juk/cache.h

   1 /***************************************************************************
   2     begin                : Sat Sep 7 2002
   3     copyright            : (C) 2002 - 2004 by Scott Wheeler
   4     email                : wheeler@kde.org
   5  ***************************************************************************/
   6
   7 /***************************************************************************
   8  *                                                                         *
   9  *   This program is free software; you can redistribute it and/or modify  *
  10  *   it under the terms of the GNU General Public License as published by  *
  11  *   the Free Software Foundation; either version 2 of the License, or     *
  12  *   (at your option) any later version.                                   *
  13  *                                                                         *
  14  ***************************************************************************/
  15
  16 #ifndef CACHE_H
  17 #define CACHE_H
  18
  19 #include <QDataStream>
  20
  21 #include "stringhash.h"
  22
  23 class Tag;
  24 class Playlist;
  25 class PlaylistCollection;
  26
  27 template<class T>
  28 class QList;
  29
  30 typedef QList<Playlist *> PlaylistList;
  31
  32 class Cache : public FileHandleHash
  33 {
  34 public:
  35     static Cache *instance();
  36     void save();
  37
  38     static void loadPlaylists(PlaylistCollection *collection);
  39     static void savePlaylists(const PlaylistList &playlists);
  40
  41     static bool cacheFileExists();
  42
  43 protected:
  44     Cache();
  45     void load();
  46
  47 private:
  48     static const int m_currentVersion = 1;
  49 };
  50
  51 /**
  52  * A simple QDataStream subclass that has an extra field to indicate the cache
  53  * version.
  54  */
  55
  56 class CacheDataStream : public QDataStream
  57 {
  58 public:
  59     CacheDataStream(QIODevice *d) : QDataStream(d), m_cacheVersion(0) {}
  60     CacheDataStream(QByteArray &a, int mode) : QDataStream(&a, mode), m_cacheVersion(0) {}
  61
  62     virtual ~CacheDataStream() {}
  63
  64     int cacheVersion() const { return m_cacheVersion; }
  65     void setCacheVersion(int v) { m_cacheVersion = v; }
  66
  67 private:
  68     int m_cacheVersion;
  69 };
  70
  71 #endif
  72
  73 // vim: set et sw=4 tw=0 sta: