lavf: improve handling of sparse streams when muxing
[libav.git] / libavutil / dict.h
1 /*
2 *
3 * This file is part of Libav.
4 *
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.
9 *
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.
14 *
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
18 */
19
20 /**
21 * @file
22 * Public dictionary API.
23 */
24
25 #ifndef AVUTIL_DICT_H
26 #define AVUTIL_DICT_H
27
28 /**
29 * @addtogroup lavu_dict AVDictionary
30 * @ingroup lavu_data
31 *
32 * @brief Simple key:value store
33 *
34 * @{
35 * Dictionaries are used for storing key:value pairs. To create
36 * an AVDictionary, simply pass an address of a NULL pointer to
37 * av_dict_set(). NULL can be used as an empty dictionary wherever
38 * a pointer to an AVDictionary is required.
39 * Use av_dict_get() to retrieve an entry or iterate over all
40 * entries and finally av_dict_free() to free the dictionary
41 * and all its contents.
42 *
43 * @code
44 * AVDictionary *d = NULL; // "create" an empty dictionary
45 * av_dict_set(&d, "foo", "bar", 0); // add an entry
46 *
47 * char *k = av_strdup("key"); // if your strings are already allocated,
48 * char *v = av_strdup("value"); // you can avoid copying them like this
49 * av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
50 *
51 * AVDictionaryEntry *t = NULL;
52 * while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
53 * <....> // iterate over all entries in d
54 * }
55 *
56 * av_dict_free(&d);
57 * @endcode
58 *
59 */
60
61 #define AV_DICT_MATCH_CASE 1
62 #define AV_DICT_IGNORE_SUFFIX 2
63 #define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been
64 allocated with av_malloc() and children. */
65 #define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
66 allocated with av_malloc() and chilren. */
67 #define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries.
68 #define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no
69 delimiter is added, the strings are simply concatenated. */
70
71 typedef struct AVDictionaryEntry {
72 char *key;
73 char *value;
74 } AVDictionaryEntry;
75
76 typedef struct AVDictionary AVDictionary;
77
78 /**
79 * Get a dictionary entry with matching key.
80 *
81 * @param prev Set to the previous matching element to find the next.
82 * If set to NULL the first matching element is returned.
83 * @param flags Allows case as well as suffix-insensitive comparisons.
84 * @return Found entry or NULL, changing key or value leads to undefined behavior.
85 */
86 AVDictionaryEntry *
87 av_dict_get(AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags);
88
89 /**
90 * Get number of entries in dictionary.
91 *
92 * @param m dictionary
93 * @return number of entries in dictionary
94 */
95 int av_dict_count(const AVDictionary *m);
96
97 /**
98 * Set the given entry in *pm, overwriting an existing entry.
99 *
100 * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL
101 * a dictionary struct is allocated and put in *pm.
102 * @param key entry key to add to *pm (will be av_strduped depending on flags)
103 * @param value entry value to add to *pm (will be av_strduped depending on flags).
104 * Passing a NULL value will cause an existing entry to be deleted.
105 * @return >= 0 on success otherwise an error code <0
106 */
107 int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
108
109 /**
110 * Parse the key/value pairs list and add to a dictionary.
111 *
112 * @param key_val_sep a 0-terminated list of characters used to separate
113 * key from value
114 * @param pairs_sep a 0-terminated list of characters used to separate
115 * two pairs from each other
116 * @param flags flags to use when adding to dictionary.
117 * AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL
118 * are ignored since the key/value tokens will always
119 * be duplicated.
120 * @return 0 on success, negative AVERROR code on failure
121 */
122 int av_dict_parse_string(AVDictionary **pm, const char *str,
123 const char *key_val_sep, const char *pairs_sep,
124 int flags);
125
126 /**
127 * Copy entries from one AVDictionary struct into another.
128 * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL,
129 * this function will allocate a struct for you and put it in *dst
130 * @param src pointer to source AVDictionary struct
131 * @param flags flags to use when setting entries in *dst
132 * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag
133 */
134 void av_dict_copy(AVDictionary **dst, AVDictionary *src, int flags);
135
136 /**
137 * Free all the memory allocated for an AVDictionary struct
138 * and all keys and values.
139 */
140 void av_dict_free(AVDictionary **m);
141
142 /**
143 * @}
144 */
145
146 #endif /* AVUTIL_DICT_H */