3 * This file is part of Libav.
5 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 * Public dictionary API.
29 * @defgroup dict_api Public Dictionary API
31 * Dictionaries are used for storing key:value pairs. To create
32 * an AVDictionary, simply pass an address of a NULL pointer to
33 * av_dict_set(). NULL can be used as an empty dictionary wherever
34 * a pointer to an AVDictionary is required.
35 * Use av_dict_get() to retrieve an entry or iterate over all
36 * entries and finally av_dict_free() to free the dictionary
37 * and all its contents.
40 * AVDictionary *d = NULL; // "create" an empty dictionary
41 * av_dict_set(&d, "foo", "bar", 0); // add an entry
43 * char *k = av_strdup("key"); // if your strings are already allocated,
44 * char *v = av_strdup("value"); // you can avoid copying them like this
45 * av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
47 * AVDictionaryEntry *t = NULL;
48 * while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
49 * <....> // iterate over all entries in d
58 #define AV_DICT_MATCH_CASE 1
59 #define AV_DICT_IGNORE_SUFFIX 2
60 #define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been
61 allocated with av_malloc() and children. */
62 #define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
63 allocated with av_malloc() and chilren. */
64 #define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries.
65 #define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no
66 delimiter is added, the strings are simply concatenated. */
73 typedef struct AVDictionary AVDictionary;
76 * Get a dictionary entry with matching key.
78 * @param prev Set to the previous matching element to find the next.
79 * If set to NULL the first matching element is returned.
80 * @param flags Allows case as well as suffix-insensitive comparisons.
81 * @return Found entry or NULL, changing key or value leads to undefined behavior.
84 av_dict_get(AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags);
87 * Set the given entry in *pm, overwriting an existing entry.
89 * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL
90 * a dictionary struct is allocated and put in *pm.
91 * @param key entry key to add to *pm (will be av_strduped depending on flags)
92 * @param value entry value to add to *pm (will be av_strduped depending on flags).
93 * Passing a NULL value will cause an existing tag to be deleted.
94 * @return >= 0 on success otherwise an error code <0
96 int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
99 * Copy entries from one AVDictionary struct into another.
100 * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL,
101 * this function will allocate a struct for you and put it in *dst
102 * @param src pointer to source AVDictionary struct
103 * @param flags flags to use when setting entries in *dst
104 * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag
106 void av_dict_copy(AVDictionary **dst, AVDictionary *src, int flags);
109 * Free all the memory allocated for an AVDictionary struct
110 * and all keys and values.
112 void av_dict_free(AVDictionary **m);
114 #endif // AVUTIL_DICT_H