lemon/bits/alteration_notifier.h
changeset 319 5e12d7734036
parent 313 64f8f7cc6168
child 361 f58410582b9b
equal deleted inserted replaced
7:e83f20f8a3fb 8:b2102e1865db
    22 #include <vector>
    22 #include <vector>
    23 #include <list>
    23 #include <list>
    24 
    24 
    25 #include <lemon/core.h>
    25 #include <lemon/core.h>
    26 
    26 
    27 ///\ingroup graphbits
    27 //\ingroup graphbits
    28 ///\file
    28 //\file
    29 ///\brief Observer notifier for graph alteration observers.
    29 //\brief Observer notifier for graph alteration observers.
    30 
    30 
    31 namespace lemon {
    31 namespace lemon {
    32 
    32 
    33   /// \ingroup graphbits
    33   // \ingroup graphbits
    34   ///
    34   //
    35   /// \brief Notifier class to notify observes about alterations in
    35   // \brief Notifier class to notify observes about alterations in
    36   /// a container.
    36   // a container.
    37   ///
    37   //
    38   /// The simple graph's can be refered as two containers, one node container
    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
    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
    40   // does not store values directly they are just key continars for more
    41   /// value containers which are the node and edge maps.
    41   // value containers which are the node and edge maps.
    42   ///
    42   //
    43   /// The graph's node and edge sets can be changed as we add or erase
    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
    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
    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
    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
    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
    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
    49   // an alteration in the graph, which cause only drawback on the
    50   /// alteration of the graph.
    50   // alteration of the graph.
    51   ///
    51   //
    52   /// This class provides an interface to the container. The \e first() and \e
    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
    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.
    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.
    55   // The \e maxId() function gives back an upper bound of the ids.
    56   ///
    56   //
    57   /// For the proper functonality of this class, we should notify it
    57   // For the proper functonality of this class, we should notify it
    58   /// about each alteration in the container. The alterations have four type
    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
    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
    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
    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
    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
    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
    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
    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.
    66   // first extend the container and just after that signal the alteration.
    67   ///
    67   //
    68   /// The alteration can be observed with a class inherited from the
    68   // The alteration can be observed with a class inherited from the
    69   /// \e ObserverBase nested class. The signals can be handled with
    69   // \e ObserverBase nested class. The signals can be handled with
    70   /// overriding the virtual functions defined in the base class.  The
    70   // overriding the virtual functions defined in the base class.  The
    71   /// observer base can be attached to the notifier with the
    71   // observer base can be attached to the notifier with the
    72   /// \e attach() member and can be detached with detach() function. The
    72   // \e attach() member and can be detached with detach() function. The
    73   /// alteration handlers should not call any function which signals
    73   // alteration handlers should not call any function which signals
    74   /// an other alteration in the same notifier and should not
    74   // an other alteration in the same notifier and should not
    75   /// detach any observer from the notifier.
    75   // detach any observer from the notifier.
    76   ///
    76   //
    77   /// Alteration observers try to be exception safe. If an \e add() or
    77   // Alteration observers try to be exception safe. If an \e add() or
    78   /// a \e clear() function throws an exception then the remaining
    78   // a \e clear() function throws an exception then the remaining
    79   /// observeres will not be notified and the fulfilled additions will
    79   // observeres will not be notified and the fulfilled additions will
    80   /// be rolled back by calling the \e erase() or \e clear()
    80   // be rolled back by calling the \e erase() or \e clear()
    81   /// functions. Thence the \e erase() and \e clear() should not throw
    81   // functions. Thence the \e erase() and \e clear() should not throw
    82   /// exception. Actullay, it can be throw only \ref ImmediateDetach 
    82   // exception. Actullay, it can be throw only \ref ImmediateDetach
    83   /// exception which detach the observer from the notifier.
    83   // exception which detach the observer from the notifier.
    84   ///
    84   //
    85   /// There are some place when the alteration observing is not completly
    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
    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
    87   // as in the \ref InDegMap and we use the reverseEdge that cause
    88   /// unreliable functionality. Because the alteration observing signals
    88   // unreliable functionality. Because the alteration observing signals
    89   /// only erasing and adding but not the reversing it will stores bad
    89   // only erasing and adding but not the reversing it will stores bad
    90   /// degrees. The sub graph adaptors cannot signal the alterations because
    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
    91   // just a setting in the filter map can modify the graph and this cannot
    92   /// be watched in any way.
    92   // be watched in any way.
    93   ///
    93   //
    94   /// \param _Container The container which is observed.
    94   // \param _Container The container which is observed.
    95   /// \param _Item The item type which is obserbved.
    95   // \param _Item The item type which is obserbved.
    96 
    96 
    97   template <typename _Container, typename _Item>
    97   template <typename _Container, typename _Item>
    98   class AlterationNotifier {
    98   class AlterationNotifier {
    99   public:
    99   public:
   100 
   100 
   101     typedef True Notifier;
   101     typedef True Notifier;
   102 
   102 
   103     typedef _Container Container;
   103     typedef _Container Container;
   104     typedef _Item Item;
   104     typedef _Item Item;
   105 
   105 
   106     /// \brief Exception which can be called from \e clear() and
   106     // \brief Exception which can be called from \e clear() and
   107     /// \e erase().
   107     // \e erase().
   108     ///
   108     //
   109     /// From the \e clear() and \e erase() function only this
   109     // From the \e clear() and \e erase() function only this
   110     /// exception is allowed to throw. The exception immediatly
   110     // exception is allowed to throw. The exception immediatly
   111     /// detaches the current observer from the notifier. Because the
   111     // detaches the current observer from the notifier. Because the
   112     /// \e clear() and \e erase() should not throw other exceptions
   112     // \e clear() and \e erase() should not throw other exceptions
   113     /// it can be used to invalidate the observer.
   113     // it can be used to invalidate the observer.
   114     struct ImmediateDetach {};
   114     struct ImmediateDetach {};
   115 
   115 
   116     /// \brief ObserverBase is the base class for the observers.
   116     // \brief ObserverBase is the base class for the observers.
   117     ///
   117     //
   118     /// ObserverBase is the abstract 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
   119     // It will be notified about an item was inserted into or
   120     /// erased from the graph.
   120     // erased from the graph.
   121     ///
   121     //
   122     /// The observer interface contains some pure virtual functions
   122     // The observer interface contains some pure virtual functions
   123     /// to override. The add() and erase() functions are
   123     // to override. The add() and erase() functions are
   124     /// to notify the oberver when one item is added or
   124     // to notify the oberver when one item is added or
   125     /// erased.
   125     // erased.
   126     ///
   126     //
   127     /// The build() and clear() members are to notify the observer
   127     // The build() and clear() members are to notify the observer
   128     /// about the container is built from an empty container or
   128     // about the container is built from an empty container or
   129     /// is cleared to an empty container.
   129     // is cleared to an empty container.
   130 
       
   131     class ObserverBase {
   130     class ObserverBase {
   132     protected:
   131     protected:
   133       typedef AlterationNotifier Notifier;
   132       typedef AlterationNotifier Notifier;
   134 
   133 
   135       friend class AlterationNotifier;
   134       friend class AlterationNotifier;
   136 
   135 
   137       /// \brief Default constructor.
   136       // \brief Default constructor.
   138       ///
   137       //
   139       /// Default constructor for ObserverBase.
   138       // Default constructor for ObserverBase.
   140       ///
       
   141       ObserverBase() : _notifier(0) {}
   139       ObserverBase() : _notifier(0) {}
   142 
   140 
   143       /// \brief Constructor which attach the observer into notifier.
   141       // \brief Constructor which attach the observer into notifier.
   144       ///
   142       //
   145       /// Constructor which attach the observer into notifier.
   143       // Constructor which attach the observer into notifier.
   146       ObserverBase(AlterationNotifier& nf) {
   144       ObserverBase(AlterationNotifier& nf) {
   147         attach(nf);
   145         attach(nf);
   148       }
   146       }
   149 
   147 
   150       /// \brief Constructor which attach the obserever to the same notifier.
   148       // \brief Constructor which attach the obserever to the same notifier.
   151       ///
   149       //
   152       /// Constructor which attach the obserever to the same notifier as
   150       // Constructor which attach the obserever to the same notifier as
   153       /// the other observer is attached to.
   151       // the other observer is attached to.
   154       ObserverBase(const ObserverBase& copy) {
   152       ObserverBase(const ObserverBase& copy) {
   155         if (copy.attached()) {
   153         if (copy.attached()) {
   156           attach(*copy.notifier());
   154           attach(*copy.notifier());
   157         }
   155         }
   158       }
   156       }
   159 
   157 
   160       /// \brief Destructor
   158       // \brief Destructor
   161       virtual ~ObserverBase() {
   159       virtual ~ObserverBase() {
   162         if (attached()) {
   160         if (attached()) {
   163           detach();
   161           detach();
   164         }
   162         }
   165       }
   163       }
   166 
   164 
   167       /// \brief Attaches the observer into an AlterationNotifier.
   165       // \brief Attaches the observer into an AlterationNotifier.
   168       ///
   166       //
   169       /// This member attaches the observer into an AlterationNotifier.
   167       // This member attaches the observer into an AlterationNotifier.
   170       ///
       
   171       void attach(AlterationNotifier& nf) {
   168       void attach(AlterationNotifier& nf) {
   172         nf.attach(*this);
   169         nf.attach(*this);
   173       }
   170       }
   174 
   171 
   175       /// \brief Detaches the observer into an AlterationNotifier.
   172       // \brief Detaches the observer into an AlterationNotifier.
   176       ///
   173       //
   177       /// This member detaches the observer from an AlterationNotifier.
   174       // This member detaches the observer from an AlterationNotifier.
   178       ///
       
   179       void detach() {
   175       void detach() {
   180         _notifier->detach(*this);
   176         _notifier->detach(*this);
   181       }
   177       }
   182 
   178 
   183       /// \brief Gives back a pointer to the notifier which the map
   179       // \brief Gives back a pointer to the notifier which the map
   184       /// attached into.
   180       // attached into.
   185       ///
   181       //
   186       /// This function gives back a pointer to the notifier which the map
   182       // This function gives back a pointer to the notifier which the map
   187       /// attached into.
   183       // attached into.
   188       ///
       
   189       Notifier* notifier() const { return const_cast<Notifier*>(_notifier); }
   184       Notifier* notifier() const { return const_cast<Notifier*>(_notifier); }
   190 
   185 
   191       /// Gives back true when the observer is attached into a notifier.
   186       // Gives back true when the observer is attached into a notifier.
   192       bool attached() const { return _notifier != 0; }
   187       bool attached() const { return _notifier != 0; }
   193 
   188 
   194     private:
   189     private:
   195 
   190 
   196       ObserverBase& operator=(const ObserverBase& copy);
   191       ObserverBase& operator=(const ObserverBase& copy);
   198     protected:
   193     protected:
   199 
   194 
   200       Notifier* _notifier;
   195       Notifier* _notifier;
   201       typename std::list<ObserverBase*>::iterator _index;
   196       typename std::list<ObserverBase*>::iterator _index;
   202 
   197 
   203       /// \brief The member function to notificate the observer about an
   198       // \brief The member function to notificate the observer about an
   204       /// item is added to the container.
   199       // item is added to the container.
   205       ///
   200       //
   206       /// The add() member function notificates the observer about an item
   201       // The add() member function notificates the observer about an item
   207       /// is added to the container. It have to be overrided in the
   202       // is added to the container. It have to be overrided in the
   208       /// subclasses.
   203       // subclasses.
   209       virtual void add(const Item&) = 0;
   204       virtual void add(const Item&) = 0;
   210 
   205 
   211       /// \brief The member function to notificate the observer about
   206       // \brief The member function to notificate the observer about
   212       /// more item is added to the container.
   207       // more item is added to the container.
   213       ///
   208       //
   214       /// The add() member function notificates the observer about more item
   209       // The add() member function notificates the observer about more item
   215       /// is added to the container. It have to be overrided in the
   210       // is added to the container. It have to be overrided in the
   216       /// subclasses.
   211       // subclasses.
   217       virtual void add(const std::vector<Item>& items) = 0;
   212       virtual void add(const std::vector<Item>& items) = 0;
   218 
   213 
   219       /// \brief The member function to notificate the observer about an
   214       // \brief The member function to notificate the observer about an
   220       /// item is erased from the container.
   215       // item is erased from the container.
   221       ///
   216       //
   222       /// The erase() member function notificates the observer about an
   217       // The erase() member function notificates the observer about an
   223       /// item is erased from the container. It have to be overrided in
   218       // item is erased from the container. It have to be overrided in
   224       /// the subclasses.
   219       // the subclasses.
   225       virtual void erase(const Item&) = 0;
   220       virtual void erase(const Item&) = 0;
   226 
   221 
   227       /// \brief The member function to notificate the observer about
   222       // \brief The member function to notificate the observer about
   228       /// more item is erased from the container.
   223       // more item is erased from the container.
   229       ///
   224       //
   230       /// The erase() member function notificates the observer about more item
   225       // The erase() member function notificates the observer about more item
   231       /// is erased from the container. It have to be overrided in the
   226       // is erased from the container. It have to be overrided in the
   232       /// subclasses.
   227       // subclasses.
   233       virtual void erase(const std::vector<Item>& items) = 0;
   228       virtual void erase(const std::vector<Item>& items) = 0;
   234 
   229 
   235       /// \brief The member function to notificate the observer about the
   230       // \brief The member function to notificate the observer about the
   236       /// container is built.
   231       // container is built.
   237       ///
   232       //
   238       /// The build() member function notificates the observer about the
   233       // The build() member function notificates the observer about the
   239       /// container is built from an empty container. It have to be
   234       // container is built from an empty container. It have to be
   240       /// overrided in the subclasses.
   235       // overrided in the subclasses.
   241 
       
   242       virtual void build() = 0;
   236       virtual void build() = 0;
   243 
   237 
   244       /// \brief The member function to notificate the observer about all
   238       // \brief The member function to notificate the observer about all
   245       /// items are erased from the container.
   239       // items are erased from the container.
   246       ///
   240       //
   247       /// The clear() member function notificates the observer about all
   241       // The clear() member function notificates the observer about all
   248       /// items are erased from the container. It have to be overrided in
   242       // items are erased from the container. It have to be overrided in
   249       /// the subclasses.
   243       // the subclasses.
   250       virtual void clear() = 0;
   244       virtual void clear() = 0;
   251 
   245 
   252     };
   246     };
   253 
   247 
   254   protected:
   248   protected:
   259     Observers _observers;
   253     Observers _observers;
   260 
   254 
   261 
   255 
   262   public:
   256   public:
   263 
   257 
   264     /// \brief Default constructor.
   258     // \brief Default constructor.
   265     ///
   259     //
   266     /// The default constructor of the AlterationNotifier.
   260     // The default constructor of the AlterationNotifier.
   267     /// It creates an empty notifier.
   261     // It creates an empty notifier.
   268     AlterationNotifier()
   262     AlterationNotifier()
   269       : container(0) {}
   263       : container(0) {}
   270 
   264 
   271     /// \brief Constructor.
   265     // \brief Constructor.
   272     ///
   266     //
   273     /// Constructor with the observed container parameter.
   267     // Constructor with the observed container parameter.
   274     AlterationNotifier(const Container& _container)
   268     AlterationNotifier(const Container& _container)
   275       : container(&_container) {}
   269       : container(&_container) {}
   276 
   270 
   277     /// \brief Copy Constructor of the AlterationNotifier.
   271     // \brief Copy Constructor of the AlterationNotifier.
   278     ///
   272     //
   279     /// Copy constructor of the AlterationNotifier.
   273     // Copy constructor of the AlterationNotifier.
   280     /// It creates only an empty notifier because the copiable
   274     // It creates only an empty notifier because the copiable
   281     /// notifier's observers have to be registered still into that notifier.
   275     // notifier's observers have to be registered still into that notifier.
   282     AlterationNotifier(const AlterationNotifier& _notifier)
   276     AlterationNotifier(const AlterationNotifier& _notifier)
   283       : container(_notifier.container) {}
   277       : container(_notifier.container) {}
   284 
   278 
   285     /// \brief Destructor.
   279     // \brief Destructor.
   286     ///
   280     //
   287     /// Destructor of the AlterationNotifier.
   281     // Destructor of the AlterationNotifier.
   288     ///
       
   289     ~AlterationNotifier() {
   282     ~AlterationNotifier() {
   290       typename Observers::iterator it;
   283       typename Observers::iterator it;
   291       for (it = _observers.begin(); it != _observers.end(); ++it) {
   284       for (it = _observers.begin(); it != _observers.end(); ++it) {
   292         (*it)->_notifier = 0;
   285         (*it)->_notifier = 0;
   293       }
   286       }
   294     }
   287     }
   295 
   288 
   296     /// \brief Sets the container.
   289     // \brief Sets the container.
   297     ///
   290     //
   298     /// Sets the container.
   291     // Sets the container.
   299     void setContainer(const Container& _container) {
   292     void setContainer(const Container& _container) {
   300       container = &_container;
   293       container = &_container;
   301     }
   294     }
   302 
   295 
   303   protected:
   296   protected:
   304 
   297 
   305     AlterationNotifier& operator=(const AlterationNotifier&);
   298     AlterationNotifier& operator=(const AlterationNotifier&);
   306 
   299 
   307   public:
   300   public:
   308 
   301 
   309 
   302     // \brief First item in the container.
   310 
   303     //
   311     /// \brief First item in the container.
   304     // Returns the first item in the container. It is
   312     ///
   305     // for start the iteration on 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 {
   306     void first(Item& item) const {
   316       container->first(item);
   307       container->first(item);
   317     }
   308     }
   318 
   309 
   319     /// \brief Next item in the container.
   310     // \brief Next item in the container.
   320     ///
   311     //
   321     /// Returns the next item in the container. It is
   312     // Returns the next item in the container. It is
   322     /// for iterate on the container.
   313     // for iterate on the container.
   323     void next(Item& item) const {
   314     void next(Item& item) const {
   324       container->next(item);
   315       container->next(item);
   325     }
   316     }
   326 
   317 
   327     /// \brief Returns the id of the item.
   318     // \brief Returns the id of the item.
   328     ///
   319     //
   329     /// Returns the id of the item provided by the container.
   320     // Returns the id of the item provided by the container.
   330     int id(const Item& item) const {
   321     int id(const Item& item) const {
   331       return container->id(item);
   322       return container->id(item);
   332     }
   323     }
   333 
   324 
   334     /// \brief Returns the maximum id of the container.
   325     // \brief Returns the maximum id of the container.
   335     ///
   326     //
   336     /// Returns the maximum id of the container.
   327     // Returns the maximum id of the container.
   337     int maxId() const {
   328     int maxId() const {
   338       return container->maxId(Item());
   329       return container->maxId(Item());
   339     }
   330     }
   340 
   331 
   341   protected:
   332   protected:
   351       observer._notifier = 0;
   342       observer._notifier = 0;
   352     }
   343     }
   353 
   344 
   354   public:
   345   public:
   355 
   346 
   356     /// \brief Notifies all the registed observers about an item added to
   347     // \brief Notifies all the registed observers about an item added to
   357     /// the container.
   348     // the container.
   358     ///
   349     //
   359     /// It notifies all the registed observers about an item added to
   350     // It notifies all the registed observers about an item added to
   360     /// the container.
   351     // the container.
   361     ///
       
   362     void add(const Item& item) {
   352     void add(const Item& item) {
   363       typename Observers::reverse_iterator it;
   353       typename Observers::reverse_iterator it;
   364       try {
   354       try {
   365         for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
   355         for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
   366           (*it)->add(item);
   356           (*it)->add(item);
   372         }
   362         }
   373         throw;
   363         throw;
   374       }
   364       }
   375     }
   365     }
   376 
   366 
   377     /// \brief Notifies all the registed observers about more item added to
   367     // \brief Notifies all the registed observers about more item added to
   378     /// the container.
   368     // the container.
   379     ///
   369     //
   380     /// It notifies all the registed observers about more item added to
   370     // It notifies all the registed observers about more item added to
   381     /// the container.
   371     // the container.
   382     ///
       
   383     void add(const std::vector<Item>& items) {
   372     void add(const std::vector<Item>& items) {
   384       typename Observers::reverse_iterator it;
   373       typename Observers::reverse_iterator it;
   385       try {
   374       try {
   386         for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
   375         for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
   387           (*it)->add(items);
   376           (*it)->add(items);
   393         }
   382         }
   394         throw;
   383         throw;
   395       }
   384       }
   396     }
   385     }
   397 
   386 
   398     /// \brief Notifies all the registed observers about an item erased from
   387     // \brief Notifies all the registed observers about an item erased from
   399     /// the container.
   388     // the container.
   400     ///
   389     //
   401     /// It notifies all the registed observers about an item erased from
   390     // It notifies all the registed observers about an item erased from
   402     /// the container.
   391     // the container.
   403     ///
       
   404     void erase(const Item& item) throw() {
   392     void erase(const Item& item) throw() {
   405       typename Observers::iterator it = _observers.begin();
   393       typename Observers::iterator it = _observers.begin();
   406       while (it != _observers.end()) {
   394       while (it != _observers.end()) {
   407         try {
   395         try {
   408           (*it)->erase(item);
   396           (*it)->erase(item);
   413           it = _observers.erase(it);
   401           it = _observers.erase(it);
   414         }
   402         }
   415       }
   403       }
   416     }
   404     }
   417 
   405 
   418     /// \brief Notifies all the registed observers about more item erased
   406     // \brief Notifies all the registed observers about more item erased
   419     /// from the container.
   407     // from the container.
   420     ///
   408     //
   421     /// It notifies all the registed observers about more item erased from
   409     // It notifies all the registed observers about more item erased from
   422     /// the container.
   410     // the container.
   423     ///
       
   424     void erase(const std::vector<Item>& items) {
   411     void erase(const std::vector<Item>& items) {
   425       typename Observers::iterator it = _observers.begin();
   412       typename Observers::iterator it = _observers.begin();
   426       while (it != _observers.end()) {
   413       while (it != _observers.end()) {
   427         try {
   414         try {
   428           (*it)->erase(items);
   415           (*it)->erase(items);
   433           it = _observers.erase(it);
   420           it = _observers.erase(it);
   434         }
   421         }
   435       }
   422       }
   436     }
   423     }
   437 
   424 
   438     /// \brief Notifies all the registed observers about the container is
   425     // \brief Notifies all the registed observers about the container is
   439     /// built.
   426     // built.
   440     ///
   427     //
   441     /// Notifies all the registed observers about the container is built
   428     // Notifies all the registed observers about the container is built
   442     /// from an empty container.
   429     // from an empty container.
   443     void build() {
   430     void build() {
   444       typename Observers::reverse_iterator it;
   431       typename Observers::reverse_iterator it;
   445       try {
   432       try {
   446         for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
   433         for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
   447           (*it)->build();
   434           (*it)->build();
   453         }
   440         }
   454         throw;
   441         throw;
   455       }
   442       }
   456     }
   443     }
   457 
   444 
   458     /// \brief Notifies all the registed observers about all items are
   445     // \brief Notifies all the registed observers about all items are
   459     /// erased.
   446     // erased.
   460     ///
   447     //
   461     /// Notifies all the registed observers about all items are erased
   448     // Notifies all the registed observers about all items are erased
   462     /// from the container.
   449     // from the container.
   463     void clear() {
   450     void clear() {
   464       typename Observers::iterator it = _observers.begin();
   451       typename Observers::iterator it = _observers.begin();
   465       while (it != _observers.end()) {
   452       while (it != _observers.end()) {
   466         try {
   453         try {
   467           (*it)->clear();
   454           (*it)->clear();