FFmpeg 5.1.5
dict.h
Go to the documentation of this file.
1/*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19/**
20 * @file
21 * Public dictionary API.
22 * @deprecated
23 * AVDictionary is provided for compatibility with libav. It is both in
24 * implementation as well as API inefficient. It does not scale and is
25 * extremely slow with large dictionaries.
26 * It is recommended that new code uses our tree container from tree.c/h
27 * where applicable, which uses AVL trees to achieve O(log n) performance.
28 */
29
30#ifndef AVUTIL_DICT_H
31#define AVUTIL_DICT_H
32
33#include <stdint.h>
34
35/**
36 * @addtogroup lavu_dict AVDictionary
37 * @ingroup lavu_data
38 *
39 * @brief Simple key:value store
40 *
41 * @{
42 * Dictionaries are used for storing key:value pairs. To create
43 * an AVDictionary, simply pass an address of a NULL pointer to
44 * av_dict_set(). NULL can be used as an empty dictionary wherever
45 * a pointer to an AVDictionary is required.
46 * Use av_dict_get() to retrieve an entry or iterate over all
47 * entries and finally av_dict_free() to free the dictionary
48 * and all its contents.
49 *
50 @code
51 AVDictionary *d = NULL; // "create" an empty dictionary
52 AVDictionaryEntry *t = NULL;
53
54 av_dict_set(&d, "foo", "bar", 0); // add an entry
55
56 char *k = av_strdup("key"); // if your strings are already allocated,
57 char *v = av_strdup("value"); // you can avoid copying them like this
58 av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
59
60 while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
61 <....> // iterate over all entries in d
62 }
63 av_dict_free(&d);
64 @endcode
65 */
66
67#define AV_DICT_MATCH_CASE 1 /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */
68#define AV_DICT_IGNORE_SUFFIX 2 /**< Return first entry in a dictionary whose first part corresponds to the search key,
69 ignoring the suffix of the found key string. Only relevant in av_dict_get(). */
70#define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been
71 allocated with av_malloc() or another memory allocation function. */
72#define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
73 allocated with av_malloc() or another memory allocation function. */
74#define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries.
75#define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no
76 delimiter is added, the strings are simply concatenated. */
77#define AV_DICT_MULTIKEY 64 /**< Allow to store several equal keys in the dictionary */
78
79typedef struct AVDictionaryEntry {
80 char *key;
81 char *value;
83
85
86/**
87 * Get a dictionary entry with matching key.
88 *
89 * The returned entry key or value must not be changed, or it will
90 * cause undefined behavior.
91 *
92 * To iterate through all the dictionary entries, you can set the matching key
93 * to the null string "" and set the AV_DICT_IGNORE_SUFFIX flag.
94 *
95 * @param prev Set to the previous matching element to find the next.
96 * If set to NULL the first matching element is returned.
97 * @param key matching key
98 * @param flags a collection of AV_DICT_* flags controlling how the entry is retrieved
99 * @return found entry or NULL in case no matching entry was found in the dictionary
100 */
101AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key,
102 const AVDictionaryEntry *prev, int flags);
103
104/**
105 * Get number of entries in dictionary.
106 *
107 * @param m dictionary
108 * @return number of entries in dictionary
109 */
111
112/**
113 * Set the given entry in *pm, overwriting an existing entry.
114 *
115 * Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set,
116 * these arguments will be freed on error.
117 *
118 * Warning: Adding a new entry to a dictionary invalidates all existing entries
119 * previously returned with av_dict_get.
120 *
121 * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL
122 * a dictionary struct is allocated and put in *pm.
123 * @param key entry key to add to *pm (will either be av_strduped or added as a new key depending on flags)
124 * @param value entry value to add to *pm (will be av_strduped or added as a new key depending on flags).
125 * Passing a NULL value will cause an existing entry to be deleted.
126 * @return >= 0 on success otherwise an error code <0
127 */
128int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
129
130/**
131 * Convenience wrapper for av_dict_set that converts the value to a string
132 * and stores it.
133 *
134 * Note: If AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error.
135 */
136int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags);
137
138/**
139 * Parse the key/value pairs list and add the parsed entries to a dictionary.
140 *
141 * In case of failure, all the successfully set entries are stored in
142 * *pm. You may need to manually free the created dictionary.
143 *
144 * @param key_val_sep a 0-terminated list of characters used to separate
145 * key from value
146 * @param pairs_sep a 0-terminated list of characters used to separate
147 * two pairs from each other
148 * @param flags flags to use when adding to dictionary.
149 * AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL
150 * are ignored since the key/value tokens will always
151 * be duplicated.
152 * @return 0 on success, negative AVERROR code on failure
153 */
154int av_dict_parse_string(AVDictionary **pm, const char *str,
155 const char *key_val_sep, const char *pairs_sep,
156 int flags);
157
158/**
159 * Copy entries from one AVDictionary struct into another.
160 * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL,
161 * this function will allocate a struct for you and put it in *dst
162 * @param src pointer to source AVDictionary struct
163 * @param flags flags to use when setting entries in *dst
164 * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag
165 * @return 0 on success, negative AVERROR code on failure. If dst was allocated
166 * by this function, callers should free the associated memory.
167 */
168int av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags);
169
170/**
171 * Free all the memory allocated for an AVDictionary struct
172 * and all keys and values.
173 */
175
176/**
177 * Get dictionary entries as a string.
178 *
179 * Create a string containing dictionary's entries.
180 * Such string may be passed back to av_dict_parse_string().
181 * @note String is escaped with backslashes ('\').
182 *
183 * @param[in] m dictionary
184 * @param[out] buffer Pointer to buffer that will be allocated with string containg entries.
185 * Buffer must be freed by the caller when is no longer needed.
186 * @param[in] key_val_sep character used to separate key from value
187 * @param[in] pairs_sep character used to separate two pairs from each other
188 * @return >= 0 on success, negative on error
189 * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
190 */
191int av_dict_get_string(const AVDictionary *m, char **buffer,
192 const char key_val_sep, const char pairs_sep);
193
194/**
195 * @}
196 */
197
198#endif /* AVUTIL_DICT_H */
void av_dict_free(AVDictionary **m)
Free all the memory allocated for an AVDictionary struct and all keys and values.
struct AVDictionary AVDictionary
Definition: dict.h:84
AVDictionaryEntry * av_dict_get(const AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags)
Get a dictionary entry with matching key.
int av_dict_get_string(const AVDictionary *m, char **buffer, const char key_val_sep, const char pairs_sep)
Get dictionary entries as a string.
int av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags)
Copy entries from one AVDictionary struct into another.
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
int av_dict_parse_string(AVDictionary **pm, const char *str, const char *key_val_sep, const char *pairs_sep, int flags)
Parse the key/value pairs list and add the parsed entries to a dictionary.
int av_dict_count(const AVDictionary *m)
Get number of entries in dictionary.
int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags)
Convenience wrapper for av_dict_set that converts the value to a string and stores it.
char * key
Definition: dict.h:80
char * value
Definition: dict.h:81