/* * Copyright (C) 2003-2011 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_TAG_H #define MPD_TAG_H #include "gcc.h" #include <stdint.h> #include <stddef.h> #include <stdbool.h> #include <string.h> /** * Codes for the type of a tag item. */ enum tag_type { TAG_ARTIST, TAG_ARTIST_SORT, TAG_ALBUM, TAG_ALBUM_ARTIST, TAG_ALBUM_ARTIST_SORT, TAG_TITLE, TAG_TRACK, TAG_NAME, TAG_GENRE, TAG_DATE, TAG_COMPOSER, TAG_PERFORMER, TAG_COMMENT, TAG_DISC, TAG_MUSICBRAINZ_ARTISTID, TAG_MUSICBRAINZ_ALBUMID, TAG_MUSICBRAINZ_ALBUMARTISTID, TAG_MUSICBRAINZ_TRACKID, TAG_NUM_OF_ITEM_TYPES }; /** * An array of strings, which map the #tag_type to its machine * readable name (specific to the MPD protocol). */ extern const char *tag_item_names[]; /** * One tag value. It is a mapping of #tag_type to am arbitrary string * value. Each tag can have multiple items of one tag type (although * few clients support that). */ struct tag_item { /** the type of this item */ enum tag_type type; /** * the value of this tag; this is a variable length string */ char value[sizeof(long)]; } gcc_packed; /** * The meta information about a song file. It is a MPD specific * subset of tags (e.g. from ID3, vorbis comments, ...). */ struct tag { /** * The duration of the song (in seconds). A value of zero * means that the length is unknown. If the duration is * really between zero and one second, you should round up to * 1. */ int time; /** an array of tag items */ struct tag_item **items; /** the total number of tag items in the #items array */ unsigned num_items; }; /** * Parse the string, and convert it into a #tag_type. Returns * #TAG_NUM_OF_ITEM_TYPES if the string could not be recognized. */ enum tag_type tag_name_parse(const char *name); /** * Parse the string, and convert it into a #tag_type. Returns * #TAG_NUM_OF_ITEM_TYPES if the string could not be recognized. * * Case does not matter. */ enum tag_type tag_name_parse_i(const char *name); /** * Creates an empty #tag. */ struct tag *tag_new(void); /** * Initializes the tag library. */ void tag_lib_init(void); /** * Clear all tag items with the specified type. */ void tag_clear_items_by_type(struct tag *tag, enum tag_type type); /** * Frees a #tag object and all its items. */ void tag_free(struct tag *tag); /** * Gives an optional hint to the tag library that we will now add * several tag items; this is used by the library to optimize memory * allocation. Only one tag may be in this state, and this tag must * not have any items yet. You must call tag_end_add() when you are * done. */ void tag_begin_add(struct tag *tag); /** * Finishes the operation started with tag_begin_add(). */ void tag_end_add(struct tag *tag); /** * Appends a new tag item. * * @param tag the #tag object * @param type the type of the new tag item * @param value the value of the tag item (not null-terminated) * @param len the length of #value */ void tag_add_item_n(struct tag *tag, enum tag_type type, const char *value, size_t len); /** * Appends a new tag item. * * @param tag the #tag object * @param type the type of the new tag item * @param value the value of the tag item (null-terminated) */ static inline void tag_add_item(struct tag *tag, enum tag_type type, const char *value) { tag_add_item_n(tag, type, value, strlen(value)); } /** * Duplicates a #tag object. */ struct tag *tag_dup(const struct tag *tag); /** * Merges the data from two tags. If both tags share data for the * same tag_type, only data from "add" is used. * * @return a newly allocated tag, which must be freed with tag_free() */ struct tag * tag_merge(const struct tag *base, const struct tag *add); /** * Merges the data from two tags. Any of the two may be NULL. Both * are freed by this function. * * @return a newly allocated tag, which must be freed with tag_free() */ struct tag * tag_merge_replace(struct tag *base, struct tag *add); /** * Returns true if the tag contains no items. This ignores the "time" * attribute. */ static inline bool tag_is_empty(const struct tag *tag) { return tag->num_items == 0; } /** * Returns true if the tag contains any information. */ static inline bool tag_is_defined(const struct tag *tag) { return !tag_is_empty(tag) || tag->time >= 0; } /** * Returns the first value of the specified tag type, or NULL if none * is present in this tag object. */ const char * tag_get_value(const struct tag *tag, enum tag_type type); /** * Checks whether the tag contains one or more items with * the specified type. */ bool tag_has_type(const struct tag *tag, enum tag_type type); /** * Compares two tags, including the duration and all tag items. The * order of the tag items matters. */ bool tag_equal(const struct tag *tag1, const struct tag *tag2); #endif