FFmpeg
dict.h
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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
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11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
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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 
89 typedef struct AVDictionaryEntry {
90  char *key;
91  char *value;
93 
94 typedef 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  */
110 AVDictionaryEntry *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  */
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  */
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  */
165 int 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  */
173 int 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  */
192 int 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  */
209 int 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  */
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  */
234 int 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 */
char * str
Buffer to print data progressively.
Definition: bprint.h:99
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:94
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.
const AVDictionaryEntry * av_dict_iterate(const AVDictionary *m, const AVDictionaryEntry *prev)
Iterate over a dictionary.
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.
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_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:90
char * value
Definition: dict.h:91