libavutil/dict.h

   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 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 */