3 * This file is part of FFmpeg.
5 * FFmpeg is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
10 * FFmpeg is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with FFmpeg; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 * Public dictionary API.
24 * AVDictionary is provided for compatibility with libav. It is both in
25 * implementation as well as API inefficient. It does not scale and is
26 * extremely slow with large dictionaries.
27 * It is recommended that new code uses our tree container from tree.c/h
28 * where applicable, which uses AVL trees to achieve O(log n) performance.
35 * @defgroup dict_api Public Dictionary API
37 * Dictionaries are used for storing key:value pairs. To create
38 * an AVDictionary, simply pass an address of a NULL pointer to
39 * av_dict_set(). NULL can be used as an empty dictionary wherever
40 * a pointer to an AVDictionary is required.
41 * Use av_dict_get() to retrieve an entry or iterate over all
42 * entries and finally av_dict_free() to free the dictionary
43 * and all its contents.
46 * AVDictionary *d = NULL; // "create" an empty dictionary
47 * av_dict_set(&d, "foo", "bar", 0); // add an entry
49 * char *k = av_strdup("key"); // if your strings are already allocated,
50 * char *v = av_strdup("value"); // you can avoid copying them like this
51 * av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
53 * AVDictionaryEntry *t = NULL;
54 * while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
55 * <....> // iterate over all entries in d
64 #define AV_DICT_MATCH_CASE 1
65 #define AV_DICT_IGNORE_SUFFIX 2
66 #define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been
67 allocated with av_malloc() and children. */
68 #define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
69 allocated with av_malloc() and chilren. */
70 #define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries.
71 #define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no
72 delimiter is added, the strings are simply concatenated. */
79 typedef struct AVDictionary AVDictionary;
82 * Get a dictionary entry with matching key.
84 * @param prev Set to the previous matching element to find the next.
85 * If set to NULL the first matching element is returned.
86 * @param flags Allows case as well as suffix-insensitive comparisons.
87 * @return Found entry or NULL, changing key or value leads to undefined behavior.
90 av_dict_get(AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags);
93 * Set the given entry in *pm, overwriting an existing entry.
95 * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL
96 * a dictionary struct is allocated and put in *pm.
97 * @param key entry key to add to *pm (will be av_strduped depending on flags)
98 * @param value entry value to add to *pm (will be av_strduped depending on flags).
99 * Passing a NULL value will cause an existing tag to be deleted.
100 * @return >= 0 on success otherwise an error code <0
102 int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
105 * Copy entries from one AVDictionary struct into another.
106 * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL,
107 * this function will allocate a struct for you and put it in *dst
108 * @param src pointer to source AVDictionary struct
109 * @param flags flags to use when setting entries in *dst
110 * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag
112 void av_dict_copy(AVDictionary **dst, AVDictionary *src, int flags);
115 * Free all the memory allocated for an AVDictionary struct
116 * and all keys and values.
118 void av_dict_free(AVDictionary **m);
120 #endif // AVUTIL_DICT_H