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avutil/dict: Improve documentation

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Mostly consistent formatting and consistently ordering of
warnings/notes to be next to the description.

Additionally group the AV_DICT_* macros.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Marvin Scholz 2022-09-24 16:36:59 +02:00 committed by Anton Khirnov
parent 3101b8afb3
commit 2508e846a8
1 changed files with 55 additions and 36 deletions
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91
libavutil/dict.h
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@ -39,13 +39,15 @@
* @brief Simple key:value store * @brief Simple key:value store
* *
* @{ * @{
* Dictionaries are used for storing key:value pairs. To create * Dictionaries are used for storing key-value pairs.
* an AVDictionary, simply pass an address of a NULL pointer to *
* av_dict_set(). NULL can be used as an empty dictionary wherever * - To **create an AVDictionary**, simply pass an address of a NULL
* a pointer to an AVDictionary is required. * pointer to av_dict_set(). NULL can be used as an empty dictionary
* Use av_dict_get() to retrieve an entry and av_dict_iterate() to * wherever a pointer to an AVDictionary is required.
* iterate over all entries and finally av_dict_free() to free the * - To **insert an entry**, use av_dict_set().
* dictionary and all its contents. * - Use av_dict_get() to **retrieve an entry**.
* - To **iterate over all entries**, use av_dict_iterate().
* - In order to **free the dictionary and all its contents**, use av_dict_free().
* *
@code @code
AVDictionary *d = NULL; // "create" an empty dictionary AVDictionary *d = NULL; // "create" an empty dictionary
@ -57,13 +59,18 @@
char *v = av_strdup("value"); // you can avoid copying them like this char *v = av_strdup("value"); // you can avoid copying them like this
av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL); av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
while (t = av_dict_iterate(d, t)) { while ((t = av_dict_iterate(d, t))) {
<....> // iterate over all entries in d <....> // iterate over all entries in d
} }
av_dict_free(&d); av_dict_free(&d);
@endcode @endcode
*/ */
/**
* @name AVDictionary Flags
* Flags that influence behavior of the matching of keys or insertion to the dictionary.
* @{
*/
#define AV_DICT_MATCH_CASE 1 /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */ #define AV_DICT_MATCH_CASE 1 /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */
#define AV_DICT_IGNORE_SUFFIX 2 /**< Return first entry in a dictionary whose first part corresponds to the search key, #define AV_DICT_IGNORE_SUFFIX 2 /**< Return first entry in a dictionary whose first part corresponds to the search key,
ignoring the suffix of the found key string. Only relevant in av_dict_get(). */ ignoring the suffix of the found key string. Only relevant in av_dict_get(). */
@ -71,10 +78,13 @@
allocated with av_malloc() or another memory allocation function. */ allocated with av_malloc() or another memory allocation function. */
#define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been #define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
allocated with av_malloc() or another memory allocation function. */ allocated with av_malloc() or another memory allocation function. */
#define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries. #define AV_DICT_DONT_OVERWRITE 16 /**< Don't overwrite existing entries. */
#define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no #define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no
delimiter is added, the strings are simply concatenated. */ delimiter is added, the strings are simply concatenated. */
#define AV_DICT_MULTIKEY 64 /**< Allow to store several equal keys in the dictionary */ #define AV_DICT_MULTIKEY 64 /**< Allow to store several equal keys in the dictionary */
/**
* @}
*/
typedef struct AVDictionaryEntry { typedef struct AVDictionaryEntry {
char *key; char *key;
@ -89,11 +99,13 @@ typedef struct AVDictionary AVDictionary;
* The returned entry key or value must not be changed, or it will * The returned entry key or value must not be changed, or it will
* cause undefined behavior. * cause undefined behavior.
* *
* @param prev Set to the previous matching element to find the next. * @param prev Set to the previous matching element to find the next.
* If set to NULL the first matching element is returned. * If set to NULL the first matching element is returned.
* @param key matching key * @param key Matching key
* @param flags a collection of AV_DICT_* flags controlling how the entry is retrieved * @param flags A collection of AV_DICT_* flags controlling how the
* @return found entry or NULL in case no matching entry was found in the dictionary * entry is retrieved
*
* @return Found entry or NULL in case no matching entry was found in the dictionary
*/ */
AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key, AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key,
const AVDictionaryEntry *prev, int flags); const AVDictionaryEntry *prev, int flags);
@ -142,20 +154,21 @@ int av_dict_count(const AVDictionary *m);
* @warning Adding a new entry to a dictionary invalidates all existing entries * @warning Adding a new entry to a dictionary invalidates all existing entries
* previously returned with av_dict_get() or av_dict_iterate(). * previously returned with av_dict_get() or av_dict_iterate().
* *
* @param pm pointer to a pointer to a dictionary struct. If *pm is NULL * @param pm Pointer to a pointer to a dictionary struct. If *pm is NULL
* a dictionary struct is allocated and put in *pm. * a dictionary struct is allocated and put in *pm.
* @param key entry key to add to *pm (will either be av_strduped or added as a new key depending on flags) * @param key Entry key to add to *pm (will either be av_strduped or added as a new key depending on flags)
* @param value entry value to add to *pm (will be av_strduped or added as a new key depending on flags). * @param value Entry value to add to *pm (will be av_strduped or added as a new key depending on flags).
* Passing a NULL value will cause an existing entry to be deleted. * Passing a NULL value will cause an existing entry to be deleted.
* @return >= 0 on success otherwise an error code <0 *
* @return >= 0 on success otherwise an error code <0
*/ */
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags); int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
/** /**
* Convenience wrapper for av_dict_set that converts the value to a string * Convenience wrapper for av_dict_set() that converts the value to a string
* and stores it. * and stores it.
* *
* Note: If AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error. * Note: If ::AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error.
*/ */
int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags); int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags);
@ -165,14 +178,15 @@ int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags
* In case of failure, all the successfully set entries are stored in * In case of failure, all the successfully set entries are stored in
* *pm. You may need to manually free the created dictionary. * *pm. You may need to manually free the created dictionary.
* *
* @param key_val_sep a 0-terminated list of characters used to separate * @param key_val_sep A 0-terminated list of characters used to separate
* key from value * key from value
* @param pairs_sep a 0-terminated list of characters used to separate * @param pairs_sep A 0-terminated list of characters used to separate
* two pairs from each other * two pairs from each other
* @param flags flags to use when adding to dictionary. * @param flags Flags to use when adding to the dictionary.
* AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL * ::AV_DICT_DONT_STRDUP_KEY and ::AV_DICT_DONT_STRDUP_VAL
* are ignored since the key/value tokens will always * are ignored since the key/value tokens will always
* be duplicated. * be duplicated.
*
* @return 0 on success, negative AVERROR code on failure * @return 0 on success, negative AVERROR code on failure
*/ */
int av_dict_parse_string(AVDictionary **pm, const char *str, int av_dict_parse_string(AVDictionary **pm, const char *str,
@ -181,11 +195,14 @@ int av_dict_parse_string(AVDictionary **pm, const char *str,
/** /**
* Copy entries from one AVDictionary struct into another. * Copy entries from one AVDictionary struct into another.
* @param dst pointer to a pointer to a AVDictionary struct. If *dst is NULL, *
* this function will allocate a struct for you and put it in *dst * @note Metadata is read using the ::AV_DICT_IGNORE_SUFFIX flag
* @param src pointer to source AVDictionary struct *
* @param flags flags to use when setting entries in *dst * @param dst Pointer to a pointer to a AVDictionary struct to copy into. If *dst is NULL,
* @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag * this function will allocate a struct for you and put it in *dst
* @param src Pointer to the source AVDictionary struct to copy items from.
* @param flags Flags to use when setting entries in *dst
*
* @return 0 on success, negative AVERROR code on failure. If dst was allocated * @return 0 on success, negative AVERROR code on failure. If dst was allocated
* by this function, callers should free the associated memory. * by this function, callers should free the associated memory.
*/ */
@ -204,13 +221,15 @@ void av_dict_free(AVDictionary **m);
* Such string may be passed back to av_dict_parse_string(). * Such string may be passed back to av_dict_parse_string().
* @note String is escaped with backslashes ('\'). * @note String is escaped with backslashes ('\').
* *
* @param[in] m dictionary * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
*
* @param[in] m The dictionary
* @param[out] buffer Pointer to buffer that will be allocated with string containg entries. * @param[out] buffer Pointer to buffer that will be allocated with string containg entries.
* Buffer must be freed by the caller when is no longer needed. * Buffer must be freed by the caller when is no longer needed.
* @param[in] key_val_sep character used to separate key from value * @param[in] key_val_sep Character used to separate key from value
* @param[in] pairs_sep character used to separate two pairs from each other * @param[in] pairs_sep Character used to separate two pairs from each other
*
* @return >= 0 on success, negative on error * @return >= 0 on success, negative on error
* @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
*/ */
int av_dict_get_string(const AVDictionary *m, char **buffer, int av_dict_get_string(const AVDictionary *m, char **buffer,
const char key_val_sep, const char pairs_sep); const char key_val_sep, const char pairs_sep);