1 /* 2 * 3 * This file is part of Libav. 4 * 5 * Libav 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 * Libav 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 Libav; 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 */ 24 25 #ifndef AVUTIL_DICT_H 26 #define AVUTIL_DICT_H 27 28 /** 29 * @addtogroup lavu_dict AVDictionary 30 * @ingroup lavu_data 31 * 32 * @brief Simple key:value store 33 * 34 * @{ 35 * Dictionaries are used for storing key:value pairs. To create 36 * an AVDictionary, simply pass an address of a NULL pointer to 37 * av_dict_set(). NULL can be used as an empty dictionary wherever 38 * a pointer to an AVDictionary is required. 39 * Use av_dict_get() to retrieve an entry or iterate over all 40 * entries and finally av_dict_free() to free the dictionary 41 * and all its contents. 42 * 43 * @code 44 * AVDictionary *d = NULL; // "create" an empty dictionary 45 * av_dict_set(&d, "foo", "bar", 0); // add an entry 46 * 47 * char *k = av_strdup("key"); // if your strings are already allocated, 48 * char *v = av_strdup("value"); // you can avoid copying them like this 49 * av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL); 50 * 51 * AVDictionaryEntry *t = NULL; 52 * while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) { 53 * <....> // iterate over all entries in d 54 * } 55 * 56 * av_dict_free(&d); 57 * @endcode 58 * 59 */ 60 61 #define AV_DICT_MATCH_CASE 1 62 #define AV_DICT_IGNORE_SUFFIX 2 63 #define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been 64 allocated with av_malloc() and children. */ 65 #define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been 66 allocated with av_malloc() and chilren. */ 67 #define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries. 68 #define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no 69 delimiter is added, the strings are simply concatenated. */ 70 71 typedef struct { 72 char *key; 73 char *value; 74 } AVDictionaryEntry; 75 76 typedef struct AVDictionary AVDictionary; 77 78 /** 79 * Get a dictionary entry with matching key. 80 * 81 * @param prev Set to the previous matching element to find the next. 82 * If set to NULL the first matching element is returned. 83 * @param flags Allows case as well as suffix-insensitive comparisons. 84 * @return Found entry or NULL, changing key or value leads to undefined behavior. 85 */ 86 AVDictionaryEntry * 87 av_dict_get(AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags); 88 89 /** 90 * Set the given entry in *pm, overwriting an existing entry. 91 * 92 * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL 93 * a dictionary struct is allocated and put in *pm. 94 * @param key entry key to add to *pm (will be av_strduped depending on flags) 95 * @param value entry value to add to *pm (will be av_strduped depending on flags). 96 * Passing a NULL value will cause an existing tag to be deleted. 97 * @return >= 0 on success otherwise an error code <0 98 */ 99 int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags); 100 101 /** 102 * Copy entries from one AVDictionary struct into another. 103 * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL, 104 * this function will allocate a struct for you and put it in *dst 105 * @param src pointer to source AVDictionary struct 106 * @param flags flags to use when setting entries in *dst 107 * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag 108 */ 109 void av_dict_copy(AVDictionary **dst, AVDictionary *src, int flags); 110 111 /** 112 * Free all the memory allocated for an AVDictionary struct 113 * and all keys and values. 114 */ 115 void av_dict_free(AVDictionary **m); 116 117 /** 118 * @} 119 */ 120 121 #endif // AVUTIL_DICT_H 122