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  1. /*
  2.  *
  3.  * This file is part of FFmpeg.
  4.  *
  5.  * FFmpeg 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.  * FFmpeg 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 FFmpeg; 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.  * @deprecated
  24.  *  AVDictionary is provided for compatibility with libav. It is both in
  25.  *  implementation as well as API inefficient. It does not scale and is
  26.  *  extremely slow with large dictionaries.
  27.  *  It is recommended that new code uses our tree container from tree.c/h
  28.  *  where applicable, which uses AVL trees to achieve O(log n) performance.
  29.  */
  30.  
  31. #ifndef AVUTIL_DICT_H
  32. #define AVUTIL_DICT_H
  33.  
  34. #include <stdint.h>
  35.  
  36. #include "version.h"
  37.  
  38. /**
  39.  * @addtogroup lavu_dict AVDictionary
  40.  * @ingroup lavu_data
  41.  *
  42.  * @brief Simple key:value store
  43.  *
  44.  * @{
  45.  * Dictionaries are used for storing key:value pairs. To create
  46.  * an AVDictionary, simply pass an address of a NULL pointer to
  47.  * av_dict_set(). NULL can be used as an empty dictionary wherever
  48.  * a pointer to an AVDictionary is required.
  49.  * Use av_dict_get() to retrieve an entry or iterate over all
  50.  * entries and finally av_dict_free() to free the dictionary
  51.  * and all its contents.
  52.  *
  53.  @code
  54.    AVDictionary *d = NULL;           // "create" an empty dictionary
  55.    AVDictionaryEntry *t = NULL;
  56.  
  57.    av_dict_set(&d, "foo", "bar", 0); // add an entry
  58.  
  59.    char *k = av_strdup("key");       // if your strings are already allocated,
  60.    char *v = av_strdup("value");     // you can avoid copying them like this
  61.    av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
  62.  
  63.    while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
  64.        <....>                             // iterate over all entries in d
  65.    }
  66.    av_dict_free(&d);
  67.  @endcode
  68.  *
  69.  */
  70.  
  71. #define AV_DICT_MATCH_CASE      1   /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */
  72. #define AV_DICT_IGNORE_SUFFIX   2   /**< Return first entry in a dictionary whose first part corresponds to the search key,
  73.                                          ignoring the suffix of the found key string. Only relevant in av_dict_get(). */
  74. #define AV_DICT_DONT_STRDUP_KEY 4   /**< Take ownership of a key that's been
  75.                                          allocated with av_malloc() or another memory allocation function. */
  76. #define AV_DICT_DONT_STRDUP_VAL 8   /**< Take ownership of a value that's been
  77.                                          allocated with av_malloc() or another memory allocation function. */
  78. #define AV_DICT_DONT_OVERWRITE 16   ///< Don't overwrite existing entries.
  79. #define AV_DICT_APPEND         32   /**< If the entry already exists, append to it.  Note that no
  80.                                       delimiter is added, the strings are simply concatenated. */
  81.  
  82. typedef struct AVDictionaryEntry {
  83.     char *key;
  84.     char *value;
  85. } AVDictionaryEntry;
  86.  
  87. typedef struct AVDictionary AVDictionary;
  88.  
  89. /**
  90.  * Get a dictionary entry with matching key.
  91.  *
  92.  * The returned entry key or value must not be changed, or it will
  93.  * cause undefined behavior.
  94.  *
  95.  * To iterate through all the dictionary entries, you can set the matching key
  96.  * to the null string "" and set the AV_DICT_IGNORE_SUFFIX flag.
  97.  *
  98.  * @param prev Set to the previous matching element to find the next.
  99.  *             If set to NULL the first matching element is returned.
  100.  * @param key matching key
  101.  * @param flags a collection of AV_DICT_* flags controlling how the entry is retrieved
  102.  * @return found entry or NULL in case no matching entry was found in the dictionary
  103.  */
  104. AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key,
  105.                                const AVDictionaryEntry *prev, int flags);
  106.  
  107. /**
  108.  * Get number of entries in dictionary.
  109.  *
  110.  * @param m dictionary
  111.  * @return  number of entries in dictionary
  112.  */
  113. int av_dict_count(const AVDictionary *m);
  114.  
  115. /**
  116.  * Set the given entry in *pm, overwriting an existing entry.
  117.  *
  118.  * Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set,
  119.  * these arguments will be freed on error.
  120.  *
  121.  * @param pm pointer to a pointer to a dictionary struct. If *pm is NULL
  122.  * a dictionary struct is allocated and put in *pm.
  123.  * @param key entry key to add to *pm (will be av_strduped depending on flags)
  124.  * @param value entry value to add to *pm (will be av_strduped depending on flags).
  125.  *        Passing a NULL value will cause an existing entry to be deleted.
  126.  * @return >= 0 on success otherwise an error code <0
  127.  */
  128. int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
  129.  
  130. /**
  131.  * Convenience wrapper for av_dict_set that converts the value to a string
  132.  * and stores it.
  133.  *
  134.  * Note: If AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error.
  135.  */
  136. int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags);
  137.  
  138. /**
  139.  * Parse the key/value pairs list and add the parsed entries to a dictionary.
  140.  *
  141.  * In case of failure, all the successfully set entries are stored in
  142.  * *pm. You may need to manually free the created dictionary.
  143.  *
  144.  * @param key_val_sep  a 0-terminated list of characters used to separate
  145.  *                     key from value
  146.  * @param pairs_sep    a 0-terminated list of characters used to separate
  147.  *                     two pairs from each other
  148.  * @param flags        flags to use when adding to dictionary.
  149.  *                     AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL
  150.  *                     are ignored since the key/value tokens will always
  151.  *                     be duplicated.
  152.  * @return             0 on success, negative AVERROR code on failure
  153.  */
  154. int av_dict_parse_string(AVDictionary **pm, const char *str,
  155.                          const char *key_val_sep, const char *pairs_sep,
  156.                          int flags);
  157.  
  158. /**
  159.  * Copy entries from one AVDictionary struct into another.
  160.  * @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL,
  161.  *            this function will allocate a struct for you and put it in *dst
  162.  * @param src pointer to source AVDictionary struct
  163.  * @param flags flags to use when setting entries in *dst
  164.  * @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag
  165.  */
  166. void av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags);
  167.  
  168. /**
  169.  * Free all the memory allocated for an AVDictionary struct
  170.  * and all keys and values.
  171.  */
  172. void av_dict_free(AVDictionary **m);
  173.  
  174. /**
  175.  * Get dictionary entries as a string.
  176.  *
  177.  * Create a string containing dictionary's entries.
  178.  * Such string may be passed back to av_dict_parse_string().
  179.  * @note String is escaped with backslashes ('\').
  180.  *
  181.  * @param[in]  m             dictionary
  182.  * @param[out] buffer        Pointer to buffer that will be allocated with string containg entries.
  183.  *                           Buffer must be freed by the caller when is no longer needed.
  184.  * @param[in]  key_val_sep   character used to separate key from value
  185.  * @param[in]  pairs_sep     character used to separate two pairs from each other
  186.  * @return                   >= 0 on success, negative on error
  187.  * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
  188.  */
  189. int av_dict_get_string(const AVDictionary *m, char **buffer,
  190.                        const char key_val_sep, const char pairs_sep);
  191.  
  192. /**
  193.  * @}
  194.  */
  195.  
  196. #endif /* AVUTIL_DICT_H */
  197.