COIN-OR::LEMON - Graph Library

source: lemon-1.2/lemon/concepts/graph_components.h @ 580:2313edd0db0b

Last change on this file since 580:2313edd0db0b was 580:2313edd0db0b, checked in by Peter Kovacs <kpeter@…>, 11 years ago

Standard graph maps are required to be reference maps (#190)

File size: 47.9 KB
Line 
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///\ingroup graph_concepts
20///\file
21///\brief The concept of graph components.
22
23#ifndef LEMON_CONCEPTS_GRAPH_COMPONENTS_H
24#define LEMON_CONCEPTS_GRAPH_COMPONENTS_H
25
26#include <lemon/core.h>
27#include <lemon/concepts/maps.h>
28
29#include <lemon/bits/alteration_notifier.h>
30
31namespace lemon {
32  namespace concepts {
33
34    /// \brief Concept class for \c Node, \c Arc and \c Edge types.
35    ///
36    /// This class describes the concept of \c Node, \c Arc and \c Edge
37    /// subtypes of digraph and graph types.
38    ///
39    /// \note This class is a template class so that we can use it to
40    /// create graph skeleton classes. The reason for this is that \c Node
41    /// and \c Arc (or \c Edge) types should \e not derive from the same
42    /// base class. For \c Node you should instantiate it with character
43    /// \c 'n', for \c Arc with \c 'a' and for \c Edge with \c 'e'.
44#ifndef DOXYGEN
45    template <char sel = '0'>
46#endif
47    class GraphItem {
48    public:
49      /// \brief Default constructor.
50      ///
51      /// Default constructor.
52      /// \warning The default constructor is not required to set
53      /// the item to some well-defined value. So you should consider it
54      /// as uninitialized.
55      GraphItem() {}
56
57      /// \brief Copy constructor.
58      ///
59      /// Copy constructor.
60      GraphItem(const GraphItem &) {}
61
62      /// \brief Constructor for conversion from \c INVALID.
63      ///
64      /// Constructor for conversion from \c INVALID.
65      /// It initializes the item to be invalid.
66      /// \sa Invalid for more details.
67      GraphItem(Invalid) {}
68
69      /// \brief Assignment operator.
70      ///
71      /// Assignment operator for the item.
72      GraphItem& operator=(const GraphItem&) { return *this; }
73
74      /// \brief Equality operator.
75      ///
76      /// Equality operator.
77      bool operator==(const GraphItem&) const { return false; }
78
79      /// \brief Inequality operator.
80      ///
81      /// Inequality operator.
82      bool operator!=(const GraphItem&) const { return false; }
83
84      /// \brief Ordering operator.
85      ///
86      /// This operator defines an ordering of the items.
87      /// It makes possible to use graph item types as key types in
88      /// associative containers (e.g. \c std::map).
89      ///
90      /// \note This operator only have to define some strict ordering of
91      /// the items; this order has nothing to do with the iteration
92      /// ordering of the items.
93      bool operator<(const GraphItem&) const { return false; }
94
95      template<typename _GraphItem>
96      struct Constraints {
97        void constraints() {
98          _GraphItem i1;
99          _GraphItem i2 = i1;
100          _GraphItem i3 = INVALID;
101
102          i1 = i2 = i3;
103
104          bool b;
105          b = (ia == ib) && (ia != ib);
106          b = (ia == INVALID) && (ib != INVALID);
107          b = (ia < ib);
108        }
109
110        const _GraphItem &ia;
111        const _GraphItem &ib;
112      };
113    };
114
115    /// \brief Base skeleton class for directed graphs.
116    ///
117    /// This class describes the base interface of directed graph types.
118    /// All digraph %concepts have to conform to this class.
119    /// It just provides types for nodes and arcs and functions
120    /// to get the source and the target nodes of arcs.
121    class BaseDigraphComponent {
122    public:
123
124      typedef BaseDigraphComponent Digraph;
125
126      /// \brief Node class of the digraph.
127      ///
128      /// This class represents the nodes of the digraph.
129      typedef GraphItem<'n'> Node;
130
131      /// \brief Arc class of the digraph.
132      ///
133      /// This class represents the arcs of the digraph.
134      typedef GraphItem<'a'> Arc;
135
136      /// \brief Return the source node of an arc.
137      ///
138      /// This function returns the source node of an arc.
139      Node source(const Arc&) const { return INVALID; }
140
141      /// \brief Return the target node of an arc.
142      ///
143      /// This function returns the target node of an arc.
144      Node target(const Arc&) const { return INVALID; }
145
146      /// \brief Return the opposite node on the given arc.
147      ///
148      /// This function returns the opposite node on the given arc.
149      Node oppositeNode(const Node&, const Arc&) const {
150        return INVALID;
151      }
152
153      template <typename _Digraph>
154      struct Constraints {
155        typedef typename _Digraph::Node Node;
156        typedef typename _Digraph::Arc Arc;
157
158        void constraints() {
159          checkConcept<GraphItem<'n'>, Node>();
160          checkConcept<GraphItem<'a'>, Arc>();
161          {
162            Node n;
163            Arc e(INVALID);
164            n = digraph.source(e);
165            n = digraph.target(e);
166            n = digraph.oppositeNode(n, e);
167          }
168        }
169
170        const _Digraph& digraph;
171      };
172    };
173
174    /// \brief Base skeleton class for undirected graphs.
175    ///
176    /// This class describes the base interface of undirected graph types.
177    /// All graph %concepts have to conform to this class.
178    /// It extends the interface of \ref BaseDigraphComponent with an
179    /// \c Edge type and functions to get the end nodes of edges,
180    /// to convert from arcs to edges and to get both direction of edges.
181    class BaseGraphComponent : public BaseDigraphComponent {
182    public:
183      typedef BaseDigraphComponent::Node Node;
184      typedef BaseDigraphComponent::Arc Arc;
185
186      /// \brief Undirected edge class of the graph.
187      ///
188      /// This class represents the undirected edges of the graph.
189      /// Undirected graphs can be used as directed graphs, each edge is
190      /// represented by two opposite directed arcs.
191      class Edge : public GraphItem<'e'> {
192      public:
193        typedef GraphItem<'e'> Parent;
194
195        /// \brief Default constructor.
196        ///
197        /// Default constructor.
198        /// \warning The default constructor is not required to set
199        /// the item to some well-defined value. So you should consider it
200        /// as uninitialized.
201        Edge() {}
202
203        /// \brief Copy constructor.
204        ///
205        /// Copy constructor.
206        Edge(const Edge &) : Parent() {}
207
208        /// \brief Constructor for conversion from \c INVALID.
209        ///
210        /// Constructor for conversion from \c INVALID.
211        /// It initializes the item to be invalid.
212        /// \sa Invalid for more details.
213        Edge(Invalid) {}
214
215        /// \brief Constructor for conversion from an arc.
216        ///
217        /// Constructor for conversion from an arc.
218        /// Besides the core graph item functionality each arc should
219        /// be convertible to the represented edge.
220        Edge(const Arc&) {}
221
222        /// \brief Assign an arc to an edge.
223        ///
224        /// This function assigns an arc to an edge.
225        /// Besides the core graph item functionality each arc should
226        /// be convertible to the represented edge.
227        Edge& operator=(const Arc&) { return *this; }
228      };
229
230      /// \brief Return one end node of an edge.
231      ///
232      /// This function returns one end node of an edge.
233      Node u(const Edge&) const { return INVALID; }
234
235      /// \brief Return the other end node of an edge.
236      ///
237      /// This function returns the other end node of an edge.
238      Node v(const Edge&) const { return INVALID; }
239
240      /// \brief Return a directed arc related to an edge.
241      ///
242      /// This function returns a directed arc from its direction and the
243      /// represented edge.
244      Arc direct(const Edge&, bool) const { return INVALID; }
245
246      /// \brief Return a directed arc related to an edge.
247      ///
248      /// This function returns a directed arc from its source node and the
249      /// represented edge.
250      Arc direct(const Edge&, const Node&) const { return INVALID; }
251
252      /// \brief Return the direction of the arc.
253      ///
254      /// Returns the direction of the arc. Each arc represents an
255      /// edge with a direction. It gives back the
256      /// direction.
257      bool direction(const Arc&) const { return true; }
258
259      /// \brief Return the opposite arc.
260      ///
261      /// This function returns the opposite arc, i.e. the arc representing
262      /// the same edge and has opposite direction.
263      Arc oppositeArc(const Arc&) const { return INVALID; }
264
265      template <typename _Graph>
266      struct Constraints {
267        typedef typename _Graph::Node Node;
268        typedef typename _Graph::Arc Arc;
269        typedef typename _Graph::Edge Edge;
270
271        void constraints() {
272          checkConcept<BaseDigraphComponent, _Graph>();
273          checkConcept<GraphItem<'e'>, Edge>();
274          {
275            Node n;
276            Edge ue(INVALID);
277            Arc e;
278            n = graph.u(ue);
279            n = graph.v(ue);
280            e = graph.direct(ue, true);
281            e = graph.direct(ue, false);
282            e = graph.direct(ue, n);
283            e = graph.oppositeArc(e);
284            ue = e;
285            bool d = graph.direction(e);
286            ignore_unused_variable_warning(d);
287          }
288        }
289
290        const _Graph& graph;
291      };
292
293    };
294
295    /// \brief Skeleton class for \e idable directed graphs.
296    ///
297    /// This class describes the interface of \e idable directed graphs.
298    /// It extends \ref BaseDigraphComponent with the core ID functions.
299    /// The ids of the items must be unique and immutable.
300    /// This concept is part of the Digraph concept.
301    template <typename BAS = BaseDigraphComponent>
302    class IDableDigraphComponent : public BAS {
303    public:
304
305      typedef BAS Base;
306      typedef typename Base::Node Node;
307      typedef typename Base::Arc Arc;
308
309      /// \brief Return a unique integer id for the given node.
310      ///
311      /// This function returns a unique integer id for the given node.
312      int id(const Node&) const { return -1; }
313
314      /// \brief Return the node by its unique id.
315      ///
316      /// This function returns the node by its unique id.
317      /// If the digraph does not contain a node with the given id,
318      /// then the result of the function is undefined.
319      Node nodeFromId(int) const { return INVALID; }
320
321      /// \brief Return a unique integer id for the given arc.
322      ///
323      /// This function returns a unique integer id for the given arc.
324      int id(const Arc&) const { return -1; }
325
326      /// \brief Return the arc by its unique id.
327      ///
328      /// This function returns the arc by its unique id.
329      /// If the digraph does not contain an arc with the given id,
330      /// then the result of the function is undefined.
331      Arc arcFromId(int) const { return INVALID; }
332
333      /// \brief Return an integer greater or equal to the maximum
334      /// node id.
335      ///
336      /// This function returns an integer greater or equal to the
337      /// maximum node id.
338      int maxNodeId() const { return -1; }
339
340      /// \brief Return an integer greater or equal to the maximum
341      /// arc id.
342      ///
343      /// This function returns an integer greater or equal to the
344      /// maximum arc id.
345      int maxArcId() const { return -1; }
346
347      template <typename _Digraph>
348      struct Constraints {
349
350        void constraints() {
351          checkConcept<Base, _Digraph >();
352          typename _Digraph::Node node;
353          int nid = digraph.id(node);
354          nid = digraph.id(node);
355          node = digraph.nodeFromId(nid);
356          typename _Digraph::Arc arc;
357          int eid = digraph.id(arc);
358          eid = digraph.id(arc);
359          arc = digraph.arcFromId(eid);
360
361          nid = digraph.maxNodeId();
362          ignore_unused_variable_warning(nid);
363          eid = digraph.maxArcId();
364          ignore_unused_variable_warning(eid);
365        }
366
367        const _Digraph& digraph;
368      };
369    };
370
371    /// \brief Skeleton class for \e idable undirected graphs.
372    ///
373    /// This class describes the interface of \e idable undirected
374    /// graphs. It extends \ref IDableDigraphComponent with the core ID
375    /// functions of undirected graphs.
376    /// The ids of the items must be unique and immutable.
377    /// This concept is part of the Graph concept.
378    template <typename BAS = BaseGraphComponent>
379    class IDableGraphComponent : public IDableDigraphComponent<BAS> {
380    public:
381
382      typedef BAS Base;
383      typedef typename Base::Edge Edge;
384
385      using IDableDigraphComponent<Base>::id;
386
387      /// \brief Return a unique integer id for the given edge.
388      ///
389      /// This function returns a unique integer id for the given edge.
390      int id(const Edge&) const { return -1; }
391
392      /// \brief Return the edge by its unique id.
393      ///
394      /// This function returns the edge by its unique id.
395      /// If the graph does not contain an edge with the given id,
396      /// then the result of the function is undefined.
397      Edge edgeFromId(int) const { return INVALID; }
398
399      /// \brief Return an integer greater or equal to the maximum
400      /// edge id.
401      ///
402      /// This function returns an integer greater or equal to the
403      /// maximum edge id.
404      int maxEdgeId() const { return -1; }
405
406      template <typename _Graph>
407      struct Constraints {
408
409        void constraints() {
410          checkConcept<IDableDigraphComponent<Base>, _Graph >();
411          typename _Graph::Edge edge;
412          int ueid = graph.id(edge);
413          ueid = graph.id(edge);
414          edge = graph.edgeFromId(ueid);
415          ueid = graph.maxEdgeId();
416          ignore_unused_variable_warning(ueid);
417        }
418
419        const _Graph& graph;
420      };
421    };
422
423    /// \brief Concept class for \c NodeIt, \c ArcIt and \c EdgeIt types.
424    ///
425    /// This class describes the concept of \c NodeIt, \c ArcIt and
426    /// \c EdgeIt subtypes of digraph and graph types.
427    template <typename GR, typename Item>
428    class GraphItemIt : public Item {
429    public:
430      /// \brief Default constructor.
431      ///
432      /// Default constructor.
433      /// \warning The default constructor is not required to set
434      /// the iterator to some well-defined value. So you should consider it
435      /// as uninitialized.
436      GraphItemIt() {}
437
438      /// \brief Copy constructor.
439      ///
440      /// Copy constructor.
441      GraphItemIt(const GraphItemIt& it) : Item(it) {}
442
443      /// \brief Constructor that sets the iterator to the first item.
444      ///
445      /// Constructor that sets the iterator to the first item.
446      explicit GraphItemIt(const GR&) {}
447
448      /// \brief Constructor for conversion from \c INVALID.
449      ///
450      /// Constructor for conversion from \c INVALID.
451      /// It initializes the iterator to be invalid.
452      /// \sa Invalid for more details.
453      GraphItemIt(Invalid) {}
454
455      /// \brief Assignment operator.
456      ///
457      /// Assignment operator for the iterator.
458      GraphItemIt& operator=(const GraphItemIt&) { return *this; }
459
460      /// \brief Increment the iterator.
461      ///
462      /// This operator increments the iterator, i.e. assigns it to the
463      /// next item.
464      GraphItemIt& operator++() { return *this; }
465 
466      /// \brief Equality operator
467      ///
468      /// Equality operator.
469      /// Two iterators are equal if and only if they point to the
470      /// same object or both are invalid.
471      bool operator==(const GraphItemIt&) const { return true;}
472
473      /// \brief Inequality operator
474      ///
475      /// Inequality operator.
476      /// Two iterators are equal if and only if they point to the
477      /// same object or both are invalid.
478      bool operator!=(const GraphItemIt&) const { return true;}
479
480      template<typename _GraphItemIt>
481      struct Constraints {
482        void constraints() {
483          checkConcept<GraphItem<>, _GraphItemIt>();
484          _GraphItemIt it1(g);
485          _GraphItemIt it2;
486          _GraphItemIt it3 = it1;
487          _GraphItemIt it4 = INVALID;
488
489          it2 = ++it1;
490          ++it2 = it1;
491          ++(++it1);
492
493          Item bi = it1;
494          bi = it2;
495        }
496        const GR& g;
497      };
498    };
499
500    /// \brief Concept class for \c InArcIt, \c OutArcIt and
501    /// \c IncEdgeIt types.
502    ///
503    /// This class describes the concept of \c InArcIt, \c OutArcIt
504    /// and \c IncEdgeIt subtypes of digraph and graph types.
505    ///
506    /// \note Since these iterator classes do not inherit from the same
507    /// base class, there is an additional template parameter (selector)
508    /// \c sel. For \c InArcIt you should instantiate it with character
509    /// \c 'i', for \c OutArcIt with \c 'o' and for \c IncEdgeIt with \c 'e'.
510    template <typename GR,
511              typename Item = typename GR::Arc,
512              typename Base = typename GR::Node,
513              char sel = '0'>
514    class GraphIncIt : public Item {
515    public:
516      /// \brief Default constructor.
517      ///
518      /// Default constructor.
519      /// \warning The default constructor is not required to set
520      /// the iterator to some well-defined value. So you should consider it
521      /// as uninitialized.
522      GraphIncIt() {}
523
524      /// \brief Copy constructor.
525      ///
526      /// Copy constructor.
527      GraphIncIt(const GraphIncIt& it) : Item(it) {}
528
529      /// \brief Constructor that sets the iterator to the first
530      /// incoming or outgoing arc.
531      ///
532      /// Constructor that sets the iterator to the first arc
533      /// incoming to or outgoing from the given node.
534      explicit GraphIncIt(const GR&, const Base&) {}
535
536      /// \brief Constructor for conversion from \c INVALID.
537      ///
538      /// Constructor for conversion from \c INVALID.
539      /// It initializes the iterator to be invalid.
540      /// \sa Invalid for more details.
541      GraphIncIt(Invalid) {}
542
543      /// \brief Assignment operator.
544      ///
545      /// Assignment operator for the iterator.
546      GraphIncIt& operator=(const GraphIncIt&) { return *this; }
547
548      /// \brief Increment the iterator.
549      ///
550      /// This operator increments the iterator, i.e. assigns it to the
551      /// next arc incoming to or outgoing from the given node.
552      GraphIncIt& operator++() { return *this; }
553
554      /// \brief Equality operator
555      ///
556      /// Equality operator.
557      /// Two iterators are equal if and only if they point to the
558      /// same object or both are invalid.
559      bool operator==(const GraphIncIt&) const { return true;}
560
561      /// \brief Inequality operator
562      ///
563      /// Inequality operator.
564      /// Two iterators are equal if and only if they point to the
565      /// same object or both are invalid.
566      bool operator!=(const GraphIncIt&) const { return true;}
567
568      template <typename _GraphIncIt>
569      struct Constraints {
570        void constraints() {
571          checkConcept<GraphItem<sel>, _GraphIncIt>();
572          _GraphIncIt it1(graph, node);
573          _GraphIncIt it2;
574          _GraphIncIt it3 = it1;
575          _GraphIncIt it4 = INVALID;
576
577          it2 = ++it1;
578          ++it2 = it1;
579          ++(++it1);
580          Item e = it1;
581          e = it2;
582        }
583        const Base& node;
584        const GR& graph;
585      };
586    };
587
588    /// \brief Skeleton class for iterable directed graphs.
589    ///
590    /// This class describes the interface of iterable directed
591    /// graphs. It extends \ref BaseDigraphComponent with the core
592    /// iterable interface.
593    /// This concept is part of the Digraph concept.
594    template <typename BAS = BaseDigraphComponent>
595    class IterableDigraphComponent : public BAS {
596
597    public:
598
599      typedef BAS Base;
600      typedef typename Base::Node Node;
601      typedef typename Base::Arc Arc;
602
603      typedef IterableDigraphComponent Digraph;
604
605      /// \name Base iteration
606      ///
607      /// This interface provides functions for iteration on digraph items.
608      ///
609      /// @{
610
611      /// \brief Return the first node.
612      ///
613      /// This function gives back the first node in the iteration order.
614      void first(Node&) const {}
615
616      /// \brief Return the next node.
617      ///
618      /// This function gives back the next node in the iteration order.
619      void next(Node&) const {}
620
621      /// \brief Return the first arc.
622      ///
623      /// This function gives back the first arc in the iteration order.
624      void first(Arc&) const {}
625
626      /// \brief Return the next arc.
627      ///
628      /// This function gives back the next arc in the iteration order.
629      void next(Arc&) const {}
630
631      /// \brief Return the first arc incomming to the given node.
632      ///
633      /// This function gives back the first arc incomming to the
634      /// given node.
635      void firstIn(Arc&, const Node&) const {}
636
637      /// \brief Return the next arc incomming to the given node.
638      ///
639      /// This function gives back the next arc incomming to the
640      /// given node.
641      void nextIn(Arc&) const {}
642
643      /// \brief Return the first arc outgoing form the given node.
644      ///
645      /// This function gives back the first arc outgoing form the
646      /// given node.
647      void firstOut(Arc&, const Node&) const {}
648
649      /// \brief Return the next arc outgoing form the given node.
650      ///
651      /// This function gives back the next arc outgoing form the
652      /// given node.
653      void nextOut(Arc&) const {}
654
655      /// @}
656
657      /// \name Class based iteration
658      ///
659      /// This interface provides iterator classes for digraph items.
660      ///
661      /// @{
662
663      /// \brief This iterator goes through each node.
664      ///
665      /// This iterator goes through each node.
666      ///
667      typedef GraphItemIt<Digraph, Node> NodeIt;
668
669      /// \brief This iterator goes through each arc.
670      ///
671      /// This iterator goes through each arc.
672      ///
673      typedef GraphItemIt<Digraph, Arc> ArcIt;
674
675      /// \brief This iterator goes trough the incoming arcs of a node.
676      ///
677      /// This iterator goes trough the \e incoming arcs of a certain node
678      /// of a digraph.
679      typedef GraphIncIt<Digraph, Arc, Node, 'i'> InArcIt;
680
681      /// \brief This iterator goes trough the outgoing arcs of a node.
682      ///
683      /// This iterator goes trough the \e outgoing arcs of a certain node
684      /// of a digraph.
685      typedef GraphIncIt<Digraph, Arc, Node, 'o'> OutArcIt;
686
687      /// \brief The base node of the iterator.
688      ///
689      /// This function gives back the base node of the iterator.
690      /// It is always the target node of the pointed arc.
691      Node baseNode(const InArcIt&) const { return INVALID; }
692
693      /// \brief The running node of the iterator.
694      ///
695      /// This function gives back the running node of the iterator.
696      /// It is always the source node of the pointed arc.
697      Node runningNode(const InArcIt&) const { return INVALID; }
698
699      /// \brief The base node of the iterator.
700      ///
701      /// This function gives back the base node of the iterator.
702      /// It is always the source node of the pointed arc.
703      Node baseNode(const OutArcIt&) const { return INVALID; }
704
705      /// \brief The running node of the iterator.
706      ///
707      /// This function gives back the running node of the iterator.
708      /// It is always the target node of the pointed arc.
709      Node runningNode(const OutArcIt&) const { return INVALID; }
710
711      /// @}
712
713      template <typename _Digraph>
714      struct Constraints {
715        void constraints() {
716          checkConcept<Base, _Digraph>();
717
718          {
719            typename _Digraph::Node node(INVALID);
720            typename _Digraph::Arc arc(INVALID);
721            {
722              digraph.first(node);
723              digraph.next(node);
724            }
725            {
726              digraph.first(arc);
727              digraph.next(arc);
728            }
729            {
730              digraph.firstIn(arc, node);
731              digraph.nextIn(arc);
732            }
733            {
734              digraph.firstOut(arc, node);
735              digraph.nextOut(arc);
736            }
737          }
738
739          {
740            checkConcept<GraphItemIt<_Digraph, typename _Digraph::Arc>,
741              typename _Digraph::ArcIt >();
742            checkConcept<GraphItemIt<_Digraph, typename _Digraph::Node>,
743              typename _Digraph::NodeIt >();
744            checkConcept<GraphIncIt<_Digraph, typename _Digraph::Arc,
745              typename _Digraph::Node, 'i'>, typename _Digraph::InArcIt>();
746            checkConcept<GraphIncIt<_Digraph, typename _Digraph::Arc,
747              typename _Digraph::Node, 'o'>, typename _Digraph::OutArcIt>();
748
749            typename _Digraph::Node n;
750            const typename _Digraph::InArcIt iait(INVALID);
751            const typename _Digraph::OutArcIt oait(INVALID);
752            n = digraph.baseNode(iait);
753            n = digraph.runningNode(iait);
754            n = digraph.baseNode(oait);
755            n = digraph.runningNode(oait);
756            ignore_unused_variable_warning(n);
757          }
758        }
759
760        const _Digraph& digraph;
761      };
762    };
763
764    /// \brief Skeleton class for iterable undirected graphs.
765    ///
766    /// This class describes the interface of iterable undirected
767    /// graphs. It extends \ref IterableDigraphComponent with the core
768    /// iterable interface of undirected graphs.
769    /// This concept is part of the Graph concept.
770    template <typename BAS = BaseGraphComponent>
771    class IterableGraphComponent : public IterableDigraphComponent<BAS> {
772    public:
773
774      typedef BAS Base;
775      typedef typename Base::Node Node;
776      typedef typename Base::Arc Arc;
777      typedef typename Base::Edge Edge;
778
779
780      typedef IterableGraphComponent Graph;
781
782      /// \name Base iteration
783      ///
784      /// This interface provides functions for iteration on edges.
785      ///
786      /// @{
787
788      using IterableDigraphComponent<Base>::first;
789      using IterableDigraphComponent<Base>::next;
790
791      /// \brief Return the first edge.
792      ///
793      /// This function gives back the first edge in the iteration order.
794      void first(Edge&) const {}
795
796      /// \brief Return the next edge.
797      ///
798      /// This function gives back the next edge in the iteration order.
799      void next(Edge&) const {}
800
801      /// \brief Return the first edge incident to the given node.
802      ///
803      /// This function gives back the first edge incident to the given
804      /// node. The bool parameter gives back the direction for which the
805      /// source node of the directed arc representing the edge is the
806      /// given node.
807      void firstInc(Edge&, bool&, const Node&) const {}
808
809      /// \brief Gives back the next of the edges from the
810      /// given node.
811      ///
812      /// This function gives back the next edge incident to the given
813      /// node. The bool parameter should be used as \c firstInc() use it.
814      void nextInc(Edge&, bool&) const {}
815
816      using IterableDigraphComponent<Base>::baseNode;
817      using IterableDigraphComponent<Base>::runningNode;
818
819      /// @}
820
821      /// \name Class based iteration
822      ///
823      /// This interface provides iterator classes for edges.
824      ///
825      /// @{
826
827      /// \brief This iterator goes through each edge.
828      ///
829      /// This iterator goes through each edge.
830      typedef GraphItemIt<Graph, Edge> EdgeIt;
831
832      /// \brief This iterator goes trough the incident edges of a
833      /// node.
834      ///
835      /// This iterator goes trough the incident edges of a certain
836      /// node of a graph.
837      typedef GraphIncIt<Graph, Edge, Node, 'e'> IncEdgeIt;
838
839      /// \brief The base node of the iterator.
840      ///
841      /// This function gives back the base node of the iterator.
842      Node baseNode(const IncEdgeIt&) const { return INVALID; }
843
844      /// \brief The running node of the iterator.
845      ///
846      /// This function gives back the running node of the iterator.
847      Node runningNode(const IncEdgeIt&) const { return INVALID; }
848
849      /// @}
850
851      template <typename _Graph>
852      struct Constraints {
853        void constraints() {
854          checkConcept<IterableDigraphComponent<Base>, _Graph>();
855
856          {
857            typename _Graph::Node node(INVALID);
858            typename _Graph::Edge edge(INVALID);
859            bool dir;
860            {
861              graph.first(edge);
862              graph.next(edge);
863            }
864            {
865              graph.firstInc(edge, dir, node);
866              graph.nextInc(edge, dir);
867            }
868
869          }
870
871          {
872            checkConcept<GraphItemIt<_Graph, typename _Graph::Edge>,
873              typename _Graph::EdgeIt >();
874            checkConcept<GraphIncIt<_Graph, typename _Graph::Edge,
875              typename _Graph::Node, 'e'>, typename _Graph::IncEdgeIt>();
876
877            typename _Graph::Node n;
878            const typename _Graph::IncEdgeIt ieit(INVALID);
879            n = graph.baseNode(ieit);
880            n = graph.runningNode(ieit);
881          }
882        }
883
884        const _Graph& graph;
885      };
886    };
887
888    /// \brief Skeleton class for alterable directed graphs.
889    ///
890    /// This class describes the interface of alterable directed
891    /// graphs. It extends \ref BaseDigraphComponent with the alteration
892    /// notifier interface. It implements
893    /// an observer-notifier pattern for each digraph item. More
894    /// obsevers can be registered into the notifier and whenever an
895    /// alteration occured in the digraph all the observers will be
896    /// notified about it.
897    template <typename BAS = BaseDigraphComponent>
898    class AlterableDigraphComponent : public BAS {
899    public:
900
901      typedef BAS Base;
902      typedef typename Base::Node Node;
903      typedef typename Base::Arc Arc;
904
905
906      /// Node alteration notifier class.
907      typedef AlterationNotifier<AlterableDigraphComponent, Node>
908      NodeNotifier;
909      /// Arc alteration notifier class.
910      typedef AlterationNotifier<AlterableDigraphComponent, Arc>
911      ArcNotifier;
912
913      /// \brief Return the node alteration notifier.
914      ///
915      /// This function gives back the node alteration notifier.
916      NodeNotifier& notifier(Node) const {
917         return NodeNotifier();
918      }
919
920      /// \brief Return the arc alteration notifier.
921      ///
922      /// This function gives back the arc alteration notifier.
923      ArcNotifier& notifier(Arc) const {
924        return ArcNotifier();
925      }
926
927      template <typename _Digraph>
928      struct Constraints {
929        void constraints() {
930          checkConcept<Base, _Digraph>();
931          typename _Digraph::NodeNotifier& nn
932            = digraph.notifier(typename _Digraph::Node());
933
934          typename _Digraph::ArcNotifier& en
935            = digraph.notifier(typename _Digraph::Arc());
936
937          ignore_unused_variable_warning(nn);
938          ignore_unused_variable_warning(en);
939        }
940
941        const _Digraph& digraph;
942      };
943    };
944
945    /// \brief Skeleton class for alterable undirected graphs.
946    ///
947    /// This class describes the interface of alterable undirected
948    /// graphs. It extends \ref AlterableDigraphComponent with the alteration
949    /// notifier interface of undirected graphs. It implements
950    /// an observer-notifier pattern for the edges. More
951    /// obsevers can be registered into the notifier and whenever an
952    /// alteration occured in the graph all the observers will be
953    /// notified about it.
954    template <typename BAS = BaseGraphComponent>
955    class AlterableGraphComponent : public AlterableDigraphComponent<BAS> {
956    public:
957
958      typedef BAS Base;
959      typedef typename Base::Edge Edge;
960
961
962      /// Edge alteration notifier class.
963      typedef AlterationNotifier<AlterableGraphComponent, Edge>
964      EdgeNotifier;
965
966      /// \brief Return the edge alteration notifier.
967      ///
968      /// This function gives back the edge alteration notifier.
969      EdgeNotifier& notifier(Edge) const {
970        return EdgeNotifier();
971      }
972
973      template <typename _Graph>
974      struct Constraints {
975        void constraints() {
976          checkConcept<AlterableDigraphComponent<Base>, _Graph>();
977          typename _Graph::EdgeNotifier& uen
978            = graph.notifier(typename _Graph::Edge());
979          ignore_unused_variable_warning(uen);
980        }
981
982        const _Graph& graph;
983      };
984    };
985
986    /// \brief Concept class for standard graph maps.
987    ///
988    /// This class describes the concept of standard graph maps, i.e.
989    /// the \c NodeMap, \c ArcMap and \c EdgeMap subtypes of digraph and
990    /// graph types, which can be used for associating data to graph items.
991    /// The standard graph maps must conform to the ReferenceMap concept.
992    template <typename GR, typename K, typename V>
993    class GraphMap : public ReferenceMap<K, V, V&, const V&> {
994    public:
995
996      typedef ReadWriteMap<K, V> Parent;
997
998      /// The graph type of the map.
999      typedef GR Graph;
1000      /// The key type of the map.
1001      typedef K Key;
1002      /// The value type of the map.
1003      typedef V Value;
1004      /// The reference type of the map.
1005      typedef Value& Reference;
1006      /// The const reference type of the map.
1007      typedef const Value& ConstReference;
1008
1009      // The reference map tag.
1010      typedef True ReferenceMapTag;
1011
1012      /// \brief Construct a new map.
1013      ///
1014      /// Construct a new map for the graph.
1015      explicit GraphMap(const Graph&) {}
1016      /// \brief Construct a new map with default value.
1017      ///
1018      /// Construct a new map for the graph and initalize the values.
1019      GraphMap(const Graph&, const Value&) {}
1020
1021    private:
1022      /// \brief Copy constructor.
1023      ///
1024      /// Copy Constructor.
1025      GraphMap(const GraphMap&) : Parent() {}
1026
1027      /// \brief Assignment operator.
1028      ///
1029      /// Assignment operator. It does not mofify the underlying graph,
1030      /// it just iterates on the current item set and set the  map
1031      /// with the value returned by the assigned map.
1032      template <typename CMap>
1033      GraphMap& operator=(const CMap&) {
1034        checkConcept<ReadMap<Key, Value>, CMap>();
1035        return *this;
1036      }
1037
1038    public:
1039      template<typename _Map>
1040      struct Constraints {
1041        void constraints() {
1042          checkConcept
1043            <ReferenceMap<Key, Value, Value&, const Value&>, _Map>();
1044          _Map m1(g);
1045          _Map m2(g,t);
1046         
1047          // Copy constructor
1048          // _Map m3(m);
1049
1050          // Assignment operator
1051          // ReadMap<Key, Value> cmap;
1052          // m3 = cmap;
1053
1054          ignore_unused_variable_warning(m1);
1055          ignore_unused_variable_warning(m2);
1056          // ignore_unused_variable_warning(m3);
1057        }
1058
1059        const _Map &m;
1060        const Graph &g;
1061        const typename GraphMap::Value &t;
1062      };
1063
1064    };
1065
1066    /// \brief Skeleton class for mappable directed graphs.
1067    ///
1068    /// This class describes the interface of mappable directed graphs.
1069    /// It extends \ref BaseDigraphComponent with the standard digraph
1070    /// map classes, namely \c NodeMap and \c ArcMap.
1071    /// This concept is part of the Digraph concept.
1072    template <typename BAS = BaseDigraphComponent>
1073    class MappableDigraphComponent : public BAS  {
1074    public:
1075
1076      typedef BAS Base;
1077      typedef typename Base::Node Node;
1078      typedef typename Base::Arc Arc;
1079
1080      typedef MappableDigraphComponent Digraph;
1081
1082      /// \brief Standard graph map for the nodes.
1083      ///
1084      /// Standard graph map for the nodes.
1085      /// It conforms to the ReferenceMap concept.
1086      template <typename V>
1087      class NodeMap : public GraphMap<MappableDigraphComponent, Node, V> {
1088      public:
1089        typedef GraphMap<MappableDigraphComponent, Node, V> Parent;
1090
1091        /// \brief Construct a new map.
1092        ///
1093        /// Construct a new map for the digraph.
1094        explicit NodeMap(const MappableDigraphComponent& digraph)
1095          : Parent(digraph) {}
1096
1097        /// \brief Construct a new map with default value.
1098        ///
1099        /// Construct a new map for the digraph and initalize the values.
1100        NodeMap(const MappableDigraphComponent& digraph, const V& value)
1101          : Parent(digraph, value) {}
1102
1103      private:
1104        /// \brief Copy constructor.
1105        ///
1106        /// Copy Constructor.
1107        NodeMap(const NodeMap& nm) : Parent(nm) {}
1108
1109        /// \brief Assignment operator.
1110        ///
1111        /// Assignment operator.
1112        template <typename CMap>
1113        NodeMap& operator=(const CMap&) {
1114          checkConcept<ReadMap<Node, V>, CMap>();
1115          return *this;
1116        }
1117
1118      };
1119
1120      /// \brief Standard graph map for the arcs.
1121      ///
1122      /// Standard graph map for the arcs.
1123      /// It conforms to the ReferenceMap concept.
1124      template <typename V>
1125      class ArcMap : public GraphMap<MappableDigraphComponent, Arc, V> {
1126      public:
1127        typedef GraphMap<MappableDigraphComponent, Arc, V> Parent;
1128
1129        /// \brief Construct a new map.
1130        ///
1131        /// Construct a new map for the digraph.
1132        explicit ArcMap(const MappableDigraphComponent& digraph)
1133          : Parent(digraph) {}
1134
1135        /// \brief Construct a new map with default value.
1136        ///
1137        /// Construct a new map for the digraph and initalize the values.
1138        ArcMap(const MappableDigraphComponent& digraph, const V& value)
1139          : Parent(digraph, value) {}
1140
1141      private:
1142        /// \brief Copy constructor.
1143        ///
1144        /// Copy Constructor.
1145        ArcMap(const ArcMap& nm) : Parent(nm) {}
1146
1147        /// \brief Assignment operator.
1148        ///
1149        /// Assignment operator.
1150        template <typename CMap>
1151        ArcMap& operator=(const CMap&) {
1152          checkConcept<ReadMap<Arc, V>, CMap>();
1153          return *this;
1154        }
1155
1156      };
1157
1158
1159      template <typename _Digraph>
1160      struct Constraints {
1161
1162        struct Dummy {
1163          int value;
1164          Dummy() : value(0) {}
1165          Dummy(int _v) : value(_v) {}
1166        };
1167
1168        void constraints() {
1169          checkConcept<Base, _Digraph>();
1170          { // int map test
1171            typedef typename _Digraph::template NodeMap<int> IntNodeMap;
1172            checkConcept<GraphMap<_Digraph, typename _Digraph::Node, int>,
1173              IntNodeMap >();
1174          } { // bool map test
1175            typedef typename _Digraph::template NodeMap<bool> BoolNodeMap;
1176            checkConcept<GraphMap<_Digraph, typename _Digraph::Node, bool>,
1177              BoolNodeMap >();
1178          } { // Dummy map test
1179            typedef typename _Digraph::template NodeMap<Dummy> DummyNodeMap;
1180            checkConcept<GraphMap<_Digraph, typename _Digraph::Node, Dummy>,
1181              DummyNodeMap >();
1182          }
1183
1184          { // int map test
1185            typedef typename _Digraph::template ArcMap<int> IntArcMap;
1186            checkConcept<GraphMap<_Digraph, typename _Digraph::Arc, int>,
1187              IntArcMap >();
1188          } { // bool map test
1189            typedef typename _Digraph::template ArcMap<bool> BoolArcMap;
1190            checkConcept<GraphMap<_Digraph, typename _Digraph::Arc, bool>,
1191              BoolArcMap >();
1192          } { // Dummy map test
1193            typedef typename _Digraph::template ArcMap<Dummy> DummyArcMap;
1194            checkConcept<GraphMap<_Digraph, typename _Digraph::Arc, Dummy>,
1195              DummyArcMap >();
1196          }
1197        }
1198
1199        const _Digraph& digraph;
1200      };
1201    };
1202
1203    /// \brief Skeleton class for mappable undirected graphs.
1204    ///
1205    /// This class describes the interface of mappable undirected graphs.
1206    /// It extends \ref MappableDigraphComponent with the standard graph
1207    /// map class for edges (\c EdgeMap).
1208    /// This concept is part of the Graph concept.
1209    template <typename BAS = BaseGraphComponent>
1210    class MappableGraphComponent : public MappableDigraphComponent<BAS>  {
1211    public:
1212
1213      typedef BAS Base;
1214      typedef typename Base::Edge Edge;
1215
1216      typedef MappableGraphComponent Graph;
1217
1218      /// \brief Standard graph map for the edges.
1219      ///
1220      /// Standard graph map for the edges.
1221      /// It conforms to the ReferenceMap concept.
1222      template <typename V>
1223      class EdgeMap : public GraphMap<MappableGraphComponent, Edge, V> {
1224      public:
1225        typedef GraphMap<MappableGraphComponent, Edge, V> Parent;
1226
1227        /// \brief Construct a new map.
1228        ///
1229        /// Construct a new map for the graph.
1230        explicit EdgeMap(const MappableGraphComponent& graph)
1231          : Parent(graph) {}
1232
1233        /// \brief Construct a new map with default value.
1234        ///
1235        /// Construct a new map for the graph and initalize the values.
1236        EdgeMap(const MappableGraphComponent& graph, const V& value)
1237          : Parent(graph, value) {}
1238
1239      private:
1240        /// \brief Copy constructor.
1241        ///
1242        /// Copy Constructor.
1243        EdgeMap(const EdgeMap& nm) : Parent(nm) {}
1244
1245        /// \brief Assignment operator.
1246        ///
1247        /// Assignment operator.
1248        template <typename CMap>
1249        EdgeMap& operator=(const CMap&) {
1250          checkConcept<ReadMap<Edge, V>, CMap>();
1251          return *this;
1252        }
1253
1254      };
1255
1256
1257      template <typename _Graph>
1258      struct Constraints {
1259
1260        struct Dummy {
1261          int value;
1262          Dummy() : value(0) {}
1263          Dummy(int _v) : value(_v) {}
1264        };
1265
1266        void constraints() {
1267          checkConcept<MappableDigraphComponent<Base>, _Graph>();
1268
1269          { // int map test
1270            typedef typename _Graph::template EdgeMap<int> IntEdgeMap;
1271            checkConcept<GraphMap<_Graph, typename _Graph::Edge, int>,
1272              IntEdgeMap >();
1273          } { // bool map test
1274            typedef typename _Graph::template EdgeMap<bool> BoolEdgeMap;
1275            checkConcept<GraphMap<_Graph, typename _Graph::Edge, bool>,
1276              BoolEdgeMap >();
1277          } { // Dummy map test
1278            typedef typename _Graph::template EdgeMap<Dummy> DummyEdgeMap;
1279            checkConcept<GraphMap<_Graph, typename _Graph::Edge, Dummy>,
1280              DummyEdgeMap >();
1281          }
1282        }
1283
1284        const _Graph& graph;
1285      };
1286    };
1287
1288    /// \brief Skeleton class for extendable directed graphs.
1289    ///
1290    /// This class describes the interface of extendable directed graphs.
1291    /// It extends \ref BaseDigraphComponent with functions for adding
1292    /// nodes and arcs to the digraph.
1293    /// This concept requires \ref AlterableDigraphComponent.
1294    template <typename BAS = BaseDigraphComponent>
1295    class ExtendableDigraphComponent : public BAS {
1296    public:
1297      typedef BAS Base;
1298
1299      typedef typename Base::Node Node;
1300      typedef typename Base::Arc Arc;
1301
1302      /// \brief Add a new node to the digraph.
1303      ///
1304      /// This function adds a new node to the digraph.
1305      Node addNode() {
1306        return INVALID;
1307      }
1308
1309      /// \brief Add a new arc connecting the given two nodes.
1310      ///
1311      /// This function adds a new arc connecting the given two nodes
1312      /// of the digraph.
1313      Arc addArc(const Node&, const Node&) {
1314        return INVALID;
1315      }
1316
1317      template <typename _Digraph>
1318      struct Constraints {
1319        void constraints() {
1320          checkConcept<Base, _Digraph>();
1321          typename _Digraph::Node node_a, node_b;
1322          node_a = digraph.addNode();
1323          node_b = digraph.addNode();
1324          typename _Digraph::Arc arc;
1325          arc = digraph.addArc(node_a, node_b);
1326        }
1327
1328        _Digraph& digraph;
1329      };
1330    };
1331
1332    /// \brief Skeleton class for extendable undirected graphs.
1333    ///
1334    /// This class describes the interface of extendable undirected graphs.
1335    /// It extends \ref BaseGraphComponent with functions for adding
1336    /// nodes and edges to the graph.
1337    /// This concept requires \ref AlterableGraphComponent.
1338    template <typename BAS = BaseGraphComponent>
1339    class ExtendableGraphComponent : public BAS {
1340    public:
1341
1342      typedef BAS Base;
1343      typedef typename Base::Node Node;
1344      typedef typename Base::Edge Edge;
1345
1346      /// \brief Add a new node to the digraph.
1347      ///
1348      /// This function adds a new node to the digraph.
1349      Node addNode() {
1350        return INVALID;
1351      }
1352
1353      /// \brief Add a new edge connecting the given two nodes.
1354      ///
1355      /// This function adds a new edge connecting the given two nodes
1356      /// of the graph.
1357      Edge addEdge(const Node&, const Node&) {
1358        return INVALID;
1359      }
1360
1361      template <typename _Graph>
1362      struct Constraints {
1363        void constraints() {
1364          checkConcept<Base, _Graph>();
1365          typename _Graph::Node node_a, node_b;
1366          node_a = graph.addNode();
1367          node_b = graph.addNode();
1368          typename _Graph::Edge edge;
1369          edge = graph.addEdge(node_a, node_b);
1370        }
1371
1372        _Graph& graph;
1373      };
1374    };
1375
1376    /// \brief Skeleton class for erasable directed graphs.
1377    ///
1378    /// This class describes the interface of erasable directed graphs.
1379    /// It extends \ref BaseDigraphComponent with functions for removing
1380    /// nodes and arcs from the digraph.
1381    /// This concept requires \ref AlterableDigraphComponent.
1382    template <typename BAS = BaseDigraphComponent>
1383    class ErasableDigraphComponent : public BAS {
1384    public:
1385
1386      typedef BAS Base;
1387      typedef typename Base::Node Node;
1388      typedef typename Base::Arc Arc;
1389
1390      /// \brief Erase a node from the digraph.
1391      ///
1392      /// This function erases the given node from the digraph and all arcs
1393      /// connected to the node.
1394      void erase(const Node&) {}
1395
1396      /// \brief Erase an arc from the digraph.
1397      ///
1398      /// This function erases the given arc from the digraph.
1399      void erase(const Arc&) {}
1400
1401      template <typename _Digraph>
1402      struct Constraints {
1403        void constraints() {
1404          checkConcept<Base, _Digraph>();
1405          const typename _Digraph::Node node(INVALID);
1406          digraph.erase(node);
1407          const typename _Digraph::Arc arc(INVALID);
1408          digraph.erase(arc);
1409        }
1410
1411        _Digraph& digraph;
1412      };
1413    };
1414
1415    /// \brief Skeleton class for erasable undirected graphs.
1416    ///
1417    /// This class describes the interface of erasable undirected graphs.
1418    /// It extends \ref BaseGraphComponent with functions for removing
1419    /// nodes and edges from the graph.
1420    /// This concept requires \ref AlterableGraphComponent.
1421    template <typename BAS = BaseGraphComponent>
1422    class ErasableGraphComponent : public BAS {
1423    public:
1424
1425      typedef BAS Base;
1426      typedef typename Base::Node Node;
1427      typedef typename Base::Edge Edge;
1428
1429      /// \brief Erase a node from the graph.
1430      ///
1431      /// This function erases the given node from the graph and all edges
1432      /// connected to the node.
1433      void erase(const Node&) {}
1434
1435      /// \brief Erase an edge from the digraph.
1436      ///
1437      /// This function erases the given edge from the digraph.
1438      void erase(const Edge&) {}
1439
1440      template <typename _Graph>
1441      struct Constraints {
1442        void constraints() {
1443          checkConcept<Base, _Graph>();
1444          const typename _Graph::Node node(INVALID);
1445          graph.erase(node);
1446          const typename _Graph::Edge edge(INVALID);
1447          graph.erase(edge);
1448        }
1449
1450        _Graph& graph;
1451      };
1452    };
1453
1454    /// \brief Skeleton class for clearable directed graphs.
1455    ///
1456    /// This class describes the interface of clearable directed graphs.
1457    /// It extends \ref BaseDigraphComponent with a function for clearing
1458    /// the digraph.
1459    /// This concept requires \ref AlterableDigraphComponent.
1460    template <typename BAS = BaseDigraphComponent>
1461    class ClearableDigraphComponent : public BAS {
1462    public:
1463
1464      typedef BAS Base;
1465
1466      /// \brief Erase all nodes and arcs from the digraph.
1467      ///
1468      /// This function erases all nodes and arcs from the digraph.
1469      void clear() {}
1470
1471      template <typename _Digraph>
1472      struct Constraints {
1473        void constraints() {
1474          checkConcept<Base, _Digraph>();
1475          digraph.clear();
1476        }
1477
1478        _Digraph& digraph;
1479      };
1480    };
1481
1482    /// \brief Skeleton class for clearable undirected graphs.
1483    ///
1484    /// This class describes the interface of clearable undirected graphs.
1485    /// It extends \ref BaseGraphComponent with a function for clearing
1486    /// the graph.
1487    /// This concept requires \ref AlterableGraphComponent.
1488    template <typename BAS = BaseGraphComponent>
1489    class ClearableGraphComponent : public ClearableDigraphComponent<BAS> {
1490    public:
1491
1492      typedef BAS Base;
1493
1494      /// \brief Erase all nodes and edges from the graph.
1495      ///
1496      /// This function erases all nodes and edges from the graph.
1497      void clear() {}
1498
1499      template <typename _Graph>
1500      struct Constraints {
1501        void constraints() {
1502          checkConcept<Base, _Graph>();
1503          graph.clear();
1504        }
1505
1506        _Graph& graph;
1507      };
1508    };
1509
1510  }
1511
1512}
1513
1514#endif
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