COIN-OR::LEMON - Graph Library

source: lemon-1.0/lemon/bits/alteration_notifier.h @ 92:5d4decd1b870

Last change on this file since 92:5d4decd1b870 was 57:c1acf0018c0a, checked in by Balazs Dezso <deba@…>, 12 years ago

Port ListDigraph? and ListGraph? from svn -r 3433
Details:

  • port Digraph and Graph concepts
  • port ListDigraph? and ListGraph?
  • port Basic graph constructing tools
  • port Digraph and Graph tests
File size: 15.7 KB
Line 
1/* -*- C++ -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library
4 *
5 * Copyright (C) 2003-2007
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_BITS_ALTERATION_NOTIFIER_H
20#define LEMON_BITS_ALTERATION_NOTIFIER_H
21
22#include <vector>
23#include <list>
24
25#include <lemon/bits/utility.h>
26
27///\ingroup graphbits
28///\file
29///\brief Observer notifier for graph alteration observers.
30
31namespace lemon {
32
33  /// \ingroup graphbits
34  ///
35  /// \brief Notifier class to notify observes about alterations in
36  /// a container.
37  ///
38  /// The simple graph's can be refered as two containers, one node container
39  /// and one edge container. But they are not standard containers they
40  /// does not store values directly they are just key continars for more
41  /// value containers which are the node and edge maps.
42  ///
43  /// The graph's node and edge sets can be changed as we add or erase
44  /// nodes and edges in the graph. Lemon would like to handle easily
45  /// that the node and edge maps should contain values for all nodes or
46  /// edges. If we want to check on every indicing if the map contains
47  /// the current indicing key that cause a drawback in the performance
48  /// in the library. We use another solution we notify all maps about
49  /// an alteration in the graph, which cause only drawback on the
50  /// alteration of the graph.
51  ///
52  /// This class provides an interface to the container. The \e first() and \e
53  /// next() member functions make possible to iterate on the keys of the
54  /// container. The \e id() function returns an integer id for each key.
55  /// The \e maxId() function gives back an upper bound of the ids.
56  ///
57  /// For the proper functonality of this class, we should notify it
58  /// about each alteration in the container. The alterations have four type
59  /// as \e add(), \e erase(), \e build() and \e clear(). The \e add() and
60  /// \e erase() signals that only one or few items added or erased to or
61  /// from the graph. If all items are erased from the graph or from an empty
62  /// graph a new graph is builded then it can be signaled with the
63  /// clear() and build() members. Important rule that if we erase items
64  /// from graph we should first signal the alteration and after that erase
65  /// them from the container, on the other way on item addition we should
66  /// first extend the container and just after that signal the alteration.
67  ///
68  /// The alteration can be observed with a class inherited from the
69  /// \e ObserverBase nested class. The signals can be handled with
70  /// overriding the virtual functions defined in the base class.  The
71  /// observer base can be attached to the notifier with the
72  /// \e attach() member and can be detached with detach() function. The
73  /// alteration handlers should not call any function which signals
74  /// an other alteration in the same notifier and should not
75  /// detach any observer from the notifier.
76  ///
77  /// Alteration observers try to be exception safe. If an \e add() or
78  /// a \e clear() function throws an exception then the remaining
79  /// observeres will not be notified and the fulfilled additions will
80  /// be rolled back by calling the \e erase() or \e clear()
81  /// functions. Thence the \e erase() and \e clear() should not throw
82  /// exception. Actullay, it can be throw only
83  /// \ref AlterationObserver::ImmediateDetach ImmediateDetach
84  /// exception which detach the observer from the notifier.
85  ///
86  /// There are some place when the alteration observing is not completly
87  /// reliable. If we want to carry out the node degree in the graph
88  /// as in the \ref InDegMap and we use the reverseEdge that cause
89  /// unreliable functionality. Because the alteration observing signals
90  /// only erasing and adding but not the reversing it will stores bad
91  /// degrees. The sub graph adaptors cannot signal the alterations because
92  /// just a setting in the filter map can modify the graph and this cannot
93  /// be watched in any way.
94  ///
95  /// \param _Container The container which is observed.
96  /// \param _Item The item type which is obserbved.
97  ///
98  /// \author Balazs Dezso
99
100  template <typename _Container, typename _Item>
101  class AlterationNotifier {
102  public:
103
104    typedef True Notifier;
105
106    typedef _Container Container;
107    typedef _Item Item;
108
109    /// \brief Exception which can be called from \e clear() and
110    /// \e erase().
111    ///
112    /// From the \e clear() and \e erase() function only this
113    /// exception is allowed to throw. The exception immediatly
114    /// detaches the current observer from the notifier. Because the
115    /// \e clear() and \e erase() should not throw other exceptions
116    /// it can be used to invalidate the observer.
117    struct ImmediateDetach {};
118
119    /// \brief ObserverBase is the base class for the observers.
120    ///
121    /// ObserverBase is the abstract base class for the observers.
122    /// It will be notified about an item was inserted into or
123    /// erased from the graph.
124    ///
125    /// The observer interface contains some pure virtual functions
126    /// to override. The add() and erase() functions are
127    /// to notify the oberver when one item is added or
128    /// erased.
129    ///
130    /// The build() and clear() members are to notify the observer
131    /// about the container is built from an empty container or
132    /// is cleared to an empty container.
133    ///
134    /// \author Balazs Dezso
135
136    class ObserverBase {
137    protected:
138      typedef AlterationNotifier Notifier;
139
140      friend class AlterationNotifier;
141
142      /// \brief Default constructor.
143      ///
144      /// Default constructor for ObserverBase.
145      ///
146      ObserverBase() : _notifier(0) {}
147
148      /// \brief Constructor which attach the observer into notifier.
149      ///
150      /// Constructor which attach the observer into notifier.
151      ObserverBase(AlterationNotifier& nf) {
152        attach(nf);
153      }
154
155      /// \brief Constructor which attach the obserever to the same notifier.
156      ///
157      /// Constructor which attach the obserever to the same notifier as
158      /// the other observer is attached to.
159      ObserverBase(const ObserverBase& copy) {
160        if (copy.attached()) {
161          attach(*copy.notifier());
162        }
163      }
164       
165      /// \brief Destructor
166      virtual ~ObserverBase() {
167        if (attached()) {
168          detach();
169        }
170      }
171
172      /// \brief Attaches the observer into an AlterationNotifier.
173      ///
174      /// This member attaches the observer into an AlterationNotifier.
175      ///
176      void attach(AlterationNotifier& nf) {
177        nf.attach(*this);
178      }
179     
180      /// \brief Detaches the observer into an AlterationNotifier.
181      ///
182      /// This member detaches the observer from an AlterationNotifier.
183      ///
184      void detach() {
185        _notifier->detach(*this);
186      }
187     
188      /// \brief Gives back a pointer to the notifier which the map
189      /// attached into.
190      ///
191      /// This function gives back a pointer to the notifier which the map
192      /// attached into.
193      ///
194      Notifier* notifier() const { return const_cast<Notifier*>(_notifier); }
195     
196      /// Gives back true when the observer is attached into a notifier.
197      bool attached() const { return _notifier != 0; }
198
199    private:
200
201      ObserverBase& operator=(const ObserverBase& copy);
202
203    protected:
204     
205      Notifier* _notifier;
206      typename std::list<ObserverBase*>::iterator _index;
207
208      /// \brief The member function to notificate the observer about an
209      /// item is added to the container.
210      ///
211      /// The add() member function notificates the observer about an item
212      /// is added to the container. It have to be overrided in the
213      /// subclasses.
214      virtual void add(const Item&) = 0;
215
216      /// \brief The member function to notificate the observer about
217      /// more item is added to the container.
218      ///
219      /// The add() member function notificates the observer about more item
220      /// is added to the container. It have to be overrided in the
221      /// subclasses.
222      virtual void add(const std::vector<Item>& items) = 0;
223
224      /// \brief The member function to notificate the observer about an
225      /// item is erased from the container.
226      ///
227      /// The erase() member function notificates the observer about an
228      /// item is erased from the container. It have to be overrided in
229      /// the subclasses.       
230      virtual void erase(const Item&) = 0;
231
232      /// \brief The member function to notificate the observer about
233      /// more item is erased from the container.
234      ///
235      /// The erase() member function notificates the observer about more item
236      /// is erased from the container. It have to be overrided in the
237      /// subclasses.
238      virtual void erase(const std::vector<Item>& items) = 0;
239
240      /// \brief The member function to notificate the observer about the
241      /// container is built.
242      ///
243      /// The build() member function notificates the observer about the
244      /// container is built from an empty container. It have to be
245      /// overrided in the subclasses.
246
247      virtual void build() = 0;
248
249      /// \brief The member function to notificate the observer about all
250      /// items are erased from the container.
251      ///
252      /// The clear() member function notificates the observer about all
253      /// items are erased from the container. It have to be overrided in
254      /// the subclasses.     
255      virtual void clear() = 0;
256
257    };
258       
259  protected:
260
261    const Container* container;
262
263    typedef std::list<ObserverBase*> Observers;
264    Observers _observers;
265
266               
267  public:
268
269    /// \brief Default constructor.
270    ///
271    /// The default constructor of the AlterationNotifier.
272    /// It creates an empty notifier.
273    AlterationNotifier()
274      : container(0) {}
275
276    /// \brief Constructor.
277    ///
278    /// Constructor with the observed container parameter.
279    AlterationNotifier(const Container& _container)
280      : container(&_container) {}
281
282    /// \brief Copy Constructor of the AlterationNotifier.
283    ///
284    /// Copy constructor of the AlterationNotifier.
285    /// It creates only an empty notifier because the copiable
286    /// notifier's observers have to be registered still into that notifier.
287    AlterationNotifier(const AlterationNotifier& _notifier)
288      : container(_notifier.container) {}
289
290    /// \brief Destructor.
291    ///         
292    /// Destructor of the AlterationNotifier.
293    ///
294    ~AlterationNotifier() {
295      typename Observers::iterator it;
296      for (it = _observers.begin(); it != _observers.end(); ++it) {
297        (*it)->_notifier = 0;
298      }
299    }
300
301    /// \brief Sets the container.
302    ///
303    /// Sets the container.
304    void setContainer(const Container& _container) {
305      container = &_container;
306    }
307
308  protected:
309
310    AlterationNotifier& operator=(const AlterationNotifier&);
311
312  public:
313
314
315
316    /// \brief First item in the container.
317    ///
318    /// Returns the first item in the container. It is
319    /// for start the iteration on the container.
320    void first(Item& item) const {
321      container->first(item);
322    }
323
324    /// \brief Next item in the container.
325    ///
326    /// Returns the next item in the container. It is
327    /// for iterate on the container.
328    void next(Item& item) const {
329      container->next(item);
330    }
331
332    /// \brief Returns the id of the item.
333    ///
334    /// Returns the id of the item provided by the container.
335    int id(const Item& item) const {
336      return container->id(item);
337    }
338
339    /// \brief Returns the maximum id of the container.
340    ///
341    /// Returns the maximum id of the container.
342    int maxId() const {
343      return container->maxId(Item());
344    }
345               
346  protected:
347
348    void attach(ObserverBase& observer) {
349      observer._index = _observers.insert(_observers.begin(), &observer);
350      observer._notifier = this;
351    }
352
353    void detach(ObserverBase& observer) {
354      _observers.erase(observer._index);
355      observer._index = _observers.end();
356      observer._notifier = 0;
357    }
358
359  public:
360       
361    /// \brief Notifies all the registed observers about an item added to
362    /// the container.
363    ///
364    /// It notifies all the registed observers about an item added to
365    /// the container.
366    ///
367    void add(const Item& item) {
368      typename Observers::reverse_iterator it;
369      try {
370        for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
371          (*it)->add(item);
372        }
373      } catch (...) {
374        typename Observers::iterator jt;
375        for (jt = it.base(); jt != _observers.end(); ++jt) {
376          (*jt)->erase(item);
377        }
378        throw;
379      }
380    }   
381
382    /// \brief Notifies all the registed observers about more item added to
383    /// the container.
384    ///
385    /// It notifies all the registed observers about more item added to
386    /// the container.
387    ///
388    void add(const std::vector<Item>& items) {
389      typename Observers::reverse_iterator it;
390      try {
391        for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
392          (*it)->add(items);
393        }
394      } catch (...) {
395        typename Observers::iterator jt;
396        for (jt = it.base(); jt != _observers.end(); ++jt) {
397          (*jt)->erase(items);
398        }
399        throw;
400      }
401    }   
402
403    /// \brief Notifies all the registed observers about an item erased from
404    /// the container.
405    ///
406    /// It notifies all the registed observers about an item erased from
407    /// the container.
408    ///
409    void erase(const Item& item) throw() {
410      typename Observers::iterator it = _observers.begin();
411      while (it != _observers.end()) {
412        try {
413          (*it)->erase(item);
414          ++it;
415        } catch (const ImmediateDetach&) {
416          it = _observers.erase(it);
417          (*it)->_index = _observers.end();
418          (*it)->_notifier = 0;
419        }
420      }
421    }
422
423    /// \brief Notifies all the registed observers about more item erased 
424    /// from the container.
425    ///
426    /// It notifies all the registed observers about more item erased from
427    /// the container.
428    ///
429    void erase(const std::vector<Item>& items) {
430      typename Observers::iterator it = _observers.begin();
431      while (it != _observers.end()) {
432        try {
433          (*it)->erase(items);
434          ++it;
435        } catch (const ImmediateDetach&) {
436          it = _observers.erase(it);
437          (*it)->_index = _observers.end();
438          (*it)->_notifier = 0;
439        }
440      }
441    }
442
443    /// \brief Notifies all the registed observers about the container is
444    /// built.
445    ///         
446    /// Notifies all the registed observers about the container is built
447    /// from an empty container.
448    void build() {
449      typename Observers::reverse_iterator it;
450      try {
451        for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
452          (*it)->build();
453        }
454      } catch (...) {
455        typename Observers::iterator jt;
456        for (jt = it.base(); jt != _observers.end(); ++jt) {
457          (*jt)->clear();
458        }
459        throw;
460      }
461    }
462
463    /// \brief Notifies all the registed observers about all items are
464    /// erased.
465    ///
466    /// Notifies all the registed observers about all items are erased
467    /// from the container.
468    void clear() {
469      typename Observers::iterator it = _observers.begin();
470      while (it != _observers.end()) {
471        try {
472          (*it)->clear();
473          ++it;
474        } catch (const ImmediateDetach&) {
475          it = _observers.erase(it);
476          (*it)->_index = _observers.end();
477          (*it)->_notifier = 0;
478        }
479      }
480    }
481  };
482
483}
484
485#endif
Note: See TracBrowser for help on using the repository browser.