COIN-OR::LEMON - Graph Library

source: lemon-0.x/src/work/klao/path.h @ 619:e09818232531

Last change on this file since 619:e09818232531 was 619:e09818232531, checked in by Mihaly Barasz, 17 years ago

path improvements

File size: 28.3 KB
Line 
1// -*- c++ -*- //
2
3///\ingroup datas
4///\file
5///\brief Classes for representing paths in graphs.
6
7#ifndef HUGO_PATH_H
8#define HUGO_PATH_H
9
10#include <deque>
11#include <vector>
12#include <algorithm>
13
14#include <hugo/invalid.h>
15#include <hugo/error.h>
16#include <debug.h>
17
18namespace hugo {
19
20  /// \addtogroup datas
21  /// @{
22
23
24  //! \brief A structure for representing directed path in a graph.
25  //!
26  //! A structure for representing directed path in a graph.
27  //! \param Graph The graph type in which the path is.
28  //! \param DM DebugMode, defaults to DefaultDebugMode.
29  //!
30  //! In a sense, the path can be treated as a graph, for is has \c NodeIt
31  //! and \c EdgeIt with the same usage. These types converts to the \c Node
32  //! and \c Edge of the original graph.
33  //!
34  //! \todo Thoroughfully check all the range and consistency tests.
35  template<typename Graph, typename DM = DefaultDebugMode>
36  class DirPath {
37  public:
38    typedef typename Graph::Edge GraphEdge;
39    typedef typename Graph::Node GraphNode;
40    class NodeIt;
41    class EdgeIt;
42
43  protected:
44    const Graph *gr;
45    typedef std::vector<GraphEdge> Container;
46    Container edges;
47
48  public:
49
50    /// \param _G The graph in which the path is.
51    ///
52    DirPath(const Graph &_G) : gr(&_G) {}
53
54    /// \brief Subpath constructor.
55    ///
56    /// Subpath defined by two nodes.
57    /// \warning It is an error if the two edges are not in order!
58    DirPath(const DirPath &P, const NodeIt &a, const NodeIt &b) {
59      if( DM::range_check && (!a.valid() || !b.valid) ) {
60        // FIXME: this check should be more elaborate...
61        fault("DirPath, subpath ctor: invalid bounding nodes");
62      }
63      gr = P.gr;
64      edges.insert(edges.end(), P.edges.begin()+a.idx, P.edges.begin()+b.idx);
65    }
66
67    /// \brief Subpath constructor.
68    ///
69    /// Subpath defined by two edges. Contains edges in [a,b)
70    /// \warning It is an error if the two edges are not in order!
71    DirPath(const DirPath &P, const EdgeIt &a, const EdgeIt &b) {
72      if( DM::range_check && (!a.valid() || !b.valid) ) {
73        // FIXME: this check should be more elaborate...
74        fault("DirPath, subpath ctor: invalid bounding nodes");
75      }
76      gr = P.gr;
77      edges.insert(edges.end(), P.edges.begin()+a.idx, P.edges.begin()+b.idx);
78    }
79
80    /// Length of the path.
81    size_t length() const { return edges.size(); }
82    /// Returns whether the path is empty.
83    bool empty() const { return edges.empty(); }
84
85    /// Resets the path to an empty path.
86    void clear() { edges.clear(); }
87
88    /// \brief Starting point of the path.
89    ///
90    /// Starting point of the path.
91    /// Returns INVALID if the path is empty.
92    GraphNode from() const {
93      return empty() ? INVALID : gr->tail(edges[0]);
94    }
95    /// \brief End point of the path.
96    ///
97    /// End point of the path.
98    /// Returns INVALID if the path is empty.
99    GraphNode to() const {
100      return empty() ? INVALID : gr->head(edges[length()-1]);
101    }
102
103    /// \brief Initializes node or edge iterator to point to the first
104    /// node or edge.
105    ///
106    /// \sa nth
107    template<typename It>
108    It& first(It &i) const { return i=It(*this); }
109
110    /// \brief Initializes node iterator to point to the node of a given index.
111    NodeIt& nth(NodeIt &i, int n) const {
112      if( DM::range_check && (n<0 || n>int(length())) )
113        fault("DirPath::nth: index out of range");
114      return i=NodeIt(*this, n);
115    }
116
117    /// \brief Initializes edge iterator to point to the edge of a given index.
118    EdgeIt& nth(EdgeIt &i, int n) const {
119      if( DM::range_check && (n<0 || n>=int(length())) )
120        fault("DirPath::nth: index out of range");
121      return i=EdgeIt(*this, n);
122    }
123
124    /// Checks validity of a node or edge iterator.
125    template<typename It>
126    static
127    bool valid(const It &i) { return i.valid(); }
128
129    /// Steps the given node or edge iterator.
130    template<typename It>
131    static
132    It& next(It &e) {
133      if( DM::range_check && !e.valid() )
134        fault("DirPath::next() on invalid iterator");
135      return ++e;
136    }
137
138    /// \brief Returns node iterator pointing to the head node of the
139    /// given edge iterator.
140    NodeIt head(const EdgeIt& e) const {
141      if( DM::range_check && !e.valid() )
142        fault("DirPath::head() on invalid iterator");
143      return NodeIt(*this, e.idx+1);
144    }
145
146    /// \brief Returns node iterator pointing to the tail node of the
147    /// given edge iterator.
148    NodeIt tail(const EdgeIt& e) const {
149      if( DM::range_check && !e.valid() )
150        fault("DirPath::tail() on invalid iterator");
151      return NodeIt(*this, e.idx);
152    }
153
154
155    /*** Iterator classes ***/
156    class EdgeIt {
157      friend class DirPath;
158
159      int idx;
160      const DirPath *p;
161    public:
162      EdgeIt() {}
163      EdgeIt(Invalid) : idx(-1), p(0) {}
164      EdgeIt(const DirPath &_p, int _idx = 0) :
165        idx(_idx), p(&_p) { validate(); }
166
167      bool valid() const { return idx!=-1; }
168
169      operator GraphEdge () const {
170        return valid() ? p->edges[idx] : INVALID;
171      }
172      EdgeIt& operator++() { ++idx; validate(); return *this; }
173
174      bool operator==(const EdgeIt& e) const { return idx==e.idx; }
175      bool operator!=(const EdgeIt& e) const { return idx!=e.idx; }
176      bool operator<(const EdgeIt& e) const { return idx<e.idx; }
177
178    private:
179      // FIXME: comparison between signed and unsigned...
180      // Jo ez igy? Vagy esetleg legyen a length() int?
181      void validate() { if( size_t(idx) >= p->length() ) idx=-1; }
182    };
183
184    class NodeIt {
185      friend class DirPath;
186
187      int idx;
188      const DirPath *p;
189    public:
190      NodeIt() {}
191      NodeIt(Invalid) : idx(-1), p(0) {}
192      NodeIt(const DirPath &_p, int _idx = 0) :
193        idx(_idx), p(&_p) { validate(); }
194
195      bool valid() const { return idx!=-1; }
196
197      operator const GraphNode& () const {
198        if(idx >= p->length())
199          return p->to();
200        else if(idx >= 0)
201          return p->gr->tail(p->edges[idx]);
202        else
203          return INVALID;
204      }
205      NodeIt& operator++() { ++idx; validate(); return *this; }
206
207      bool operator==(const NodeIt& e) const { return idx==e.idx; }
208      bool operator!=(const NodeIt& e) const { return idx!=e.idx; }
209      bool operator<(const NodeIt& e) const { return idx<e.idx; }
210
211    private:
212      void validate() { if( size_t(idx) > p->length() ) idx=-1; }
213    };
214
215    friend class Builder;   
216
217    /**
218     * \brief Class to build paths
219     *
220     * \ingroup datas
221     * This class is used to fill a path with edges.
222     *
223     * You can push new edges to the front and to the back of the path in
224     * arbitrary order then you should commit these changes to the graph.
225     *
226     * Fundamentally, for most "Paths" (classes fulfilling the
227     * PathConcept) while the builder is active (after the first modifying
228     * operation and until the commit()) the original Path is in a
229     * "transitional" state (operations ot it have undefined result). But
230     * in the case of DirPath the original path is unchanged until the
231     * commit. However we don't recomend that you use this feature.
232     */
233    class Builder {
234      DirPath &P;
235      Container front, back;
236
237    public:
238      ///\param _P the path you want to fill in.
239      ///
240      Builder(DirPath &_P) : P(_P) {}
241
242      /// Sets the starting node of the path.
243     
244      /// Sets the starting node of the path. Edge added to the path
245      /// afterwards have to be incident to this node.
246      /// It should be called iff the path is empty and before any call to
247      /// \ref pushFront() or \ref pushBack()
248      void setStart(const GraphNode &) {}
249
250      ///Push a new edge to the front of the path
251
252      ///Push a new edge to the front of the path.
253      ///\sa setStart
254      void pushFront(const GraphEdge& e) {
255        if( DM::consistensy_check && !empty() && P.gr->head(e)!=from() ) {
256          fault("DirPath::Builder::pushFront: nonincident edge");
257        }
258        front.push_back(e);
259      }
260
261      ///Push a new edge to the back of the path
262
263      ///Push a new edge to the back of the path.
264      ///\sa setStart
265      void pushBack(const GraphEdge& e) {
266        if( DM::consistensy_check && !empty() && P.gr->tail(e)!=to() ) {
267          fault("DirPath::Builder::pushBack: nonincident edge");
268        }
269        back.push_back(e);
270      }
271
272      ///Commit the changes to the path.
273      void commit() {
274        if( !(front.empty() && back.empty()) ) {
275          Container tmp;
276          tmp.reserve(front.size()+back.size()+P.length());
277          tmp.insert(tmp.end(), front.rbegin(), front.rend());
278          tmp.insert(tmp.end(), P.edges.begin(), P.edges.end());
279          tmp.insert(tmp.end(), back.begin(), back.end());
280          P.edges.swap(tmp);
281          front.clear();
282          back.clear();
283        }
284      }
285
286      // FIXME: Hmm, pontosan hogy is kene ezt csinalni?
287      // Hogy kenyelmes egy ilyet hasznalni?
288      void reserve(size_t r) {
289        front.reserve(r);
290        back.reserve(r);
291      }
292
293    private:
294      bool empty() {
295        return front.empty() && back.empty() && P.empty();
296      }
297
298      GraphNode from() const {
299        if( ! front.empty() )
300          return P.gr->tail(front[front.size()-1]);
301        else if( ! P.empty() )
302          return P.gr->tail(P.edges[0]);
303        else if( ! back.empty() )
304          return P.gr->tail(back[0]);
305        else
306          return INVALID;
307      }
308      GraphNode to() const {
309        if( ! back.empty() )
310          return P.gr->head(back[back.size()-1]);
311        else if( ! P.empty() )
312          return P.gr->head(P.edges[P.length()-1]);
313        else if( ! front.empty() )
314          return P.gr->head(front[0]);
315        else
316          return INVALID;
317      }
318
319    };
320
321  };
322
323
324
325
326
327
328
329
330
331
332  /**********************************************************************/
333
334
335  //! \brief A structure for representing undirected path in a graph.
336  //!
337  //! A structure for representing undirected path in a graph. Ie. this is
338  //! a path in a \e directed graph but the edges should not be directed
339  //! forward.
340  //!
341  //! \param Graph The graph type in which the path is.
342  //! \param DM DebugMode, defaults to DefaultDebugMode.
343  //!
344  //! In a sense, the path can be treated as a graph, for is has \c NodeIt
345  //! and \c EdgeIt with the same usage. These types converts to the \c Node
346  //! and \c Edge of the original graph.
347  //!
348  //! \todo Thoroughfully check all the range and consistency tests.
349  template<typename Graph, typename DM = DefaultDebugMode>
350  class UndirPath {
351  public:
352    typedef typename Graph::Edge GraphEdge;
353    typedef typename Graph::Node GraphNode;
354    class NodeIt;
355    class EdgeIt;
356
357  protected:
358    const Graph *gr;
359    typedef std::vector<GraphEdge> Container;
360    Container edges;
361
362  public:
363
364    /// \param _G The graph in which the path is.
365    ///
366    UndirPath(const Graph &_G) : gr(&_G) {}
367
368    /// \brief Subpath constructor.
369    ///
370    /// Subpath defined by two nodes.
371    /// \warning It is an error if the two edges are not in order!
372    UndirPath(const UndirPath &P, const NodeIt &a, const NodeIt &b) {
373      if( DM::range_check && (!a.valid() || !b.valid) ) {
374        // FIXME: this check should be more elaborate...
375        fault("UndirPath, subpath ctor: invalid bounding nodes");
376      }
377      gr = P.gr;
378      edges.insert(edges.end(), P.edges.begin()+a.idx, P.edges.begin()+b.idx);
379    }
380
381    /// \brief Subpath constructor.
382    ///
383    /// Subpath defined by two edges. Contains edges in [a,b)
384    /// \warning It is an error if the two edges are not in order!
385    UndirPath(const UndirPath &P, const EdgeIt &a, const EdgeIt &b) {
386      if( DM::range_check && (!a.valid() || !b.valid) ) {
387        // FIXME: this check should be more elaborate...
388        fault("UndirPath, subpath ctor: invalid bounding nodes");
389      }
390      gr = P.gr;
391      edges.insert(edges.end(), P.edges.begin()+a.idx, P.edges.begin()+b.idx);
392    }
393
394    /// Length of the path.
395    size_t length() const { return edges.size(); }
396    /// Returns whether the path is empty.
397    bool empty() const { return edges.empty(); }
398
399    /// Resets the path to an empty path.
400    void clear() { edges.clear(); }
401
402    /// \brief Starting point of the path.
403    ///
404    /// Starting point of the path.
405    /// Returns INVALID if the path is empty.
406    GraphNode from() const {
407      return empty() ? INVALID : gr->tail(edges[0]);
408    }
409    /// \brief End point of the path.
410    ///
411    /// End point of the path.
412    /// Returns INVALID if the path is empty.
413    GraphNode to() const {
414      return empty() ? INVALID : gr->head(edges[length()-1]);
415    }
416
417    /// \brief Initializes node or edge iterator to point to the first
418    /// node or edge.
419    ///
420    /// \sa nth
421    template<typename It>
422    It& first(It &i) const { return i=It(*this); }
423
424    /// \brief Initializes node iterator to point to the node of a given index.
425    NodeIt& nth(NodeIt &i, int n) const {
426      if( DM::range_check && (n<0 || n>int(length())) )
427        fault("UndirPath::nth: index out of range");
428      return i=NodeIt(*this, n);
429    }
430
431    /// \brief Initializes edge iterator to point to the edge of a given index.
432    EdgeIt& nth(EdgeIt &i, int n) const {
433      if( DM::range_check && (n<0 || n>=int(length())) )
434        fault("UndirPath::nth: index out of range");
435      return i=EdgeIt(*this, n);
436    }
437
438    /// Checks validity of a node or edge iterator.
439    template<typename It>
440    static
441    bool valid(const It &i) { return i.valid(); }
442
443    /// Steps the given node or edge iterator.
444    template<typename It>
445    static
446    It& next(It &e) {
447      if( DM::range_check && !e.valid() )
448        fault("UndirPath::next() on invalid iterator");
449      return ++e;
450    }
451
452    /// \brief Returns node iterator pointing to the head node of the
453    /// given edge iterator.
454    NodeIt head(const EdgeIt& e) const {
455      if( DM::range_check && !e.valid() )
456        fault("UndirPath::head() on invalid iterator");
457      return NodeIt(*this, e.idx+1);
458    }
459
460    /// \brief Returns node iterator pointing to the tail node of the
461    /// given edge iterator.
462    NodeIt tail(const EdgeIt& e) const {
463      if( DM::range_check && !e.valid() )
464        fault("UndirPath::tail() on invalid iterator");
465      return NodeIt(*this, e.idx);
466    }
467
468
469    /*** Iterator classes ***/
470    class EdgeIt {
471      friend class UndirPath;
472
473      int idx;
474      const UndirPath *p;
475    public:
476      EdgeIt() {}
477      EdgeIt(Invalid) : idx(-1), p(0) {}
478      EdgeIt(const UndirPath &_p, int _idx = 0) :
479        idx(_idx), p(&_p) { validate(); }
480
481      bool valid() const { return idx!=-1; }
482
483      operator GraphEdge () const {
484        return valid() ? p->edges[idx] : INVALID;
485      }
486      EdgeIt& operator++() { ++idx; validate(); return *this; }
487
488      bool operator==(const EdgeIt& e) const { return idx==e.idx; }
489      bool operator!=(const EdgeIt& e) const { return idx!=e.idx; }
490      bool operator<(const EdgeIt& e) const { return idx<e.idx; }
491
492    private:
493      // FIXME: comparison between signed and unsigned...
494      // Jo ez igy? Vagy esetleg legyen a length() int?
495      void validate() { if( size_t(idx) >= p->length() ) idx=-1; }
496    };
497
498    class NodeIt {
499      friend class UndirPath;
500
501      int idx;
502      const UndirPath *p;
503    public:
504      NodeIt() {}
505      NodeIt(Invalid) : idx(-1), p(0) {}
506      NodeIt(const UndirPath &_p, int _idx = 0) :
507        idx(_idx), p(&_p) { validate(); }
508
509      bool valid() const { return idx!=-1; }
510
511      operator const GraphNode& () const {
512        if(idx >= p->length())
513          return p->to();
514        else if(idx >= 0)
515          return p->gr->tail(p->edges[idx]);
516        else
517          return INVALID;
518      }
519      NodeIt& operator++() { ++idx; validate(); return *this; }
520
521      bool operator==(const NodeIt& e) const { return idx==e.idx; }
522      bool operator!=(const NodeIt& e) const { return idx!=e.idx; }
523      bool operator<(const NodeIt& e) const { return idx<e.idx; }
524
525    private:
526      void validate() { if( size_t(idx) > p->length() ) idx=-1; }
527    };
528
529    friend class Builder;   
530
531    /**
532     * \brief Class to build paths
533     *
534     * \ingroup datas
535     * This class is used to fill a path with edges.
536     *
537     * You can push new edges to the front and to the back of the path in
538     * arbitrary order then you should commit these changes to the graph.
539     *
540     * Fundamentally, for most "Paths" (classes fulfilling the
541     * PathConcept) while the builder is active (after the first modifying
542     * operation and until the commit()) the original Path is in a
543     * "transitional" state (operations ot it have undefined result). But
544     * in the case of UndirPath the original path is unchanged until the
545     * commit. However we don't recomend that you use this feature.
546     */
547    class Builder {
548      UndirPath &P;
549      Container front, back;
550
551    public:
552      ///\param _P the path you want to fill in.
553      ///
554      Builder(UndirPath &_P) : P(_P) {}
555
556      /// Sets the starting node of the path.
557     
558      /// Sets the starting node of the path. Edge added to the path
559      /// afterwards have to be incident to this node.
560      /// It should be called iff the path is empty and before any call to
561      /// \ref pushFront() or \ref pushBack()
562      void setStart(const GraphNode &) {}
563
564      ///Push a new edge to the front of the path
565
566      ///Push a new edge to the front of the path.
567      ///\sa setStart
568      void pushFront(const GraphEdge& e) {
569        if( DM::consistensy_check && !empty() && P.gr->head(e)!=from() ) {
570          fault("UndirPath::Builder::pushFront: nonincident edge");
571        }
572        front.push_back(e);
573      }
574
575      ///Push a new edge to the back of the path
576
577      ///Push a new edge to the back of the path.
578      ///\sa setStart
579      void pushBack(const GraphEdge& e) {
580        if( DM::consistensy_check && !empty() && P.gr->tail(e)!=to() ) {
581          fault("UndirPath::Builder::pushBack: nonincident edge");
582        }
583        back.push_back(e);
584      }
585
586      ///Commit the changes to the path.
587      void commit() {
588        if( !(front.empty() && back.empty()) ) {
589          Container tmp;
590          tmp.reserve(front.size()+back.size()+P.length());
591          tmp.insert(tmp.end(), front.rbegin(), front.rend());
592          tmp.insert(tmp.end(), P.edges.begin(), P.edges.end());
593          tmp.insert(tmp.end(), back.begin(), back.end());
594          P.edges.swap(tmp);
595          front.clear();
596          back.clear();
597        }
598      }
599
600      // FIXME: Hmm, pontosan hogy is kene ezt csinalni?
601      // Hogy kenyelmes egy ilyet hasznalni?
602      void reserve(size_t r) {
603        front.reserve(r);
604        back.reserve(r);
605      }
606
607    private:
608      bool empty() {
609        return front.empty() && back.empty() && P.empty();
610      }
611
612      GraphNode from() const {
613        if( ! front.empty() )
614          return P.gr->tail(front[front.size()-1]);
615        else if( ! P.empty() )
616          return P.gr->tail(P.edges[0]);
617        else if( ! back.empty() )
618          return P.gr->tail(back[0]);
619        else
620          return INVALID;
621      }
622      GraphNode to() const {
623        if( ! back.empty() )
624          return P.gr->head(back[back.size()-1]);
625        else if( ! P.empty() )
626          return P.gr->head(P.edges[P.length()-1]);
627        else if( ! front.empty() )
628          return P.gr->head(front[0]);
629        else
630          return INVALID;
631      }
632
633    };
634
635  };
636
637
638
639
640
641
642
643
644
645
646  /**********************************************************************/
647
648
649  /* Ennek az allocatorosdinak sokkal jobban utana kene nezni a hasznalata
650     elott. Eleg bonyinak nez ki, ahogyan azokat az STL-ben hasznaljak. */
651
652  template<typename Graph>
653  class DynamicPath {
654
655  public:
656    typedef typename Graph::Edge GraphEdge;
657    typedef typename Graph::Node GraphNode;
658    class NodeIt;
659    class EdgeIt;
660
661  protected:
662    Graph& G;
663    // FIXME: ehelyett eleg lenne tarolni ket boolt: a ket szelso el
664    // iranyitasat:
665    GraphNode _first, _last;
666    typedef std::deque<GraphEdge> Container;
667    Container edges;
668
669  public:
670
671    DynamicPath(Graph &_G) : G(_G), _first(INVALID), _last(INVALID) {}
672
673    /// Subpath defined by two nodes.
674    /// Nodes may be in reversed order, then
675    /// we contstruct the reversed path.
676    DynamicPath(const DynamicPath &P, const NodeIt &a, const NodeIt &b);
677    /// Subpath defined by two edges. Contains edges in [a,b)
678    /// It is an error if the two edges are not in order!
679    DynamicPath(const DynamicPath &P, const EdgeIt &a, const EdgeIt &b);
680   
681    size_t length() const { return edges.size(); }
682    GraphNode from() const { return _first; }
683    GraphNode to() const { return _last; }
684
685    NodeIt& first(NodeIt &n) const { return nth(n, 0); }
686    EdgeIt& first(EdgeIt &e) const { return nth(e, 0); }
687    template<typename It>
688    It first() const {
689      It e;
690      first(e);
691      return e;
692    }
693
694    NodeIt& nth(NodeIt &, size_t) const;
695    EdgeIt& nth(EdgeIt &, size_t) const;
696    template<typename It>
697    It nth(size_t n) const {
698      It e;
699      nth(e, n);
700      return e;
701    }
702
703    bool valid(const NodeIt &n) const { return n.idx <= length(); }
704    bool valid(const EdgeIt &e) const { return e.it < edges.end(); }
705
706    bool isForward(const EdgeIt &e) const { return e.forw; }
707
708    /// index of a node on the path. Returns length+2 for the invalid NodeIt
709    int index(const NodeIt &n) const { return n.idx; }
710    /// index of an edge on the path. Returns length+1 for the invalid EdgeIt
711    int index(const EdgeIt &e) const { return e.it - edges.begin(); }
712
713    EdgeIt& next(EdgeIt &e) const;
714    NodeIt& next(NodeIt &n) const;
715    template <typename It>
716    It getNext(It it) const {
717      It tmp(it); return next(tmp);
718    }
719
720    // A path is constructed using the following four functions.
721    // They return false if the requested operation is inconsistent
722    // with the path constructed so far.
723    // If your path has only one edge you MUST set either "from" or "to"!
724    // So you probably SHOULD call it in any case to be safe (and check the
725    // returned value to check if your path is consistent with your idea).
726    bool pushFront(const GraphEdge &e);
727    bool pushBack(const GraphEdge &e);
728    bool setFrom(const GraphNode &n);
729    bool setTo(const GraphNode &n);
730
731    // WARNING: these two functions return the head/tail of an edge with
732    // respect to the direction of the path!
733    // So G.head(P.graphEdge(e)) == P.graphNode(P.head(e)) holds only if
734    // P.forward(e) is true (or the edge is a loop)!
735    NodeIt head(const EdgeIt& e) const;
736    NodeIt tail(const EdgeIt& e) const;
737
738    // FIXME: ezeknek valami jobb nev kellene!!!
739    GraphEdge graphEdge(const EdgeIt& e) const;
740    GraphNode graphNode(const NodeIt& n) const;
741
742
743    /*** Iterator classes ***/
744    class EdgeIt {
745      friend class DynamicPath;
746
747      typename Container::const_iterator it;
748      bool forw;
749    public:
750      // FIXME: jarna neki ilyen is...
751      // EdgeIt(Invalid);
752
753      bool forward() const { return forw; }
754
755      bool operator==(const EdgeIt& e) const { return it==e.it; }
756      bool operator!=(const EdgeIt& e) const { return it!=e.it; }
757      bool operator<(const EdgeIt& e) const { return it<e.it; }
758    };
759
760    class NodeIt {
761      friend class DynamicPath;
762
763      size_t idx;
764      bool tail;  // Is this node the tail of the edge with same idx?
765
766    public:
767      // FIXME: jarna neki ilyen is...
768      // NodeIt(Invalid);
769
770      bool operator==(const NodeIt& n) const { return idx==n.idx; }
771      bool operator!=(const NodeIt& n) const { return idx!=n.idx; }
772      bool operator<(const NodeIt& n) const { return idx<n.idx; }
773    };
774
775  private:
776    bool edgeIncident(const GraphEdge &e, const GraphNode &a,
777                      GraphNode &b);
778    bool connectTwoEdges(const GraphEdge &e, const GraphEdge &f);
779  };
780
781  template<typename Gr>
782  typename DynamicPath<Gr>::EdgeIt&
783  DynamicPath<Gr>::next(DynamicPath::EdgeIt &e) const {
784    if( e.it == edges.end() )
785      return e;
786
787    GraphNode common_node = ( e.forw ? G.head(*e.it) : G.tail(*e.it) );
788    ++e.it;
789
790    // Invalid edgeit is always forward :)
791    if( e.it == edges.end() ) {
792      e.forw = true;
793      return e;
794    }
795
796    e.forw = ( G.tail(*e.it) == common_node );
797    return e;
798  }
799
800  template<typename Gr>
801  typename DynamicPath<Gr>::NodeIt& DynamicPath<Gr>::next(NodeIt &n) const {
802    if( n.idx >= length() ) {
803      // FIXME: invalid
804      n.idx = length()+1;
805      return n;
806    }
807
808   
809    GraphNode next_node = ( n.tail ? G.head(edges[n.idx]) :
810                              G.tail(edges[n.idx]) );
811    ++n.idx;
812    if( n.idx < length() ) {
813      n.tail = ( next_node == G.tail(edges[n.idx]) );
814    }
815    else {
816      n.tail = true;
817    }
818
819    return n;
820  }
821
822  template<typename Gr>
823  bool DynamicPath<Gr>::edgeIncident(const GraphEdge &e, const GraphNode &a,
824                          GraphNode &b) {
825    if( G.tail(e) == a ) {
826      b=G.head(e);
827      return true;
828    }
829    if( G.head(e) == a ) {
830      b=G.tail(e);
831      return true;
832    }
833    return false;
834  }
835
836  template<typename Gr>
837  bool DynamicPath<Gr>::connectTwoEdges(const GraphEdge &e,
838                             const GraphEdge &f) {
839    if( edgeIncident(f, G.tail(e), _last) ) {
840      _first = G.head(e);
841      return true;
842    }
843    if( edgeIncident(f, G.head(e), _last) ) {
844      _first = G.tail(e);
845      return true;
846    }
847    return false;
848  }
849
850  template<typename Gr>
851  bool DynamicPath<Gr>::pushFront(const GraphEdge &e) {
852    if( G.valid(_first) ) {
853        if( edgeIncident(e, _first, _first) ) {
854          edges.push_front(e);
855          return true;
856        }
857        else
858          return false;
859    }
860    else if( length() < 1 || connectTwoEdges(e, edges[0]) ) {
861      edges.push_front(e);
862      return true;
863    }
864    else
865      return false;
866  }
867
868  template<typename Gr>
869  bool DynamicPath<Gr>::pushBack(const GraphEdge &e) {
870    if( G.valid(_last) ) {
871        if( edgeIncident(e, _last, _last) ) {
872          edges.push_back(e);
873          return true;
874        }
875        else
876          return false;
877    }
878    else if( length() < 1 || connectTwoEdges(edges[0], e) ) {
879      edges.push_back(e);
880      return true;
881    }
882    else
883      return false;
884  }
885
886
887  template<typename Gr>
888  bool DynamicPath<Gr>::setFrom(const GraphNode &n) {
889    if( G.valid(_first) ) {
890      return _first == n;
891    }
892    else {
893      if( length() > 0) {
894        if( edgeIncident(edges[0], n, _last) ) {
895          _first = n;
896          return true;
897        }
898        else return false;
899      }
900      else {
901        _first = _last = n;
902        return true;
903      }
904    }
905  }
906
907  template<typename Gr>
908  bool DynamicPath<Gr>::setTo(const GraphNode &n) {
909    if( G.valid(_last) ) {
910      return _last == n;
911    }
912    else {
913      if( length() > 0) {
914        if( edgeIncident(edges[0], n, _first) ) {
915          _last = n;
916          return true;
917        }
918        else return false;
919      }
920      else {
921        _first = _last = n;
922        return true;
923      }
924    }
925  }
926
927
928  template<typename Gr>
929  typename DynamicPath<Gr>::NodeIt
930  DynamicPath<Gr>::tail(const EdgeIt& e) const {
931    NodeIt n;
932
933    if( e.it == edges.end() ) {
934      // FIXME: invalid-> invalid
935      n.idx = length() + 1;
936      n.tail = true;
937      return n;
938    }
939
940    n.idx = e.it-edges.begin();
941    n.tail = e.forw;
942    return n;
943  }
944
945  template<typename Gr>
946  typename DynamicPath<Gr>::NodeIt
947  DynamicPath<Gr>::head(const EdgeIt& e) const {
948    if( e.it == edges.end()-1 ) {
949      return _last;
950    }
951
952    EdgeIt next_edge = e;
953    next(next_edge);
954    return tail(next_edge);
955  }
956     
957  template<typename Gr>
958  typename DynamicPath<Gr>::GraphEdge
959  DynamicPath<Gr>::graphEdge(const EdgeIt& e) const {
960    if( e.it != edges.end() ) {
961      return *e.it;
962    }
963    else {
964      return INVALID;
965    }
966  }
967 
968  template<typename Gr>
969  typename DynamicPath<Gr>::GraphNode
970  DynamicPath<Gr>::graphNode(const NodeIt& n) const {
971    if( n.idx < length() ) {
972      return n.tail ? G.tail(edges[n.idx]) : G.head(edges[n.idx]);
973    }
974    else if( n.idx == length() ) {
975      return _last;
976    }
977    else {
978      return INVALID;
979    }
980  }
981
982  template<typename Gr>
983  typename DynamicPath<Gr>::EdgeIt&
984  DynamicPath<Gr>::nth(EdgeIt &e, size_t k) const {
985    if( k>=length() ) {
986      // FIXME: invalid EdgeIt
987      e.it = edges.end();
988      e.forw = true;
989      return e;
990    }
991
992    e.it = edges.begin()+k;
993    if(k==0) {
994      e.forw = ( G.tail(*e.it) == _first );
995    }
996    else {
997      e.forw = ( G.tail(*e.it) == G.tail(edges[k-1]) ||
998                 G.tail(*e.it) == G.head(edges[k-1]) );
999    }
1000    return e;
1001  }
1002   
1003  template<typename Gr>
1004  typename DynamicPath<Gr>::NodeIt&
1005  DynamicPath<Gr>::nth(NodeIt &n, size_t k) const {
1006    if( k>length() ) {
1007      // FIXME: invalid NodeIt
1008      n.idx = length()+1;
1009      n.tail = true;
1010      return n;
1011    }
1012    if( k==length() ) {
1013      n.idx = length();
1014      n.tail = true;
1015      return n;
1016    }
1017    n = tail(nth<EdgeIt>(k));
1018    return n;
1019  }
1020
1021  // Reszut konstruktorok:
1022
1023
1024  template<typename Gr>
1025  DynamicPath<Gr>::DynamicPath(const DynamicPath &P, const EdgeIt &a,
1026                               const EdgeIt &b) :
1027    G(P.G), edges(a.it, b.it)    // WARNING: if b.it < a.it this will blow up!
1028  {
1029    if( G.valid(P._first) && a.it < P.edges.end() ) {
1030      _first = ( a.forw ? G.tail(*a.it) : G.head(*a.it) );
1031      if( b.it < P.edges.end() ) {
1032        _last = ( b.forw ? G.tail(*b.it) : G.head(*b.it) );
1033      }
1034      else {
1035        _last = P._last;
1036      }
1037    }
1038  }
1039
1040  template<typename Gr>
1041  DynamicPath<Gr>::DynamicPath(const DynamicPath &P, const NodeIt &a,
1042                               const NodeIt &b) : G(P.G)
1043  {
1044    if( !P.valid(a) || !P.valid(b) )
1045      return;
1046
1047    int ai = a.idx, bi = b.idx;
1048    if( bi<ai )
1049      std::swap(ai,bi);
1050   
1051    edges.resize(bi-ai);
1052    copy(P.edges.begin()+ai, P.edges.begin()+bi, edges.begin());
1053
1054    _first = P.graphNode(a);
1055    _last = P.graphNode(b);
1056  }
1057
1058  ///@}
1059
1060} // namespace hugo
1061
1062#endif // HUGO_PATH_H
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