1 /* -*- mode: C++; indent-tabs-mode: nil; -*-
3 * This file is a part of LEMON, a generic C++ optimization library.
5 * Copyright (C) 2003-2008
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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.
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
19 #ifndef LEMON_BITS_ALTERATION_NOTIFIER_H
20 #define LEMON_BITS_ALTERATION_NOTIFIER_H
25 #include <lemon/core.h>
29 ///\brief Observer notifier for graph alteration observers.
33 /// \ingroup graphbits
35 /// \brief Notifier class to notify observes about alterations in
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.
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.
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.
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.
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.
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 \ref ImmediateDetach
83 /// exception which detach the observer from the notifier.
85 /// There are some place when the alteration observing is not completly
86 /// reliable. If we want to carry out the node degree in the graph
87 /// as in the \ref InDegMap and we use the reverseEdge that cause
88 /// unreliable functionality. Because the alteration observing signals
89 /// only erasing and adding but not the reversing it will stores bad
90 /// degrees. The sub graph adaptors cannot signal the alterations because
91 /// just a setting in the filter map can modify the graph and this cannot
92 /// be watched in any way.
94 /// \param _Container The container which is observed.
95 /// \param _Item The item type which is obserbved.
97 template <typename _Container, typename _Item>
98 class AlterationNotifier {
101 typedef True Notifier;
103 typedef _Container Container;
106 /// \brief Exception which can be called from \e clear() and
109 /// From the \e clear() and \e erase() function only this
110 /// exception is allowed to throw. The exception immediatly
111 /// detaches the current observer from the notifier. Because the
112 /// \e clear() and \e erase() should not throw other exceptions
113 /// it can be used to invalidate the observer.
114 struct ImmediateDetach {};
116 /// \brief ObserverBase is the base class for the observers.
118 /// ObserverBase is the abstract base class for the observers.
119 /// It will be notified about an item was inserted into or
120 /// erased from the graph.
122 /// The observer interface contains some pure virtual functions
123 /// to override. The add() and erase() functions are
124 /// to notify the oberver when one item is added or
127 /// The build() and clear() members are to notify the observer
128 /// about the container is built from an empty container or
129 /// is cleared to an empty container.
133 typedef AlterationNotifier Notifier;
135 friend class AlterationNotifier;
137 /// \brief Default constructor.
139 /// Default constructor for ObserverBase.
141 ObserverBase() : _notifier(0) {}
143 /// \brief Constructor which attach the observer into notifier.
145 /// Constructor which attach the observer into notifier.
146 ObserverBase(AlterationNotifier& nf) {
150 /// \brief Constructor which attach the obserever to the same notifier.
152 /// Constructor which attach the obserever to the same notifier as
153 /// the other observer is attached to.
154 ObserverBase(const ObserverBase& copy) {
155 if (copy.attached()) {
156 attach(*copy.notifier());
160 /// \brief Destructor
161 virtual ~ObserverBase() {
167 /// \brief Attaches the observer into an AlterationNotifier.
169 /// This member attaches the observer into an AlterationNotifier.
171 void attach(AlterationNotifier& nf) {
175 /// \brief Detaches the observer into an AlterationNotifier.
177 /// This member detaches the observer from an AlterationNotifier.
180 _notifier->detach(*this);
183 /// \brief Gives back a pointer to the notifier which the map
186 /// This function gives back a pointer to the notifier which the map
189 Notifier* notifier() const { return const_cast<Notifier*>(_notifier); }
191 /// Gives back true when the observer is attached into a notifier.
192 bool attached() const { return _notifier != 0; }
196 ObserverBase& operator=(const ObserverBase& copy);
201 typename std::list<ObserverBase*>::iterator _index;
203 /// \brief The member function to notificate the observer about an
204 /// item is added to the container.
206 /// The add() member function notificates the observer about an item
207 /// is added to the container. It have to be overrided in the
209 virtual void add(const Item&) = 0;
211 /// \brief The member function to notificate the observer about
212 /// more item is added to the container.
214 /// The add() member function notificates the observer about more item
215 /// is added to the container. It have to be overrided in the
217 virtual void add(const std::vector<Item>& items) = 0;
219 /// \brief The member function to notificate the observer about an
220 /// item is erased from the container.
222 /// The erase() member function notificates the observer about an
223 /// item is erased from the container. It have to be overrided in
225 virtual void erase(const Item&) = 0;
227 /// \brief The member function to notificate the observer about
228 /// more item is erased from the container.
230 /// The erase() member function notificates the observer about more item
231 /// is erased from the container. It have to be overrided in the
233 virtual void erase(const std::vector<Item>& items) = 0;
235 /// \brief The member function to notificate the observer about the
236 /// container is built.
238 /// The build() member function notificates the observer about the
239 /// container is built from an empty container. It have to be
240 /// overrided in the subclasses.
242 virtual void build() = 0;
244 /// \brief The member function to notificate the observer about all
245 /// items are erased from the container.
247 /// The clear() member function notificates the observer about all
248 /// items are erased from the container. It have to be overrided in
250 virtual void clear() = 0;
256 const Container* container;
258 typedef std::list<ObserverBase*> Observers;
259 Observers _observers;
264 /// \brief Default constructor.
266 /// The default constructor of the AlterationNotifier.
267 /// It creates an empty notifier.
271 /// \brief Constructor.
273 /// Constructor with the observed container parameter.
274 AlterationNotifier(const Container& _container)
275 : container(&_container) {}
277 /// \brief Copy Constructor of the AlterationNotifier.
279 /// Copy constructor of the AlterationNotifier.
280 /// It creates only an empty notifier because the copiable
281 /// notifier's observers have to be registered still into that notifier.
282 AlterationNotifier(const AlterationNotifier& _notifier)
283 : container(_notifier.container) {}
285 /// \brief Destructor.
287 /// Destructor of the AlterationNotifier.
289 ~AlterationNotifier() {
290 typename Observers::iterator it;
291 for (it = _observers.begin(); it != _observers.end(); ++it) {
292 (*it)->_notifier = 0;
296 /// \brief Sets the container.
298 /// Sets the container.
299 void setContainer(const Container& _container) {
300 container = &_container;
305 AlterationNotifier& operator=(const AlterationNotifier&);
311 /// \brief First item in the container.
313 /// Returns the first item in the container. It is
314 /// for start the iteration on the container.
315 void first(Item& item) const {
316 container->first(item);
319 /// \brief Next item in the container.
321 /// Returns the next item in the container. It is
322 /// for iterate on the container.
323 void next(Item& item) const {
324 container->next(item);
327 /// \brief Returns the id of the item.
329 /// Returns the id of the item provided by the container.
330 int id(const Item& item) const {
331 return container->id(item);
334 /// \brief Returns the maximum id of the container.
336 /// Returns the maximum id of the container.
338 return container->maxId(Item());
343 void attach(ObserverBase& observer) {
344 observer._index = _observers.insert(_observers.begin(), &observer);
345 observer._notifier = this;
348 void detach(ObserverBase& observer) {
349 _observers.erase(observer._index);
350 observer._index = _observers.end();
351 observer._notifier = 0;
356 /// \brief Notifies all the registed observers about an item added to
359 /// It notifies all the registed observers about an item added to
362 void add(const Item& item) {
363 typename Observers::reverse_iterator it;
365 for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
369 typename Observers::iterator jt;
370 for (jt = it.base(); jt != _observers.end(); ++jt) {
377 /// \brief Notifies all the registed observers about more item added to
380 /// It notifies all the registed observers about more item added to
383 void add(const std::vector<Item>& items) {
384 typename Observers::reverse_iterator it;
386 for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
390 typename Observers::iterator jt;
391 for (jt = it.base(); jt != _observers.end(); ++jt) {
398 /// \brief Notifies all the registed observers about an item erased from
401 /// It notifies all the registed observers about an item erased from
404 void erase(const Item& item) throw() {
405 typename Observers::iterator it = _observers.begin();
406 while (it != _observers.end()) {
410 } catch (const ImmediateDetach&) {
411 (*it)->_index = _observers.end();
412 (*it)->_notifier = 0;
413 it = _observers.erase(it);
418 /// \brief Notifies all the registed observers about more item erased
419 /// from the container.
421 /// It notifies all the registed observers about more item erased from
424 void erase(const std::vector<Item>& items) {
425 typename Observers::iterator it = _observers.begin();
426 while (it != _observers.end()) {
430 } catch (const ImmediateDetach&) {
431 (*it)->_index = _observers.end();
432 (*it)->_notifier = 0;
433 it = _observers.erase(it);
438 /// \brief Notifies all the registed observers about the container is
441 /// Notifies all the registed observers about the container is built
442 /// from an empty container.
444 typename Observers::reverse_iterator it;
446 for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
450 typename Observers::iterator jt;
451 for (jt = it.base(); jt != _observers.end(); ++jt) {
458 /// \brief Notifies all the registed observers about all items are
461 /// Notifies all the registed observers about all items are erased
462 /// from the container.
464 typename Observers::iterator it = _observers.begin();
465 while (it != _observers.end()) {
469 } catch (const ImmediateDetach&) {
470 (*it)->_index = _observers.end();
471 (*it)->_notifier = 0;
472 it = _observers.erase(it);