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/*
* Copyright 2003-2018 The Music Player Daemon Project
* http://www.musicpd.org
*
* 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_DATABASE_VISITOR_HELPER_HXX
#define MPD_DATABASE_VISITOR_HELPER_HXX
#include "Visitor.hxx"
#include "Selection.hxx"
#include "song/DetachedSong.hxx"
#include <vector>
class DetachedSong;
/**
* This class helps implementing Database::Visit() by emulating
* #DatabaseSelection features that the #Database implementation
* doesn't have, e.g. filtering, sorting and window.
*
* To use this class, construct it, passing unsupported features and
* the visitor callback to the constructor; before leaving Visit(),
* call Commit() (unless an error has occurred).
*/
class DatabaseVisitorHelper {
const DatabaseSelection selection;
/**
* If the plugin can't sort, then this container will collect
* all songs, sort them and report them to the visitor in
* Commit().
*/
std::vector<DetachedSong> songs;
VisitSong original_visit_song;
/**
* Used to emulate the "window".
*/
unsigned counter = 0;
public:
/**
* @param selection a #DatabaseSelection instance with only
* features enabled which shall be emulated by this class
* @param visit_song the callback function passed to
* Database::Visit(); may be replaced by this class
*/
DatabaseVisitorHelper(const DatabaseSelection &selection,
VisitSong &visit_song) noexcept;
~DatabaseVisitorHelper() noexcept;
void Commit();
};
#endif
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