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.
43 *
44 * - To **create an AVDictionary**, simply pass an address of a NULL
45 * pointer to av_dict_set(). NULL can be used as an empty dictionary
46 * wherever a pointer to an AVDictionary is required.
47 * - To **insert an entry**, use av_dict_set().
48 * - Use av_dict_get() to **retrieve an entry**.
49 * - To **iterate over all entries**, use av_dict_iterate().
50 * - In order to **free the dictionary and all its contents**, use av_dict_free().
51 *
52 @code
53 AVDictionary *d = NULL; // "create" an empty dictionary
54 AVDictionaryEntry *t = NULL;
55
56 av_dict_set(&d, "foo", "bar", 0); // add an entry
57
58 char *k = av_strdup("key"); // if your strings are already allocated,
59 char *v = av_strdup("value"); // you can avoid copying them like this
60 av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
61
62 while ((t = av_dict_iterate(d, t))) {
63 <....> // iterate over all entries in d
64 }
65 av_dict_free(&d);
66 @endcode
67 */
68
69/**
70 * @name AVDictionary Flags
71 * Flags that influence behavior of the matching of keys or insertion to the dictionary.
72 * @{
73 */
74#define AV_DICT_MATCH_CASE 1 /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */
75#define AV_DICT_IGNORE_SUFFIX 2 /**< Return first entry in a dictionary whose first part corresponds to the search key,
76 ignoring the suffix of the found key string. Only relevant in av_dict_get(). */
77#define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been
78 allocated with av_malloc() or another memory allocation function. */
79#define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
80 allocated with av_malloc() or another memory allocation function. */
81#define AV_DICT_DONT_OVERWRITE 16 /**< Don't overwrite existing entries. */
82#define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no
83 delimiter is added, the strings are simply concatenated. */
84#define AV_DICT_MULTIKEY 64 /**< Allow to store several equal keys in the dictionary */
85/**
86 * @}
87 */
88
89typedef struct AVDictionaryEntry {
90 char *key;
91 char *value;
92} AVDictionaryEntry;
93
94typedef struct AVDictionary AVDictionary;
95
96/**
97 * Get a dictionary entry with matching key.
98 *
99 * The returned entry key or value must not be changed, or it will
100 * cause undefined behavior.
101 *
102 * @param prev Set to the previous matching element to find the next.
103 * If set to NULL the first matching element is returned.
104 * @param key Matching key
105 * @param flags A collection of AV_DICT_* flags controlling how the
106 * entry is retrieved
107 *
108 * @return Found entry or NULL in case no matching entry was found in the dictionary
109 */
110AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key,
111 const AVDictionaryEntry *prev, int flags);
112
113/**
114 * Iterate over a dictionary
115 *
116 * Iterates through all entries in the dictionary.
117 *
118 * @warning The returned AVDictionaryEntry key/value must not be changed.
119 *
120 * @warning As av_dict_set() invalidates all previous entries returned
121 * by this function, it must not be called while iterating over the dict.
122 *
123 * Typical usage:
124 * @code
125 * const AVDictionaryEntry *e = NULL;
126 * while ((e = av_dict_iterate(m, e))) {
127 * // ...
128 * }
129 * @endcode
130 *
131 * @param m The dictionary to iterate over
132 * @param prev Pointer to the previous AVDictionaryEntry, NULL initially
133 *
134 * @retval AVDictionaryEntry* The next element in the dictionary
135 * @retval NULL No more elements in the dictionary
136 */
137const AVDictionaryEntry *av_dict_iterate(const AVDictionary *m,
138 const AVDictionaryEntry *prev);
139
140/**
141 * Get number of entries in dictionary.
142 *
143 * @param m dictionary
144 * @return number of entries in dictionary
145 */
146int av_dict_count(const AVDictionary *m);
147
148/**
149 * Set the given entry in *pm, overwriting an existing entry.
150 *
151 * Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set,
152 * these arguments will be freed on error.
153 *
154 * @warning Adding a new entry to a dictionary invalidates all existing entries
155 * previously returned with av_dict_get() or av_dict_iterate().
156 *
157 * @param pm Pointer to a pointer to a dictionary struct. If *pm is NULL
158 * a dictionary struct is allocated and put in *pm.
159 * @param key Entry key to add to *pm (will either be av_strduped or added as a new key depending on flags)
160 * @param value Entry value to add to *pm (will be av_strduped or added as a new key depending on flags).
161 * Passing a NULL value will cause an existing entry to be deleted.
162 *
163 * @return >= 0 on success otherwise an error code <0
164 */
165int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
166
167/**
168 * Convenience wrapper for av_dict_set() that converts the value to a string
169 * and stores it.
170 *
171 * Note: If ::AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error.
172 */
173int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags);
174
175/**
176 * Parse the key/value pairs list and add the parsed entries to a dictionary.
177 *
178 * In case of failure, all the successfully set entries are stored in
179 * *pm. You may need to manually free the created dictionary.
180 *
181 * @param key_val_sep A 0-terminated list of characters used to separate
182 * key from value
183 * @param pairs_sep A 0-terminated list of characters used to separate
184 * two pairs from each other
185 * @param flags Flags to use when adding to the dictionary.
186 * ::AV_DICT_DONT_STRDUP_KEY and ::AV_DICT_DONT_STRDUP_VAL
187 * are ignored since the key/value tokens will always
188 * be duplicated.
189 *
190 * @return 0 on success, negative AVERROR code on failure
191 */
192int av_dict_parse_string(AVDictionary **pm, const char *str,
193 const char *key_val_sep, const char *pairs_sep,
194 int flags);
195
196/**
197 * Copy entries from one AVDictionary struct into another.
198 *
199 * @note Metadata is read using the ::AV_DICT_IGNORE_SUFFIX flag
200 *
201 * @param dst Pointer to a pointer to a AVDictionary struct to copy into. If *dst is NULL,
202 * this function will allocate a struct for you and put it in *dst
203 * @param src Pointer to the source AVDictionary struct to copy items from.
204 * @param flags Flags to use when setting entries in *dst
205 *
206 * @return 0 on success, negative AVERROR code on failure. If dst was allocated
207 * by this function, callers should free the associated memory.
208 */
209int av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags);
210
211/**
212 * Free all the memory allocated for an AVDictionary struct
213 * and all keys and values.
214 */
215void av_dict_free(AVDictionary **m);
216
217/**
218 * Get dictionary entries as a string.
219 *
220 * Create a string containing dictionary's entries.
221 * Such string may be passed back to av_dict_parse_string().
222 * @note String is escaped with backslashes ('\').
223 *
224 * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
225 *
226 * @param[in] m The dictionary
227 * @param[out] buffer Pointer to buffer that will be allocated with string containg entries.
228 * Buffer must be freed by the caller when is no longer needed.
229 * @param[in] key_val_sep Character used to separate key from value
230 * @param[in] pairs_sep Character used to separate two pairs from each other
231 *
232 * @return >= 0 on success, negative on error
233 */
234int av_dict_get_string(const AVDictionary *m, char **buffer,
235 const char key_val_sep, const char pairs_sep);
236
237/**
238 * @}
239 */
240
241#endif /* AVUTIL_DICT_H */
242