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  * Copy entries from one AVDictionary struct into another.

   111  * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL,

   112  *            this function will allocate a struct for you and put it in *dst

   113  * @param src pointer to source AVDictionary struct

   114  * @param flags flags to use when setting entries in *dst

   115  * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag

   116  */

   117 void av_dict_copy(AVDictionary **dst, AVDictionary *src, int flags);

   118 

   119 /**

   120  * Free all the memory allocated for an AVDictionary struct

   121  * and all keys and values.

   122  */

   123 void av_dict_free(AVDictionary **m);

   124 

   125 /**

   126  * @}

   127  */

   128 

   129 #endif /* AVUTIL_DICT_H */