#ifndef ENGINE_FWD_H#define ENGINE_FWD_H/// Used by eg engineobserver.h, and thus we reduce header dependencies on enginebase.hnamespace Engine{    class SimpleMetaBundle;    class Base;    /**     * You should return:     * Playing when playing,     * Paused when paused     * Idle when you still have a URL loaded (ie you have not been told to stop())     * Empty when you have been told to stop(), or an error occurred and you stopped yourself     *     * It is vital to be Idle just after the track has ended!     */    enum State { Empty, Idle, Playing, Paused };}typedef Engine::Base EngineBase;#endif