * Permission to use, modify and distribute this software is granted
10 10
 * provided that this copyright notice appears in all copies. For
11 11
 * precise terms see the accompanying LICENSE file.
12 12
 *
13 13
 * This software is provided "AS IS" with no warranty of any kind,
14 14
 * express or implied, and with no claim as to its suitability for any
15 15
 * purpose.
16 16
 *
17 17
 */
18 18

	
19 19
#ifndef LEMON_DFS_H
20 20
#define LEMON_DFS_H
21 21

	
22 22
///\ingroup search
23 23
///\file
24 24
///\brief DFS algorithm.
25 25

	
26 26
#include <lemon/list_graph.h>
27 27
#include <lemon/bits/path_dump.h>
28 28
#include <lemon/core.h>
29 29
#include <lemon/error.h>
30 30
#include <lemon/assert.h>
31 31
#include <lemon/maps.h>
32 32

	
33 33
namespace lemon {
34 34

	
35 35
  ///Default traits class of Dfs class.
36 36

	
37 37
  ///Default traits class of Dfs class.
38 38
  ///\tparam GR Digraph type.
39 39
  template<class GR>
40 40
  struct DfsDefaultTraits
41 41
  {
42 42
    ///The type of the digraph the algorithm runs on.
43 43
    typedef GR Digraph;
44 44

	
45 45
    ///\brief The type of the map that stores the predecessor
46 46
    ///arcs of the %DFS paths.
47 47
    ///
48 48
    ///The type of the map that stores the predecessor
49 49
    ///arcs of the %DFS paths.
50 50
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
51 51
    typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
52 52
    ///Instantiates a \ref PredMap.
53 53

	
54 54
    ///This function instantiates a \ref PredMap.
55 55
    ///\param g is the digraph, to which we would like to define the
56 56
    ///\ref PredMap.
57 57
    ///\todo The digraph alone may be insufficient to initialize
58 58
    static PredMap *createPredMap(const Digraph &g)
59 59
    {
60 60
      return new PredMap(g);
61 61
    }
62 62

	
63 63
    ///The type of the map that indicates which nodes are processed.
64 64

	
65 65
    ///The type of the map that indicates which nodes are processed.
66 66
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
67 67
    ///By default it is a NullMap.
68 68
    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
69 69
    ///Instantiates a \ref ProcessedMap.
70 70

	
71 71
    ///This function instantiates a \ref ProcessedMap.
72 72
    ///\param g is the digraph, to which
73 73
    ///we would like to define the \ref ProcessedMap
74 74
#ifdef DOXYGEN
75 75
    static ProcessedMap *createProcessedMap(const Digraph &g)
76 76
#else
77 77
    static ProcessedMap *createProcessedMap(const Digraph &)
78 78
#endif
79 79
    {
80 80
      return new ProcessedMap();
81 81
    }
82 82

	
83 83
    ///The type of the map that indicates which nodes are reached.
84 84

	
85 85
    ///The type of the map that indicates which nodes are reached.
86 86
    ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
87 87
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
88 88
    ///Instantiates a \ref ReachedMap.
89 89

	
90 90
    ///This function instantiates a \ref ReachedMap.
91 91
    ///\param g is the digraph, to which
92 92
    ///we would like to define the \ref ReachedMap.
93 93
    static ReachedMap *createReachedMap(const Digraph &g)
94 94
    {
95 95
      return new ReachedMap(g);
96 96
    }
97 97

	
98 98
    ///The type of the map that stores the distances of the nodes.
99 99

	
100 100
    ///The type of the map that stores the distances of the nodes.
101 101
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
102 102
    typedef typename Digraph::template NodeMap<int> DistMap;
103 103
    ///Instantiates a \ref DistMap.
104 104

	
105 105
    ///This function instantiates a \ref DistMap.
106 106
    ///\param g is the digraph, to which we would like to define the
107 107
    ///\ref DistMap.
108 108
    static DistMap *createDistMap(const Digraph &g)
109 109
    {
110 110
      return new DistMap(g);
111 111
    }
112 112
  };
113 113

	
114 114
  ///%DFS algorithm class.
115 115

	
116 116
  ///\ingroup search
117 117
  ///This class provides an efficient implementation of the %DFS algorithm.
118 118
  ///
119 119
  ///There is also a \ref dfs() "function type interface" for the DFS
120 120
  ///algorithm, which is convenient in the simplier cases and it can be
121 121
  ///used easier.
122 122
  ///
123 123
  ///\tparam GR The type of the digraph the algorithm runs on.
124 124
  ///The default value is \ref ListDigraph. The value of GR is not used
125 125
  ///directly by \ref Dfs, it is only passed to \ref DfsDefaultTraits.
126 126
  ///\tparam TR Traits class to set various data types used by the algorithm.
127 127
  ///The default traits class is
128 128
  ///\ref DfsDefaultTraits "DfsDefaultTraits<GR>".
129 129
  ///See \ref DfsDefaultTraits for the documentation of
130 130
  ///a Dfs traits class.
131 131
#ifdef DOXYGEN
132 132
  template <typename GR,
133 133
            typename TR>
134 134
#else
135 135
  template <typename GR=ListDigraph,
136 136
            typename TR=DfsDefaultTraits<GR> >
137 137
#endif
138 138
  class Dfs {
139 139
  public:
140 140
    ///\ref Exception for uninitialized parameters.
141 141

	
142 142
    ///This error represents problems in the initialization of the
143 143
    ///parameters of the algorithm.
144 144
    class UninitializedParameter : public lemon::UninitializedParameter {
145 145
    public:
146 146
      virtual const char* what() const throw() {
147 147
        return "lemon::Dfs::UninitializedParameter";
148 148
      }
149 149
    };
150 150

	
151 151
    ///The type of the digraph the algorithm runs on.
152 152
    typedef typename TR::Digraph Digraph;
153 153

	
154 154
    ///\brief The type of the map that stores the predecessor arcs of the
155 155
    ///DFS paths.
156 156
    typedef typename TR::PredMap PredMap;
157 157
    ///The type of the map that stores the distances of the nodes.
158 158
    typedef typename TR::DistMap DistMap;
159 159
    ///The type of the map that indicates which nodes are reached.
160 160
    typedef typename TR::ReachedMap ReachedMap;
161 161
    ///The type of the map that indicates which nodes are processed.
162 162
    typedef typename TR::ProcessedMap ProcessedMap;
163 163
    ///The type of the paths.
164 164
    typedef PredMapPath<Digraph, PredMap> Path;
165 165

	
166 166
    ///The traits class.
167 167
    typedef TR Traits;
168 168

	
169 169
  private:
170 170

	
171 171
    typedef typename Digraph::Node Node;
172 172
    typedef typename Digraph::NodeIt NodeIt;
173 173
    typedef typename Digraph::Arc Arc;
174 174
    typedef typename Digraph::OutArcIt OutArcIt;
175 175

	
176 176
    //Pointer to the underlying digraph.
177 177
    const Digraph *G;
178 178
    //Pointer to the map of predecessor arcs.
179 179
    PredMap *_pred;
180 180
    //Indicates if _pred is locally allocated (true) or not.
181 181
    bool local_pred;
182 182
    //Pointer to the map of distances.
183 183
    DistMap *_dist;
184 184
    //Indicates if _dist is locally allocated (true) or not.
185 185
    bool local_dist;
186 186
    //Pointer to the map of reached status of the nodes.
187 187
    ReachedMap *_reached;
188 188
    //Indicates if _reached is locally allocated (true) or not.
189 189
    bool local_reached;
190 190
    //Pointer to the map of processed status of the nodes.
191 191
    ProcessedMap *_processed;
192 192
    //Indicates if _processed is locally allocated (true) or not.
193 193
    bool local_processed;
194 194

	
195 195
    std::vector<typename Digraph::OutArcIt> _stack;
196 196
    int _stack_head;
197 197

	
198 198
    ///Creates the maps if necessary.
199 199
    ///\todo Better memory allocation (instead of new).
200 200
    void create_maps()
201 201
    {
202 202
      if(!_pred) {
203 203
        local_pred = true;
204 204
        _pred = Traits::createPredMap(*G);
205 205
      }
206 206
      if(!_dist) {
207 207
        local_dist = true;
208 208
        _dist = Traits::createDistMap(*G);
209 209
      }
210 210
      if(!_reached) {
211 211
        local_reached = true;
212 212
        _reached = Traits::createReachedMap(*G);
213 213
      }
214 214
      if(!_processed) {
215 215
        local_processed = true;
216 216
        _processed = Traits::createProcessedMap(*G);
217 217
      }
218 218
    }
219 219

	
220 220
  protected:
221 221

	
222 222
    Dfs() {}
223 223

	
224 224
  public:
225 225

	
226 226
    typedef Dfs Create;
227 227

	
228 228
    ///\name Named template parameters
229 229

	
230 230
    ///@{
231 231

	
232 232
    template <class T>
233 233
    struct DefPredMapTraits : public Traits {
234 234
      typedef T PredMap;
235 235
      static PredMap *createPredMap(const Digraph &)
236 236
      {
237 237
        throw UninitializedParameter();
238 238
      }
239 239
    };
240 240
    ///\brief \ref named-templ-param "Named parameter" for setting
241 241
    ///\ref PredMap type.
242 242
    ///
243 243
    ///\ref named-templ-param "Named parameter" for setting
244 244
    ///\ref PredMap type.
245 245
    template <class T>
246 246
    struct DefPredMap : public Dfs<Digraph, DefPredMapTraits<T> > {
247 247
      typedef Dfs<Digraph, DefPredMapTraits<T> > Create;
248 248
    };
249 249

	
250 250
    template <class T>
251 251
    struct DefDistMapTraits : public Traits {
252 252
      typedef T DistMap;
253 253
      static DistMap *createDistMap(const Digraph &)
254 254
      {
255 255
        throw UninitializedParameter();
256 256
      }
257 257
    };
258 258
    ///\brief \ref named-templ-param "Named parameter" for setting
259 259
    ///\ref DistMap type.
260 260
    ///
261 261
    ///\ref named-templ-param "Named parameter" for setting
262 262
    ///\ref DistMap type.
263 263
    template <class T>
264 264
    struct DefDistMap : public Dfs< Digraph, DefDistMapTraits<T> > {
265 265
      typedef Dfs<Digraph, DefDistMapTraits<T> > Create;
266 266
    };
267 267

	
268 268
    template <class T>
269 269
    struct DefReachedMapTraits : public Traits {
270 270
      typedef T ReachedMap;
271 271
      static ReachedMap *createReachedMap(const Digraph &)
272 272
      {
273 273
        throw UninitializedParameter();
274 274
      }
275 275
    };
276 276
    ///\brief \ref named-templ-param "Named parameter" for setting
277 277
    ///\ref ReachedMap type.
278 278
    ///
279 279
    ///\ref named-templ-param "Named parameter" for setting
280 280
    ///\ref ReachedMap type.
281 281
    template <class T>
282 282
    struct DefReachedMap : public Dfs< Digraph, DefReachedMapTraits<T> > {
283 283
      typedef Dfs< Digraph, DefReachedMapTraits<T> > Create;
284 284
    };
285 285

	
286 286
    template <class T>
287 287
    struct DefProcessedMapTraits : public Traits {
288 288
      typedef T ProcessedMap;
289 289
      static ProcessedMap *createProcessedMap(const Digraph &)
290 290
      {
291 291
        throw UninitializedParameter();
292 292
      }
293 293
    };
294 294
    ///\brief \ref named-templ-param "Named parameter" for setting
295 295
    ///\ref ProcessedMap type.
296 296
    ///
297 297
    ///\ref named-templ-param "Named parameter" for setting
298 298
    ///\ref ProcessedMap type.
299 299
    template <class T>
300 300
    struct DefProcessedMap : public Dfs< Digraph, DefProcessedMapTraits<T> > {
301 301
      typedef Dfs< Digraph, DefProcessedMapTraits<T> > Create;
302 302
    };
303 303

	
304 304
    struct DefDigraphProcessedMapTraits : public Traits {
305 305
      typedef typename Digraph::template NodeMap<bool> ProcessedMap;
306 306
      static ProcessedMap *createProcessedMap(const Digraph &g)
307 307
      {
308 308
        return new ProcessedMap(g);
309 309
      }
310 310
    };
311 311
    ///\brief \ref named-templ-param "Named parameter" for setting
312 312
    ///\ref ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
313 313
    ///
314 314
    ///\ref named-templ-param "Named parameter" for setting
315 315
    ///\ref ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
316 316
    ///If you don't set it explicitly, it will be automatically allocated.
317 317
    template <class T>
318 318
    struct DefProcessedMapToBeDefaultMap :
319 319
      public Dfs< Digraph, DefDigraphProcessedMapTraits> {
320 320
      typedef Dfs< Digraph, DefDigraphProcessedMapTraits> Create;
321 321
    };
322 322

	
323 323
    ///@}
324 324

	
325 325
  public:
326 326

	
327 327
    ///Constructor.
328 328

	
329 329
    ///Constructor.
330 330
    ///\param g The digraph the algorithm runs on.
331 331
    Dfs(const Digraph &g) :
332 332
      G(&g),
333 333
      _pred(NULL), local_pred(false),
334 334
      _dist(NULL), local_dist(false),
335 335
      _reached(NULL), local_reached(false),
336 336
      _processed(NULL), local_processed(false)
337 337
    { }
338 338

	
339 339
    ///Destructor.
340 340
    ~Dfs()
341 341
    {
342 342
      if(local_pred) delete _pred;
343 343
      if(local_dist) delete _dist;
344 344
      if(local_reached) delete _reached;
345 345
      if(local_processed) delete _processed;
346 346
    }
347 347

	
348 348
    ///Sets the map that stores the predecessor arcs.
349 349

	
350 350
    ///Sets the map that stores the predecessor arcs.
351 351
    ///If you don't use this function before calling \ref run(),
352 352
    ///it will allocate one. The destructor deallocates this
353 353
    ///automatically allocated map, of course.
354 354
    ///\return <tt> (*this) </tt>
355 355
    Dfs &predMap(PredMap &m)
356 356
    {
357 357
      if(local_pred) {
358 358
        delete _pred;
359 359
        local_pred=false;
360 360
      }
361 361
      _pred = &m;
362 362
      return *this;
363 363
    }
364 364

	
365 365
    ///Sets the map that indicates which nodes are reached.
366 366

	
367 367
    ///Sets the map that indicates which nodes are reached.
368 368
    ///If you don't use this function before calling \ref run(),
369 369
    ///it will allocate one. The destructor deallocates this
370 370
    ///automatically allocated map, of course.
371 371
    ///\return <tt> (*this) </tt>
372 372
    Dfs &reachedMap(ReachedMap &m)
373 373
    {
374 374
      if(local_reached) {
375 375
        delete _reached;
376 376
        local_reached=false;
377 377
      }
378 378
      _reached = &m;
379 379
      return *this;
380 380
    }
381 381

	
382 382
    ///Sets the map that indicates which nodes are processed.
383 383

	
384 384
    ///Sets the map that indicates which nodes are processed.
385 385
    ///If you don't use this function before calling \ref run(),
386 386
    ///it will allocate one. The destructor deallocates this
387 387
    ///automatically allocated map, of course.
388 388
    ///\return <tt> (*this) </tt>
389 389
    Dfs &processedMap(ProcessedMap &m)
390 390
    {
391 391
      if(local_processed) {
392 392
        delete _processed;
393 393
        local_processed=false;
394 394
      }
395 395
      _processed = &m;
396 396
      return *this;
397 397
    }
398 398

	
399 399
    ///Sets the map that stores the distances of the nodes.
400 400

	
401 401
    ///Sets the map that stores the distances of the nodes calculated by
402 402
    ///the algorithm.
403 403
    ///If you don't use this function before calling \ref run(),
404 404
    ///it will allocate one. The destructor deallocates this
405 405
    ///automatically allocated map, of course.
406 406
    ///\return <tt> (*this) </tt>
407 407
    Dfs &distMap(DistMap &m)
408 408
    {
409 409
      if(local_dist) {
410 410
        delete _dist;
411 411
        local_dist=false;
412 412
      }
413 413
      _dist = &m;
414 414
      return *this;
415 415
    }
416 416

	
417 417
  public:
418 418

	
419 419
    ///\name Execution control
420 420
    ///The simplest way to execute the algorithm is to use
421 421
    ///one of the member functions called \ref lemon::Dfs::run() "run()".
422 422
    ///\n
423 423
    ///If you need more control on the execution, first you must call
424 424
    ///\ref lemon::Dfs::init() "init()", then you can add a source node
425 425
    ///with \ref lemon::Dfs::addSource() "addSource()".
426 426
    ///Finally \ref lemon::Dfs::start() "start()" will perform the
427 427
    ///actual path computation.
428 428

	
429 429
    ///@{
430 430

	
431 431
    ///Initializes the internal data structures.
432 432

	
433 433
    ///Initializes the internal data structures.
434 434
    ///
435 435
    void init()
436 436
    {
437 437
      create_maps();
438 438
      _stack.resize(countNodes(*G));
439 439
      _stack_head=-1;
440 440
      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
441 441
        _pred->set(u,INVALID);
442 442
        _reached->set(u,false);
443 443
        _processed->set(u,false);
444 444
      }
445 445
    }
446 446

	
447 447
    ///Adds a new source node.
448 448

	
449 449
    ///Adds a new source node to the set of nodes to be processed.
450 450
    ///
451 451
    ///\pre The stack must be empty. (Otherwise the algorithm gives
452 452
    ///false results.)
453 453
    ///
454 454
    ///\warning Distances will be wrong (or at least strange) in case of
455 455
    ///multiple sources.
456 456
    void addSource(Node s)
457 457
    {
458 458
      LEMON_DEBUG(emptyQueue(), "The stack is not empty.");
459 459
      if(!(*_reached)[s])
460 460
        {
461 461
          _reached->set(s,true);
462 462
          _pred->set(s,INVALID);
463 463
          OutArcIt e(*G,s);
464 464
          if(e!=INVALID) {
465 465
            _stack[++_stack_head]=e;
466 466
            _dist->set(s,_stack_head);
467 467
          }
468 468
          else {
469 469
            _processed->set(s,true);
470 470
            _dist->set(s,0);
471 471
          }
472 472
        }
473 473
    }
474 474

	
475 475
    ///Processes the next arc.
476 476

	
477 477
    ///Processes the next arc.
478 478
    ///
479 479
    ///\return The processed arc.
480 480
    ///
481 481
    ///\pre The stack must not be empty.
482 482
    Arc processNextArc()
483 483
    {
484 484
      Node m;
485 485
      Arc e=_stack[_stack_head];
486 486
      if(!(*_reached)[m=G->target(e)]) {
487 487
        _pred->set(m,e);
488 488
        _reached->set(m,true);
489 489
        ++_stack_head;
490 490
        _stack[_stack_head] = OutArcIt(*G, m);
491 491
        _dist->set(m,_stack_head);
492 492
      }
493 493
      else {
494 494
        m=G->source(e);
495 495
        ++_stack[_stack_head];
496 496
      }
497 497
      while(_stack_head>=0 && _stack[_stack_head]==INVALID) {
498 498
        _processed->set(m,true);
499 499
        --_stack_head;
500 500
        if(_stack_head>=0) {
501 501
          m=G->source(_stack[_stack_head]);
502 502
          ++_stack[_stack_head];
503 503
        }
504 504
      }
505 505
      return e;
506 506
    }
507 507

	
508 508
    ///Next arc to be processed.
509 509

	
510 510
    ///Next arc to be processed.
511 511
    ///
512 512
    ///\return The next arc to be processed or \c INVALID if the stack
513 513
    ///is empty.
514 514
    OutArcIt nextArc() const
515 515
    {
516 516
      return _stack_head>=0?_stack[_stack_head]:INVALID;
517 517
    }
518 518

	
519 519
    ///\brief Returns \c false if there are nodes
520 520
    ///to be processed.
521 521
    ///
522 522
    ///Returns \c false if there are nodes
523 523
    ///to be processed in the queue (stack).
524 524
    bool emptyQueue() const { return _stack_head<0; }
525 525

	
526 526
    ///Returns the number of the nodes to be processed.
527 527

	
528 528
    ///Returns the number of the nodes to be processed in the queue (stack).
529 529
    int queueSize() const { return _stack_head+1; }
530 530

	
531 531
    ///Executes the algorithm.
532 532

	
533 533
    ///Executes the algorithm.
534 534
    ///
535 535
    ///This method runs the %DFS algorithm from the root node
536 536
    ///in order to compute the DFS path to each node.
537 537
    ///
538 538
    /// The algorithm computes
539 539
    ///- the %DFS tree,
540 540
    ///- the distance of each node from the root in the %DFS tree.
541 541
    ///
542 542
    ///\pre init() must be called and a root node should be
543 543
    ///added with addSource() before using this function.
544 544
    ///
545 545
    ///\note <tt>d.start()</tt> is just a shortcut of the following code.
546 546
    ///\code
547 547
    ///  while ( !d.emptyQueue() ) {
548 548
    ///    d.processNextArc();
549 549
    ///  }
550 550
    ///\endcode
551 551
    void start()
552 552
    {
553 553
      while ( !emptyQueue() ) processNextArc();
554 554
    }
555 555

	
556 556
    ///Executes the algorithm until the given target node is reached.
557 557

	
558 558
    ///Executes the algorithm until the given target node is reached.
559 559
    ///
560 560
    ///This method runs the %DFS algorithm from the root node
561 561
    ///in order to compute the DFS path to \c dest.
562 562
    ///
563 563
    ///The algorithm computes
564 564
    ///- the %DFS path to \c dest,
565 565
    ///- the distance of \c dest from the root in the %DFS tree.
566 566
    ///
567 567
    ///\pre init() must be called and a root node should be
568 568
    ///added with addSource() before using this function.
569 569
    void start(Node dest)
570 570
    {
571 571
      while ( !emptyQueue() && G->target(_stack[_stack_head])!=dest )
572 572
        processNextArc();
573 573
    }
574 574

	
575 575
    ///Executes the algorithm until a condition is met.
576 576

	
577 577
    ///Executes the algorithm until a condition is met.
578 578
    ///
579 579
    ///This method runs the %DFS algorithm from the root node
580 580
    ///until an arc \c a with <tt>am[a]</tt> true is found.
581 581
    ///
582 582
    ///\param am A \c bool (or convertible) arc map. The algorithm
583 583
    ///will stop when it reaches an arc \c a with <tt>am[a]</tt> true.
584 584
    ///
585 585
    ///\return The reached arc \c a with <tt>am[a]</tt> true or
586 586
    ///\c INVALID if no such arc was found.
587 587
    ///
588 588
    ///\pre init() must be called and a root node should be
589 589
    ///added with addSource() before using this function.
590 590
    ///
591 591
    ///\warning Contrary to \ref Bfs and \ref Dijkstra, \c am is an arc map,
592 592
    ///not a node map.
593 593
    template<class ArcBoolMap>
594 594
    Arc start(const ArcBoolMap &am)
595 595
    {
596 596
      while ( !emptyQueue() && !am[_stack[_stack_head]] )
597 597
        processNextArc();
598 598
      return emptyQueue() ? INVALID : _stack[_stack_head];
599 599
    }
600 600

	
601 601
    ///Runs the algorithm from the given node.
602 602

	
603 603
    ///This method runs the %DFS algorithm from node \c s
604 604
    ///in order to compute the DFS path to each node.
605 605
    ///
606 606
    ///The algorithm computes
607 607
    ///- the %DFS tree,
608 608
    ///- the distance of each node from the root in the %DFS tree.
609 609
    ///
610 610
    ///\note <tt>d.run(s)</tt> is just a shortcut of the following code.
611 611
    ///\code
612 612
    ///  d.init();
613 613
    ///  d.addSource(s);
614 614
    ///  d.start();
615 615
    ///\endcode
616 616
    void run(Node s) {
617 617
      init();
618 618
      addSource(s);
619 619
      start();
620 620
    }
621 621

	
622 622
    ///Finds the %DFS path between \c s and \c t.
623 623

	
624 624
    ///This method runs the %DFS algorithm from node \c s
625 625
    ///in order to compute the DFS path to \c t.
626 626
    ///
627 627
    ///\return The length of the <tt>s</tt>--<tt>t</tt> DFS path,
628 628
    ///if \c t is reachable form \c s, \c 0 otherwise.
629 629
    ///
630 630
    ///\note Apart from the return value, <tt>d.run(s,t)</tt> is
631 631
    ///just a shortcut of the following code.
632 632
    ///\code
633 633
    ///  d.init();
634 634
    ///  d.addSource(s);
635 635
    ///  d.start(t);
636 636
    ///\endcode
637 637
    int run(Node s,Node t) {
638 638
      init();
639 639
      addSource(s);
640 640
      start(t);
641 641
      return reached(t)?_stack_head+1:0;
642 642
    }
643 643

	
644 644
    ///Runs the algorithm to visit all nodes in the digraph.
645 645

	
646 646
    ///This method runs the %DFS algorithm in order to compute the
647 647
    ///%DFS path to each node.
648 648
    ///
649 649
    ///The algorithm computes
650 650
    ///- the %DFS tree,
651 651
    ///- the distance of each node from the root in the %DFS tree.
652 652
    ///
653 653
    ///\note <tt>d.run()</tt> is just a shortcut of the following code.
654 654
    ///\code
655 655
    ///  d.init();
656 656
    ///  for (NodeIt n(digraph); n != INVALID; ++n) {
657 657
    ///    if (!d.reached(n)) {
658 658
    ///      d.addSource(n);
659 659
    ///      d.start();
660 660
    ///    }
661 661
    ///  }
662 662
    ///\endcode
663 663
    void run() {
664 664
      init();
665 665
      for (NodeIt it(*G); it != INVALID; ++it) {
666 666
        if (!reached(it)) {
667 667
          addSource(it);
668 668
          start();
669 669
        }
670 670
      }
671 671
    }
672 672

	
673 673
    ///@}
674 674

	
675 675
    ///\name Query Functions
676 676
    ///The result of the %DFS algorithm can be obtained using these
677 677
    ///functions.\n
678 678
    ///Either \ref lemon::Dfs::run() "run()" or \ref lemon::Dfs::start()
679 679
    ///"start()" must be called before using them.
680 680

	
681 681
    ///@{
682 682

	
683 683
    ///The DFS path to a node.
684 684

	
685 685
    ///Returns the DFS path to a node.
686 686
    ///
687 687
    ///\warning \c t should be reachable from the root.
688 688
    ///
689 689
    ///\pre Either \ref run() or \ref start() must be called before
690 690
    ///using this function.
691 691
    Path path(Node t) const { return Path(*G, *_pred, t); }
692 692

	
693 693
    ///The distance of a node from the root.
694 694

	
695 695
    ///Returns the distance of a node from the root.
696 696
    ///
697 697
    ///\warning If node \c v is not reachable from the root, then
698 698
    ///the return value of this function is undefined.
699 699
    ///
700 700
    ///\pre Either \ref run() or \ref start() must be called before
701 701
    ///using this function.
702 702
    int dist(Node v) const { return (*_dist)[v]; }
703 703

	
704 704
    ///Returns the 'previous arc' of the %DFS tree for a node.
705 705

	
706 706
    ///This function returns the 'previous arc' of the %DFS tree for the
707 707
    ///node \c v, i.e. it returns the last arc of a %DFS path from the
708 708
    ///root to \c v. It is \c INVALID
709 709
    ///if \c v is not reachable from the root(s) or if \c v is a root.
710 710
    ///
711 711
    ///The %DFS tree used here is equal to the %DFS tree used in
712 712
    ///\ref predNode().
713 713
    ///
714 714
    ///\pre Either \ref run() or \ref start() must be called before using
715 715
    ///this function.
716 716
    Arc predArc(Node v) const { return (*_pred)[v];}
717 717

	
718 718
    ///Returns the 'previous node' of the %DFS tree.
719 719

	
720 720
    ///This function returns the 'previous node' of the %DFS
721 721
    ///tree for the node \c v, i.e. it returns the last but one node
722 722
    ///from a %DFS path from the root to \c v. It is \c INVALID
723 723
    ///if \c v is not reachable from the root(s) or if \c v is a root.
724 724
    ///
725 725
    ///The %DFS tree used here is equal to the %DFS tree used in
726 726
    ///\ref predArc().
727 727
    ///
728 728
    ///\pre Either \ref run() or \ref start() must be called before
729 729
    ///using this function.
730 730
    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
731 731
                                  G->source((*_pred)[v]); }
732 732

	
733 733
    ///\brief Returns a const reference to the node map that stores the
734 734
    ///distances of the nodes.
735 735
    ///
736 736
    ///Returns a const reference to the node map that stores the
737 737
    ///distances of the nodes calculated by the algorithm.
738 738
    ///
739 739
    ///\pre Either \ref run() or \ref init()
740 740
    ///must be called before using this function.
741 741
    const DistMap &distMap() const { return *_dist;}
742 742

	
743 743
    ///\brief Returns a const reference to the node map that stores the
744 744
    ///predecessor arcs.
745 745
    ///
746 746
    ///Returns a const reference to the node map that stores the predecessor
747 747
    ///arcs, which form the DFS tree.
748 748
    ///
749 749
    ///\pre Either \ref run() or \ref init()
750 750
    ///must be called before using this function.
751 751
    const PredMap &predMap() const { return *_pred;}
752 752

	
753 753
    ///Checks if a node is reachable from the root(s).
754 754

	
755 755
    ///Returns \c true if \c v is reachable from the root(s).
756 756
    ///\pre Either \ref run() or \ref start()
757 757
    ///must be called before using this function.
758 758
    bool reached(Node v) const { return (*_reached)[v]; }
759 759

	
760 760
    ///@}
761 761
  };
762 762

	
763 763
  ///Default traits class of dfs() function.
764 764

	
765 765
  ///Default traits class of dfs() function.
766 766
  ///\tparam GR Digraph type.
767 767
  template<class GR>
768 768
  struct DfsWizardDefaultTraits
769 769
  {
770 770
    ///The type of the digraph the algorithm runs on.
771 771
    typedef GR Digraph;
772 772

	
773 773
    ///\brief The type of the map that stores the predecessor
774 774
    ///arcs of the %DFS paths.
775 775
    ///
776 776
    ///The type of the map that stores the predecessor
777 777
    ///arcs of the %DFS paths.
778 778
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
779 779
    ///
780 780
    typedef NullMap<typename Digraph::Node,typename Digraph::Arc> PredMap;
781 781
    ///Instantiates a \ref PredMap.
782 782

	
783 783
    ///This function instantiates a \ref PredMap.
784 784
    ///\param g is the digraph, to which we would like to define the
785 785
    ///\ref PredMap.
786 786
    ///\todo The digraph alone may be insufficient to initialize
787 787
#ifdef DOXYGEN
788 788
    static PredMap *createPredMap(const Digraph &g)
789 789
#else
790 790
    static PredMap *createPredMap(const Digraph &)
791 791
#endif
792 792
    {
793 793
      return new PredMap();
794 794
    }
795 795

	
796 796
    ///The type of the map that indicates which nodes are processed.
797 797

	
798 798
    ///The type of the map that indicates which nodes are processed.
799 799
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
800 800
    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
801 801
    ///Instantiates a \ref ProcessedMap.
802 802

	
803 803
    ///This function instantiates a \ref ProcessedMap.
804 804
    ///\param g is the digraph, to which
805 805
    ///we would like to define the \ref ProcessedMap.
806 806
#ifdef DOXYGEN
807 807
    static ProcessedMap *createProcessedMap(const Digraph &g)
808 808
#else
809 809
    static ProcessedMap *createProcessedMap(const Digraph &)
810 810
#endif
811 811
    {
812 812
      return new ProcessedMap();
813 813
    }
814 814

	
815 815
    ///The type of the map that indicates which nodes are reached.
816 816

	
817 817
    ///The type of the map that indicates which nodes are reached.
818 818
    ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
819 819
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
820 820
    ///Instantiates a \ref ReachedMap.
821 821

	
822 822
    ///This function instantiates a \ref ReachedMap.
823 823
    ///\param g is the digraph, to which
824 824
    ///we would like to define the \ref ReachedMap.
825 825
    static ReachedMap *createReachedMap(const Digraph &g)
826 826
    {
827 827
      return new ReachedMap(g);
828 828
    }
829 829

	
830 830
    ///The type of the map that stores the distances of the nodes.
831 831

	
832 832
    ///The type of the map that stores the distances of the nodes.
833 833
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
834 834
    ///
835 835
    typedef NullMap<typename Digraph::Node,int> DistMap;
836 836
    ///Instantiates a \ref DistMap.
837 837

	
838 838
    ///This function instantiates a \ref DistMap.
839 839
    ///\param g is the digraph, to which we would like to define
840 840
    ///the \ref DistMap
841 841
#ifdef DOXYGEN
842 842
    static DistMap *createDistMap(const Digraph &g)
843 843
#else
844 844
    static DistMap *createDistMap(const Digraph &)
845 845
#endif
846 846
    {
847 847
      return new DistMap();
848 848
    }
849 849
  };
850 850

	
851 851
  /// Default traits class used by \ref DfsWizard
852 852

	
853 853
  /// To make it easier to use Dfs algorithm
854 854
  /// we have created a wizard class.
855 855
  /// This \ref DfsWizard class needs default traits,
856 856
  /// as well as the \ref Dfs class.
857 857
  /// The \ref DfsWizardBase is a class to be the default traits of the
858 858
  /// \ref DfsWizard class.
859 859
  template<class GR>
860 860
  class DfsWizardBase : public DfsWizardDefaultTraits<GR>
861 861
  {
862 862

	
863 863
    typedef DfsWizardDefaultTraits<GR> Base;
864 864
  protected:
865 865
    //The type of the nodes in the digraph.
866 866
    typedef typename Base::Digraph::Node Node;
867 867

	
868 868
    //Pointer to the digraph the algorithm runs on.
869 869
    void *_g;
870 870
    //Pointer to the map of reached nodes.
871 871
    void *_reached;
872 872
    //Pointer to the map of processed nodes.
873 873
    void *_processed;
874 874
    //Pointer to the map of predecessors arcs.
875 875
    void *_pred;
876 876
    //Pointer to the map of distances.
877 877
    void *_dist;
878 878
    //Pointer to the source node.
879 879
    Node _source;
880 880

	
881 881
    public:
882 882
    /// Constructor.
883 883

	
884 884
    /// This constructor does not require parameters, therefore it initiates
885 885
    /// all of the attributes to default values (0, INVALID).
886 886
    DfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0),
887 887
                      _dist(0), _source(INVALID) {}
888 888

	
889 889
    /// Constructor.
890 890

	
891 891
    /// This constructor requires some parameters,
892 892
    /// listed in the parameters list.
893 893
    /// Others are initiated to 0.
894 894
    /// \param g The digraph the algorithm runs on.
895 895
    /// \param s The source node.
896 896
    DfsWizardBase(const GR &g, Node s=INVALID) :
897 897
      _g(reinterpret_cast<void*>(const_cast<GR*>(&g))),
898 898
      _reached(0), _processed(0), _pred(0), _dist(0), _source(s) {}
899 899

	
900 900
  };
901 901

	
902 902
  /// Auxiliary class for the function type interface of DFS algorithm.
903 903

	
904 904
  /// This auxiliary class is created to implement the function type
905 905
  /// interface of \ref Dfs algorithm. It uses the functions and features
906 906
  /// of the plain \ref Dfs, but it is much simpler to use it.
907 907
  /// It should only be used through the \ref dfs() function, which makes
908 908
  /// it easier to use the algorithm.
909 909
  ///
910 910
  /// Simplicity means that the way to change the types defined
911 911
  /// in the traits class is based on functions that returns the new class
912 912
  /// and not on templatable built-in classes.
913 913
  /// When using the plain \ref Dfs
914 914
  /// the new class with the modified type comes from
915 915
  /// the original class by using the ::
916 916
  /// operator. In the case of \ref DfsWizard only
917 917
  /// a function have to be called, and it will
918 918
  /// return the needed class.
919 919
  ///
920 920
  /// It does not have own \ref run() method. When its \ref run() method
921 921
  /// is called, it initiates a plain \ref Dfs object, and calls the
922 922
  /// \ref Dfs::run() method of it.
923 923
  template<class TR>
924 924
  class DfsWizard : public TR
925 925
  {
926 926
    typedef TR Base;
927 927

	
928 928
    ///The type of the digraph the algorithm runs on.
929 929
    typedef typename TR::Digraph Digraph;
930 930

	
931 931
    typedef typename Digraph::Node Node;
932 932
    typedef typename Digraph::NodeIt NodeIt;
933 933
    typedef typename Digraph::Arc Arc;
934 934
    typedef typename Digraph::OutArcIt OutArcIt;
935 935

	
936 936
    ///\brief The type of the map that stores the predecessor
937 937
    ///arcs of the shortest paths.
938 938
    typedef typename TR::PredMap PredMap;
939 939
    ///\brief The type of the map that stores the distances of the nodes.
940 940
    typedef typename TR::DistMap DistMap;
941 941
    ///\brief The type of the map that indicates which nodes are reached.
942 942
    typedef typename TR::ReachedMap ReachedMap;
943 943
    ///\brief The type of the map that indicates which nodes are processed.
944 944
    typedef typename TR::ProcessedMap ProcessedMap;
945 945

	
946 946
  public:
947 947

	
948 948
    /// Constructor.
949 949
    DfsWizard() : TR() {}
950 950

	
951 951
    /// Constructor that requires parameters.
952 952

	
953 953
    /// Constructor that requires parameters.
954 954
    /// These parameters will be the default values for the traits class.
955 955
    DfsWizard(const Digraph &g, Node s=INVALID) :
956 956
      TR(g,s) {}
957 957

	
958 958
    ///Copy constructor
959 959
    DfsWizard(const TR &b) : TR(b) {}
960 960

	
961 961
    ~DfsWizard() {}
962 962

	
963 963
    ///Runs DFS algorithm from a source node.
964 964

	
965 965
    ///Runs DFS algorithm from a source node.
966 966
    ///The node can be given with the \ref source() function.
967 967
    void run()
968 968
    {
969 969
      if(Base::_source==INVALID) throw UninitializedParameter();
970 970
      Dfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
971 971
      if(Base::_reached)
972 972
        alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
973 973
      if(Base::_processed)
974 974
        alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
975 975
      if(Base::_pred)
976 976
        alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
977 977
      if(Base::_dist)
978 978
        alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
979 979
      alg.run(Base::_source);
980 980
    }
981 981

	
982 982
    ///Runs DFS algorithm from the given node.
983 983

	
984 984
    ///Runs DFS algorithm from the given node.
985 985
    ///\param s is the given source.
986 986
    void run(Node s)
987 987
    {
988 988
      Base::_source=s;
989 989
      run();
990 990
    }
991 991

	
992 992
    /// Sets the source node, from which the Dfs algorithm runs.
993 993

	
994 994
    /// Sets the source node, from which the Dfs algorithm runs.
995 995
    /// \param s is the source node.
996 996
    DfsWizard<TR> &source(Node s)
997 997
    {
998 998
      Base::_source=s;
999 999
      return *this;
1000 1000
    }
1001 1001

	
1002 1002
    template<class T>
1003 1003
    struct DefPredMapBase : public Base {
1004 1004
      typedef T PredMap;
1005 1005
      static PredMap *createPredMap(const Digraph &) { return 0; };
1006 1006
      DefPredMapBase(const TR &b) : TR(b) {}
1007 1007
    };
1008 1008
    ///\brief \ref named-templ-param "Named parameter"
1009 1009
    ///for setting \ref PredMap object.
1010 1010
    ///
1011 1011
    ///\ref named-templ-param "Named parameter"
1012 1012
    ///for setting \ref PredMap object.
1013 1013
    template<class T>
1014 1014
    DfsWizard<DefPredMapBase<T> > predMap(const T &t)
1015 1015
    {
1016 1016
      Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
1017 1017
      return DfsWizard<DefPredMapBase<T> >(*this);
1018 1018
    }
1019 1019

	
1020 1020
    template<class T>
1021 1021
    struct DefReachedMapBase : public Base {
1022 1022
      typedef T ReachedMap;
1023 1023
      static ReachedMap *createReachedMap(const Digraph &) { return 0; };
1024 1024
      DefReachedMapBase(const TR &b) : TR(b) {}
1025 1025
    };
1026 1026
    ///\brief \ref named-templ-param "Named parameter"
1027 1027
    ///for setting \ref ReachedMap object.
1028 1028
    ///
1029 1029
    /// \ref named-templ-param "Named parameter"
1030 1030
    ///for setting \ref ReachedMap object.
1031 1031
    template<class T>
1032 1032
    DfsWizard<DefReachedMapBase<T> > reachedMap(const T &t)
1033 1033
    {
1034 1034
      Base::_reached=reinterpret_cast<void*>(const_cast<T*>(&t));
1035 1035
      return DfsWizard<DefReachedMapBase<T> >(*this);
1036 1036
    }
1037 1037

	
1038 1038
    template<class T>
1039 1039
    struct DefProcessedMapBase : public Base {
1040 1040
      typedef T ProcessedMap;
1041 1041
      static ProcessedMap *createProcessedMap(const Digraph &) { return 0; };
1042 1042
      DefProcessedMapBase(const TR &b) : TR(b) {}
1043 1043
    };
1044 1044
    ///\brief \ref named-templ-param "Named parameter"
1045 1045
    ///for setting \ref ProcessedMap object.
1046 1046
    ///
1047 1047
    /// \ref named-templ-param "Named parameter"
1048 1048
    ///for setting \ref ProcessedMap object.
1049 1049
    template<class T>
1050 1050
    DfsWizard<DefProcessedMapBase<T> > processedMap(const T &t)
1051 1051
    {
1052 1052
      Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t));
1053 1053
      return DfsWizard<DefProcessedMapBase<T> >(*this);
1054 1054
    }
1055 1055

	
1056 1056
    template<class T>
1057 1057
    struct DefDistMapBase : public Base {
1058 1058
      typedef T DistMap;
1059 1059
      static DistMap *createDistMap(const Digraph &) { return 0; };
1060 1060
      DefDistMapBase(const TR &b) : TR(b) {}
1061 1061
    };
1062 1062
    ///\brief \ref named-templ-param "Named parameter"
1063 1063
    ///for setting \ref DistMap object.
1064 1064
    ///
1065 1065
    ///\ref named-templ-param "Named parameter"
1066 1066
    ///for setting \ref DistMap object.
1067 1067
    template<class T>
1068 1068
    DfsWizard<DefDistMapBase<T> > distMap(const T &t)
1069 1069
    {
1070 1070
      Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
1071 1071
      return DfsWizard<DefDistMapBase<T> >(*this);
1072 1072
    }
1073 1073

	
1074 1074
  };
1075 1075

	
1076 1076
  ///Function type interface for Dfs algorithm.
1077 1077

	
1078 1078
  ///\ingroup search
1079 1079
  ///Function type interface for Dfs algorithm.
1080 1080
  ///
1081 1081
  ///This function also has several
1082 1082
  ///\ref named-templ-func-param "named parameters",
1083 1083
  ///they are declared as the members of class \ref DfsWizard.
1084 1084
  ///The following
1085 1085
  ///example shows how to use these parameters.
1086 1086
  ///\code
1087 1087
  ///  dfs(g,source).predMap(preds).run();
1088 1088
  ///\endcode
1089 1089
  ///\warning Don't forget to put the \ref DfsWizard::run() "run()"
1090 1090
  ///to the end of the parameter list.
1091 1091
  ///\sa DfsWizard
1092 1092
  ///\sa Dfs
1093 1093
  template<class GR>
1094 1094
  DfsWizard<DfsWizardBase<GR> >
1095 1095
  dfs(const GR &g,typename GR::Node s=INVALID)
1096 1096
  {
1097 1097
    return DfsWizard<DfsWizardBase<GR> >(g,s);
1098 1098
  }
1099 1099

	
1100 1100
#ifdef DOXYGEN
1101 1101
  /// \brief Visitor class for DFS.
1102 1102
  ///
1103 1103
  /// This class defines the interface of the DfsVisit events, and
1104 1104
  /// it could be the base of a real visitor class.
1105 1105
  template <typename _Digraph>
1106 1106
  struct DfsVisitor {
1107 1107
    typedef _Digraph Digraph;
1108 1108
    typedef typename Digraph::Arc Arc;
1109 1109
    typedef typename Digraph::Node Node;
1110 1110
    /// \brief Called for the source node of the DFS.
1111 1111
    ///
1112 1112
    /// This function is called for the source node of the DFS.
1113 1113
    void start(const Node& node) {}
1114 1114
    /// \brief Called when the source node is leaved.
1115 1115
    ///
1116 1116
    /// This function is called when the source node is leaved.
1117 1117
    void stop(const Node& node) {}
1118 1118
    /// \brief Called when a node is reached first time.
1119 1119
    ///
1120 1120
    /// This function is called when a node is reached first time.
1121 1121
    void reach(const Node& node) {}
1122 1122
    /// \brief Called when an arc reaches a new node.
1123 1123
    ///
1124 1124
    /// This function is called when the DFS finds an arc whose target node
1125 1125
    /// is not reached yet.
1126 1126
    void discover(const Arc& arc) {}
1127 1127
    /// \brief Called when an arc is examined but its target node is
1128 1128
    /// already discovered.
1129 1129
    ///
1130 1130
    /// This function is called when an arc is examined but its target node is
1131 1131
    /// already discovered.
1132 1132
    void examine(const Arc& arc) {}
1133 1133
    /// \brief Called when the DFS steps back from a node.
1134 1134
    ///
1135 1135
    /// This function is called when the DFS steps back from a node.
1136 1136
    void leave(const Node& node) {}
1137 1137
    /// \brief Called when the DFS steps back on an arc.
1138 1138
    ///
1139 1139
    /// This function is called when the DFS steps back on an arc.
1140 1140
    void backtrack(const Arc& arc) {}
1141 1141
  };
1142 1142
#else
1143 1143
  template <typename _Digraph>
1144 1144
  struct DfsVisitor {
1145 1145
    typedef _Digraph Digraph;
1146 1146
    typedef typename Digraph::Arc Arc;
1147 1147
    typedef typename Digraph::Node Node;
1148 1148
    void start(const Node&) {}
1149 1149
    void stop(const Node&) {}
1150 1150
    void reach(const Node&) {}
1151 1151
    void discover(const Arc&) {}
1152 1152
    void examine(const Arc&) {}
1153 1153
    void leave(const Node&) {}
1154 1154
    void backtrack(const Arc&) {}
1155 1155

	
1156 1156
    template <typename _Visitor>
1157 1157
    struct Constraints {
1158 1158
      void constraints() {
1159 1159
        Arc arc;
1160 1160
        Node node;
1161 1161
        visitor.start(node);
1162 1162
        visitor.stop(arc);
1163 1163
        visitor.reach(node);
1164 1164
        visitor.discover(arc);
1165 1165
        visitor.examine(arc);
1166 1166
        visitor.leave(node);
1167 1167
        visitor.backtrack(arc);
1168 1168
      }
1169 1169
      _Visitor& visitor;
1170 1170
    };
1171 1171
  };
1172 1172
#endif
1173 1173

	
1174 1174
  /// \brief Default traits class of DfsVisit class.
1175 1175
  ///
1176 1176
  /// Default traits class of DfsVisit class.
1177 1177
  /// \tparam _Digraph The type of the digraph the algorithm runs on.
1178 1178
  template<class _Digraph>
1179 1179
  struct DfsVisitDefaultTraits {
1180 1180

	
1181 1181
    /// \brief The type of the digraph the algorithm runs on.
1182 1182
    typedef _Digraph Digraph;
1183 1183

	
1184 1184
    /// \brief The type of the map that indicates which nodes are reached.
1185 1185
    ///
1186 1186
    /// The type of the map that indicates which nodes are reached.
1187 1187
    /// It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
1188 1188
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
1189 1189

	
1190 1190
    /// \brief Instantiates a \ref ReachedMap.
1191 1191
    ///
1192 1192
    /// This function instantiates a \ref ReachedMap.
1193 1193
    /// \param digraph is the digraph, to which
1194 1194
    /// we would like to define the \ref ReachedMap.
1195 1195
    static ReachedMap *createReachedMap(const Digraph &digraph) {
1196 1196
      return new ReachedMap(digraph);
1197 1197
    }
1198 1198

	
1199 1199
  };
1200 1200

	
1201 1201
  /// \ingroup search
1202 1202
  ///
1203 1203
  /// \brief %DFS algorithm class with visitor interface.
1204 1204
  ///
1205 1205
  /// This class provides an efficient implementation of the %DFS algorithm
1206 1206
  /// with visitor interface.
1207 1207
  ///
1208 1208
  /// The %DfsVisit class provides an alternative interface to the Dfs
1209 1209
  /// class. It works with callback mechanism, the DfsVisit object calls
1210 1210
  /// the member functions of the \c Visitor class on every DFS event.
1211 1211
  ///
1212
  /// This interface of the DFS algorithm should be used in special cases
1213
  /// when extra actions have to be performed in connection with certain
1214
  /// events of the DFS algorithm. Otherwise consider to use Dfs or dfs()
1215
  /// instead.
1216
  ///
1212 1217
  /// \tparam _Digraph The type of the digraph the algorithm runs on.
1213 1218
  /// The default value is
1214 1219
  /// \ref ListDigraph. The value of _Digraph is not used directly by
1215 1220
  /// \ref DfsVisit, it is only passed to \ref DfsVisitDefaultTraits.
1216 1221
  /// \tparam _Visitor The Visitor type that is used by the algorithm.
1217 1222
  /// \ref DfsVisitor "DfsVisitor<_Digraph>" is an empty visitor, which
1218 1223
  /// does not observe the DFS events. If you want to observe the DFS
1219 1224
  /// events, you should implement your own visitor class.
1220 1225
  /// \tparam _Traits Traits class to set various data types used by the
1221 1226
  /// algorithm. The default traits class is
1222 1227
  /// \ref DfsVisitDefaultTraits "DfsVisitDefaultTraits<_Digraph>".
1223 1228
  /// See \ref DfsVisitDefaultTraits for the documentation of
1224 1229
  /// a DFS visit traits class.
1225 1230
#ifdef DOXYGEN
1226 1231
  template <typename _Digraph, typename _Visitor, typename _Traits>
1227 1232
#else
1228 1233
  template <typename _Digraph = ListDigraph,
1229 1234
            typename _Visitor = DfsVisitor<_Digraph>,
1230 1235
            typename _Traits = DfsDefaultTraits<_Digraph> >
1231 1236
#endif
1232 1237
  class DfsVisit {
1233 1238
  public:
1234 1239

	
1235 1240
    /// \brief \ref Exception for uninitialized parameters.
1236 1241
    ///
1237 1242
    /// This error represents problems in the initialization
1238 1243
    /// of the parameters of the algorithm.
1239 1244
    class UninitializedParameter : public lemon::UninitializedParameter {
1240 1245
    public:
1241 1246
      virtual const char* what() const throw()
1242 1247
      {
1243 1248
        return "lemon::DfsVisit::UninitializedParameter";
1244 1249
      }
1245 1250
    };
1246 1251

	
1247 1252
    ///The traits class.
1248 1253
    typedef _Traits Traits;
1249 1254

	
1250 1255
    ///The type of the digraph the algorithm runs on.
1251 1256
    typedef typename Traits::Digraph Digraph;
1252 1257

	
1253 1258
    ///The visitor type used by the algorithm.
1254 1259
    typedef _Visitor Visitor;
1255 1260

	
1256 1261
    ///The type of the map that indicates which nodes are reached.
1257 1262
    typedef typename Traits::ReachedMap ReachedMap;
1258 1263

	
1259 1264
  private:
1260 1265

	
1261 1266
    typedef typename Digraph::Node Node;
1262 1267
    typedef typename Digraph::NodeIt NodeIt;
1263 1268
    typedef typename Digraph::Arc Arc;
1264 1269
    typedef typename Digraph::OutArcIt OutArcIt;
1265 1270

	
1266 1271
    //Pointer to the underlying digraph.
1267 1272
    const Digraph *_digraph;
1268 1273
    //Pointer to the visitor object.
1269 1274
    Visitor *_visitor;
1270 1275
    //Pointer to the map of reached status of the nodes.
1271 1276
    ReachedMap *_reached;
1272 1277
    //Indicates if _reached is locally allocated (true) or not.
1273 1278
    bool local_reached;
1274 1279

	
1275 1280
    std::vector<typename Digraph::Arc> _stack;
1276 1281
    int _stack_head;
1277 1282

	
1278 1283
    ///Creates the maps if necessary.
1279 1284
    ///\todo Better memory allocation (instead of new).
1280 1285
    void create_maps() {
1281 1286
      if(!_reached) {
1282 1287
        local_reached = true;
1283 1288
        _reached = Traits::createReachedMap(*_digraph);
1284 1289
      }
1285 1290
    }
1286 1291

	
1287 1292
  protected:
1288 1293

	
1289 1294
    DfsVisit() {}
1290 1295

	
1291 1296
  public:
1292 1297

	
1293 1298
    typedef DfsVisit Create;
1294 1299

	
1295 1300
    /// \name Named template parameters
1296 1301

	
1297 1302
    ///@{
1298 1303
    template <class T>
1299 1304
    struct DefReachedMapTraits : public Traits {
1300 1305
      typedef T ReachedMap;
1301 1306
      static ReachedMap *createReachedMap(const Digraph &digraph) {
1302 1307
        throw UninitializedParameter();
1303 1308
      }
1304 1309
    };
1305 1310
    /// \brief \ref named-templ-param "Named parameter" for setting
1306 1311
    /// ReachedMap type.
1307 1312
    ///
1308 1313
    /// \ref named-templ-param "Named parameter" for setting ReachedMap type.
1309 1314
    template <class T>
1310 1315
    struct DefReachedMap : public DfsVisit< Digraph, Visitor,
1311 1316
                                            DefReachedMapTraits<T> > {
1312 1317
      typedef DfsVisit< Digraph, Visitor, DefReachedMapTraits<T> > Create;
1313 1318
    };
1314 1319
    ///@}
1315 1320

	
1316 1321
  public:
1317 1322

	
1318 1323
    /// \brief Constructor.
1319 1324
    ///
1320 1325
    /// Constructor.
1321 1326
    ///
1322 1327
    /// \param digraph The digraph the algorithm runs on.
1323 1328
    /// \param visitor The visitor object of the algorithm.
1324 1329
    DfsVisit(const Digraph& digraph, Visitor& visitor)
1325 1330
      : _digraph(&digraph), _visitor(&visitor),
1326 1331
        _reached(0), local_reached(false) {}
1327 1332

	
1328 1333
    /// \brief Destructor.
1329 1334
    ~DfsVisit() {
1330 1335
      if(local_reached) delete _reached;
1331 1336
    }
1332 1337

	
1333 1338
    /// \brief Sets the map that indicates which nodes are reached.
1334 1339
    ///
1335 1340
    /// Sets the map that indicates which nodes are reached.
1336 1341
    /// If you don't use this function before calling \ref run(),
1337 1342
    /// it will allocate one. The destructor deallocates this
1338 1343
    /// automatically allocated map, of course.
1339 1344
    /// \return <tt> (*this) </tt>
1340 1345
    DfsVisit &reachedMap(ReachedMap &m) {
1341 1346
      if(local_reached) {
1342 1347
        delete _reached;
1343 1348
        local_reached=false;
1344 1349
      }
1345 1350
      _reached = &m;
1346 1351
      return *this;
1347 1352
    }
1348 1353

	
1349 1354
  public:
1350 1355

	
1351 1356
    /// \name Execution control
1352 1357
    /// The simplest way to execute the algorithm is to use
1353 1358
    /// one of the member functions called \ref lemon::DfsVisit::run()
1354 1359
    /// "run()".
1355 1360
    /// \n
1356 1361
    /// If you need more control on the execution, first you must call
1357 1362
    /// \ref lemon::DfsVisit::init() "init()", then you can add several
1358 1363
    /// source nodes with \ref lemon::DfsVisit::addSource() "addSource()".
1359 1364
    /// Finally \ref lemon::DfsVisit::start() "start()" will perform the
1360 1365
    /// actual path computation.
1361 1366

	
1362 1367
    /// @{
1363 1368

	
1364 1369
    /// \brief Initializes the internal data structures.
1365 1370
    ///
1366 1371
    /// Initializes the internal data structures.
1367 1372
    void init() {
1368 1373
      create_maps();
1369 1374
      _stack.resize(countNodes(*_digraph));
1370 1375
      _stack_head = -1;
1371 1376
      for (NodeIt u(*_digraph) ; u != INVALID ; ++u) {
1372 1377
        _reached->set(u, false);
1373 1378
      }
1374 1379
    }
1375 1380

	
1376 1381
    ///Adds a new source node.
1377 1382

	
1378 1383
    ///Adds a new source node to the set of nodes to be processed.
1379 1384
    ///
1380 1385
    ///\pre The stack must be empty. (Otherwise the algorithm gives
1381 1386
    ///false results.)
1382 1387
    ///
1383 1388
    ///\warning Distances will be wrong (or at least strange) in case of
1384 1389
    ///multiple sources.
1385 1390
    void addSource(Node s)
1386 1391
    {
1387 1392
      LEMON_DEBUG(emptyQueue(), "The stack is not empty.");
1388 1393
      if(!(*_reached)[s]) {
1389 1394
          _reached->set(s,true);
1390 1395
          _visitor->start(s);
1391 1396
          _visitor->reach(s);
1392 1397
          Arc e;
1393 1398
          _digraph->firstOut(e, s);
1394 1399
          if (e != INVALID) {
1395 1400
            _stack[++_stack_head] = e;
1396 1401
          } else {
1397 1402
            _visitor->leave(s);
1398 1403
          }
1399 1404
        }
1400 1405
    }
1401 1406

	
1402 1407
    /// \brief Processes the next arc.
1403 1408
    ///
1404 1409
    /// Processes the next arc.
1405 1410
    ///
1406 1411
    /// \return The processed arc.
1407 1412
    ///
1408 1413
    /// \pre The stack must not be empty.
1409 1414
    Arc processNextArc() {
1410 1415
      Arc e = _stack[_stack_head];
1411 1416
      Node m = _digraph->target(e);
1412 1417
      if(!(*_reached)[m]) {
1413 1418
        _visitor->discover(e);
1414 1419
        _visitor->reach(m);
1415 1420
        _reached->set(m, true);
1416 1421
        _digraph->firstOut(_stack[++_stack_head], m);
1417 1422
      } else {
1418 1423
        _visitor->examine(e);
1419 1424
        m = _digraph->source(e);
1420 1425
        _digraph->nextOut(_stack[_stack_head]);
1421 1426
      }
1422 1427
      while (_stack_head>=0 && _stack[_stack_head] == INVALID) {
1423 1428
        _visitor->leave(m);
1424 1429
        --_stack_head;
1425 1430
        if (_stack_head >= 0) {
1426 1431
          _visitor->backtrack(_stack[_stack_head]);
1427 1432
          m = _digraph->source(_stack[_stack_head]);
1428 1433
          _digraph->nextOut(_stack[_stack_head]);
1429 1434
        } else {
1430 1435
          _visitor->stop(m);
1431 1436
        }
1432 1437
      }
1433 1438
      return e;
1434 1439
    }
1435 1440

	
1436 1441
    /// \brief Next arc to be processed.
1437 1442
    ///
1438 1443
    /// Next arc to be processed.
1439 1444
    ///
1440 1445
    /// \return The next arc to be processed or INVALID if the stack is
1441 1446
    /// empty.
1442 1447
    Arc nextArc() const {
1443 1448
      return _stack_head >= 0 ? _stack[_stack_head] : INVALID;
1444 1449
    }
1445 1450

	
1446 1451
    /// \brief Returns \c false if there are nodes
1447 1452
    /// to be processed.
1448 1453
    ///
1449 1454
    /// Returns \c false if there are nodes
1450 1455
    /// to be processed in the queue (stack).
1451 1456
    bool emptyQueue() const { return _stack_head < 0; }
1452 1457

	
1453 1458
    /// \brief Returns the number of the nodes to be processed.
1454 1459
    ///
1455 1460
    /// Returns the number of the nodes to be processed in the queue (stack).
1456 1461
    int queueSize() const { return _stack_head + 1; }
1457 1462

	
1458 1463
    /// \brief Executes the algorithm.
1459 1464
    ///
1460 1465
    /// Executes the algorithm.
1461 1466
    ///
1462 1467
    /// This method runs the %DFS algorithm from the root node
1463 1468
    /// in order to compute the %DFS path to each node.
1464 1469
    ///
1465 1470
    /// The algorithm computes
1466 1471
    /// - the %DFS tree,
1467 1472
    /// - the distance of each node from the root in the %DFS tree.
1468 1473
    ///
1469 1474
    /// \pre init() must be called and a root node should be
1470 1475
    /// added with addSource() before using this function.
1471 1476
    ///
1472 1477
    /// \note <tt>d.start()</tt> is just a shortcut of the following code.
1473 1478
    /// \code
1474 1479
    ///   while ( !d.emptyQueue() ) {
1475 1480
    ///     d.processNextArc();
1476 1481
    ///   }
1477 1482
    /// \endcode
1478 1483
    void start() {
1479 1484
      while ( !emptyQueue() ) processNextArc();
1480 1485
    }
1481 1486

	
1482 1487
    /// \brief Executes the algorithm until the given target node is reached.
1483 1488
    ///
1484 1489
    /// Executes the algorithm until the given target node is reached.
1485 1490
    ///
1486 1491
    /// This method runs the %DFS algorithm from the root node
1487 1492
    /// in order to compute the DFS path to \c dest.
1488 1493
    ///
1489 1494
    /// The algorithm computes
1490 1495
    /// - the %DFS path to \c dest,
1491 1496
    /// - the distance of \c dest from the root in the %DFS tree.
1492 1497
    ///
1493 1498
    /// \pre init() must be called and a root node should be added
1494 1499
    /// with addSource() before using this function.
1495 1500
    void start(Node dest) {
1496 1501
      while ( !emptyQueue() && _digraph->target(_stack[_stack_head]) != dest )
1497 1502
        processNextArc();
1498 1503
    }
1499 1504

	
1500 1505
    /// \brief Executes the algorithm until a condition is met.
1501 1506
    ///
1502 1507
    /// Executes the algorithm until a condition is met.
1503 1508
    ///
1504 1509
    /// This method runs the %DFS algorithm from the root node
1505 1510
    /// until an arc \c a with <tt>am[a]</tt> true is found.
1506 1511
    ///
1507 1512
    /// \param am A \c bool (or convertible) arc map. The algorithm
1508 1513
    /// will stop when it reaches an arc \c a with <tt>am[a]</tt> true.
1509 1514
    ///
1510 1515
    /// \return The reached arc \c a with <tt>am[a]</tt> true or
1511 1516
    /// \c INVALID if no such arc was found.
1512 1517
    ///
1513 1518
    /// \pre init() must be called and a root node should be added
1514 1519
    /// with addSource() before using this function.
1515 1520
    ///
1516 1521
    /// \warning Contrary to \ref Bfs and \ref Dijkstra, \c am is an arc map,
1517 1522
    /// not a node map.
1518 1523
    template <typename AM>
1519 1524
    Arc start(const AM &am) {
1520 1525
      while ( !emptyQueue() && !am[_stack[_stack_head]] )
1521 1526
        processNextArc();
1522 1527
      return emptyQueue() ? INVALID : _stack[_stack_head];
1523 1528
    }
1524 1529

	
1525 1530
    /// \brief Runs the algorithm from the given node.
1526 1531
    ///
1527 1532
    /// This method runs the %DFS algorithm from node \c s.
1528 1533
    /// in order to compute the DFS path to each node.
1529 1534
    ///
1530 1535
    /// The algorithm computes
1531 1536
    /// - the %DFS tree,
1532 1537
    /// - the distance of each node from the root in the %DFS tree.
1533 1538
    ///
1534 1539
    /// \note <tt>d.run(s)</tt> is just a shortcut of the following code.
1535 1540
    ///\code
1536 1541
    ///   d.init();
1537 1542
    ///   d.addSource(s);
1538 1543
    ///   d.start();
1539 1544
    ///\endcode
1540 1545
    void run(Node s) {
1541 1546
      init();
1542 1547
      addSource(s);
1543 1548
      start();
1544 1549
    }
1545 1550

	
1546 1551
    /// \brief Finds the %DFS path between \c s and \c t.
1547 1552

	
1548 1553
    /// This method runs the %DFS algorithm from node \c s
1549 1554
    /// in order to compute the DFS path to \c t.
1550 1555
    ///
1551 1556
    /// \return The length of the <tt>s</tt>--<tt>t</tt> DFS path,
1552 1557
    /// if \c t is reachable form \c s, \c 0 otherwise.
1553 1558
    ///
1554 1559
    /// \note Apart from the return value, <tt>d.run(s,t)</tt> is
1555 1560
    /// just a shortcut of the following code.
1556 1561
    ///\code
1557 1562
    ///   d.init();
1558 1563
    ///   d.addSource(s);
1559 1564
    ///   d.start(t);
1560 1565
    ///\endcode
1561 1566
    int run(Node s,Node t) {
1562 1567
      init();
1563 1568
      addSource(s);
1564 1569
      start(t);
1565 1570
      return reached(t)?_stack_head+1:0;
1566 1571
    }
1567 1572

	
1568 1573
    /// \brief Runs the algorithm to visit all nodes in the digraph.
1569 1574

	
1570 1575
    /// This method runs the %DFS algorithm in order to
1571 1576
    /// compute the %DFS path to each node.
1572 1577
    ///
1573 1578
    /// The algorithm computes
1574 1579
    /// - the %DFS tree,
1575 1580
    /// - the distance of each node from the root in the %DFS tree.
1576 1581
    ///
1577 1582
    /// \note <tt>d.run()</tt> is just a shortcut of the following code.
1578 1583
    ///\code
1579 1584
    ///   d.init();
1580 1585
    ///   for (NodeIt n(digraph); n != INVALID; ++n) {
1581 1586
    ///     if (!d.reached(n)) {
1582 1587
    ///       d.addSource(n);
1583 1588
    ///       d.start();
1584 1589
    ///     }
1585 1590
    ///   }
1586 1591
    ///\endcode
1587 1592
    void run() {
1588 1593
      init();
1589 1594
      for (NodeIt it(*_digraph); it != INVALID; ++it) {
1590 1595
        if (!reached(it)) {
1591 1596
          addSource(it);
1592 1597
          start();
1593 1598
        }
1594 1599
      }
1595 1600
    }
1596 1601

	
1597 1602
    ///@}
1598 1603

	
1599 1604
    /// \name Query Functions
1600 1605
    /// The result of the %DFS algorithm can be obtained using these
1601 1606
    /// functions.\n
1602 1607
    /// Either \ref lemon::DfsVisit::run() "run()" or
1603 1608
    /// \ref lemon::DfsVisit::start() "start()" must be called before
1604 1609
    /// using them.
1605 1610
    ///@{
1606 1611

	
1607 1612
    /// \brief Checks if a node is reachable from the root(s).
1608 1613
    ///
1609 1614
    /// Returns \c true if \c v is reachable from the root(s).
1610 1615
    /// \pre Either \ref run() or \ref start()
1611 1616
    /// must be called before using this function.
1612 1617
    bool reached(Node v) { return (*_reached)[v]; }
1613 1618

	
1614 1619
    ///@}
1615 1620

	
1616 1621
  };
1617 1622

	
1618 1623
} //END OF NAMESPACE LEMON
1619 1624

	
1620 1625
#endif
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