dict.h (8010B)
1 /* 2 * 3 * This file is part of FFmpeg. 4 * 5 * FFmpeg is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU Lesser General Public 7 * License as published by the Free Software Foundation; either 8 * version 2.1 of the License, or (at your option) any later version. 9 * 10 * FFmpeg is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 * Lesser General Public License for more details. 14 * 15 * You should have received a copy of the GNU Lesser General Public 16 * License along with FFmpeg; if not, write to the Free Software 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 18 */ 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 #include <stdint.h> 35 36 #include "version.h" 37 38 /** 39 * @addtogroup lavu_dict AVDictionary 40 * @ingroup lavu_data 41 * 42 * @brief Simple key:value store 43 * 44 * @{ 45 * Dictionaries are used for storing key:value pairs. To create 46 * an AVDictionary, simply pass an address of a NULL pointer to 47 * av_dict_set(). NULL can be used as an empty dictionary wherever 48 * a pointer to an AVDictionary is required. 49 * Use av_dict_get() to retrieve an entry or iterate over all 50 * entries and finally av_dict_free() to free the dictionary 51 * and all its contents. 52 * 53 @code 54 AVDictionary *d = NULL; // "create" an empty dictionary 55 AVDictionaryEntry *t = NULL; 56 57 av_dict_set(&d, "foo", "bar", 0); // add an entry 58 59 char *k = av_strdup("key"); // if your strings are already allocated, 60 char *v = av_strdup("value"); // you can avoid copying them like this 61 av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL); 62 63 while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) { 64 <....> // iterate over all entries in d 65 } 66 av_dict_free(&d); 67 @endcode 68 * 69 */ 70 71 #define AV_DICT_MATCH_CASE 1 /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */ 72 #define AV_DICT_IGNORE_SUFFIX 2 /**< Return first entry in a dictionary whose first part corresponds to the search key, 73 ignoring the suffix of the found key string. Only relevant in av_dict_get(). */ 74 #define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been 75 allocated with av_malloc() or another memory allocation function. */ 76 #define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been 77 allocated with av_malloc() or another memory allocation function. */ 78 #define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries. 79 #define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no 80 delimiter is added, the strings are simply concatenated. */ 81 82 typedef struct AVDictionaryEntry { 83 char *key; 84 char *value; 85 } AVDictionaryEntry; 86 87 typedef struct AVDictionary AVDictionary; 88 89 /** 90 * Get a dictionary entry with matching key. 91 * 92 * The returned entry key or value must not be changed, or it will 93 * cause undefined behavior. 94 * 95 * To iterate through all the dictionary entries, you can set the matching key 96 * to the null string "" and set the AV_DICT_IGNORE_SUFFIX flag. 97 * 98 * @param prev Set to the previous matching element to find the next. 99 * If set to NULL the first matching element is returned. 100 * @param key matching key 101 * @param flags a collection of AV_DICT_* flags controlling how the entry is retrieved 102 * @return found entry or NULL in case no matching entry was found in the dictionary 103 */ 104 AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key, 105 const AVDictionaryEntry *prev, int flags); 106 107 /** 108 * Get number of entries in dictionary. 109 * 110 * @param m dictionary 111 * @return number of entries in dictionary 112 */ 113 int av_dict_count(const AVDictionary *m); 114 115 /** 116 * Set the given entry in *pm, overwriting an existing entry. 117 * 118 * Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set, 119 * these arguments will be freed on error. 120 * 121 * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL 122 * a dictionary struct is allocated and put in *pm. 123 * @param key entry key to add to *pm (will be av_strduped depending on flags) 124 * @param value entry value to add to *pm (will be av_strduped depending on flags). 125 * Passing a NULL value will cause an existing entry to be deleted. 126 * @return >= 0 on success otherwise an error code <0 127 */ 128 int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags); 129 130 /** 131 * Convenience wrapper for av_dict_set that converts the value to a string 132 * and stores it. 133 * 134 * Note: If AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error. 135 */ 136 int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags); 137 138 /** 139 * Parse the key/value pairs list and add the parsed entries to a dictionary. 140 * 141 * In case of failure, all the successfully set entries are stored in 142 * *pm. You may need to manually free the created dictionary. 143 * 144 * @param key_val_sep a 0-terminated list of characters used to separate 145 * key from value 146 * @param pairs_sep a 0-terminated list of characters used to separate 147 * two pairs from each other 148 * @param flags flags to use when adding to dictionary. 149 * AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL 150 * are ignored since the key/value tokens will always 151 * be duplicated. 152 * @return 0 on success, negative AVERROR code on failure 153 */ 154 int av_dict_parse_string(AVDictionary **pm, const char *str, 155 const char *key_val_sep, const char *pairs_sep, 156 int flags); 157 158 /** 159 * Copy entries from one AVDictionary struct into another. 160 * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL, 161 * this function will allocate a struct for you and put it in *dst 162 * @param src pointer to source AVDictionary struct 163 * @param flags flags to use when setting entries in *dst 164 * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag 165 * @return 0 on success, negative AVERROR code on failure. If dst was allocated 166 * by this function, callers should free the associated memory. 167 */ 168 int av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags); 169 170 /** 171 * Free all the memory allocated for an AVDictionary struct 172 * and all keys and values. 173 */ 174 void av_dict_free(AVDictionary **m); 175 176 /** 177 * Get dictionary entries as a string. 178 * 179 * Create a string containing dictionary's entries. 180 * Such string may be passed back to av_dict_parse_string(). 181 * @note String is escaped with backslashes ('\'). 182 * 183 * @param[in] m dictionary 184 * @param[out] buffer Pointer to buffer that will be allocated with string containg entries. 185 * Buffer must be freed by the caller when is no longer needed. 186 * @param[in] key_val_sep character used to separate key from value 187 * @param[in] pairs_sep character used to separate two pairs from each other 188 * @return >= 0 on success, negative on error 189 * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same. 190 */ 191 int av_dict_get_string(const AVDictionary *m, char **buffer, 192 const char key_val_sep, const char pairs_sep); 193 194 /** 195 * @} 196 */ 197 198 #endif /* AVUTIL_DICT_H */