summaryrefslogtreecommitdiffstats
path: root/libavutil/dict.h
blob: f2df687c039d4f87625668ae4f4ca256e74392d6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
/*
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * Public dictionary API.
 * @deprecated
 *  AVDictionary is provided for compatibility with libav. It is both in
 *  implementation as well as API inefficient. It does not scale and is
 *  extremely slow with large dictionaries.
 *  It is recommended that new code uses our tree container from tree.c/h
 *  where applicable, which uses AVL trees to achieve O(log n) performance.
 */

#ifndef AVUTIL_DICT_H
#define AVUTIL_DICT_H

#include <stdint.h>

#include "version.h"

/**
 * @addtogroup lavu_dict AVDictionary
 * @ingroup lavu_data
 *
 * @brief Simple key:value store
 *
 * @{
 * Dictionaries are used for storing key:value pairs. To create
 * an AVDictionary, simply pass an address of a NULL pointer to
 * av_dict_set(). NULL can be used as an empty dictionary wherever
 * a pointer to an AVDictionary is required.
 * Use av_dict_get() to retrieve an entry or iterate over all
 * entries and finally av_dict_free() to free the dictionary
 * and all its contents.
 *
 @code
   AVDictionary *d = NULL;           // "create" an empty dictionary
   AVDictionaryEntry *t = NULL;

   av_dict_set(&d, "foo", "bar", 0); // add an entry

   char *k = av_strdup("key");       // if your strings are already allocated,
   char *v = av_strdup("value");     // you can avoid copying them like this
   av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);

   while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
       <....>                             // iterate over all entries in d
   }
   av_dict_free(&d);
 @endcode
 *
 */

#define AV_DICT_MATCH_CASE      1   /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */
#define AV_DICT_IGNORE_SUFFIX   2   /**< Return first entry in a dictionary whose first part corresponds to the search key,
                                         ignoring the suffix of the found key string. Only relevant in av_dict_get(). */
#define AV_DICT_DONT_STRDUP_KEY 4   /**< Take ownership of a key that's been
                                         allocated with av_malloc() or another memory allocation function. */
#define AV_DICT_DONT_STRDUP_VAL 8   /**< Take ownership of a value that's been
                                         allocated with av_malloc() or another memory allocation function. */
#define AV_DICT_DONT_OVERWRITE 16   ///< Don't overwrite existing entries.
#define AV_DICT_APPEND         32   /**< If the entry already exists, append to it.  Note that no
                                      delimiter is added, the strings are simply concatenated. */

typedef struct AVDictionaryEntry {
    char *key;
    char *value;
} AVDictionaryEntry;

typedef struct AVDictionary AVDictionary;

/**
 * Get a dictionary entry with matching key.
 *
 * The returned entry key or value must not be changed, or it will
 * cause undefined behavior.
 *
 * To iterate through all the dictionary entries, you can set the matching key
 * to the null string "" and set the AV_DICT_IGNORE_SUFFIX flag.
 *
 * @param prev Set to the previous matching element to find the next.
 *             If set to NULL the first matching element is returned.
 * @param key matching key
 * @param flags a collection of AV_DICT_* flags controlling how the entry is retrieved
 * @return found entry or NULL in case no matching entry was found in the dictionary
 */
AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key,
                               const AVDictionaryEntry *prev, int flags);

/**
 * Get number of entries in dictionary.
 *
 * @param m dictionary
 * @return  number of entries in dictionary
 */
int av_dict_count(const AVDictionary *m);

/**
 * Set the given entry in *pm, overwriting an existing entry.
 *
 * Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set,
 * these arguments will be freed on error.
 *
 * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL
 * a dictionary struct is allocated and put in *pm.
 * @param key entry key to add to *pm (will be av_strduped depending on flags)
 * @param value entry value to add to *pm (will be av_strduped depending on flags).
 *        Passing a NULL value will cause an existing entry to be deleted.
 * @return >= 0 on success otherwise an error code <0
 */
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);

/**
 * Convenience wrapper for av_dict_set that converts the value to a string
 * and stores it.
 *
 * Note: If AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error.
 */
int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags);

/**
 * Parse the key/value pairs list and add the parsed entries to a dictionary.
 *
 * In case of failure, all the successfully set entries are stored in
 * *pm. You may need to manually free the created dictionary.
 *
 * @param key_val_sep  a 0-terminated list of characters used to separate
 *                     key from value
 * @param pairs_sep    a 0-terminated list of characters used to separate
 *                     two pairs from each other
 * @param flags        flags to use when adding to dictionary.
 *                     AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL
 *                     are ignored since the key/value tokens will always
 *                     be duplicated.
 * @return             0 on success, negative AVERROR code on failure
 */
int av_dict_parse_string(AVDictionary **pm, const char *str,
                         const char *key_val_sep, const char *pairs_sep,
                         int flags);

/**
 * Copy entries from one AVDictionary struct into another.
 * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL,
 *            this function will allocate a struct for you and put it in *dst
 * @param src pointer to source AVDictionary struct
 * @param flags flags to use when setting entries in *dst
 * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag
 */
void av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags);

/**
 * Free all the memory allocated for an AVDictionary struct
 * and all keys and values.
 */
void av_dict_free(AVDictionary **m);

/**
 * Get dictionary entries as a string.
 *
 * Create a string containing dictionary's entries.
 * Such string may be passed back to av_dict_parse_string().
 * @note String is escaped with backslashes ('\').
 *
 * @param[in]  m             dictionary
 * @param[out] buffer        Pointer to buffer that will be allocated with string containg entries.
 *                           Buffer must be freed by the caller when is no longer needed.
 * @param[in]  key_val_sep   character used to separate key from value
 * @param[in]  pairs_sep     character used to separate two pairs from each other
 * @return                   >= 0 on success, negative on error
 * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
 */
int av_dict_get_string(const AVDictionary *m, char **buffer,
                       const char key_val_sep, const char pairs_sep);

/**
 * @}
 */

#endif /* AVUTIL_DICT_H */
OpenPOWER on IntegriCloud