json

JSON implementation, based on jsmn by Serge Zaitsev. More...

Macros
#define	JSMN_STATIC
	Hides jsmn API definitions to avoid linking errors. More...
#define	json_item(json_str, obj_tok, idx)

Functions
int	json_null_terminate (char *json_str, const jsmntok_t *obj_tok, int num_tok)
	Add null-terminators to the input JSON string. Useful to further extract token values as null-terminated strings. More...
bool	json_is_key (const jsmntok_t *json_tok, int obj_idx, int num_tok)
	Determines if pointed token corresponds to a key in a key:value pair. More...
int	json_object_next (const jsmntok_t *obj_tok, int obj_idx, int parent_idx, int num_tok)
	Return the index of the next item. This function only works properly when specified token is of JSMN_OBJECT type. More...
int	json_key_next (const jsmntok_t *json_tok, int obj_idx, int parent_idx, int num_tok)
	Return the index of the next key in the current JSON level. More...
int	json_key_search (const char *key, const char *json_str, const jsmntok_t *json_tok, int obj_idx, int parent_idx, int num_tok)
	Search for a given key in the current JSON level. More...
int	json_bool_get (const char *json_str, const jsmntok_t *json_tok, int obj_idx)
	Obtains the boolean value corresponding to the indicated token. More...

Detailed Description

JSON implementation, based on jsmn by Serge Zaitsev.

This module just adds some helper functions to jsmn to ease navigating the JSON structure and extracting values.

Author

Jesus Alonso (doragasu)

Date

2019

Todo:

Add more functions to extract data.

Macro Definition Documentation

JSMN_STATIC

#define JSMN_STATIC

Hides jsmn API definitions to avoid linking errors.

Definition at line 26 of file json.h.

json_item

#define json_item	(		json_str,
			obj_tok,
			idx
	)

Value:

    (idx) < 0 ? NULL : \
    &((json_str)[(obj_tok)[idx].start])

Macro to extract the item (as string) from a token. Requires the json_str to have the null terminations added by json_null_terminate().

Definition at line 31 of file json.h.

Function Documentation

json_bool_get()

int json_bool_get	(	const char *	json_str,
		const jsmntok_t *	json_tok,
		int	obj_idx
	)

Obtains the boolean value corresponding to the indicated token.

Parameters

[in]	json_str	JSON string.
[in]	json_tok	JSON token array extracted from json_str.
[in]	obj_idx	Index of the token to analyse.

Returns

1 if true, 0 if false, less than 0 if token is not a proper boolean.

json_is_key()

bool json_is_key	(	const jsmntok_t *	json_tok,
		int	obj_idx,
		int	num_tok
	)

Determines if pointed token corresponds to a key in a key:value pair.

Parameters

[in]	json_tok	JSON token array.
[in]	obj_idx	Index of the token to analyse.
[in]	num_tok	Number of tokens in json_tok.

Returns

true if token is a key token. false otherwise.

json_key_next()

int json_key_next	(	const jsmntok_t *	json_tok,
		int	obj_idx,
		int	parent_idx,
		int	num_tok
	)

Return the index of the next key in the current JSON level.

Parameters

[in]	json_tok	JSON token array.
[in]	obj_idx	Index of the token to analyse.
[in]	parent_idx	Index of the parent object or array token.
[in]	num_tok	Number of tokens in obj_tok.

Returns

The index of the next key item on success, of JSMN_ERROR_PART if there are no more key items available in the parent object.

json_key_search()

int json_key_search	(	const char *	key,
		const char *	json_str,
		const jsmntok_t *	json_tok,
		int	obj_idx,
		int	parent_idx,
		int	num_tok
	)

Search for a given key in the current JSON level.

Parameters

[in]	key	key string to search.
[in]	json_str	JSON string.
[in]	json_tok	JSON token array.
[in]	obj_idx	Index of the token to analyse.
[in]	parent_idx	Index of the parent object or array token.
[in]	num_tok	Number of tokens in obj_tok.

Returns

The index of the value token on success, or JSMN_ERROR_PART if the specified key was not found in parent object.

Note

The returned value on success is the index of the value token, it is NOT the index of the found key token.

json_null_terminate()

int json_null_terminate	(	char *	json_str,
		const jsmntok_t *	obj_tok,
		int	num_tok
	)

Add null-terminators to the input JSON string. Useful to further extract token values as null-terminated strings.

Parameters

[in,out]	json_str	The JSON string to add null terminators to.
[in]	obj_tok	Tokens extracted from json_str.
[in]	num_tok	Number of tokens in obj_tok.

Returns

0 on success, JSMN_ERROR_INVAL if string ends prematurely.

Warning

Resulting string can no longer be used as a valid json.

json_object_next()

int json_object_next	(	const jsmntok_t *	obj_tok,
		int	obj_idx,
		int	parent_idx,
		int	num_tok
	)

Return the index of the next item. This function only works properly when specified token is of JSMN_OBJECT type.

Parameters

[in]	obj_tok	JSON token array.
[in]	obj_idx	Index of the token to analyse.
[in]	parent_idx	Index of the parent object or array token.
[in]	num_tok	Number of tokens in obj_tok.

Returns

The index of the next item on success, of JSMN_ERROR_PART if there are no more items available in the parent object.