diff -r 9bd0d6e0c279 -r c1acf0018c0a lemon/bits/alteration_notifier.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/lemon/bits/alteration_notifier.h Sun Jan 20 20:43:48 2008 +0100 @@ -0,0 +1,485 @@ +/* -*- C++ -*- + * + * This file is a part of LEMON, a generic C++ optimization library + * + * Copyright (C) 2003-2007 + * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport + * (Egervary Research Group on Combinatorial Optimization, EGRES). + * + * Permission to use, modify and distribute this software is granted + * provided that this copyright notice appears in all copies. For + * precise terms see the accompanying LICENSE file. + * + * This software is provided "AS IS" with no warranty of any kind, + * express or implied, and with no claim as to its suitability for any + * purpose. + * + */ + +#ifndef LEMON_BITS_ALTERATION_NOTIFIER_H +#define LEMON_BITS_ALTERATION_NOTIFIER_H + +#include +#include + +#include + +///\ingroup graphbits +///\file +///\brief Observer notifier for graph alteration observers. + +namespace lemon { + + /// \ingroup graphbits + /// + /// \brief Notifier class to notify observes about alterations in + /// a container. + /// + /// The simple graph's can be refered as two containers, one node container + /// and one edge container. But they are not standard containers they + /// does not store values directly they are just key continars for more + /// value containers which are the node and edge maps. + /// + /// The graph's node and edge sets can be changed as we add or erase + /// nodes and edges in the graph. Lemon would like to handle easily + /// that the node and edge maps should contain values for all nodes or + /// edges. If we want to check on every indicing if the map contains + /// the current indicing key that cause a drawback in the performance + /// in the library. We use another solution we notify all maps about + /// an alteration in the graph, which cause only drawback on the + /// alteration of the graph. + /// + /// This class provides an interface to the container. The \e first() and \e + /// next() member functions make possible to iterate on the keys of the + /// container. The \e id() function returns an integer id for each key. + /// The \e maxId() function gives back an upper bound of the ids. + /// + /// For the proper functonality of this class, we should notify it + /// about each alteration in the container. The alterations have four type + /// as \e add(), \e erase(), \e build() and \e clear(). The \e add() and + /// \e erase() signals that only one or few items added or erased to or + /// from the graph. If all items are erased from the graph or from an empty + /// graph a new graph is builded then it can be signaled with the + /// clear() and build() members. Important rule that if we erase items + /// from graph we should first signal the alteration and after that erase + /// them from the container, on the other way on item addition we should + /// first extend the container and just after that signal the alteration. + /// + /// The alteration can be observed with a class inherited from the + /// \e ObserverBase nested class. The signals can be handled with + /// overriding the virtual functions defined in the base class. The + /// observer base can be attached to the notifier with the + /// \e attach() member and can be detached with detach() function. The + /// alteration handlers should not call any function which signals + /// an other alteration in the same notifier and should not + /// detach any observer from the notifier. + /// + /// Alteration observers try to be exception safe. If an \e add() or + /// a \e clear() function throws an exception then the remaining + /// observeres will not be notified and the fulfilled additions will + /// be rolled back by calling the \e erase() or \e clear() + /// functions. Thence the \e erase() and \e clear() should not throw + /// exception. Actullay, it can be throw only + /// \ref AlterationObserver::ImmediateDetach ImmediateDetach + /// exception which detach the observer from the notifier. + /// + /// There are some place when the alteration observing is not completly + /// reliable. If we want to carry out the node degree in the graph + /// as in the \ref InDegMap and we use the reverseEdge that cause + /// unreliable functionality. Because the alteration observing signals + /// only erasing and adding but not the reversing it will stores bad + /// degrees. The sub graph adaptors cannot signal the alterations because + /// just a setting in the filter map can modify the graph and this cannot + /// be watched in any way. + /// + /// \param _Container The container which is observed. + /// \param _Item The item type which is obserbved. + /// + /// \author Balazs Dezso + + template + class AlterationNotifier { + public: + + typedef True Notifier; + + typedef _Container Container; + typedef _Item Item; + + /// \brief Exception which can be called from \e clear() and + /// \e erase(). + /// + /// From the \e clear() and \e erase() function only this + /// exception is allowed to throw. The exception immediatly + /// detaches the current observer from the notifier. Because the + /// \e clear() and \e erase() should not throw other exceptions + /// it can be used to invalidate the observer. + struct ImmediateDetach {}; + + /// \brief ObserverBase is the base class for the observers. + /// + /// ObserverBase is the abstract base class for the observers. + /// It will be notified about an item was inserted into or + /// erased from the graph. + /// + /// The observer interface contains some pure virtual functions + /// to override. The add() and erase() functions are + /// to notify the oberver when one item is added or + /// erased. + /// + /// The build() and clear() members are to notify the observer + /// about the container is built from an empty container or + /// is cleared to an empty container. + /// + /// \author Balazs Dezso + + class ObserverBase { + protected: + typedef AlterationNotifier Notifier; + + friend class AlterationNotifier; + + /// \brief Default constructor. + /// + /// Default constructor for ObserverBase. + /// + ObserverBase() : _notifier(0) {} + + /// \brief Constructor which attach the observer into notifier. + /// + /// Constructor which attach the observer into notifier. + ObserverBase(AlterationNotifier& nf) { + attach(nf); + } + + /// \brief Constructor which attach the obserever to the same notifier. + /// + /// Constructor which attach the obserever to the same notifier as + /// the other observer is attached to. + ObserverBase(const ObserverBase& copy) { + if (copy.attached()) { + attach(*copy.notifier()); + } + } + + /// \brief Destructor + virtual ~ObserverBase() { + if (attached()) { + detach(); + } + } + + /// \brief Attaches the observer into an AlterationNotifier. + /// + /// This member attaches the observer into an AlterationNotifier. + /// + void attach(AlterationNotifier& nf) { + nf.attach(*this); + } + + /// \brief Detaches the observer into an AlterationNotifier. + /// + /// This member detaches the observer from an AlterationNotifier. + /// + void detach() { + _notifier->detach(*this); + } + + /// \brief Gives back a pointer to the notifier which the map + /// attached into. + /// + /// This function gives back a pointer to the notifier which the map + /// attached into. + /// + Notifier* notifier() const { return const_cast(_notifier); } + + /// Gives back true when the observer is attached into a notifier. + bool attached() const { return _notifier != 0; } + + private: + + ObserverBase& operator=(const ObserverBase& copy); + + protected: + + Notifier* _notifier; + typename std::list::iterator _index; + + /// \brief The member function to notificate the observer about an + /// item is added to the container. + /// + /// The add() member function notificates the observer about an item + /// is added to the container. It have to be overrided in the + /// subclasses. + virtual void add(const Item&) = 0; + + /// \brief The member function to notificate the observer about + /// more item is added to the container. + /// + /// The add() member function notificates the observer about more item + /// is added to the container. It have to be overrided in the + /// subclasses. + virtual void add(const std::vector& items) = 0; + + /// \brief The member function to notificate the observer about an + /// item is erased from the container. + /// + /// The erase() member function notificates the observer about an + /// item is erased from the container. It have to be overrided in + /// the subclasses. + virtual void erase(const Item&) = 0; + + /// \brief The member function to notificate the observer about + /// more item is erased from the container. + /// + /// The erase() member function notificates the observer about more item + /// is erased from the container. It have to be overrided in the + /// subclasses. + virtual void erase(const std::vector& items) = 0; + + /// \brief The member function to notificate the observer about the + /// container is built. + /// + /// The build() member function notificates the observer about the + /// container is built from an empty container. It have to be + /// overrided in the subclasses. + + virtual void build() = 0; + + /// \brief The member function to notificate the observer about all + /// items are erased from the container. + /// + /// The clear() member function notificates the observer about all + /// items are erased from the container. It have to be overrided in + /// the subclasses. + virtual void clear() = 0; + + }; + + protected: + + const Container* container; + + typedef std::list Observers; + Observers _observers; + + + public: + + /// \brief Default constructor. + /// + /// The default constructor of the AlterationNotifier. + /// It creates an empty notifier. + AlterationNotifier() + : container(0) {} + + /// \brief Constructor. + /// + /// Constructor with the observed container parameter. + AlterationNotifier(const Container& _container) + : container(&_container) {} + + /// \brief Copy Constructor of the AlterationNotifier. + /// + /// Copy constructor of the AlterationNotifier. + /// It creates only an empty notifier because the copiable + /// notifier's observers have to be registered still into that notifier. + AlterationNotifier(const AlterationNotifier& _notifier) + : container(_notifier.container) {} + + /// \brief Destructor. + /// + /// Destructor of the AlterationNotifier. + /// + ~AlterationNotifier() { + typename Observers::iterator it; + for (it = _observers.begin(); it != _observers.end(); ++it) { + (*it)->_notifier = 0; + } + } + + /// \brief Sets the container. + /// + /// Sets the container. + void setContainer(const Container& _container) { + container = &_container; + } + + protected: + + AlterationNotifier& operator=(const AlterationNotifier&); + + public: + + + + /// \brief First item in the container. + /// + /// Returns the first item in the container. It is + /// for start the iteration on the container. + void first(Item& item) const { + container->first(item); + } + + /// \brief Next item in the container. + /// + /// Returns the next item in the container. It is + /// for iterate on the container. + void next(Item& item) const { + container->next(item); + } + + /// \brief Returns the id of the item. + /// + /// Returns the id of the item provided by the container. + int id(const Item& item) const { + return container->id(item); + } + + /// \brief Returns the maximum id of the container. + /// + /// Returns the maximum id of the container. + int maxId() const { + return container->maxId(Item()); + } + + protected: + + void attach(ObserverBase& observer) { + observer._index = _observers.insert(_observers.begin(), &observer); + observer._notifier = this; + } + + void detach(ObserverBase& observer) { + _observers.erase(observer._index); + observer._index = _observers.end(); + observer._notifier = 0; + } + + public: + + /// \brief Notifies all the registed observers about an item added to + /// the container. + /// + /// It notifies all the registed observers about an item added to + /// the container. + /// + void add(const Item& item) { + typename Observers::reverse_iterator it; + try { + for (it = _observers.rbegin(); it != _observers.rend(); ++it) { + (*it)->add(item); + } + } catch (...) { + typename Observers::iterator jt; + for (jt = it.base(); jt != _observers.end(); ++jt) { + (*jt)->erase(item); + } + throw; + } + } + + /// \brief Notifies all the registed observers about more item added to + /// the container. + /// + /// It notifies all the registed observers about more item added to + /// the container. + /// + void add(const std::vector& items) { + typename Observers::reverse_iterator it; + try { + for (it = _observers.rbegin(); it != _observers.rend(); ++it) { + (*it)->add(items); + } + } catch (...) { + typename Observers::iterator jt; + for (jt = it.base(); jt != _observers.end(); ++jt) { + (*jt)->erase(items); + } + throw; + } + } + + /// \brief Notifies all the registed observers about an item erased from + /// the container. + /// + /// It notifies all the registed observers about an item erased from + /// the container. + /// + void erase(const Item& item) throw() { + typename Observers::iterator it = _observers.begin(); + while (it != _observers.end()) { + try { + (*it)->erase(item); + ++it; + } catch (const ImmediateDetach&) { + it = _observers.erase(it); + (*it)->_index = _observers.end(); + (*it)->_notifier = 0; + } + } + } + + /// \brief Notifies all the registed observers about more item erased + /// from the container. + /// + /// It notifies all the registed observers about more item erased from + /// the container. + /// + void erase(const std::vector& items) { + typename Observers::iterator it = _observers.begin(); + while (it != _observers.end()) { + try { + (*it)->erase(items); + ++it; + } catch (const ImmediateDetach&) { + it = _observers.erase(it); + (*it)->_index = _observers.end(); + (*it)->_notifier = 0; + } + } + } + + /// \brief Notifies all the registed observers about the container is + /// built. + /// + /// Notifies all the registed observers about the container is built + /// from an empty container. + void build() { + typename Observers::reverse_iterator it; + try { + for (it = _observers.rbegin(); it != _observers.rend(); ++it) { + (*it)->build(); + } + } catch (...) { + typename Observers::iterator jt; + for (jt = it.base(); jt != _observers.end(); ++jt) { + (*jt)->clear(); + } + throw; + } + } + + /// \brief Notifies all the registed observers about all items are + /// erased. + /// + /// Notifies all the registed observers about all items are erased + /// from the container. + void clear() { + typename Observers::iterator it = _observers.begin(); + while (it != _observers.end()) { + try { + (*it)->clear(); + ++it; + } catch (const ImmediateDetach&) { + it = _observers.erase(it); + (*it)->_index = _observers.end(); + (*it)->_notifier = 0; + } + } + } + }; + +} + +#endif