dict.h (8275B)
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 #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; 84 } AVDictionaryEntry; 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 */