deba@57: /* -*- C++ -*-
deba@57:  *
deba@57:  * This file is a part of LEMON, a generic C++ optimization library
deba@57:  *
deba@57:  * Copyright (C) 2003-2007
deba@57:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
deba@57:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
deba@57:  *
deba@57:  * Permission to use, modify and distribute this software is granted
deba@57:  * provided that this copyright notice appears in all copies. For
deba@57:  * precise terms see the accompanying LICENSE file.
deba@57:  *
deba@57:  * This software is provided "AS IS" with no warranty of any kind,
deba@57:  * express or implied, and with no claim as to its suitability for any
deba@57:  * purpose.
deba@57:  *
deba@57:  */
deba@57: 
deba@57: #ifndef LEMON_BITS_ALTERATION_NOTIFIER_H
deba@57: #define LEMON_BITS_ALTERATION_NOTIFIER_H
deba@57: 
deba@57: #include <vector>
deba@57: #include <list>
deba@57: 
deba@57: #include <lemon/bits/utility.h>
deba@57: 
deba@57: ///\ingroup graphbits
deba@57: ///\file
deba@57: ///\brief Observer notifier for graph alteration observers.
deba@57: 
deba@57: namespace lemon {
deba@57: 
deba@57:   /// \ingroup graphbits
deba@57:   ///
deba@57:   /// \brief Notifier class to notify observes about alterations in 
deba@57:   /// a container.
deba@57:   ///
deba@57:   /// The simple graph's can be refered as two containers, one node container
deba@57:   /// and one edge container. But they are not standard containers they
deba@57:   /// does not store values directly they are just key continars for more
deba@57:   /// value containers which are the node and edge maps.
deba@57:   ///
deba@57:   /// The graph's node and edge sets can be changed as we add or erase
deba@57:   /// nodes and edges in the graph. Lemon would like to handle easily
deba@57:   /// that the node and edge maps should contain values for all nodes or
deba@57:   /// edges. If we want to check on every indicing if the map contains
deba@57:   /// the current indicing key that cause a drawback in the performance
deba@57:   /// in the library. We use another solution we notify all maps about
deba@57:   /// an alteration in the graph, which cause only drawback on the
deba@57:   /// alteration of the graph.
deba@57:   ///
deba@57:   /// This class provides an interface to the container. The \e first() and \e 
deba@57:   /// next() member functions make possible to iterate on the keys of the
deba@57:   /// container. The \e id() function returns an integer id for each key.
deba@57:   /// The \e maxId() function gives back an upper bound of the ids.
deba@57:   ///
deba@57:   /// For the proper functonality of this class, we should notify it
deba@57:   /// about each alteration in the container. The alterations have four type
deba@57:   /// as \e add(), \e erase(), \e build() and \e clear(). The \e add() and
deba@57:   /// \e erase() signals that only one or few items added or erased to or
deba@57:   /// from the graph. If all items are erased from the graph or from an empty
deba@57:   /// graph a new graph is builded then it can be signaled with the
deba@57:   /// clear() and build() members. Important rule that if we erase items 
deba@57:   /// from graph we should first signal the alteration and after that erase
deba@57:   /// them from the container, on the other way on item addition we should
deba@57:   /// first extend the container and just after that signal the alteration.
deba@57:   ///
deba@57:   /// The alteration can be observed with a class inherited from the
deba@57:   /// \e ObserverBase nested class. The signals can be handled with
deba@57:   /// overriding the virtual functions defined in the base class.  The
deba@57:   /// observer base can be attached to the notifier with the 
deba@57:   /// \e attach() member and can be detached with detach() function. The
deba@57:   /// alteration handlers should not call any function which signals
deba@57:   /// an other alteration in the same notifier and should not
deba@57:   /// detach any observer from the notifier.
deba@57:   ///
deba@57:   /// Alteration observers try to be exception safe. If an \e add() or
deba@57:   /// a \e clear() function throws an exception then the remaining
deba@57:   /// observeres will not be notified and the fulfilled additions will
deba@57:   /// be rolled back by calling the \e erase() or \e clear()
deba@57:   /// functions. Thence the \e erase() and \e clear() should not throw
deba@57:   /// exception. Actullay, it can be throw only 
deba@57:   /// \ref AlterationObserver::ImmediateDetach ImmediateDetach
deba@57:   /// exception which detach the observer from the notifier.
deba@57:   ///
deba@57:   /// There are some place when the alteration observing is not completly
deba@57:   /// reliable. If we want to carry out the node degree in the graph
deba@57:   /// as in the \ref InDegMap and we use the reverseEdge that cause 
deba@57:   /// unreliable functionality. Because the alteration observing signals
deba@57:   /// only erasing and adding but not the reversing it will stores bad
deba@57:   /// degrees. The sub graph adaptors cannot signal the alterations because
deba@57:   /// just a setting in the filter map can modify the graph and this cannot
deba@57:   /// be watched in any way.
deba@57:   ///
deba@57:   /// \param _Container The container which is observed.
deba@57:   /// \param _Item The item type which is obserbved.
deba@57:   ///
deba@57:   /// \author Balazs Dezso
deba@57: 
deba@57:   template <typename _Container, typename _Item>
deba@57:   class AlterationNotifier {
deba@57:   public:
deba@57: 
deba@57:     typedef True Notifier;
deba@57: 
deba@57:     typedef _Container Container;
deba@57:     typedef _Item Item;
deba@57: 
deba@57:     /// \brief Exception which can be called from \e clear() and 
deba@57:     /// \e erase().
deba@57:     ///
deba@57:     /// From the \e clear() and \e erase() function only this
deba@57:     /// exception is allowed to throw. The exception immediatly
deba@57:     /// detaches the current observer from the notifier. Because the
deba@57:     /// \e clear() and \e erase() should not throw other exceptions
deba@57:     /// it can be used to invalidate the observer.
deba@57:     struct ImmediateDetach {};
deba@57: 
deba@57:     /// \brief ObserverBase is the base class for the observers.
deba@57:     ///
deba@57:     /// ObserverBase is the abstract base class for the observers.
deba@57:     /// It will be notified about an item was inserted into or
deba@57:     /// erased from the graph.
deba@57:     ///
deba@57:     /// The observer interface contains some pure virtual functions
deba@57:     /// to override. The add() and erase() functions are
deba@57:     /// to notify the oberver when one item is added or
deba@57:     /// erased.
deba@57:     ///
deba@57:     /// The build() and clear() members are to notify the observer
deba@57:     /// about the container is built from an empty container or
deba@57:     /// is cleared to an empty container. 
deba@57:     /// 
deba@57:     /// \author Balazs Dezso
deba@57: 
deba@57:     class ObserverBase {
deba@57:     protected:
deba@57:       typedef AlterationNotifier Notifier;
deba@57: 
deba@57:       friend class AlterationNotifier;
deba@57: 
deba@57:       /// \brief Default constructor.
deba@57:       ///
deba@57:       /// Default constructor for ObserverBase.
deba@57:       /// 
deba@57:       ObserverBase() : _notifier(0) {}
deba@57: 
deba@57:       /// \brief Constructor which attach the observer into notifier.
deba@57:       ///
deba@57:       /// Constructor which attach the observer into notifier.
deba@57:       ObserverBase(AlterationNotifier& nf) {
deba@57:         attach(nf);
deba@57:       }
deba@57: 
deba@57:       /// \brief Constructor which attach the obserever to the same notifier.
deba@57:       ///
deba@57:       /// Constructor which attach the obserever to the same notifier as
deba@57:       /// the other observer is attached to. 
deba@57:       ObserverBase(const ObserverBase& copy) {
deba@57: 	if (copy.attached()) {
deba@57:           attach(*copy.notifier());
deba@57: 	}
deba@57:       }
deba@57: 	
deba@57:       /// \brief Destructor
deba@57:       virtual ~ObserverBase() {
deba@57:         if (attached()) {
deba@57:           detach();
deba@57:         }
deba@57:       }
deba@57: 
deba@57:       /// \brief Attaches the observer into an AlterationNotifier.
deba@57:       ///
deba@57:       /// This member attaches the observer into an AlterationNotifier.
deba@57:       ///
deba@57:       void attach(AlterationNotifier& nf) {
deba@57: 	nf.attach(*this);
deba@57:       }
deba@57:       
deba@57:       /// \brief Detaches the observer into an AlterationNotifier.
deba@57:       ///
deba@57:       /// This member detaches the observer from an AlterationNotifier.
deba@57:       ///
deba@57:       void detach() {
deba@57:         _notifier->detach(*this);
deba@57:       }
deba@57:       
deba@57:       /// \brief Gives back a pointer to the notifier which the map 
deba@57:       /// attached into.
deba@57:       ///
deba@57:       /// This function gives back a pointer to the notifier which the map
deba@57:       /// attached into.
deba@57:       ///
deba@57:       Notifier* notifier() const { return const_cast<Notifier*>(_notifier); }
deba@57:       
deba@57:       /// Gives back true when the observer is attached into a notifier.
deba@57:       bool attached() const { return _notifier != 0; }
deba@57: 
deba@57:     private:
deba@57: 
deba@57:       ObserverBase& operator=(const ObserverBase& copy);
deba@57: 
deba@57:     protected:
deba@57:       
deba@57:       Notifier* _notifier;
deba@57:       typename std::list<ObserverBase*>::iterator _index;
deba@57: 
deba@57:       /// \brief The member function to notificate the observer about an
deba@57:       /// item is added to the container.
deba@57:       ///
deba@57:       /// The add() member function notificates the observer about an item
deba@57:       /// is added to the container. It have to be overrided in the
deba@57:       /// subclasses.
deba@57:       virtual void add(const Item&) = 0;
deba@57: 
deba@57:       /// \brief The member function to notificate the observer about 
deba@57:       /// more item is added to the container.
deba@57:       ///
deba@57:       /// The add() member function notificates the observer about more item
deba@57:       /// is added to the container. It have to be overrided in the
deba@57:       /// subclasses.
deba@57:       virtual void add(const std::vector<Item>& items) = 0;
deba@57: 
deba@57:       /// \brief The member function to notificate the observer about an
deba@57:       /// item is erased from the container.
deba@57:       ///
deba@57:       /// The erase() member function notificates the observer about an
deba@57:       /// item is erased from the container. It have to be overrided in
deba@57:       /// the subclasses.	
deba@57:       virtual void erase(const Item&) = 0;
deba@57: 
deba@57:       /// \brief The member function to notificate the observer about 
deba@57:       /// more item is erased from the container.
deba@57:       ///
deba@57:       /// The erase() member function notificates the observer about more item
deba@57:       /// is erased from the container. It have to be overrided in the
deba@57:       /// subclasses.
deba@57:       virtual void erase(const std::vector<Item>& items) = 0;
deba@57: 
deba@57:       /// \brief The member function to notificate the observer about the
deba@57:       /// container is built.
deba@57:       ///
deba@57:       /// The build() member function notificates the observer about the
deba@57:       /// container is built from an empty container. It have to be
deba@57:       /// overrided in the subclasses.
deba@57: 
deba@57:       virtual void build() = 0;
deba@57: 
deba@57:       /// \brief The member function to notificate the observer about all
deba@57:       /// items are erased from the container.
deba@57:       ///
deba@57:       /// The clear() member function notificates the observer about all
deba@57:       /// items are erased from the container. It have to be overrided in
deba@57:       /// the subclasses.      
deba@57:       virtual void clear() = 0;
deba@57: 
deba@57:     };
deba@57: 	
deba@57:   protected:
deba@57: 
deba@57:     const Container* container;
deba@57: 
deba@57:     typedef std::list<ObserverBase*> Observers; 
deba@57:     Observers _observers;
deba@57: 
deba@57: 		
deba@57:   public:
deba@57: 
deba@57:     /// \brief Default constructor.
deba@57:     ///
deba@57:     /// The default constructor of the AlterationNotifier. 
deba@57:     /// It creates an empty notifier.
deba@57:     AlterationNotifier() 
deba@57:       : container(0) {}
deba@57: 
deba@57:     /// \brief Constructor.
deba@57:     ///
deba@57:     /// Constructor with the observed container parameter.
deba@57:     AlterationNotifier(const Container& _container) 
deba@57:       : container(&_container) {}
deba@57: 
deba@57:     /// \brief Copy Constructor of the AlterationNotifier. 
deba@57:     ///
deba@57:     /// Copy constructor of the AlterationNotifier. 
deba@57:     /// It creates only an empty notifier because the copiable
deba@57:     /// notifier's observers have to be registered still into that notifier.
deba@57:     AlterationNotifier(const AlterationNotifier& _notifier) 
deba@57:       : container(_notifier.container) {}
deba@57: 
deba@57:     /// \brief Destructor.
deba@57:     ///		
deba@57:     /// Destructor of the AlterationNotifier.
deba@57:     ///
deba@57:     ~AlterationNotifier() {
deba@57:       typename Observers::iterator it;
deba@57:       for (it = _observers.begin(); it != _observers.end(); ++it) {
deba@57: 	(*it)->_notifier = 0;
deba@57:       }
deba@57:     }
deba@57: 
deba@57:     /// \brief Sets the container.
deba@57:     ///
deba@57:     /// Sets the container.
deba@57:     void setContainer(const Container& _container) {
deba@57:       container = &_container;
deba@57:     }
deba@57: 
deba@57:   protected:
deba@57: 
deba@57:     AlterationNotifier& operator=(const AlterationNotifier&);
deba@57: 
deba@57:   public:
deba@57: 
deba@57: 
deba@57: 
deba@57:     /// \brief First item in the container.
deba@57:     ///
deba@57:     /// Returns the first item in the container. It is
deba@57:     /// for start the iteration on the container.
deba@57:     void first(Item& item) const {
deba@57:       container->first(item);
deba@57:     }
deba@57: 
deba@57:     /// \brief Next item in the container.
deba@57:     ///
deba@57:     /// Returns the next item in the container. It is
deba@57:     /// for iterate on the container.
deba@57:     void next(Item& item) const {
deba@57:       container->next(item);
deba@57:     }
deba@57: 
deba@57:     /// \brief Returns the id of the item.
deba@57:     ///
deba@57:     /// Returns the id of the item provided by the container.
deba@57:     int id(const Item& item) const {
deba@57:       return container->id(item);
deba@57:     }
deba@57: 
deba@57:     /// \brief Returns the maximum id of the container.
deba@57:     ///
deba@57:     /// Returns the maximum id of the container.
deba@57:     int maxId() const {
deba@57:       return container->maxId(Item());
deba@57:     }
deba@57: 		
deba@57:   protected:
deba@57: 
deba@57:     void attach(ObserverBase& observer) {
deba@57:       observer._index = _observers.insert(_observers.begin(), &observer);
deba@57:       observer._notifier = this;
deba@57:     } 
deba@57: 
deba@57:     void detach(ObserverBase& observer) {
deba@57:       _observers.erase(observer._index);
deba@57:       observer._index = _observers.end();
deba@57:       observer._notifier = 0;
deba@57:     }
deba@57: 
deba@57:   public:
deba@57: 	
deba@57:     /// \brief Notifies all the registed observers about an item added to 
deba@57:     /// the container.
deba@57:     ///
deba@57:     /// It notifies all the registed observers about an item added to 
deba@57:     /// the container.
deba@57:     /// 
deba@57:     void add(const Item& item) {
deba@57:       typename Observers::reverse_iterator it;
deba@57:       try {
deba@57:         for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
deba@57:           (*it)->add(item);
deba@57:         }
deba@57:       } catch (...) {
deba@57:         typename Observers::iterator jt;
deba@57:         for (jt = it.base(); jt != _observers.end(); ++jt) {
deba@57:           (*jt)->erase(item);
deba@57:         }
deba@57:         throw;
deba@57:       }
deba@57:     }	
deba@57: 
deba@57:     /// \brief Notifies all the registed observers about more item added to 
deba@57:     /// the container.
deba@57:     ///
deba@57:     /// It notifies all the registed observers about more item added to 
deba@57:     /// the container.
deba@57:     /// 
deba@57:     void add(const std::vector<Item>& items) {
deba@57:       typename Observers::reverse_iterator it;
deba@57:       try {
deba@57:         for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
deba@57:           (*it)->add(items);
deba@57:         }
deba@57:       } catch (...) {
deba@57:         typename Observers::iterator jt;
deba@57:         for (jt = it.base(); jt != _observers.end(); ++jt) {
deba@57:           (*jt)->erase(items);
deba@57:         }
deba@57:         throw;
deba@57:       }
deba@57:     }	
deba@57: 
deba@57:     /// \brief Notifies all the registed observers about an item erased from 
deba@57:     /// the container.
deba@57:     ///	
deba@57:     /// It notifies all the registed observers about an item erased from 
deba@57:     /// the container.
deba@57:     /// 
deba@57:     void erase(const Item& item) throw() {
deba@57:       typename Observers::iterator it = _observers.begin();
deba@57:       while (it != _observers.end()) {
deba@57:         try {
deba@57:           (*it)->erase(item);
deba@57:           ++it;
deba@57:         } catch (const ImmediateDetach&) {
deba@57:           it = _observers.erase(it);
deba@57:           (*it)->_index = _observers.end();
deba@57:           (*it)->_notifier = 0;
deba@57:         }
deba@57:       }
deba@57:     }
deba@57: 
deba@57:     /// \brief Notifies all the registed observers about more item erased  
deba@57:     /// from the container.
deba@57:     ///	
deba@57:     /// It notifies all the registed observers about more item erased from 
deba@57:     /// the container.
deba@57:     /// 
deba@57:     void erase(const std::vector<Item>& items) {
deba@57:       typename Observers::iterator it = _observers.begin();
deba@57:       while (it != _observers.end()) {
deba@57:         try {
deba@57:           (*it)->erase(items);
deba@57:           ++it;
deba@57:         } catch (const ImmediateDetach&) {
deba@57:           it = _observers.erase(it);
deba@57:           (*it)->_index = _observers.end();
deba@57:           (*it)->_notifier = 0;
deba@57:         }
deba@57:       }
deba@57:     }
deba@57: 
deba@57:     /// \brief Notifies all the registed observers about the container is 
deba@57:     /// built.
deba@57:     ///		
deba@57:     /// Notifies all the registed observers about the container is built
deba@57:     /// from an empty container.
deba@57:     void build() {
deba@57:       typename Observers::reverse_iterator it;
deba@57:       try {
deba@57:         for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
deba@57:           (*it)->build();
deba@57:         }
deba@57:       } catch (...) {
deba@57:         typename Observers::iterator jt;
deba@57:         for (jt = it.base(); jt != _observers.end(); ++jt) {
deba@57:           (*jt)->clear();
deba@57:         }
deba@57:         throw;
deba@57:       }
deba@57:     }
deba@57: 
deba@57:     /// \brief Notifies all the registed observers about all items are 
deba@57:     /// erased.
deba@57:     ///
deba@57:     /// Notifies all the registed observers about all items are erased
deba@57:     /// from the container.
deba@57:     void clear() {
deba@57:       typename Observers::iterator it = _observers.begin();
deba@57:       while (it != _observers.end()) {
deba@57:         try {
deba@57:           (*it)->clear();
deba@57:           ++it;
deba@57:         } catch (const ImmediateDetach&) {
deba@57:           it = _observers.erase(it);
deba@57:           (*it)->_index = _observers.end();
deba@57:           (*it)->_notifier = 0;
deba@57:         }
deba@57:       }
deba@57:     }
deba@57:   };
deba@57: 
deba@57: }
deba@57: 
deba@57: #endif