File indexing completed on 2024-05-05 04:48:30

 /****************************************************************************************
  * Copyright (c) 2008 Daniel Caleb Jones <danielcjones@gmail.com>                       *
  *                                                                                      *
  * 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) version 3 or        *
  * any later version accepted by the membership of KDE e.V. (or its successor approved  *
  * by the membership of KDE e.V.), which shall act as a proxy defined in Section 14 of  *
  * version 3 of the license.                                                            *
  *                                                                                      *
  * 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 AMAROK_TRACKSET_H
 #define AMAROK_TRACKSET_H
 
 #include "amarok_export.h"
 #include "core/meta/forward_declarations.h"
 
 #include <QBitArray>
 #include <QExplicitlySharedDataPointer>
 #include <QHash>
 #include <QMetaType>
 #include <QSharedData>
 #include <QString>
 #include <QStringList>
 
 namespace Dynamic
 {
     class TrackSet;
     class TrackCollection;
 
     typedef QExplicitlySharedDataPointer<TrackCollection> TrackCollectionPtr;
 
     /**
      * We keep a list here of the uid of every track in the set
      * collection being considered. This is unfortunately necessary
      * because the algorithm in generateInitialPlaylist performs many
      * set subtractions and intersections which would be impractical and
      * inefficient to perform using database queries. Instead we
      * represent a set of tracks as a bit list, where the n'th bit
      * indicates whether the n'th track in s_universe is included in the
      * set. Set operations can then be performed extremely quickly using
      * bitwise operations, rather than tree operations which QSet would
      * use.
      */
 
     /** The TrackCollection stores all the uids that a TrackSet can contain.
         Usually the dynamic playlist queries all the uids before computing a playlist.
     */
     class AMAROK_EXPORT TrackCollection : public QSharedData
     {
         public:
             explicit TrackCollection( const QStringList& uids );
 
             int count() const;
             QStringList uids() const;
 
         private:
             QStringList m_uids;
             QHash<QString, int> m_ids;
 
             friend class TrackSet;
     };
 
     /**
      * A representation of a set of tracks as a bit array, relative to the
      * given universe set.
      * Intersecting TrackSets from different universes is not a good idea.
      * The BiasSolver uses this class to do a lot of set operations.
      * QSet is more space efficient for sparse sets, but set
      * operations generally aren't linear.
      */
     class AMAROK_EXPORT TrackSet
     {
         public:
             /** Creates a TrackSet that is outstanding
                 @see isOutstanding() */
             TrackSet();
 
             TrackSet( const TrackSet& other );
 
             /** Creates a TrackSet that represents the whole universe.
              *  @param collection The collection of the tracks
              *  @param value If true set is set to "full". Else to "empty".
             */
             TrackSet( const Dynamic::TrackCollectionPtr &collection, bool value );
 
             /** Includes or excludes all tracks in the set.
                 @param value If true set is set to "full". Else to "empty".
             */
             void reset( bool value );
 
             /** Returns true if the results of this track set are not yet available */
             bool isOutstanding() const;
 
             /** The number of songs contained in this trackSet */
             int trackCount() const;
 
             /** True if none of the tracks are included in the set. */
             bool isEmpty() const;
 
             /** True if all of the tracks are included in the set. */
             bool isFull() const;
             bool contains( const Meta::TrackPtr& ) const;
 
             /** Returns true if the uid is included in the set */
             bool contains( const QString& uid ) const;
 
             /** Returns the uids of a random track contains in this set */
             QString getRandomTrack() const;
 
             void unite( const Meta::TrackPtr& );
             void unite( const TrackSet& );
             void unite( const QStringList& uids );
             void intersect( const TrackSet& );
             void intersect( const QStringList& uids );
             void subtract( const Meta::TrackPtr& );
             void subtract( const TrackSet& );
             void subtract( const QStringList& uids );
 
             TrackSet& operator=( const TrackSet& );
 
         private:
             QBitArray m_bits;
             TrackCollectionPtr m_collection;
     };
 }
 
 Q_DECLARE_METATYPE( Dynamic::TrackSet )
 
 #endif