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/*
* Copyright (C) 2003-2014 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.
*/
/*
* This is the sticker database library. It is the backend of all the
* sticker code in MPD.
*
* "Stickers" are pieces of information attached to existing MPD
* objects (e.g. song files, directories, albums). Clients can create
* arbitrary name/value pairs. MPD itself does not assume any special
* meaning in them.
*
* The goal is to allow clients to share additional (possibly dynamic)
* information about songs, which is neither stored on the client (not
* available to other clients), nor stored in the song files (MPD has
* no write access).
*
* Client developers should create a standard for common sticker
* names, to ensure interoperability.
*
* Examples: song ratings; statistics; deferred tag writes; lyrics;
* ...
*
*/
#ifndef MPD_STICKER_DATABASE_HXX
#define MPD_STICKER_DATABASE_HXX
#include "Compiler.h"
#include <string>
class Error;
class Path;
struct sticker;
/**
* Opens the sticker database.
*
* @return true on success, false on error
*/
bool
sticker_global_init(Path path, Error &error);
/**
* Close the sticker database.
*/
void
sticker_global_finish(void);
/**
* Returns true if the sticker database is configured and available.
*/
gcc_const
bool
sticker_enabled(void);
/**
* Returns one value from an object's sticker record. Returns an
* empty string if the value doesn't exist.
*/
std::string
sticker_load_value(const char *type, const char *uri, const char *name);
/**
* Sets a sticker value in the specified object. Overwrites existing
* values.
*/
bool
sticker_store_value(const char *type, const char *uri,
const char *name, const char *value);
/**
* Deletes a sticker from the database. All sticker values of the
* specified object are deleted.
*/
bool
sticker_delete(const char *type, const char *uri);
/**
* Deletes a sticker value. Fails if no sticker with this name
* exists.
*/
bool
sticker_delete_value(const char *type, const char *uri, const char *name);
/**
* Frees resources held by the sticker object.
*
* @param sticker the sticker object to be freed
*/
void
sticker_free(sticker *sticker);
/**
* Determines a single value in a sticker.
*
* @param sticker the sticker object
* @param name the name of the sticker
* @return the sticker value, or nullptr if none was found
*/
gcc_pure
const char *
sticker_get_value(const sticker &sticker, const char *name);
/**
* Iterates over all sticker items in a sticker.
*
* @param sticker the sticker object
* @param func a callback function
* @param user_data an opaque pointer for the callback function
*/
void
sticker_foreach(const sticker &sticker,
void (*func)(const char *name, const char *value,
void *user_data),
void *user_data);
/**
* Loads the sticker for the specified resource.
*
* @param type the resource type, e.g. "song"
* @param uri the URI of the resource, e.g. the song path
* @return a sticker object, or nullptr on error or if there is no sticker
*/
sticker *
sticker_load(const char *type, const char *uri);
/**
* Finds stickers with the specified name below the specified URI.
*
* @param type the resource type, e.g. "song"
* @param base_uri the URI prefix of the resources, or nullptr if all
* resources should be searched
* @param name the name of the sticker
* @return true on success (even if no sticker was found), false on
* failure
*/
bool
sticker_find(const char *type, const char *base_uri, const char *name,
void (*func)(const char *uri, const char *value,
void *user_data),
void *user_data);
#endif
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