dict.h (8418B)
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. To create 43 * an AVDictionary, simply pass an address of a NULL pointer to 44 * av_dict_set(). NULL can be used as an empty dictionary wherever 45 * a pointer to an AVDictionary is required. 46 * Use av_dict_get() to retrieve an entry or iterate over all 47 * entries and finally av_dict_free() to free the dictionary 48 * and all its contents. 49 * 50 @code 51 AVDictionary *d = NULL; // "create" an empty dictionary 52 AVDictionaryEntry *t = NULL; 53 54 av_dict_set(&d, "foo", "bar", 0); // add an entry 55 56 char *k = av_strdup("key"); // if your strings are already allocated, 57 char *v = av_strdup("value"); // you can avoid copying them like this 58 av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL); 59 60 while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) { 61 <....> // iterate over all entries in d 62 } 63 av_dict_free(&d); 64 @endcode 65 */ 66 67 #define AV_DICT_MATCH_CASE \ 68 1 /**< Only get an entry with exact-case key match. Only relevant in \ 69 av_dict_get(). */ 70 #define AV_DICT_IGNORE_SUFFIX \ 71 2 /**< Return first entry in a dictionary whose first part corresponds to \ 72 the search key, ignoring the suffix of the found key string. Only \ 73 relevant in av_dict_get(). */ 74 #define AV_DICT_DONT_STRDUP_KEY \ 75 4 /**< Take ownership of a key that's been \ 76 allocated with av_malloc() or another memory allocation function. */ 77 #define AV_DICT_DONT_STRDUP_VAL \ 78 8 /**< Take ownership of a value that's been \ 79 allocated with av_malloc() or another memory allocation function. */ 80 #define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries. 81 #define AV_DICT_APPEND \ 82 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 \ 85 64 /**< Allow to store several equal keys in the dictionary */ 86 87 typedef struct AVDictionaryEntry { 88 char* key; 89 char* value; 90 } AVDictionaryEntry; 91 92 typedef struct AVDictionary AVDictionary; 93 94 /** 95 * Get a dictionary entry with matching key. 96 * 97 * The returned entry key or value must not be changed, or it will 98 * cause undefined behavior. 99 * 100 * To iterate through all the dictionary entries, you can set the matching key 101 * to the null string "" and set the AV_DICT_IGNORE_SUFFIX flag. 102 * 103 * @param prev Set to the previous matching element to find the next. 104 * If set to NULL the first matching element is returned. 105 * @param key matching key 106 * @param flags a collection of AV_DICT_* flags controlling how the entry is 107 * retrieved 108 * @return found entry or NULL in case no matching entry was found in the 109 * dictionary 110 */ 111 AVDictionaryEntry* av_dict_get(const AVDictionary* m, const char* key, 112 const AVDictionaryEntry* prev, int flags); 113 114 /** 115 * Get number of entries in dictionary. 116 * 117 * @param m dictionary 118 * @return number of entries in dictionary 119 */ 120 int av_dict_count(const AVDictionary* m); 121 122 /** 123 * Set the given entry in *pm, overwriting an existing entry. 124 * 125 * Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set, 126 * these arguments will be freed on error. 127 * 128 * Warning: Adding a new entry to a dictionary invalidates all existing entries 129 * previously returned with av_dict_get. 130 * 131 * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL 132 * a dictionary struct is allocated and put in *pm. 133 * @param key entry key to add to *pm (will either be av_strduped or added as a 134 * new key depending on flags) 135 * @param value entry value to add to *pm (will be av_strduped or added as a new 136 * key depending on flags). Passing a NULL value will cause an existing entry to 137 * be deleted. 138 * @return >= 0 on success otherwise an error code <0 139 */ 140 int av_dict_set(AVDictionary** pm, const char* key, const char* value, 141 int flags); 142 143 /** 144 * Convenience wrapper for av_dict_set that converts the value to a string 145 * and stores it. 146 * 147 * Note: If AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error. 148 */ 149 int av_dict_set_int(AVDictionary** pm, const char* key, int64_t value, 150 int flags); 151 152 /** 153 * Parse the key/value pairs list and add the parsed entries to a dictionary. 154 * 155 * In case of failure, all the successfully set entries are stored in 156 * *pm. You may need to manually free the created dictionary. 157 * 158 * @param key_val_sep a 0-terminated list of characters used to separate 159 * key from value 160 * @param pairs_sep a 0-terminated list of characters used to separate 161 * two pairs from each other 162 * @param flags flags to use when adding to dictionary. 163 * AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL 164 * are ignored since the key/value tokens will always 165 * be duplicated. 166 * @return 0 on success, negative AVERROR code on failure 167 */ 168 int av_dict_parse_string(AVDictionary** pm, const char* str, 169 const char* key_val_sep, const char* pairs_sep, 170 int flags); 171 172 /** 173 * Copy entries from one AVDictionary struct into another. 174 * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL, 175 * this function will allocate a struct for you and put it in *dst 176 * @param src pointer to source AVDictionary struct 177 * @param flags flags to use when setting entries in *dst 178 * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag 179 * @return 0 on success, negative AVERROR code on failure. If dst was allocated 180 * by this function, callers should free the associated memory. 181 */ 182 int av_dict_copy(AVDictionary** dst, const AVDictionary* src, int flags); 183 184 /** 185 * Free all the memory allocated for an AVDictionary struct 186 * and all keys and values. 187 */ 188 void av_dict_free(AVDictionary** m); 189 190 /** 191 * Get dictionary entries as a string. 192 * 193 * Create a string containing dictionary's entries. 194 * Such string may be passed back to av_dict_parse_string(). 195 * @note String is escaped with backslashes ('\'). 196 * 197 * @param[in] m dictionary 198 * @param[out] buffer Pointer to buffer that will be allocated with 199 * string containg entries. Buffer must be freed by the caller when is no longer 200 * needed. 201 * @param[in] key_val_sep character used to separate key from value 202 * @param[in] pairs_sep character used to separate two pairs from each 203 * other 204 * @return >= 0 on success, negative on error 205 * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the 206 * same. 207 */ 208 int av_dict_get_string(const AVDictionary* m, char** buffer, 209 const char key_val_sep, const char pairs_sep); 210 211 /** 212 * @} 213 */ 214 215 #endif /* AVUTIL_DICT_H */