Commit 6c37aa9e authored by Sanjay Vallimanalan's avatar Sanjay Vallimanalan Committed by Chris Friedt
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include: zephyr: data: add mixed array type support for json 



Introduced a mixed array type for JSON using the struct
json_mixed_arr_descr. Added helper macros to define elements of the
descriptor array.

Signed-off-by: default avatarSanjay Vallimanalan <sanjay@linumiz.com>
parent ff9e29b3

include/zephyr/data/json.h

+227 −0
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ enum json_tokens { 
	JSON_TOK_UINT = 'u',

	JSON_TOK_TRUE = 't',

	JSON_TOK_FALSE = 'f',

	JSON_TOK_MIXED_ARRAY = 'm',

	JSON_TOK_NULL = 'n',

	JSON_TOK_ERROR = '!',

	JSON_TOK_EOF = '\0',
@@ -811,6 +812,232 @@ int json_obj_encode(const struct json_obj_descr *descr, size_t descr_len, 
int json_arr_encode(const struct json_obj_descr *descr, const void *val,

		    json_append_bytes_t append_bytes, void *data);



/**

 * @brief Descriptor for a mixed-type JSON array.

 *

 * This structure describes a top-level JSON array whose elements may be

 * of different types (primitives, objects, arrays, or nested mixed arrays).

 * Each element in the array is described by an entry in a descriptor array.

 *

 * Mixed arrays are useful for parsing and encoding JSON arrays that do not

 * have a homogeneous element type, such as:

 *

 *   [ "string", 42, { "foo": 1 }, [1,2,3], true ]

 *

 * @note This structure and its associated macros are intended for use with

 *       the mixed array parsing and encoding APIs (see json_mixed_arr_parse()).

 */

struct json_mixed_arr_descr {

	uint32_t type : 7;

	size_t count_offset;



	union {

		struct {

			size_t offset;

			size_t size;

		} primitive;



		struct {

			const struct json_obj_descr *sub_descr;

			size_t sub_descr_len;

			size_t offset;

		} object;



		struct {

			const struct json_obj_descr *element_descr;

			size_t n_elements;

			size_t offset;

		} array;



		struct {

			const struct json_mixed_arr_descr *sub_descr;

			size_t sub_descr_len;

			size_t offset;

		} mixed_array;

	};

};



/**

 * @brief Helper macro to declare a mixed array primitive element descriptor.

 *

 * @param struct_		Struct containing the value.

 * @param field_name_	Field name in the struct.

 * @param type_		Token type for the JSON value (see enum json_tokens).

 * @param count_field_	Field name in the struct for the number of elements.

 *

 * Example:

 *	struct foo { int x; size_t x_count; };

 *	const struct json_mixed_arr_descr foo_descr[] = {

 *		JSON_MIXED_ARR_DESCR_PRIM(struct foo, x, JSON_TOK_NUMBER, x_count),

 *	};

 */

#define JSON_MIXED_ARR_DESCR_PRIM(struct_, field_name_, type_, count_field_) \

{ \

	.type = type_, \

	.count_offset = offsetof(struct_, count_field_), \

	.primitive = { \

	    .offset = offsetof(struct_, field_name_), \

	    .size = SIZEOF_FIELD(struct_, field_name_) \

	} \

}



/**

 * @brief Helper macro to declare a mixed array object element descriptor.

 *

 * @param struct_		Struct containing the object.

 * @param field_name_	Field name in the struct.

 * @param sub_descr_	Array of json_obj_descr describing the object fields.

 * @param count_field_	Field name in the struct for the number of elements.

 *

 * Example:

 *	struct bar { int y; };

 *	struct foo { struct bar b; size_t b_count; };

 *	const struct json_obj_descr bar_descr[] = { ... };

 *	const struct json_mixed_arr_descr foo_descr[] = {

 *		JSON_MIXED_ARR_DESCR_OBJECT(struct foo, b, bar_descr, b_count),

 *	};

 */

#define JSON_MIXED_ARR_DESCR_OBJECT(struct_, field_name_, sub_descr_, count_field_) \

{ \

	.type = JSON_TOK_OBJECT_START, \

	.count_offset = offsetof(struct_, count_field_), \

	.object = { \

		.sub_descr = sub_descr_, \

		.sub_descr_len = ARRAY_SIZE(sub_descr_), \

		.offset = offsetof(struct_, field_name_) \

	} \

}



/**

 * @brief Helper macro to declare a mixed array homogeneous array element descriptor.

 *

 * @param struct_		Struct containing the array.

 * @param field_name_	Field name in the struct.

 * @param max_len_		Maximum number of elements in the array.

 * @param elem_descr_	Element descriptor (pointer to json_obj_descr array).

 * @param count_field_	Field name in the struct for the number of elements.

 *

 * Example:

 *	struct foo {

 *		int arr[4];

 *		size_t arr_count;

 *	};

 *	const struct json_obj_descr arr_elem_descr[] = {

 *		JSON_OBJ_DESCR_ARRAY(struct foo, arr, 4, arr_count, JSON_TOK_NUMBER),

 *	};

 *	const struct json_mixed_arr_descr foo_descr[] = {

 *		JSON_MIXED_ARR_DESCR_ARRAY(struct foo, arr, 4, arr_elem_descr, arr_count),

 *	};

 */

#define JSON_MIXED_ARR_DESCR_ARRAY(struct_, field_name_, max_len_, elem_descr_, count_field_) \

{ \

	.type = JSON_TOK_ARRAY_START, \

	.count_offset = offsetof(struct_, count_field_), \

	.array = { \

		.element_descr = elem_descr_, \

		.n_elements = (max_len_), \

		.offset = offsetof(struct_, field_name_) \

	} \

}



/**

 * @brief Helper macro to declare a nested mixed array element descriptor.

 *

 * @param struct_		Struct containing the nested mixed array.

 * @param field_name_	Field name in the struct.

 * @param sub_descr_	Mixed array descriptor for the nested array.

 * @param count_field_	Field name in the struct for the number of elements.

 *

 * Example:

 *	struct foo { ...; size_t nested_count; };

 *	const struct json_mixed_arr_descr nested_descr[] = { ... };

 *	const struct json_mixed_arr_descr foo_descr[] = {

 *		JSON_MIXED_ARR_DESCR_MIXED_ARRAY(struct foo, nested, nested_descr, nested_count),

 *	};

 */

#define JSON_MIXED_ARR_DESCR_MIXED_ARRAY(struct_, field_name_, sub_descr_, count_field_) \

{ \

	.type = JSON_TOK_MIXED_ARRAY, \

	.count_offset = offsetof(struct_, count_field_), \

	.mixed_array = { \

		.sub_descr = sub_descr_, \

		.sub_descr_len = ARRAY_SIZE(sub_descr_), \

		.offset = offsetof(struct_, field_name_) \

	} \

}



/**

 * @brief Parse a JSON mixed array into a C structure.

 *

 * This function parses a JSON array (which may contain elements of varying types)

 * according to the provided mixed array descriptor and stores the result in the

 * user-supplied structure.

 *

 * @param json		Pointer to the input JSON string.

 * @param len		Length of the input JSON string.

 * @param descr		Descriptor array describing the structure of the mixed array.

 * @param descr_len	Number of elements in the descriptor array.

 * @param val		Pointer to the structure to populate with parsed data.

 *

 * @return < 0 if error, number of elements parsed on success.

 */

int json_mixed_arr_parse(char *json, size_t len,

			 const struct json_mixed_arr_descr *descr,

			 size_t descr_len, void *val);



/**

 * @brief Encode a C structure as a JSON mixed array.

 *

 * This function encodes a C structure, described by the mixed array descriptor,

 * as a JSON array.

 *

 * @param descr		Descriptor array describing the structure of the mixed array.

 * @param descr_len	Number of elements in the descriptor array.

 * @param val		Pointer to the structure to encode.

 * @param append_bytes Function to append bytes to the output

 * @param data Data pointer to be passed to the append_bytes callback

 * function.

 *

 * @return 0 if mixed array has been successfully encoded. Negative error code on failure.

 */

int json_mixed_arr_encode(const struct json_mixed_arr_descr *descr,

			  size_t descr_len, void *val,

			  json_append_bytes_t append_bytes,

			  void *data);



/**

 * @brief Encode a C structure as a JSON mixed array into a buffer.

 *

 * This function encodes a C structure, described by the mixed array descriptor,

 * as a JSON array and writes the result into the provided buffer.

 *

 * @param descr		Descriptor array describing the structure of the mixed array.

 * @param descr_len	Number of elements in the descriptor array.

 * @param val		Pointer to the structure to encode.

 * @param buffer	Output buffer to write the JSON string.

 * @param buf_size	Size of the output buffer.

 *

 * @return 0 if mixed array has been successfully encoded. Negative error code on failure.

 */

int json_mixed_arr_encode_buf(const struct json_mixed_arr_descr *descr,

			      size_t descr_len, void *val,

			      char *buffer, size_t buf_size);



/**

 * @brief Calculate the length of the encoded JSON mixed array.

 *

 * This function calculates the number of bytes required to encode the given

 * structure as a JSON mixed array, according to the provided descriptor.

 *

 * @param descr		Descriptor array describing the structure of the mixed array.

 * @param descr_len	Number of elements in the descriptor array.

 * @param val		Pointer to the structure to encode.

 *

 * @return		Number of bytes required for encoding, or negative error code.

 */

ssize_t json_calc_mixed_arr_len(const struct json_mixed_arr_descr *descr,

				size_t descr_len, void *val);



#ifdef __cplusplus

}

#endif

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