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dict.h
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19 
20 /**
21  * @file
22  * Public dictionary API.
23  * @deprecated
24  * AVDictionary is provided for compatibility with libav. It is both in
25  * implementation as well as API inefficient. It does not scale and is
26  * extremely slow with large dictionaries.
27  * It is recommended that new code uses our tree container from tree.c/h
28  * where applicable, which uses AVL trees to achieve O(log n) performance.
29  */
30 
31 #ifndef AVUTIL_DICT_H
32 #define AVUTIL_DICT_H
33 
34 /**
35  * @addtogroup lavu_dict AVDictionary
36  * @ingroup lavu_data
37  *
38  * @brief Simple key:value store
39  *
40  * @{
41  * Dictionaries are used for storing key:value pairs. To create
42  * an AVDictionary, simply pass an address of a NULL pointer to
43  * av_dict_set(). NULL can be used as an empty dictionary wherever
44  * a pointer to an AVDictionary is required.
45  * Use av_dict_get() to retrieve an entry or iterate over all
46  * entries and finally av_dict_free() to free the dictionary
47  * and all its contents.
48  *
49  @code
50  AVDictionary *d = NULL; // "create" an empty dictionary
51  AVDictionaryEntry *t = NULL;
52 
53  av_dict_set(&d, "foo", "bar", 0); // add an entry
54 
55  char *k = av_strdup("key"); // if your strings are already allocated,
56  char *v = av_strdup("value"); // you can avoid copying them like this
57  av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
58 
59  while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
60  <....> // iterate over all entries in d
61  }
62  av_dict_free(&d);
63  @endcode
64  *
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 
78 typedef struct AVDictionaryEntry {
79  char *key;
80  char *value;
82 
83 typedef struct AVDictionary AVDictionary;
84 
85 /**
86  * Get a dictionary entry with matching key.
87  *
88  * The returned entry key or value must not be changed, or it will
89  * cause undefined behavior.
90  *
91  * To iterate through all the dictionary entries, you can set the matching key
92  * to the null string "" and set the AV_DICT_IGNORE_SUFFIX flag.
93  *
94  * @param prev Set to the previous matching element to find the next.
95  * If set to NULL the first matching element is returned.
96  * @param key matching key
97  * @param flags a collection of AV_DICT_* flags controlling how the entry is retrieved
98  * @return found entry or NULL in case no matching entry was found in the dictionary
99  */
101 av_dict_get(AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags);
102 
103 /**
104  * Get number of entries in dictionary.
105  *
106  * @param m dictionary
107  * @return number of entries in dictionary
108  */
109 int av_dict_count(const AVDictionary *m);
110 
111 /**
112  * Set the given entry in *pm, overwriting an existing entry.
113  *
114  * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL
115  * a dictionary struct is allocated and put in *pm.
116  * @param key entry key to add to *pm (will be av_strduped depending on flags)
117  * @param value entry value to add to *pm (will be av_strduped depending on flags).
118  * Passing a NULL value will cause an existing entry to be deleted.
119  * @return >= 0 on success otherwise an error code <0
120  */
121 int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
122 
123 /**
124  * Parse the key/value pairs list and add the parsed entries to a dictionary.
125  *
126  * In case of failure, all the successfully set entries are stored in
127  * *pm. You may need to manually free the created dictionary.
128  *
129  * @param key_val_sep a 0-terminated list of characters used to separate
130  * key from value
131  * @param pairs_sep a 0-terminated list of characters used to separate
132  * two pairs from each other
133  * @param flags flags to use when adding to dictionary.
134  * AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL
135  * are ignored since the key/value tokens will always
136  * be duplicated.
137  * @return 0 on success, negative AVERROR code on failure
138  */
139 int av_dict_parse_string(AVDictionary **pm, const char *str,
140  const char *key_val_sep, const char *pairs_sep,
141  int flags);
142 
143 /**
144  * Copy entries from one AVDictionary struct into another.
145  * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL,
146  * this function will allocate a struct for you and put it in *dst
147  * @param src pointer to source AVDictionary struct
148  * @param flags flags to use when setting entries in *dst
149  * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag
150  */
151 void av_dict_copy(AVDictionary **dst, AVDictionary *src, int flags);
152 
153 /**
154  * Free all the memory allocated for an AVDictionary struct
155  * and all keys and values.
156  */
157 void av_dict_free(AVDictionary **m);
158 
159 /**
160  * @}
161  */
162 
163 #endif /* AVUTIL_DICT_H */