File indexing completed on 2024-05-05 04:48:16

 /****************************************************************************************
  * Copyright (c) 2007 Maximilian Kossick <maximilian.kossick@googlemail.com>            *
  * Copyright (c) 2008 Mark Kretschmann <kretschmann@kde.org>                            *
  * Copyright (c) 2013 Matěj Laitl <matej@laitl.cz>                                      *
  *                                                                                      *
  * This program is free software; you can redistribute it and/or modify it under        *
  * the terms of the GNU General Public License as published by the Free Software        *
  * Foundation; either version 2 of the License, or (at your option) any later           *
  * version.                                                                             *
  *                                                                                      *
  * This program is distributed in the hope that it will be useful, but WITHOUT ANY      *
  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A      *
  * PARTICULAR PURPOSE. See the GNU General Public License for more details.             *
  *                                                                                      *
  * You should have received a copy of the GNU General Public License along with         *
  * this program.  If not, see <http://www.gnu.org/licenses/>.                           *
  ***************************************************************************************/
 
 #ifndef META_OBSERVER_H
 #define META_OBSERVER_H
 
 #include "core/amarokcore_export.h"
 #include "core/meta/forward_declarations.h"
 
 #include <QMutex>
 #include <QSet>
 
 class PersistentStatisticsStore;
 
 namespace Meta {
     /**
      * Subclass this class to be able to listen to changes of track, artist, album, genre,
      * composer and year metadata. Must useful just for tracks and albums though.
      *
      * If you want to override just one metadataChanged() and want to get rid of "method
      * hidden compiler warnings", use following pattern in your class declaration:
      *
      * using Observer::metadataChanged;
      * void metadataChanged( AlbumPtr album );
      *
      * This class is thread-safe.
      */
     class AMAROKCORE_EXPORT Observer
     {
         friend class Base; // so that it can call destroyedNotify()
 
         public:
             virtual ~Observer();
 
             /**
              * Subscribe to changes made by @param entity .
              *
              * Changed in 2.7: being subscribed to an entity no longer prevents its
              * destruction.
              */
             template <typename T>
             void subscribeTo( AmarokSharedPointer<T> entity ) { subscribeTo( entity.data() ); }
             template <typename T>
             void unsubscribeFrom( AmarokSharedPointer<T> entity ) { unsubscribeFrom( entity.data() ); }
 
             /**
              * This method is called when the metadata of a track has changed.
              * The called class may not cache the pointer.
              */
             virtual void metadataChanged( const TrackPtr &track );
             virtual void metadataChanged( const ArtistPtr &artist );
             virtual void metadataChanged( const AlbumPtr &album );
             virtual void metadataChanged( const GenrePtr &genre );
             virtual void metadataChanged( const ComposerPtr &composer );
             virtual void metadataChanged( const YearPtr &year );
 
             /**
              * One of the subscribed entities was destroyed. You don't get which one
              * because it is already invalid.
              */
             virtual void entityDestroyed();
 
         private:
             friend class ::PersistentStatisticsStore; // so that it can call AmarokSharedPointer-free subscribe:
             void subscribeTo( Base *ptr );
             void unsubscribeFrom( Base *ptr );
 
             /**
              * Called in Meta::Base destructor so that Observer doesn't have a stale pointer.
              */
             void destroyedNotify( Base *ptr );
 
             QSet<Base *> m_subscriptions;
             QMutex m_subscriptionsMutex; /// mutex guarding access to m_subscriptions
     };
 }
 
 #endif // META_OBSERVER_H