dict.h (5361B)
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 AVDictionaryEntry *t = NULL; 46 47 av_dict_set(&d, "foo", "bar", 0); // add an entry 48 49 char *k = av_strdup("key"); // if your strings are already allocated, 50 char *v = av_strdup("value"); // you can avoid copying them like this 51 av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL); 52 53 while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) { 54 <....> // iterate over all entries in d 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 AVDictionaryEntry { 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 * Get number of entries in dictionary. 91 * 92 * @param m dictionary 93 * @return number of entries in dictionary 94 */ 95 int av_dict_count(const AVDictionary *m); 96 97 /** 98 * Set the given entry in *pm, overwriting an existing entry. 99 * 100 * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL 101 * a dictionary struct is allocated and put in *pm. 102 * @param key entry key to add to *pm (will be av_strduped depending on flags) 103 * @param value entry value to add to *pm (will be av_strduped depending on flags). 104 * Passing a NULL value will cause an existing entry to be deleted. 105 * @return >= 0 on success otherwise an error code <0 106 */ 107 int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags); 108 109 /** 110 * Parse the key/value pairs list and add to a dictionary. 111 * 112 * @param key_val_sep a 0-terminated list of characters used to separate 113 * key from value 114 * @param pairs_sep a 0-terminated list of characters used to separate 115 * two pairs from each other 116 * @param flags flags to use when adding to dictionary. 117 * AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL 118 * are ignored since the key/value tokens will always 119 * be duplicated. 120 * @return 0 on success, negative AVERROR code on failure 121 */ 122 int av_dict_parse_string(AVDictionary **pm, const char *str, 123 const char *key_val_sep, const char *pairs_sep, 124 int flags); 125 126 /** 127 * Copy entries from one AVDictionary struct into another. 128 * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL, 129 * this function will allocate a struct for you and put it in *dst 130 * @param src pointer to source AVDictionary struct 131 * @param flags flags to use when setting entries in *dst 132 * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag 133 */ 134 void av_dict_copy(AVDictionary **dst, AVDictionary *src, int flags); 135 136 /** 137 * Free all the memory allocated for an AVDictionary struct 138 * and all keys and values. 139 */ 140 void av_dict_free(AVDictionary **m); 141 142 /** 143 * @} 144 */ 145 146 #endif /* AVUTIL_DICT_H */