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dict.h
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12  * Lesser General Public License for more details.
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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 #include "version.h"
36 
37 /**
38  * @addtogroup lavu_dict AVDictionary
39  * @ingroup lavu_data
40  *
41  * @brief Simple key:value store
42  *
43  * @{
44  * Dictionaries are used for storing key:value pairs. To create
45  * an AVDictionary, simply pass an address of a NULL pointer to
46  * av_dict_set(). NULL can be used as an empty dictionary wherever
47  * a pointer to an AVDictionary is required.
48  * Use av_dict_get() to retrieve an entry or iterate over all
49  * entries and finally av_dict_free() to free the dictionary
50  * and all its contents.
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_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
63  <....> // iterate over all entries in d
64  }
65  av_dict_free(&d);
66  @endcode
67  */
68 
69 #define AV_DICT_MATCH_CASE 1 /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */
70 #define AV_DICT_IGNORE_SUFFIX 2 /**< Return first entry in a dictionary whose first part corresponds to the search key,
71  ignoring the suffix of the found key string. Only relevant in av_dict_get(). */
72 #define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been
73  allocated with av_malloc() or another memory allocation function. */
74 #define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
75  allocated with av_malloc() or another memory allocation function. */
76 #define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries.
77 #define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no
78  delimiter is added, the strings are simply concatenated. */
79 #define AV_DICT_MULTIKEY 64 /**< Allow to store several equal keys in the dictionary */
80 
81 typedef struct AVDictionaryEntry {
82  char *key;
83  char *value;
85 
86 typedef struct AVDictionary AVDictionary;
87 
88 /**
89  * Get a dictionary entry with matching key.
90  *
91  * The returned entry key or value must not be changed, or it will
92  * cause undefined behavior.
93  *
94  * To iterate through all the dictionary entries, you can set the matching key
95  * to the null string "" and set the AV_DICT_IGNORE_SUFFIX flag.
96  *
97  * @param prev Set to the previous matching element to find the next.
98  * If set to NULL the first matching element is returned.
99  * @param key matching key
100  * @param flags a collection of AV_DICT_* flags controlling how the entry is retrieved
101  * @return found entry or NULL in case no matching entry was found in the dictionary
102  */
103 AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key,
104  const AVDictionaryEntry *prev, int flags);
105 
106 /**
107  * Get number of entries in dictionary.
108  *
109  * @param m dictionary
110  * @return number of entries in dictionary
111  */
112 int av_dict_count(const AVDictionary *m);
113 
114 /**
115  * Set the given entry in *pm, overwriting an existing entry.
116  *
117  * Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set,
118  * these arguments will be freed on error.
119  *
120  * Warning: Adding a new entry to a dictionary invalidates all existing entries
121  * previously returned with av_dict_get.
122  *
123  * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL
124  * a dictionary struct is allocated and put in *pm.
125  * @param key entry key to add to *pm (will either be av_strduped or added as a new key depending on flags)
126  * @param value entry value to add to *pm (will be av_strduped or added as a new key depending on flags).
127  * Passing a NULL value will cause an existing entry to be deleted.
128  * @return >= 0 on success otherwise an error code <0
129  */
130 int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
131 
132 /**
133  * Convenience wrapper for av_dict_set that converts the value to a string
134  * and stores it.
135  *
136  * Note: If AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error.
137  */
138 int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags);
139 
140 /**
141  * Parse the key/value pairs list and add the parsed entries to a dictionary.
142  *
143  * In case of failure, all the successfully set entries are stored in
144  * *pm. You may need to manually free the created dictionary.
145  *
146  * @param key_val_sep a 0-terminated list of characters used to separate
147  * key from value
148  * @param pairs_sep a 0-terminated list of characters used to separate
149  * two pairs from each other
150  * @param flags flags to use when adding to dictionary.
151  * AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL
152  * are ignored since the key/value tokens will always
153  * be duplicated.
154  * @return 0 on success, negative AVERROR code on failure
155  */
156 int av_dict_parse_string(AVDictionary **pm, const char *str,
157  const char *key_val_sep, const char *pairs_sep,
158  int flags);
159 
160 /**
161  * Copy entries from one AVDictionary struct into another.
162  * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL,
163  * this function will allocate a struct for you and put it in *dst
164  * @param src pointer to source AVDictionary struct
165  * @param flags flags to use when setting entries in *dst
166  * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag
167  * @return 0 on success, negative AVERROR code on failure. If dst was allocated
168  * by this function, callers should free the associated memory.
169  */
170 int av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags);
171 
172 /**
173  * Free all the memory allocated for an AVDictionary struct
174  * and all keys and values.
175  */
176 void av_dict_free(AVDictionary **m);
177 
178 /**
179  * Get dictionary entries as a string.
180  *
181  * Create a string containing dictionary's entries.
182  * Such string may be passed back to av_dict_parse_string().
183  * @note String is escaped with backslashes ('\').
184  *
185  * @param[in] m dictionary
186  * @param[out] buffer Pointer to buffer that will be allocated with string containg entries.
187  * Buffer must be freed by the caller when is no longer needed.
188  * @param[in] key_val_sep character used to separate key from value
189  * @param[in] pairs_sep character used to separate two pairs from each other
190  * @return >= 0 on success, negative on error
191  * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
192  */
193 int av_dict_get_string(const AVDictionary *m, char **buffer,
194  const char key_val_sep, const char pairs_sep);
195 
196 /**
197  * @}
198  */
199 
200 #endif /* AVUTIL_DICT_H */
int av_dict_count(const AVDictionary *m)
Get number of entries in dictionary.
Definition: dict.c:35
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.
Definition: dict.c:230
int av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags)
Copy entries from one AVDictionary struct into another.
Definition: dict.c:217
const char * key
#define src
Definition: vp8dsp.c:254
AVDictionaryEntry * av_dict_get(const AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags)
Get a dictionary entry with matching key.
Definition: dict.c:40
#define flags(name, subs,...)
Definition: cbs_h2645.c:263
void av_dict_free(AVDictionary **m)
Free all the memory allocated for an AVDictionary struct and all keys and values. ...
Definition: dict.c:203
Libavutil version macros.
GLsizei GLboolean const GLfloat * value
Definition: opengl_enc.c:109
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.
Definition: dict.c:180
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:70
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...
Definition: dict.c:147
char * key
Definition: dict.h:86
char * value
Definition: dict.h:87
GLuint buffer
Definition: opengl_enc.c:102