COIN-OR::LEMON - Graph Library

source: lemon/lemon/smart_graph.h @ 782:853fcddcf282

Last change on this file since 782:853fcddcf282 was 782:853fcddcf282, checked in by Peter Kovacs <kpeter@…>, 10 years ago

Doc improvements, fixes and unifications for graphs (#311)

File size: 21.2 KB
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1/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library.
4 *
5 * Copyright (C) 2003-2009
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#ifndef LEMON_SMART_GRAPH_H
20#define LEMON_SMART_GRAPH_H
21
22///\ingroup graphs
23///\file
24///\brief SmartDigraph and SmartGraph classes.
25
26#include <vector>
27
28#include <lemon/core.h>
29#include <lemon/error.h>
30#include <lemon/bits/graph_extender.h>
31
32namespace lemon {
33
34  class SmartDigraph;
35
36  class SmartDigraphBase {
37  protected:
38
39    struct NodeT
40    {
41      int first_in, first_out;
42      NodeT() {}
43    };
44    struct ArcT
45    {
46      int target, source, next_in, next_out;
47      ArcT() {}
48    };
49
50    std::vector<NodeT> nodes;
51    std::vector<ArcT> arcs;
52
53  public:
54
55    typedef SmartDigraphBase Digraph;
56
57    class Node;
58    class Arc;
59
60  public:
61
62    SmartDigraphBase() : nodes(), arcs() { }
63    SmartDigraphBase(const SmartDigraphBase &_g)
64      : nodes(_g.nodes), arcs(_g.arcs) { }
65
66    typedef True NodeNumTag;
67    typedef True ArcNumTag;
68
69    int nodeNum() const { return nodes.size(); }
70    int arcNum() const { return arcs.size(); }
71
72    int maxNodeId() const { return nodes.size()-1; }
73    int maxArcId() const { return arcs.size()-1; }
74
75    Node addNode() {
76      int n = nodes.size();
77      nodes.push_back(NodeT());
78      nodes[n].first_in = -1;
79      nodes[n].first_out = -1;
80      return Node(n);
81    }
82
83    Arc addArc(Node u, Node v) {
84      int n = arcs.size();
85      arcs.push_back(ArcT());
86      arcs[n].source = u._id;
87      arcs[n].target = v._id;
88      arcs[n].next_out = nodes[u._id].first_out;
89      arcs[n].next_in = nodes[v._id].first_in;
90      nodes[u._id].first_out = nodes[v._id].first_in = n;
91
92      return Arc(n);
93    }
94
95    void clear() {
96      arcs.clear();
97      nodes.clear();
98    }
99
100    Node source(Arc a) const { return Node(arcs[a._id].source); }
101    Node target(Arc a) const { return Node(arcs[a._id].target); }
102
103    static int id(Node v) { return v._id; }
104    static int id(Arc a) { return a._id; }
105
106    static Node nodeFromId(int id) { return Node(id);}
107    static Arc arcFromId(int id) { return Arc(id);}
108
109    bool valid(Node n) const {
110      return n._id >= 0 && n._id < static_cast<int>(nodes.size());
111    }
112    bool valid(Arc a) const {
113      return a._id >= 0 && a._id < static_cast<int>(arcs.size());
114    }
115
116    class Node {
117      friend class SmartDigraphBase;
118      friend class SmartDigraph;
119
120    protected:
121      int _id;
122      explicit Node(int id) : _id(id) {}
123    public:
124      Node() {}
125      Node (Invalid) : _id(-1) {}
126      bool operator==(const Node i) const {return _id == i._id;}
127      bool operator!=(const Node i) const {return _id != i._id;}
128      bool operator<(const Node i) const {return _id < i._id;}
129    };
130
131
132    class Arc {
133      friend class SmartDigraphBase;
134      friend class SmartDigraph;
135
136    protected:
137      int _id;
138      explicit Arc(int id) : _id(id) {}
139    public:
140      Arc() { }
141      Arc (Invalid) : _id(-1) {}
142      bool operator==(const Arc i) const {return _id == i._id;}
143      bool operator!=(const Arc i) const {return _id != i._id;}
144      bool operator<(const Arc i) const {return _id < i._id;}
145    };
146
147    void first(Node& node) const {
148      node._id = nodes.size() - 1;
149    }
150
151    static void next(Node& node) {
152      --node._id;
153    }
154
155    void first(Arc& arc) const {
156      arc._id = arcs.size() - 1;
157    }
158
159    static void next(Arc& arc) {
160      --arc._id;
161    }
162
163    void firstOut(Arc& arc, const Node& node) const {
164      arc._id = nodes[node._id].first_out;
165    }
166
167    void nextOut(Arc& arc) const {
168      arc._id = arcs[arc._id].next_out;
169    }
170
171    void firstIn(Arc& arc, const Node& node) const {
172      arc._id = nodes[node._id].first_in;
173    }
174
175    void nextIn(Arc& arc) const {
176      arc._id = arcs[arc._id].next_in;
177    }
178
179  };
180
181  typedef DigraphExtender<SmartDigraphBase> ExtendedSmartDigraphBase;
182
183  ///\ingroup graphs
184  ///
185  ///\brief A smart directed graph class.
186  ///
187  ///\ref SmartDigraph is a simple and fast digraph implementation.
188  ///It is also quite memory efficient but at the price
189  ///that it does not support node and arc deletion
190  ///(except for the Snapshot feature).
191  ///
192  ///This type fully conforms to the \ref concepts::Digraph "Digraph concept"
193  ///and it also provides some additional functionalities.
194  ///Most of its member functions and nested classes are documented
195  ///only in the concept class.
196  ///
197  ///\sa concepts::Digraph
198  ///\sa SmartGraph
199  class SmartDigraph : public ExtendedSmartDigraphBase {
200    typedef ExtendedSmartDigraphBase Parent;
201
202  private:
203    /// Digraphs are \e not copy constructible. Use DigraphCopy instead.
204    SmartDigraph(const SmartDigraph &) : ExtendedSmartDigraphBase() {};
205    /// \brief Assignment of a digraph to another one is \e not allowed.
206    /// Use DigraphCopy instead.
207    void operator=(const SmartDigraph &) {}
208
209  public:
210
211    /// Constructor
212
213    /// Constructor.
214    ///
215    SmartDigraph() {};
216
217    ///Add a new node to the digraph.
218
219    ///This function adds a new node to the digraph.
220    ///\return The new node.
221    Node addNode() { return Parent::addNode(); }
222
223    ///Add a new arc to the digraph.
224
225    ///This function adds a new arc to the digraph with source node \c s
226    ///and target node \c t.
227    ///\return The new arc.
228    Arc addArc(Node s, Node t) {
229      return Parent::addArc(s, t);
230    }
231
232    /// \brief Node validity check
233    ///
234    /// This function gives back \c true if the given node is valid,
235    /// i.e. it is a real node of the digraph.
236    ///
237    /// \warning A removed node (using Snapshot) could become valid again
238    /// if new nodes are added to the digraph.
239    bool valid(Node n) const { return Parent::valid(n); }
240
241    /// \brief Arc validity check
242    ///
243    /// This function gives back \c true if the given arc is valid,
244    /// i.e. it is a real arc of the digraph.
245    ///
246    /// \warning A removed arc (using Snapshot) could become valid again
247    /// if new arcs are added to the graph.
248    bool valid(Arc a) const { return Parent::valid(a); }
249
250    ///Split a node.
251
252    ///This function splits the given node. First, a new node is added
253    ///to the digraph, then the source of each outgoing arc of node \c n
254    ///is moved to this new node.
255    ///If the second parameter \c connect is \c true (this is the default
256    ///value), then a new arc from node \c n to the newly created node
257    ///is also added.
258    ///\return The newly created node.
259    ///
260    ///\note All iterators remain valid.
261    ///
262    ///\warning This functionality cannot be used together with the Snapshot
263    ///feature.
264    Node split(Node n, bool connect = true)
265    {
266      Node b = addNode();
267      nodes[b._id].first_out=nodes[n._id].first_out;
268      nodes[n._id].first_out=-1;
269      for(int i=nodes[b._id].first_out; i!=-1; i=arcs[i].next_out) {
270        arcs[i].source=b._id;
271      }
272      if(connect) addArc(n,b);
273      return b;
274    }
275
276    ///Clear the digraph.
277
278    ///This function erases all nodes and arcs from the digraph.
279    ///
280    void clear() {
281      Parent::clear();
282    }
283
284    /// Reserve memory for nodes.
285
286    /// Using this function, it is possible to avoid superfluous memory
287    /// allocation: if you know that the digraph you want to build will
288    /// be large (e.g. it will contain millions of nodes and/or arcs),
289    /// then it is worth reserving space for this amount before starting
290    /// to build the digraph.
291    /// \sa reserveArc()
292    void reserveNode(int n) { nodes.reserve(n); };
293
294    /// Reserve memory for arcs.
295
296    /// Using this function, it is possible to avoid superfluous memory
297    /// allocation: if you know that the digraph you want to build will
298    /// be large (e.g. it will contain millions of nodes and/or arcs),
299    /// then it is worth reserving space for this amount before starting
300    /// to build the digraph.
301    /// \sa reserveNode()
302    void reserveArc(int m) { arcs.reserve(m); };
303
304  public:
305
306    class Snapshot;
307
308  protected:
309
310    void restoreSnapshot(const Snapshot &s)
311    {
312      while(s.arc_num<arcs.size()) {
313        Arc arc = arcFromId(arcs.size()-1);
314        Parent::notifier(Arc()).erase(arc);
315        nodes[arcs.back().source].first_out=arcs.back().next_out;
316        nodes[arcs.back().target].first_in=arcs.back().next_in;
317        arcs.pop_back();
318      }
319      while(s.node_num<nodes.size()) {
320        Node node = nodeFromId(nodes.size()-1);
321        Parent::notifier(Node()).erase(node);
322        nodes.pop_back();
323      }
324    }
325
326  public:
327
328    ///Class to make a snapshot of the digraph and to restore it later.
329
330    ///Class to make a snapshot of the digraph and to restore it later.
331    ///
332    ///The newly added nodes and arcs can be removed using the
333    ///restore() function. This is the only way for deleting nodes and/or
334    ///arcs from a SmartDigraph structure.
335    ///
336    ///\note After a state is restored, you cannot restore a later state,
337    ///i.e. you cannot add the removed nodes and arcs again using
338    ///another Snapshot instance.
339    ///
340    ///\warning Node splitting cannot be restored.
341    ///\warning The validity of the snapshot is not stored due to
342    ///performance reasons. If you do not use the snapshot correctly,
343    ///it can cause broken program, invalid or not restored state of
344    ///the digraph or no change.
345    class Snapshot
346    {
347      SmartDigraph *_graph;
348    protected:
349      friend class SmartDigraph;
350      unsigned int node_num;
351      unsigned int arc_num;
352    public:
353      ///Default constructor.
354
355      ///Default constructor.
356      ///You have to call save() to actually make a snapshot.
357      Snapshot() : _graph(0) {}
358      ///Constructor that immediately makes a snapshot
359
360      ///This constructor immediately makes a snapshot of the given digraph.
361      ///
362      Snapshot(SmartDigraph &gr) : _graph(&gr) {
363        node_num=_graph->nodes.size();
364        arc_num=_graph->arcs.size();
365      }
366
367      ///Make a snapshot.
368
369      ///This function makes a snapshot of the given digraph.
370      ///It can be called more than once. In case of a repeated
371      ///call, the previous snapshot gets lost.
372      void save(SmartDigraph &gr) {
373        _graph=&gr;
374        node_num=_graph->nodes.size();
375        arc_num=_graph->arcs.size();
376      }
377
378      ///Undo the changes until a snapshot.
379
380      ///This function undos the changes until the last snapshot
381      ///created by save() or Snapshot(SmartDigraph&).
382      void restore()
383      {
384        _graph->restoreSnapshot(*this);
385      }
386    };
387  };
388
389
390  class SmartGraphBase {
391
392  protected:
393
394    struct NodeT {
395      int first_out;
396    };
397
398    struct ArcT {
399      int target;
400      int next_out;
401    };
402
403    std::vector<NodeT> nodes;
404    std::vector<ArcT> arcs;
405
406    int first_free_arc;
407
408  public:
409
410    typedef SmartGraphBase Graph;
411
412    class Node;
413    class Arc;
414    class Edge;
415
416    class Node {
417      friend class SmartGraphBase;
418    protected:
419
420      int _id;
421      explicit Node(int id) { _id = id;}
422
423    public:
424      Node() {}
425      Node (Invalid) { _id = -1; }
426      bool operator==(const Node& node) const {return _id == node._id;}
427      bool operator!=(const Node& node) const {return _id != node._id;}
428      bool operator<(const Node& node) const {return _id < node._id;}
429    };
430
431    class Edge {
432      friend class SmartGraphBase;
433    protected:
434
435      int _id;
436      explicit Edge(int id) { _id = id;}
437
438    public:
439      Edge() {}
440      Edge (Invalid) { _id = -1; }
441      bool operator==(const Edge& arc) const {return _id == arc._id;}
442      bool operator!=(const Edge& arc) const {return _id != arc._id;}
443      bool operator<(const Edge& arc) const {return _id < arc._id;}
444    };
445
446    class Arc {
447      friend class SmartGraphBase;
448    protected:
449
450      int _id;
451      explicit Arc(int id) { _id = id;}
452
453    public:
454      operator Edge() const {
455        return _id != -1 ? edgeFromId(_id / 2) : INVALID;
456      }
457
458      Arc() {}
459      Arc (Invalid) { _id = -1; }
460      bool operator==(const Arc& arc) const {return _id == arc._id;}
461      bool operator!=(const Arc& arc) const {return _id != arc._id;}
462      bool operator<(const Arc& arc) const {return _id < arc._id;}
463    };
464
465
466
467    SmartGraphBase()
468      : nodes(), arcs() {}
469
470    typedef True NodeNumTag;
471    typedef True EdgeNumTag;
472    typedef True ArcNumTag;
473
474    int nodeNum() const { return nodes.size(); }
475    int edgeNum() const { return arcs.size() / 2; }
476    int arcNum() const { return arcs.size(); }
477
478    int maxNodeId() const { return nodes.size()-1; }
479    int maxEdgeId() const { return arcs.size() / 2 - 1; }
480    int maxArcId() const { return arcs.size()-1; }
481
482    Node source(Arc e) const { return Node(arcs[e._id ^ 1].target); }
483    Node target(Arc e) const { return Node(arcs[e._id].target); }
484
485    Node u(Edge e) const { return Node(arcs[2 * e._id].target); }
486    Node v(Edge e) const { return Node(arcs[2 * e._id + 1].target); }
487
488    static bool direction(Arc e) {
489      return (e._id & 1) == 1;
490    }
491
492    static Arc direct(Edge e, bool d) {
493      return Arc(e._id * 2 + (d ? 1 : 0));
494    }
495
496    void first(Node& node) const {
497      node._id = nodes.size() - 1;
498    }
499
500    void next(Node& node) const {
501      --node._id;
502    }
503
504    void first(Arc& arc) const {
505      arc._id = arcs.size() - 1;
506    }
507
508    void next(Arc& arc) const {
509      --arc._id;
510    }
511
512    void first(Edge& arc) const {
513      arc._id = arcs.size() / 2 - 1;
514    }
515
516    void next(Edge& arc) const {
517      --arc._id;
518    }
519
520    void firstOut(Arc &arc, const Node& v) const {
521      arc._id = nodes[v._id].first_out;
522    }
523    void nextOut(Arc &arc) const {
524      arc._id = arcs[arc._id].next_out;
525    }
526
527    void firstIn(Arc &arc, const Node& v) const {
528      arc._id = ((nodes[v._id].first_out) ^ 1);
529      if (arc._id == -2) arc._id = -1;
530    }
531    void nextIn(Arc &arc) const {
532      arc._id = ((arcs[arc._id ^ 1].next_out) ^ 1);
533      if (arc._id == -2) arc._id = -1;
534    }
535
536    void firstInc(Edge &arc, bool& d, const Node& v) const {
537      int de = nodes[v._id].first_out;
538      if (de != -1) {
539        arc._id = de / 2;
540        d = ((de & 1) == 1);
541      } else {
542        arc._id = -1;
543        d = true;
544      }
545    }
546    void nextInc(Edge &arc, bool& d) const {
547      int de = (arcs[(arc._id * 2) | (d ? 1 : 0)].next_out);
548      if (de != -1) {
549        arc._id = de / 2;
550        d = ((de & 1) == 1);
551      } else {
552        arc._id = -1;
553        d = true;
554      }
555    }
556
557    static int id(Node v) { return v._id; }
558    static int id(Arc e) { return e._id; }
559    static int id(Edge e) { return e._id; }
560
561    static Node nodeFromId(int id) { return Node(id);}
562    static Arc arcFromId(int id) { return Arc(id);}
563    static Edge edgeFromId(int id) { return Edge(id);}
564
565    bool valid(Node n) const {
566      return n._id >= 0 && n._id < static_cast<int>(nodes.size());
567    }
568    bool valid(Arc a) const {
569      return a._id >= 0 && a._id < static_cast<int>(arcs.size());
570    }
571    bool valid(Edge e) const {
572      return e._id >= 0 && 2 * e._id < static_cast<int>(arcs.size());
573    }
574
575    Node addNode() {
576      int n = nodes.size();
577      nodes.push_back(NodeT());
578      nodes[n].first_out = -1;
579
580      return Node(n);
581    }
582
583    Edge addEdge(Node u, Node v) {
584      int n = arcs.size();
585      arcs.push_back(ArcT());
586      arcs.push_back(ArcT());
587
588      arcs[n].target = u._id;
589      arcs[n | 1].target = v._id;
590
591      arcs[n].next_out = nodes[v._id].first_out;
592      nodes[v._id].first_out = n;
593
594      arcs[n | 1].next_out = nodes[u._id].first_out;
595      nodes[u._id].first_out = (n | 1);
596
597      return Edge(n / 2);
598    }
599
600    void clear() {
601      arcs.clear();
602      nodes.clear();
603    }
604
605  };
606
607  typedef GraphExtender<SmartGraphBase> ExtendedSmartGraphBase;
608
609  /// \ingroup graphs
610  ///
611  /// \brief A smart undirected graph class.
612  ///
613  /// \ref SmartGraph is a simple and fast graph implementation.
614  /// It is also quite memory efficient but at the price
615  /// that it does not support node and edge deletion
616  /// (except for the Snapshot feature).
617  ///
618  /// This type fully conforms to the \ref concepts::Graph "Graph concept"
619  /// and it also provides some additional functionalities.
620  /// Most of its member functions and nested classes are documented
621  /// only in the concept class.
622  ///
623  /// \sa concepts::Graph
624  /// \sa SmartDigraph
625  class SmartGraph : public ExtendedSmartGraphBase {
626    typedef ExtendedSmartGraphBase Parent;
627
628  private:
629    /// Graphs are \e not copy constructible. Use GraphCopy instead.
630    SmartGraph(const SmartGraph &) : ExtendedSmartGraphBase() {};
631    /// \brief Assignment of a graph to another one is \e not allowed.
632    /// Use GraphCopy instead.
633    void operator=(const SmartGraph &) {}
634
635  public:
636
637    /// Constructor
638
639    /// Constructor.
640    ///
641    SmartGraph() {}
642
643    /// \brief Add a new node to the graph.
644    ///
645    /// This function adds a new node to the graph.
646    /// \return The new node.
647    Node addNode() { return Parent::addNode(); }
648
649    /// \brief Add a new edge to the graph.
650    ///
651    /// This function adds a new edge to the graph between nodes
652    /// \c u and \c v with inherent orientation from node \c u to
653    /// node \c v.
654    /// \return The new edge.
655    Edge addEdge(Node u, Node v) {
656      return Parent::addEdge(u, v);
657    }
658
659    /// \brief Node validity check
660    ///
661    /// This function gives back \c true if the given node is valid,
662    /// i.e. it is a real node of the graph.
663    ///
664    /// \warning A removed node (using Snapshot) could become valid again
665    /// if new nodes are added to the graph.
666    bool valid(Node n) const { return Parent::valid(n); }
667
668    /// \brief Edge validity check
669    ///
670    /// This function gives back \c true if the given edge is valid,
671    /// i.e. it is a real edge of the graph.
672    ///
673    /// \warning A removed edge (using Snapshot) could become valid again
674    /// if new edges are added to the graph.
675    bool valid(Edge e) const { return Parent::valid(e); }
676
677    /// \brief Arc validity check
678    ///
679    /// This function gives back \c true if the given arc is valid,
680    /// i.e. it is a real arc of the graph.
681    ///
682    /// \warning A removed arc (using Snapshot) could become valid again
683    /// if new edges are added to the graph.
684    bool valid(Arc a) const { return Parent::valid(a); }
685
686    ///Clear the graph.
687
688    ///This function erases all nodes and arcs from the graph.
689    ///
690    void clear() {
691      Parent::clear();
692    }
693
694  public:
695
696    class Snapshot;
697
698  protected:
699
700    void saveSnapshot(Snapshot &s)
701    {
702      s._graph = this;
703      s.node_num = nodes.size();
704      s.arc_num = arcs.size();
705    }
706
707    void restoreSnapshot(const Snapshot &s)
708    {
709      while(s.arc_num<arcs.size()) {
710        int n=arcs.size()-1;
711        Edge arc=edgeFromId(n/2);
712        Parent::notifier(Edge()).erase(arc);
713        std::vector<Arc> dir;
714        dir.push_back(arcFromId(n));
715        dir.push_back(arcFromId(n-1));
716        Parent::notifier(Arc()).erase(dir);
717        nodes[arcs[n-1].target].first_out=arcs[n].next_out;
718        nodes[arcs[n].target].first_out=arcs[n-1].next_out;
719        arcs.pop_back();
720        arcs.pop_back();
721      }
722      while(s.node_num<nodes.size()) {
723        int n=nodes.size()-1;
724        Node node = nodeFromId(n);
725        Parent::notifier(Node()).erase(node);
726        nodes.pop_back();
727      }
728    }
729
730  public:
731
732    ///Class to make a snapshot of the graph and to restore it later.
733
734    ///Class to make a snapshot of the graph and to restore it later.
735    ///
736    ///The newly added nodes and edges can be removed using the
737    ///restore() function. This is the only way for deleting nodes and/or
738    ///edges from a SmartGraph structure.
739    ///
740    ///\note After a state is restored, you cannot restore a later state,
741    ///i.e. you cannot add the removed nodes and edges again using
742    ///another Snapshot instance.
743    ///
744    ///\warning The validity of the snapshot is not stored due to
745    ///performance reasons. If you do not use the snapshot correctly,
746    ///it can cause broken program, invalid or not restored state of
747    ///the graph or no change.
748    class Snapshot
749    {
750      SmartGraph *_graph;
751    protected:
752      friend class SmartGraph;
753      unsigned int node_num;
754      unsigned int arc_num;
755    public:
756      ///Default constructor.
757
758      ///Default constructor.
759      ///You have to call save() to actually make a snapshot.
760      Snapshot() : _graph(0) {}
761      ///Constructor that immediately makes a snapshot
762
763      /// This constructor immediately makes a snapshot of the given graph.
764      ///
765      Snapshot(SmartGraph &gr) {
766        gr.saveSnapshot(*this);
767      }
768
769      ///Make a snapshot.
770
771      ///This function makes a snapshot of the given graph.
772      ///It can be called more than once. In case of a repeated
773      ///call, the previous snapshot gets lost.
774      void save(SmartGraph &gr)
775      {
776        gr.saveSnapshot(*this);
777      }
778
779      ///Undo the changes until the last snapshot.
780
781      ///This function undos the changes until the last snapshot
782      ///created by save() or Snapshot(SmartGraph&).
783      void restore()
784      {
785        _graph->restoreSnapshot(*this);
786      }
787    };
788  };
789
790} //namespace lemon
791
792
793#endif //LEMON_SMART_GRAPH_H
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