#ifndef LEMON_ALTERATION_NOTIFIER_H

 #ifndef LEMON_BITS_ALTERATION_NOTIFIER_H

 #define LEMON_ALTERATION_NOTIFIER_H

 #define LEMON_BITS_ALTERATION_NOTIFIER_H

 #include <algorithm>

 #include <lemon/bits/utility.h>

 ///\brief Observer registry for graph alteration observers.

 ///\brief Observer notifier for graph alteration observers.

   /// \addtogroup graphbits

   /// \ingroup graphbits

   /// @{

   ///

   /// \brief Notifier class to notify observes about alterations in 

   /// \brief Registry class to register objects observes alterations in 

   /// a container.

   /// the graph.

   ///

   ///

   /// The simple graph's can be refered as two containers, one node container

   /// This class is a registry for the objects which observe the

   /// and one edge container. But they are not standard containers they

   /// alterations in a container. The alteration observers can be attached

   /// does not store values directly they are just key continars for more

   /// to and detached from the registry. The observers have to inherit

   /// value containers which are the node and edge maps.

   /// from the \ref AlterationNotifier::ObserverBase and override

   ///

   /// the virtual functions in that.

   /// 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

   /// The most important application of the alteration observing is the

   /// that the node and edge maps should contain values for all nodes or

   /// dynamic map implementation.

   /// edges. If we want to check on every indicing if the map contains

   ///

   /// the current indicing key that cause a drawback in the performance

   /// \param _Item The item type what the observers are observing, usually

   /// in the library. We use an other solution we notify all maps about

   /// edge or node.

   /// 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.

   ///

   /// Alteration observers try to be exception safe. This can be achived

   /// when the observers does not throw exception on \e erase() and 

   /// \e clear(). Less strict condition is that the \e erase() should

   /// not throw exception after an \e add() with the same parameter and

   /// the \e clear() should not throw exception after a \e build(). 

   ///

   /// 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.

   template <typename _Item>

   template <typename _Container, typename _Item>

     /// ObserverBase is the base class for the observers.

     /// \brief ObserverBase is the base class for the observers.

     ///

       typedef AlterationNotifier Registry;

       typedef AlterationNotifier Notifier;

       ObserverBase() : registry(0) {}

       ObserverBase() : notifier(0) {}

       /// \brief Constructor which attach the observer into notifier.

       ///

       /// Constructor which attach the observer into notifier.

       ObserverBase(AlterationNotifier& _notifier) {

         attach(_notifier);

       }

       /// \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. 

 	  copy.getRegistry()->attach(*this);

           attach(*copy.getNotifier());

       virtual ~ObserverBase() {}

       /// \brief Destructor

       virtual ~ObserverBase() {

         if (attached()) {

           detach();

         }

       }

       void attach(AlterationNotifier& r) {

       void attach(AlterationNotifier& _notifier) {

 	registry = &r;

 	notifier = &_notifier;

 	registry->attach(*this);

 	notifier->attach(*this);

 	if (registry) {

         notifier->detach(*this);

 	  registry->detach(*this);

       }

 	}

       }

       /// \brief Gives back a pointer to the notifier which the map 

       /// Gives back a pointer to the registry what the map attached into.

       /// This function gives back a pointer to the registry what the map

       Registry* getRegistry() const { return const_cast<Registry*>(registry); }

       /// This function gives back a pointer to the notifier which the map

       /// attached into.

       ///

       Notifier* getNotifier() const { return const_cast<Notifier*>(notifier); }

       /// Gives back true when the observer is attached into a registry.

       /// Gives back true when the observer is attached into a notifier.

       bool attached() const { return registry != 0; }

       bool attached() const { return notifier != 0; }

       Registry* registry;

       Notifier* notifier;

       int registry_index;

       int notifier_index;

 	for (int i = 0; i < (int)items.size(); ++i) {

         int i;

 	  add(items[i]);

         try {

 	}

           for (i = 0; i < (int)items.size(); ++i) {

             add(items[i]);

           }

         } catch (...) {

           for (int j = 0; j < i; ++j) {

             add(items[j]);

           }          

           throw;

         }

 	for (int i = 0; i < (int)items.size(); ++i) {

         for (int i = 0; i < (int)items.size(); ++i) {

 	  erase(items[i]);

           erase(items[i]);

 	}

         }

       virtual void build() = 0;

       virtual void build() {

         Item it;

         try {

           for (notifier->first(it); it != INVALID; notifier->next(it)) {

             add(it);

           }

         } catch (...) {

           Item jt;

           for (notifier->first(jt); jt != it; notifier->next(jt)) {

             erase(jt);

           }

           throw;

         }

       }

       /// the subclasses.

       /// the subclasses.      

       virtual void clear() {

       virtual void clear() = 0;

         Item it;

         for (notifier->first(it); it != INVALID; notifier->next(it)) {

           erase(it);

         }

       }

     const Container* container;

     typedef std::vector<ObserverBase*> Container; 

     typedef std::vector<ObserverBase*> Observers; 

     Container container;

     Observers observers;

     /// Default constructor.

     /// \brief Default constructor.

     /// It creates an empty registry.

     /// It creates an empty notifier.

     AlterationNotifier() {}

     AlterationNotifier() 

       : container(0) {}

     /// Copy Constructor of the AlterationNotifier. 

     /// \brief Constructor.

     ///

     /// Constructor with the observed container parameter.

     AlterationNotifier(const Container& _container) 

       : container(&_container) {}

     /// \brief Copy Constructor of the AlterationNotifier. 

     ///

     /// It creates only an empty registry because the copiable

     /// It creates only an empty notifier because the copiable

     /// registry's observers have to be registered still into that registry.

     /// notifier's observers have to be registered still into that notifier.

     AlterationNotifier(const AlterationNotifier&) {}

     AlterationNotifier(const AlterationNotifier& _notifier) 

       : container(_notifier.container) {}

     /// Assign operator.

     /// \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());

     }

       container.push_back(&observer);

       observers.push_back(&observer);

       observer.registry = this;

       observer.notifier = this;

       observer.registry_index = container.size()-1;

       observer.notifier_index = observers.size() - 1;

     void detach(ObserverBase& base) {

     void detach(ObserverBase& observer) {

       container.back()->registry_index = base.registry_index; 

       observers.back()->notifier_index = observer.notifier_index; 

       container[base.registry_index] = container.back();

       observers[observer.notifier_index] = observers.back();

       container.pop_back();

       observers.pop_back();

       base.registry = 0;

       observer.notifier = 0;

     /// \brief Notifies all the registered observers about an Item added to 

     /// \brief Notifies all the registed observers about an item added to 

     /// the container.

     /// the container.

     ///

     ///

     /// It notifies all the registered observers about an Item added to 

     /// It notifies all the registed observers about an item added to 

       typename Container::iterator it;

       typename Observers::iterator it;

         for (it = container.begin(); it != container.end(); ++it) {

         for (it = observers.begin(); it != observers.end(); ++it) {

         typename Container::iterator jt;

         typename Observers::iterator jt;

         for (jt = container.begin(); jt != it; ++it) {

         for (jt = observers.begin(); jt != it; ++jt) {

     /// \brief Notifies all the registered observers about more Item added to 

     /// \brief Notifies all the registed observers about more item added to 

     /// the container.

     /// the container.

     ///

     ///

     /// It notifies all the registered observers about more Item added to 

     /// It notifies all the registed observers about more item added to 

       typename Container::iterator it;

       typename Observers::iterator it;

         for (it = container.begin(); it != container.end(); ++it) {

         for (it = observers.begin(); it != observers.end(); ++it) {

         typename Container::iterator jt;

         typename Observers::iterator jt;

         for (jt = container.begin(); jt != it; ++it) {

         for (jt = observers.begin(); jt != it; ++jt) {

     /// \brief Notifies all the registered observers about an Item erased from 

     /// \brief Notifies all the registed observers about an item erased from 

     /// It notifies all the registered observers about an Item erased from 

     /// It notifies all the registed observers about an item erased from 

       typename Container::iterator it;

       typename Observers::iterator it;

       for (it = container.begin(); it != container.end(); ++it) {

       for (it = observers.begin(); it != observers.end(); ++it) {

     /// \brief Notifies all the registered observers about more Item erased  

     /// \brief Notifies all the registed observers about more item erased  

     /// It notifies all the registered observers about more Item erased from 

     /// It notifies all the registed observers about more item erased from 

       typename Container::iterator it;

       typename Observers::iterator it;

       for (it = container.begin(); it != container.end(); ++it) {

       for (it = observers.begin(); it != observers.end(); ++it) {

     /// \brief Notifies all the registered observers about the container is 

     /// \brief Notifies all the registed observers about the container is 

     /// Notifies all the registered observers about the container is built

     /// Notifies all the registed observers about the container is built

       typename Container::iterator it;

       typename Observers::iterator it;

         for (it = container.begin(); it != container.end(); ++it) {

         for (it = observers.begin(); it != observers.end(); ++it) {

         typename Container::iterator jt;

         typename Observers::iterator jt;

         for (jt = container.begin(); jt != it; ++it) {

         for (jt = observers.begin(); jt != it; ++jt) {

     /// \brief Notifies all the registered observers about all Items are 

     /// \brief Notifies all the registed observers about all items are 

     /// Notifies all the registered observers about all Items are erased

     /// Notifies all the registed observers about all items are erased

       typename Container::iterator it;

       typename Observers::iterator it;

       for (it = container.begin(); it != container.end(); ++it) {

       for (it = observers.begin(); it != observers.end(); ++it) {