COIN-OR::LEMON - Graph Library

source: lemon-1.2/lemon/smart_graph.h @ 909:f112c18bc304

Last change on this file since 909:f112c18bc304 was 877:141f9c0db4a3, checked in by Alpar Juttner <alpar@…>, 10 years ago

Unify the sources (#339)

File size: 22.1 KB
RevLine 
[209]1/* -*- mode: C++; indent-tabs-mode: nil; -*-
[109]2 *
[209]3 * This file is a part of LEMON, a generic C++ optimization library.
[109]4 *
[877]5 * Copyright (C) 2003-2010
[109]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
[220]28#include <lemon/core.h>
[109]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
[209]39    struct NodeT
[109]40    {
[209]41      int first_in, first_out;
[109]42      NodeT() {}
43    };
[209]44    struct ArcT
[109]45    {
[209]46      int target, source, next_in, next_out;
47      ArcT() {}
[109]48    };
49
50    std::vector<NodeT> nodes;
51    std::vector<ArcT> arcs;
[209]52
[109]53  public:
54
[617]55    typedef SmartDigraphBase Digraph;
[109]56
57    class Node;
58    class Arc;
59
60  public:
61
62    SmartDigraphBase() : nodes(), arcs() { }
[209]63    SmartDigraphBase(const SmartDigraphBase &_g)
[109]64      : nodes(_g.nodes), arcs(_g.arcs) { }
[209]65
[109]66    typedef True NodeNumTag;
[360]67    typedef True ArcNumTag;
[109]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() {
[209]76      int n = nodes.size();
[109]77      nodes.push_back(NodeT());
78      nodes[n].first_in = -1;
79      nodes[n].first_out = -1;
80      return Node(n);
81    }
[209]82
[109]83    Arc addArc(Node u, Node v) {
[209]84      int n = arcs.size();
[109]85      arcs.push_back(ArcT());
[209]86      arcs[n].source = u._id;
[109]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
[209]109    bool valid(Node n) const {
110      return n._id >= 0 && n._id < static_cast<int>(nodes.size());
[149]111    }
[209]112    bool valid(Arc a) const {
113      return a._id >= 0 && a._id < static_cast<int>(arcs.size());
[149]114    }
115
[109]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    };
[209]130
[109]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    }
[209]174
[109]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  ///
[735]187  ///\ref SmartDigraph is a simple and fast digraph implementation.
188  ///It is also quite memory efficient but at the price
[877]189  ///that it does not support node and arc deletion
[735]190  ///(except for the Snapshot feature).
[109]191  ///
[735]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  ///
[787]197  ///This class provides constant time counting for nodes and arcs.
198  ///
[735]199  ///\sa concepts::Digraph
200  ///\sa SmartGraph
[109]201  class SmartDigraph : public ExtendedSmartDigraphBase {
202    typedef ExtendedSmartDigraphBase Parent;
203
204  private:
[735]205    /// Digraphs are \e not copy constructible. Use DigraphCopy instead.
[109]206    SmartDigraph(const SmartDigraph &) : ExtendedSmartDigraphBase() {};
[735]207    /// \brief Assignment of a digraph to another one is \e not allowed.
208    /// Use DigraphCopy instead.
[109]209    void operator=(const SmartDigraph &) {}
210
211  public:
[209]212
[109]213    /// Constructor
[209]214
[109]215    /// Constructor.
216    ///
217    SmartDigraph() {};
[209]218
[109]219    ///Add a new node to the digraph.
[209]220
[735]221    ///This function adds a new node to the digraph.
222    ///\return The new node.
[109]223    Node addNode() { return Parent::addNode(); }
[209]224
[109]225    ///Add a new arc to the digraph.
[209]226
[735]227    ///This function adds a new arc to the digraph with source node \c s
[109]228    ///and target node \c t.
[559]229    ///\return The new arc.
[735]230    Arc addArc(Node s, Node t) {
[209]231      return Parent::addArc(s, t);
[109]232    }
233
[149]234    /// \brief Node validity check
235    ///
[735]236    /// This function gives back \c true if the given node is valid,
237    /// i.e. it is a real node of the digraph.
[149]238    ///
239    /// \warning A removed node (using Snapshot) could become valid again
[735]240    /// if new nodes are added to the digraph.
[149]241    bool valid(Node n) const { return Parent::valid(n); }
242
243    /// \brief Arc validity check
244    ///
[735]245    /// This function gives back \c true if the given arc is valid,
246    /// i.e. it is a real arc of the digraph.
[149]247    ///
248    /// \warning A removed arc (using Snapshot) could become valid again
[735]249    /// if new arcs are added to the graph.
[149]250    bool valid(Arc a) const { return Parent::valid(a); }
251
[109]252    ///Split a node.
[209]253
[735]254    ///This function splits the given node. First, a new node is added
255    ///to the digraph, then the source of each outgoing arc of node \c n
256    ///is moved to this new node.
257    ///If the second parameter \c connect is \c true (this is the default
258    ///value), then a new arc from node \c n to the newly created node
259    ///is also added.
[109]260    ///\return The newly created node.
261    ///
[735]262    ///\note All iterators remain valid.
263    ///
[109]264    ///\warning This functionality cannot be used together with the Snapshot
265    ///feature.
266    Node split(Node n, bool connect = true)
267    {
268      Node b = addNode();
269      nodes[b._id].first_out=nodes[n._id].first_out;
270      nodes[n._id].first_out=-1;
[370]271      for(int i=nodes[b._id].first_out; i!=-1; i=arcs[i].next_out) {
272        arcs[i].source=b._id;
273      }
[109]274      if(connect) addArc(n,b);
275      return b;
276    }
277
[735]278    ///Clear the digraph.
279
280    ///This function erases all nodes and arcs from the digraph.
281    ///
282    void clear() {
283      Parent::clear();
284    }
285
286    /// Reserve memory for nodes.
287
288    /// Using this function, it is possible to avoid superfluous memory
289    /// allocation: if you know that the digraph you want to build will
290    /// be large (e.g. it will contain millions of nodes and/or arcs),
291    /// then it is worth reserving space for this amount before starting
292    /// to build the digraph.
293    /// \sa reserveArc()
294    void reserveNode(int n) { nodes.reserve(n); };
295
296    /// Reserve memory for arcs.
297
298    /// Using this function, it is possible to avoid superfluous memory
299    /// allocation: if you know that the digraph you want to build will
300    /// be large (e.g. it will contain millions of nodes and/or arcs),
301    /// then it is worth reserving space for this amount before starting
302    /// to build the digraph.
303    /// \sa reserveNode()
304    void reserveArc(int m) { arcs.reserve(m); };
305
[109]306  public:
[209]307
[109]308    class Snapshot;
309
310  protected:
311
312    void restoreSnapshot(const Snapshot &s)
313    {
314      while(s.arc_num<arcs.size()) {
315        Arc arc = arcFromId(arcs.size()-1);
[209]316        Parent::notifier(Arc()).erase(arc);
317        nodes[arcs.back().source].first_out=arcs.back().next_out;
318        nodes[arcs.back().target].first_in=arcs.back().next_in;
319        arcs.pop_back();
[109]320      }
321      while(s.node_num<nodes.size()) {
322        Node node = nodeFromId(nodes.size()-1);
[209]323        Parent::notifier(Node()).erase(node);
324        nodes.pop_back();
[109]325      }
[209]326    }
[109]327
328  public:
329
[735]330    ///Class to make a snapshot of the digraph and to restore it later.
[109]331
[735]332    ///Class to make a snapshot of the digraph and to restore it later.
[109]333    ///
334    ///The newly added nodes and arcs can be removed using the
[735]335    ///restore() function. This is the only way for deleting nodes and/or
336    ///arcs from a SmartDigraph structure.
[109]337    ///
[877]338    ///\note After a state is restored, you cannot restore a later state,
[735]339    ///i.e. you cannot add the removed nodes and arcs again using
340    ///another Snapshot instance.
341    ///
342    ///\warning Node splitting cannot be restored.
343    ///\warning The validity of the snapshot is not stored due to
344    ///performance reasons. If you do not use the snapshot correctly,
345    ///it can cause broken program, invalid or not restored state of
346    ///the digraph or no change.
[209]347    class Snapshot
[109]348    {
349      SmartDigraph *_graph;
350    protected:
351      friend class SmartDigraph;
352      unsigned int node_num;
353      unsigned int arc_num;
354    public:
355      ///Default constructor.
[209]356
[109]357      ///Default constructor.
[735]358      ///You have to call save() to actually make a snapshot.
[109]359      Snapshot() : _graph(0) {}
360      ///Constructor that immediately makes a snapshot
[209]361
[735]362      ///This constructor immediately makes a snapshot of the given digraph.
363      ///
364      Snapshot(SmartDigraph &gr) : _graph(&gr) {
[209]365        node_num=_graph->nodes.size();
366        arc_num=_graph->arcs.size();
[109]367      }
368
369      ///Make a snapshot.
370
[735]371      ///This function makes a snapshot of the given digraph.
372      ///It can be called more than once. In case of a repeated
[109]373      ///call, the previous snapshot gets lost.
[735]374      void save(SmartDigraph &gr) {
375        _graph=&gr;
[209]376        node_num=_graph->nodes.size();
377        arc_num=_graph->arcs.size();
[109]378      }
379
380      ///Undo the changes until a snapshot.
[209]381
[735]382      ///This function undos the changes until the last snapshot
383      ///created by save() or Snapshot(SmartDigraph&).
[109]384      void restore()
385      {
[209]386        _graph->restoreSnapshot(*this);
[109]387      }
388    };
389  };
390
391
392  class SmartGraphBase {
393
394  protected:
395
396    struct NodeT {
397      int first_out;
398    };
[209]399
[109]400    struct ArcT {
401      int target;
402      int next_out;
403    };
404
405    std::vector<NodeT> nodes;
406    std::vector<ArcT> arcs;
407
408    int first_free_arc;
[209]409
[109]410  public:
[209]411
[617]412    typedef SmartGraphBase Graph;
[109]413
414    class Node;
415    class Arc;
416    class Edge;
[209]417
[109]418    class Node {
419      friend class SmartGraphBase;
420    protected:
421
422      int _id;
423      explicit Node(int id) { _id = id;}
424
425    public:
426      Node() {}
427      Node (Invalid) { _id = -1; }
428      bool operator==(const Node& node) const {return _id == node._id;}
429      bool operator!=(const Node& node) const {return _id != node._id;}
430      bool operator<(const Node& node) const {return _id < node._id;}
431    };
432
433    class Edge {
434      friend class SmartGraphBase;
435    protected:
436
437      int _id;
438      explicit Edge(int id) { _id = id;}
439
440    public:
441      Edge() {}
442      Edge (Invalid) { _id = -1; }
443      bool operator==(const Edge& arc) const {return _id == arc._id;}
444      bool operator!=(const Edge& arc) const {return _id != arc._id;}
445      bool operator<(const Edge& arc) const {return _id < arc._id;}
446    };
447
448    class Arc {
449      friend class SmartGraphBase;
450    protected:
451
452      int _id;
453      explicit Arc(int id) { _id = id;}
454
455    public:
[329]456      operator Edge() const {
457        return _id != -1 ? edgeFromId(_id / 2) : INVALID;
[238]458      }
[109]459
460      Arc() {}
461      Arc (Invalid) { _id = -1; }
462      bool operator==(const Arc& arc) const {return _id == arc._id;}
463      bool operator!=(const Arc& arc) const {return _id != arc._id;}
464      bool operator<(const Arc& arc) const {return _id < arc._id;}
465    };
466
467
468
469    SmartGraphBase()
470      : nodes(), arcs() {}
471
[368]472    typedef True NodeNumTag;
473    typedef True EdgeNumTag;
474    typedef True ArcNumTag;
475
476    int nodeNum() const { return nodes.size(); }
477    int edgeNum() const { return arcs.size() / 2; }
478    int arcNum() const { return arcs.size(); }
[209]479
480    int maxNodeId() const { return nodes.size()-1; }
[109]481    int maxEdgeId() const { return arcs.size() / 2 - 1; }
482    int maxArcId() const { return arcs.size()-1; }
483
484    Node source(Arc e) const { return Node(arcs[e._id ^ 1].target); }
485    Node target(Arc e) const { return Node(arcs[e._id].target); }
486
[125]487    Node u(Edge e) const { return Node(arcs[2 * e._id].target); }
488    Node v(Edge e) const { return Node(arcs[2 * e._id + 1].target); }
[109]489
490    static bool direction(Arc e) {
491      return (e._id & 1) == 1;
492    }
493
494    static Arc direct(Edge e, bool d) {
495      return Arc(e._id * 2 + (d ? 1 : 0));
496    }
497
[209]498    void first(Node& node) const {
[109]499      node._id = nodes.size() - 1;
500    }
501
[778]502    static void next(Node& node) {
[109]503      --node._id;
504    }
505
[209]506    void first(Arc& arc) const {
[109]507      arc._id = arcs.size() - 1;
508    }
509
[778]510    static void next(Arc& arc) {
[109]511      --arc._id;
512    }
513
[209]514    void first(Edge& arc) const {
[109]515      arc._id = arcs.size() / 2 - 1;
516    }
517
[778]518    static void next(Edge& arc) {
[109]519      --arc._id;
520    }
521
522    void firstOut(Arc &arc, const Node& v) const {
523      arc._id = nodes[v._id].first_out;
524    }
525    void nextOut(Arc &arc) const {
526      arc._id = arcs[arc._id].next_out;
527    }
528
529    void firstIn(Arc &arc, const Node& v) const {
530      arc._id = ((nodes[v._id].first_out) ^ 1);
531      if (arc._id == -2) arc._id = -1;
532    }
533    void nextIn(Arc &arc) const {
534      arc._id = ((arcs[arc._id ^ 1].next_out) ^ 1);
535      if (arc._id == -2) arc._id = -1;
536    }
537
538    void firstInc(Edge &arc, bool& d, const Node& v) const {
539      int de = nodes[v._id].first_out;
540      if (de != -1) {
541        arc._id = de / 2;
542        d = ((de & 1) == 1);
543      } else {
544        arc._id = -1;
545        d = true;
546      }
547    }
548    void nextInc(Edge &arc, bool& d) const {
549      int de = (arcs[(arc._id * 2) | (d ? 1 : 0)].next_out);
550      if (de != -1) {
551        arc._id = de / 2;
552        d = ((de & 1) == 1);
553      } else {
554        arc._id = -1;
[209]555        d = true;
[109]556      }
557    }
[209]558
[109]559    static int id(Node v) { return v._id; }
560    static int id(Arc e) { return e._id; }
561    static int id(Edge e) { return e._id; }
562
563    static Node nodeFromId(int id) { return Node(id);}
564    static Arc arcFromId(int id) { return Arc(id);}
565    static Edge edgeFromId(int id) { return Edge(id);}
566
[209]567    bool valid(Node n) const {
568      return n._id >= 0 && n._id < static_cast<int>(nodes.size());
[149]569    }
[209]570    bool valid(Arc a) const {
[149]571      return a._id >= 0 && a._id < static_cast<int>(arcs.size());
572    }
[209]573    bool valid(Edge e) const {
574      return e._id >= 0 && 2 * e._id < static_cast<int>(arcs.size());
[149]575    }
576
[209]577    Node addNode() {
[109]578      int n = nodes.size();
579      nodes.push_back(NodeT());
580      nodes[n].first_out = -1;
[209]581
[109]582      return Node(n);
583    }
[209]584
[138]585    Edge addEdge(Node u, Node v) {
[109]586      int n = arcs.size();
587      arcs.push_back(ArcT());
588      arcs.push_back(ArcT());
[209]589
[109]590      arcs[n].target = u._id;
591      arcs[n | 1].target = v._id;
592
593      arcs[n].next_out = nodes[v._id].first_out;
594      nodes[v._id].first_out = n;
595
[209]596      arcs[n | 1].next_out = nodes[u._id].first_out;
[109]597      nodes[u._id].first_out = (n | 1);
598
599      return Edge(n / 2);
600    }
[209]601
[109]602    void clear() {
603      arcs.clear();
604      nodes.clear();
605    }
606
607  };
608
609  typedef GraphExtender<SmartGraphBase> ExtendedSmartGraphBase;
610
611  /// \ingroup graphs
612  ///
613  /// \brief A smart undirected graph class.
614  ///
[735]615  /// \ref SmartGraph is a simple and fast graph implementation.
616  /// It is also quite memory efficient but at the price
[877]617  /// that it does not support node and edge deletion
[735]618  /// (except for the Snapshot feature).
[109]619  ///
[735]620  /// This type fully conforms to the \ref concepts::Graph "Graph concept"
621  /// and it also provides some additional functionalities.
622  /// Most of its member functions and nested classes are documented
623  /// only in the concept class.
624  ///
[787]625  /// This class provides constant time counting for nodes, edges and arcs.
626  ///
[735]627  /// \sa concepts::Graph
628  /// \sa SmartDigraph
[109]629  class SmartGraph : public ExtendedSmartGraphBase {
[617]630    typedef ExtendedSmartGraphBase Parent;
631
[109]632  private:
[735]633    /// Graphs are \e not copy constructible. Use GraphCopy instead.
[109]634    SmartGraph(const SmartGraph &) : ExtendedSmartGraphBase() {};
[735]635    /// \brief Assignment of a graph to another one is \e not allowed.
636    /// Use GraphCopy instead.
[109]637    void operator=(const SmartGraph &) {}
638
639  public:
640
641    /// Constructor
[209]642
[109]643    /// Constructor.
644    ///
645    SmartGraph() {}
646
[735]647    /// \brief Add a new node to the graph.
648    ///
649    /// This function adds a new node to the graph.
[559]650    /// \return The new node.
[109]651    Node addNode() { return Parent::addNode(); }
[209]652
[735]653    /// \brief Add a new edge to the graph.
654    ///
655    /// This function adds a new edge to the graph between nodes
656    /// \c u and \c v with inherent orientation from node \c u to
657    /// node \c v.
658    /// \return The new edge.
659    Edge addEdge(Node u, Node v) {
660      return Parent::addEdge(u, v);
[109]661    }
662
[149]663    /// \brief Node validity check
664    ///
[735]665    /// This function gives back \c true if the given node is valid,
666    /// i.e. it is a real node of the graph.
[149]667    ///
668    /// \warning A removed node (using Snapshot) could become valid again
[735]669    /// if new nodes are added to the graph.
[149]670    bool valid(Node n) const { return Parent::valid(n); }
671
[735]672    /// \brief Edge validity check
673    ///
674    /// This function gives back \c true if the given edge is valid,
675    /// i.e. it is a real edge of the graph.
676    ///
677    /// \warning A removed edge (using Snapshot) could become valid again
678    /// if new edges are added to the graph.
679    bool valid(Edge e) const { return Parent::valid(e); }
680
[149]681    /// \brief Arc validity check
682    ///
[735]683    /// This function gives back \c true if the given arc is valid,
684    /// i.e. it is a real arc of the graph.
[149]685    ///
686    /// \warning A removed arc (using Snapshot) could become valid again
[735]687    /// if new edges are added to the graph.
[149]688    bool valid(Arc a) const { return Parent::valid(a); }
689
[109]690    ///Clear the graph.
[209]691
[735]692    ///This function erases all nodes and arcs from the graph.
[109]693    ///
694    void clear() {
695      Parent::clear();
696    }
697
[736]698    /// Reserve memory for nodes.
699
700    /// Using this function, it is possible to avoid superfluous memory
701    /// allocation: if you know that the graph you want to build will
702    /// be large (e.g. it will contain millions of nodes and/or edges),
703    /// then it is worth reserving space for this amount before starting
704    /// to build the graph.
705    /// \sa reserveEdge()
706    void reserveNode(int n) { nodes.reserve(n); };
707
708    /// Reserve memory for edges.
709
710    /// Using this function, it is possible to avoid superfluous memory
711    /// allocation: if you know that the graph you want to build will
712    /// be large (e.g. it will contain millions of nodes and/or edges),
713    /// then it is worth reserving space for this amount before starting
714    /// to build the graph.
715    /// \sa reserveNode()
716    void reserveEdge(int m) { arcs.reserve(2 * m); };
717
[109]718  public:
[209]719
[109]720    class Snapshot;
721
722  protected:
723
724    void saveSnapshot(Snapshot &s)
725    {
726      s._graph = this;
727      s.node_num = nodes.size();
728      s.arc_num = arcs.size();
729    }
730
731    void restoreSnapshot(const Snapshot &s)
732    {
733      while(s.arc_num<arcs.size()) {
734        int n=arcs.size()-1;
735        Edge arc=edgeFromId(n/2);
[209]736        Parent::notifier(Edge()).erase(arc);
[109]737        std::vector<Arc> dir;
738        dir.push_back(arcFromId(n));
739        dir.push_back(arcFromId(n-1));
[209]740        Parent::notifier(Arc()).erase(dir);
[373]741        nodes[arcs[n-1].target].first_out=arcs[n].next_out;
742        nodes[arcs[n].target].first_out=arcs[n-1].next_out;
[209]743        arcs.pop_back();
744        arcs.pop_back();
[109]745      }
746      while(s.node_num<nodes.size()) {
747        int n=nodes.size()-1;
748        Node node = nodeFromId(n);
[209]749        Parent::notifier(Node()).erase(node);
750        nodes.pop_back();
[109]751      }
[209]752    }
[109]753
754  public:
755
[735]756    ///Class to make a snapshot of the graph and to restore it later.
[109]757
[735]758    ///Class to make a snapshot of the graph and to restore it later.
[109]759    ///
[735]760    ///The newly added nodes and edges can be removed using the
761    ///restore() function. This is the only way for deleting nodes and/or
762    ///edges from a SmartGraph structure.
[109]763    ///
[877]764    ///\note After a state is restored, you cannot restore a later state,
[735]765    ///i.e. you cannot add the removed nodes and edges again using
766    ///another Snapshot instance.
[109]767    ///
[735]768    ///\warning The validity of the snapshot is not stored due to
769    ///performance reasons. If you do not use the snapshot correctly,
770    ///it can cause broken program, invalid or not restored state of
771    ///the graph or no change.
[209]772    class Snapshot
[109]773    {
774      SmartGraph *_graph;
775    protected:
776      friend class SmartGraph;
777      unsigned int node_num;
778      unsigned int arc_num;
779    public:
780      ///Default constructor.
[209]781
[109]782      ///Default constructor.
[735]783      ///You have to call save() to actually make a snapshot.
[109]784      Snapshot() : _graph(0) {}
785      ///Constructor that immediately makes a snapshot
[209]786
[735]787      /// This constructor immediately makes a snapshot of the given graph.
788      ///
789      Snapshot(SmartGraph &gr) {
790        gr.saveSnapshot(*this);
[109]791      }
792
793      ///Make a snapshot.
794
[735]795      ///This function makes a snapshot of the given graph.
796      ///It can be called more than once. In case of a repeated
[109]797      ///call, the previous snapshot gets lost.
[735]798      void save(SmartGraph &gr)
[109]799      {
[735]800        gr.saveSnapshot(*this);
[109]801      }
802
[735]803      ///Undo the changes until the last snapshot.
[209]804
[735]805      ///This function undos the changes until the last snapshot
806      ///created by save() or Snapshot(SmartGraph&).
[109]807      void restore()
808      {
809        _graph->restoreSnapshot(*this);
810      }
811    };
812  };
[209]813
[109]814} //namespace lemon
815
816
817#endif //LEMON_SMART_GRAPH_H
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