zephyr/lib/utils/json.c

/*
 * Copyright (c) 2017 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/sys/__assert.h>
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <math.h>
#include <zephyr/sys/printk.h>
#include <zephyr/sys/util.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <zephyr/types.h>

#include <zephyr/data/json.h>

struct json_obj_key_value {
	const char *key;
	size_t key_len;
	struct json_token value;
};

static bool lexer_consume(struct json_lexer *lex, struct json_token *tok,
			  enum json_tokens empty_token)
{
	if (lex->tok.type == empty_token) {
		return false;
	}

	*tok = lex->tok;
	lex->tok.type = empty_token;

	return true;
}

static bool lexer_next(struct json_lexer *lex, struct json_token *tok)
{
	while (lex->state) {
		if (lexer_consume(lex, tok, JSON_TOK_NONE)) {
			return true;
		}

		lex->state = lex->state(lex);
	}

	return lexer_consume(lex, tok, JSON_TOK_EOF);
}

static void *lexer_json(struct json_lexer *lex);

static void emit(struct json_lexer *lex, enum json_tokens token)
{
	lex->tok.type = token;
	lex->tok.start = lex->start;
	lex->tok.end = lex->pos;
	lex->start = lex->pos;
}

static int next(struct json_lexer *lex)
{
	if (lex->pos >= lex->end) {
		lex->pos = lex->end + 1;

		return '\0';
	}

	return *lex->pos++;
}

static void ignore(struct json_lexer *lex)
{
	lex->start = lex->pos;
}

static void backup(struct json_lexer *lex)
{
	lex->pos--;
}

static int peek(struct json_lexer *lex)
{
	int chr = next(lex);

	backup(lex);

	return chr;
}

static void *lexer_string(struct json_lexer *lex)
{
	ignore(lex);

	while (true) {
		int chr = next(lex);

		if (chr == '\0') {
			emit(lex, JSON_TOK_ERROR);
			return NULL;
		}

		if (chr == '\\') {
			switch (next(lex)) {
			case '"':
			case '\\':
			case '/':
			case 'b':
			case 'f':
			case 'n':
			case 'r':
			case 't':
				continue;
			case 'u':
				if (isxdigit(next(lex)) == 0) {
					goto error;
				}

				if (isxdigit(next(lex)) == 0) {
					goto error;
				}

				if (isxdigit(next(lex)) == 0) {
					goto error;
				}

				if (isxdigit(next(lex)) == 0) {
					goto error;
				}

				break;
			default:
				goto error;
			}
		}

		if (chr == '"') {
			backup(lex);
			emit(lex, JSON_TOK_STRING);

			next(lex);
			ignore(lex);

			return lexer_json;
		}
	}

error:
	emit(lex, JSON_TOK_ERROR);
	return NULL;
}

static int accept_run(struct json_lexer *lex, const char *run)
{
	for (; *run; run++) {
		if (next(lex) != *run) {
			return -EINVAL;
		}
	}

	return 0;
}

static void *lexer_boolean(struct json_lexer *lex)
{
	backup(lex);

	switch (next(lex)) {
	case 't':
		if (!accept_run(lex, "rue")) {
			emit(lex, JSON_TOK_TRUE);
			return lexer_json;
		}
		break;
	case 'f':
		if (!accept_run(lex, "alse")) {
			emit(lex, JSON_TOK_FALSE);
			return lexer_json;
		}
		break;
	}

	emit(lex, JSON_TOK_ERROR);
	return NULL;
}

static void *lexer_null(struct json_lexer *lex)
{
	if (accept_run(lex, "ull") < 0) {
		emit(lex, JSON_TOK_ERROR);
		return NULL;
	}

	emit(lex, JSON_TOK_NULL);
	return lexer_json;
}

static void *lexer_number(struct json_lexer *lex)
{
	while (true) {
		int chr = next(lex);

		if (isdigit(chr) != 0 || chr == '.' || chr == 'e' || chr == '+' || chr == '-') {
			continue;
		}

		backup(lex);
		emit(lex, JSON_TOK_NUMBER);

		return lexer_json;
	}
}

static void *lexer_number_nan(struct json_lexer *lex)
{
#ifdef CONFIG_JSON_LIBRARY_FP_SUPPORT
	backup(lex);

	switch (peek(lex)) {
	case 'N':
		if (!accept_run(lex, "NaN")) {
			emit(lex, JSON_TOK_NUMBER);
			return lexer_json;
		}
		break;
	case 'I':
		if (!accept_run(lex, "Infinity")) {
			emit(lex, JSON_TOK_NUMBER);
			return lexer_json;
		}
		break;
	case '-':
		if (!accept_run(lex, "-Infinity")) {
			emit(lex, JSON_TOK_NUMBER);
			return lexer_json;
		}
		break;
	}

#endif
	emit(lex, JSON_TOK_ERROR);
	return NULL;
}

static void *lexer_json(struct json_lexer *lex)
{
	while (true) {
		int chr = next(lex);

		switch (chr) {
		case '\0':
			emit(lex, JSON_TOK_EOF);
			return NULL;
		case '}':
		case '{':
		case '[':
		case ']':
		case ',':
		case ':':
			emit(lex, (enum json_tokens)chr);
			return lexer_json;
		case '"':
			return lexer_string;
		case 'n':
			return lexer_null;
		case 't':
		case 'f':
			return lexer_boolean;
		case 'N':
		case 'I':
			return lexer_number_nan;
		case '-':
			if (isdigit(peek(lex)) != 0) {
				return lexer_number;
			}
			if (peek(lex) == 'I') {
				return lexer_number_nan;
			}

			__fallthrough;
		default:
			if (isspace(chr) != 0) {
				ignore(lex);
				continue;
			}

			if (isdigit(chr) != 0) {
				return lexer_number;
			}

			emit(lex, JSON_TOK_ERROR);
			return NULL;
		}
	}
}

static void lexer_init(struct json_lexer *lex, char *data, size_t len)
{
	lex->state = lexer_json;
	lex->start = data;
	lex->pos = data;
	lex->end = data + len;
	lex->tok.type = JSON_TOK_NONE;
}

static int obj_init(struct json_obj *json, char *data, size_t len)
{
	struct json_token tok;

	lexer_init(&json->lex, data, len);

	if (!lexer_next(&json->lex, &tok)) {
		return -EINVAL;
	}

	if (tok.type != JSON_TOK_OBJECT_START) {
		return -EINVAL;
	}

	return 0;
}

static int arr_init(struct json_obj *json, char *data, size_t len)
{
	struct json_token tok;

	lexer_init(&json->lex, data, len);

	if (!lexer_next(&json->lex, &tok)) {
		return -EINVAL;
	}

	if (tok.type != JSON_TOK_ARRAY_START) {
		return -EINVAL;
	}

	return 0;
}

static int element_token(enum json_tokens token)
{
	switch (token) {
	case JSON_TOK_OBJECT_START:
	case JSON_TOK_ARRAY_START:
	case JSON_TOK_STRING:
	case JSON_TOK_STRING_BUF:
	case JSON_TOK_NUMBER:
	case JSON_TOK_INT:
	case JSON_TOK_UINT:
	case JSON_TOK_INT64:
	case JSON_TOK_UINT64:
	case JSON_TOK_FLOAT:
	case JSON_TOK_FLOAT_FP:
	case JSON_TOK_DOUBLE_FP:
	case JSON_TOK_OPAQUE:
	case JSON_TOK_OBJ_ARRAY:
	case JSON_TOK_TRUE:
	case JSON_TOK_FALSE:
		return 0;
	default:
		return -EINVAL;
	}
}

static int obj_next(struct json_obj *json,
		    struct json_obj_key_value *kv)
{
	struct json_token tok;

	if (!lexer_next(&json->lex, &tok)) {
		return -EINVAL;
	}

	/* Match end of object or next key */
	switch (tok.type) {
	case JSON_TOK_OBJECT_END:
		kv->key = NULL;
		kv->key_len = 0;
		kv->value = tok;

		return 0;
	case JSON_TOK_COMMA:
		if (!lexer_next(&json->lex, &tok)) {
			return -EINVAL;
		}

		if (tok.type != JSON_TOK_STRING) {
			return -EINVAL;
		}

		__fallthrough;
	case JSON_TOK_STRING:
		kv->key = tok.start;
		kv->key_len = (size_t)(tok.end - tok.start);
		break;
	default:
		return -EINVAL;
	}

	/* Match : after key */
	if (!lexer_next(&json->lex, &tok)) {
		return -EINVAL;
	}

	if (tok.type != JSON_TOK_COLON) {
		return -EINVAL;
	}

	/* Match value */
	if (!lexer_next(&json->lex, &kv->value)) {
		return -EINVAL;
	}

	return element_token(kv->value.type);
}

static int arr_next(struct json_obj *json, struct json_token *value)
{
	if (!lexer_next(&json->lex, value)) {
		return -EINVAL;
	}

	if (value->type == JSON_TOK_ARRAY_END) {
		return 0;
	}

	if (value->type == JSON_TOK_COMMA) {
		if (!lexer_next(&json->lex, value)) {
			return -EINVAL;
		}
	}

	return element_token(value->type);
}

static int skip_field(struct json_obj *obj, struct json_obj_key_value *kv)
{
	int field_count = 1;

	if (kv->value.type == JSON_TOK_OBJECT_START ||
	    kv->value.type == JSON_TOK_ARRAY_START) {
		while (field_count > 0 && lexer_next(&obj->lex, &kv->value)) {
			switch (kv->value.type) {
			case JSON_TOK_OBJECT_START:
			case JSON_TOK_ARRAY_START:
				field_count++;
				break;
			case JSON_TOK_OBJECT_END:
			case JSON_TOK_ARRAY_END:
				field_count--;
				break;
			case JSON_TOK_ERROR:
				return -EINVAL;
			default:
				break;
			}
		}
	}

	return 0;
}

/**
 * @brief Unescape a JSON string, can work in-place if src == dst
 * @param src Source string with escape sequences
 * @param dst Destination buffer for unescaped string (can be same as src)
 * @param src_len Length of source string
 * @param dst_size Size of destination buffer
 * @return int Number of bytes written to destination, or -EINVAL on error
 */
static int json_unescape_string(const char *src, char *dst, size_t src_len, size_t dst_size)
{
	const char *src_end = src + src_len;
	char *dst_start = dst;
	char *dst_end = dst_start + dst_size - 1; /* Point to last available byte (for null) */

	while (src < src_end && dst < dst_end) {
		if (*src == '\\') {
			src++;
			if (src >= src_end) {
				return -EINVAL;
			}

			switch (*src) {
			case '"':
				*dst++ = '"';
				break;
			case '\\':
				*dst++ = '\\';
				break;
			case '/':
				*dst++ = '/';
				break;
			case 'b':
				*dst++ = '\b';
				break;
			case 'f':
				*dst++ = '\f';
				break;
			case 'n':
				*dst++ = '\n';
				break;
			case 'r':
				*dst++ = '\r';
				break;
			case 't':
				*dst++ = '\t';
				break;
			default:
				/* Unknown escape sequence, copy as-is */
				*dst++ = '\\';
				*dst++ = *src;
				break;
			}
			src++;
		} else {
			*dst++ = *src++;
		}
	}

	*dst = '\0';
	return dst - dst_start;
}

static int decode_string_buf(const struct json_token *token, char *str, size_t size)
{
	size_t escaped_len = token->end - token->start;
	int ret;

	/* Safe approach: never copy more than (size - 1) bytes to leave room for null */
	size_t safe_len = (escaped_len < size) ? escaped_len : (size - 1);

	ret = json_unescape_string(token->start, str, safe_len, size);
	if (ret < 0) {
		return -EINVAL;
	}

	/* Check if we had to truncate due to the original escaped string being too long */
	if (escaped_len >= size) {
		return -EINVAL;
	}

	return 0;
}

static int decode_int32(const struct json_token *token, int32_t *num)
{
	/* FIXME: strtod() is not available in newlib/minimal libc,
	 * so using strtol() here.
	 */
	char *endptr;
	char prev_end;

	prev_end = *token->end;
	*token->end = '\0';

	errno = 0;
	*num = strtol(token->start, &endptr, 10);

	*token->end = prev_end;

	if (errno != 0) {
		return -errno;
	}

	if (endptr != token->end) {
		return -EINVAL;
	}

	return 0;
}

static int decode_uint32(const struct json_token *token, uint32_t *num)
{
	char *endptr;
	char prev_end;

	prev_end = *token->end;
	*token->end = '\0';

	errno = 0;
	*num = strtoul(token->start, &endptr, 10);

	*token->end = prev_end;

	if (errno != 0) {
		return -errno;
	}

	if (endptr != token->end) {
		return -EINVAL;
	}

	return 0;
}

static int decode_int64(const struct json_token *token, int64_t *num)
{
	char *endptr;
	char prev_end;

	prev_end = *token->end;
	*token->end = '\0';

	errno = 0;
	*num = strtoll(token->start, &endptr, 10);

	*token->end = prev_end;

	if (errno != 0) {
		return -errno;
	}

	if (endptr != token->end) {
		return -EINVAL;
	}

	return 0;
}

static int decode_uint64(const struct json_token *token, uint64_t *num)
{
	char *endptr;
	char prev_end;

	prev_end = *token->end;
	*token->end = '\0';

	errno = 0;
	*num = strtoull(token->start, &endptr, 10);

	*token->end = prev_end;

	if (errno != 0) {
		return -errno;
	}

	if (endptr != token->end) {
		return -EINVAL;
	}

	return 0;
}

static int decode_float(const struct json_token *token, float *num)
{
#ifdef CONFIG_JSON_LIBRARY_FP_SUPPORT
	char *endptr;
	char prev_end;

	prev_end = *token->end;
	*token->end = '\0';

	errno = 0;
	*num = strtof(token->start, &endptr);

	*token->end = prev_end;

	if (errno != 0) {
		return -errno;
	}

	if (endptr != token->end) {
		return -EINVAL;
	}

	return 0;

#else
	ARG_UNUSED(token);
	ARG_UNUSED(num);
	return -EINVAL;
#endif
}

static int decode_double(const struct json_token *token, double *num)
{
#ifdef CONFIG_JSON_LIBRARY_FP_SUPPORT
	char *endptr;
	char prev_end;

	prev_end = *token->end;
	*token->end = '\0';

	errno = 0;
	*num = strtod(token->start, &endptr);

	*token->end = prev_end;

	if (errno != 0) {
		return -errno;
	}

	if (endptr != token->end) {
		return -EINVAL;
	}

	return 0;

#else
	ARG_UNUSED(token);
	ARG_UNUSED(num);
	return -EINVAL;
#endif
}

static int decode_int8(const struct json_token *token, int8_t *num)
{
	int32_t num_i32;
	int res;

	res = decode_int32(token, &num_i32);

	if (res != 0) {
		return res;
	}

	if (num_i32 < INT8_MIN || num_i32 > INT8_MAX) {
		return -EINVAL;
	}

	*num = num_i32;

	return 0;
}

static int decode_uint8(const struct json_token *token, uint8_t *num)
{
	uint32_t num_u32;
	int res;

	res = decode_uint32(token, &num_u32);

	if (res != 0) {
		return res;
	}

	if (num_u32 > UINT8_MAX) {
		return -EINVAL;
	}

	*num = num_u32;

	return 0;
}

static int decode_int16(const struct json_token *token, int16_t *num)
{
	int32_t num_i32;
	int res;

	res = decode_int32(token, &num_i32);

	if (res != 0) {
		return res;
	}

	if (num_i32 < INT16_MIN || num_i32 > INT16_MAX) {
		return -EINVAL;
	}

	*num = num_i32;

	return 0;
}

static int decode_uint16(const struct json_token *token, uint16_t *num)
{
	uint32_t num_u32;
	int res;

	res = decode_uint32(token, &num_u32);

	if (res != 0) {
		return res;
	}

	if (num_u32 > UINT16_MAX) {
		return -EINVAL;
	}

	*num = num_u32;

	return 0;
}

static int decode_int(const struct json_token *token, void *field, size_t size)
{
	switch (size) {
	case 1: {
		int8_t *num = field;

		return decode_int8(token, num);
	}
	case 2: {
		int16_t *num = field;

		return decode_int16(token, num);
	}
	case 4: {
		int32_t *num = field;

		return decode_int32(token, num);
	}
	case 8: {
		int64_t *num = field;

		return decode_int64(token, num);
	}
	default:
		return -EINVAL;
	}
}

static int decode_uint(const struct json_token *token, void *field, size_t size)
{
	switch (size) {
	case 1: {
		uint8_t *num = field;

		return decode_uint8(token, num);
	}
	case 2: {
		uint16_t *num = field;

		return decode_uint16(token, num);
	}
	case 4: {
		uint32_t *num = field;

		return decode_uint32(token, num);
	}
	case 8: {
		uint64_t *num = field;

		return decode_uint64(token, num);
	}
	default:
		return -EINVAL;
	}
}

static bool equivalent_types(enum json_tokens type1, enum json_tokens type2)
{
	if (type1 == JSON_TOK_TRUE || type1 == JSON_TOK_FALSE) {
		return type2 == JSON_TOK_TRUE || type2 == JSON_TOK_FALSE;
	}

	if (type1 == JSON_TOK_ARRAY_START && type2 == JSON_TOK_MIXED_ARRAY) {
		return true;
	}

	if (type1 == JSON_TOK_NUMBER && type2 == JSON_TOK_FLOAT) {
		return true;
	}

	if (type1 == JSON_TOK_NUMBER && type2 == JSON_TOK_FLOAT_FP) {
		return true;
	}

	if (type1 == JSON_TOK_NUMBER && type2 == JSON_TOK_DOUBLE_FP) {
		return true;
	}

	if (type1 == JSON_TOK_NUMBER && type2 == JSON_TOK_INT) {
		return true;
	}

	if (type1 == JSON_TOK_NUMBER && type2 == JSON_TOK_UINT) {
		return true;
	}

	if (type1 == JSON_TOK_NUMBER && type2 == JSON_TOK_INT64) {
		return true;
	}

	if (type1 == JSON_TOK_NUMBER && type2 == JSON_TOK_UINT64) {
		return true;
	}

	if (type1 == JSON_TOK_STRING && type2 == JSON_TOK_OPAQUE) {
		return true;
	}

	if (type1 == JSON_TOK_STRING && type2 == JSON_TOK_STRING_BUF) {
		return true;
	}

	if (type2 == JSON_TOK_ENCODED_OBJ) {
		return (type1 == JSON_TOK_OBJECT_START ||
			type1 == JSON_TOK_ARRAY_START ||
			type1 == JSON_TOK_STRING);
	}

	if (type1 == JSON_TOK_ARRAY_START && type2 == JSON_TOK_OBJ_ARRAY) {
		return true;
	}

	return type1 == type2;
}

static int64_t obj_parse(struct json_obj *obj,
			 const struct json_obj_descr *descr, size_t descr_len,
			 void *val);
static int arr_parse(struct json_obj *obj,
		     const struct json_obj_descr *elem_descr,
		     size_t max_elements, void *field, void *val);

static int arr_data_parse(struct json_obj *obj, struct json_obj_token *val);

static int64_t decode_value(struct json_obj *obj,
			    const struct json_obj_descr *descr,
			    struct json_token *value, void *field, void *val)
{

	if (!equivalent_types(value->type, descr->type)) {
		return -EINVAL;
	}

	switch (descr->type) {
	case JSON_TOK_OBJECT_START:
		return obj_parse(obj, descr->object.sub_descr,
				 descr->object.sub_descr_len,
				 field);
	case JSON_TOK_ARRAY_START:
		return arr_parse(obj, descr->array.element_descr,
				 descr->array.n_elements, field, val);
	case JSON_TOK_OBJ_ARRAY: {
		struct json_obj_token *obj_token = field;

		obj_token->start = value->start;
		return arr_data_parse(obj, obj_token);
	}

	case JSON_TOK_FALSE:
	case JSON_TOK_TRUE: {
		bool *v = field;

		*v = value->type == JSON_TOK_TRUE;

		return 0;
	}
	case JSON_TOK_NUMBER: {
		int32_t *num = field;

		return decode_int32(value, num);
	}
	case JSON_TOK_INT: {
		return decode_int(value, field, descr->field.size);
	}
	case JSON_TOK_UINT: {
		return decode_uint(value, field, descr->field.size);
	}
	case JSON_TOK_INT64: {
		int64_t *num = field;

		return decode_int64(value, num);
	}
	case JSON_TOK_UINT64: {
		uint64_t *num = field;

		return decode_uint64(value, num);
	}
	case JSON_TOK_FLOAT_FP: {
		float *num = field;

		return decode_float(value, num);
	}
	case JSON_TOK_DOUBLE_FP: {
		double *num = field;

		return decode_double(value, num);
	}
	case JSON_TOK_OPAQUE:
	case JSON_TOK_FLOAT: {
		struct json_obj_token *obj_token = field;

		obj_token->start = value->start;
		obj_token->length = value->end - value->start;
		return 0;
	}
	case JSON_TOK_STRING: {
		char **str = field;

		*value->end = '\0';
		*str = value->start;

		return 0;
	}
	case JSON_TOK_STRING_BUF: {
		char *str = field;

		return decode_string_buf(value, str, descr->field.size);
	}
	default:
		return -EINVAL;
	}
}

static ptrdiff_t get_elem_size(const struct json_obj_descr *descr)
{
	switch (descr->type) {
	case JSON_TOK_NUMBER:
		return sizeof(int32_t);
	case JSON_TOK_INT64:
		return sizeof(int64_t);
	case JSON_TOK_UINT64:
		return sizeof(uint64_t);
	case JSON_TOK_FLOAT_FP:
		return sizeof(float);
	case JSON_TOK_DOUBLE_FP:
		return sizeof(double);
	case JSON_TOK_OPAQUE:
	case JSON_TOK_FLOAT:
	case JSON_TOK_OBJ_ARRAY:
		return sizeof(struct json_obj_token);
	case JSON_TOK_STRING:
	case JSON_TOK_ENCODED_OBJ:
		return sizeof(char *);
	case JSON_TOK_INT:
	case JSON_TOK_UINT:
	case JSON_TOK_STRING_BUF:
		return descr->field.size;
	case JSON_TOK_TRUE:
	case JSON_TOK_FALSE:
		return sizeof(bool);
	case JSON_TOK_ARRAY_START: {
		ptrdiff_t size;

		size = descr->array.n_elements * get_elem_size(descr->array.element_descr);
		/* Consider additional item count field for array objects */
		if (descr->field_name_len > 0) {
			size = size + sizeof(size_t);
		}

		return size;
	}
	case JSON_TOK_OBJECT_START: {
		ptrdiff_t total = 0;
		uint32_t align_shift = 0;
		size_t i;

		for (i = 0; i < descr->object.sub_descr_len; i++) {
			if (descr->object.sub_descr[i].align_shift > align_shift) {
				align_shift = descr->object.sub_descr[i].align_shift;
			}
		}

		i = descr->object.sub_descr_len;
		if (i > 0) {
			total = descr->object.sub_descr[i - 1].offset +
				get_elem_size(&descr->object.sub_descr[i - 1]);
		}

		return ROUND_UP(total, 1 << align_shift);
	}
	default:
		return -EINVAL;
	}
}

static int arr_parse(struct json_obj *obj,
		     const struct json_obj_descr *elem_descr,
		     size_t max_elements, void *field, void *val)
{
	void *value = val;
	size_t *elements = (size_t *)((char *)value + elem_descr->offset);
	ptrdiff_t elem_size;
	void *last_elem;
	struct json_token tok;

	/* For nested arrays, skip parent descriptor to get elements */
	if (elem_descr->type == JSON_TOK_ARRAY_START) {
		elem_descr = elem_descr->array.element_descr;
	}

	*elements = 0;
	elem_size = get_elem_size(elem_descr);
	last_elem = (char *)field + elem_size * max_elements;

	__ASSERT_NO_MSG(elem_size > 0);

	while (!arr_next(obj, &tok)) {
		if (tok.type == JSON_TOK_ARRAY_END) {
			return 0;
		}

		if (field == last_elem) {
			return -ENOSPC;
		}

		/* For nested arrays, update value to current field,
		 * so it matches descriptor's offset to length field
		 */
		if (elem_descr->type == JSON_TOK_ARRAY_START) {
			value = field;
		}

		if (decode_value(obj, elem_descr, &tok, field, value) < 0) {
			return -EINVAL;
		}

		(*elements)++;
		field = (char *)field + elem_size;
	}

	return -EINVAL;
}

static int arr_data_parse(struct json_obj *obj, struct json_obj_token *val)
{
	bool string_state = false;
	int array_in_array = 1;

	/* Init length to zero */
	val->length = 0;

	while (obj->lex.pos != obj->lex.end) {
		if (string_state) {
			if (*obj->lex.pos == JSON_TOK_STRING) {
				string_state = false;
			}
		} else {
			if (*obj->lex.pos == JSON_TOK_ARRAY_END) {
				array_in_array--;
				if (array_in_array == 0) {
					/* Set array data length + 1 object end */
					val->length = obj->lex.pos - val->start + 1;
					/* Init Lexer that Object Parse can be finished properly */
					obj->lex.state = lexer_json;
					/* Move position to before array end */
					obj->lex.pos--;
					obj->lex.tok.end = obj->lex.pos;
					obj->lex.tok.start = val->start;
					obj->lex.tok.type = JSON_TOK_NONE;
					return 0;
				}
			} else if (*obj->lex.pos == JSON_TOK_STRING) {
				string_state = true;
			} else if (*obj->lex.pos == JSON_TOK_ARRAY_START) {
				/* array in array update structure count */
				array_in_array++;
			}
		}
		obj->lex.pos++;
	}

	return -EINVAL;
}

static int64_t obj_parse(struct json_obj *obj, const struct json_obj_descr *descr,
			 size_t descr_len, void *val)
{
	struct json_obj_key_value kv;
	int64_t decoded_fields = 0;
	size_t i;
	int ret;

	while (!obj_next(obj, &kv)) {
		if (kv.value.type == JSON_TOK_OBJECT_END) {
			return decoded_fields;
		}

		for (i = 0; i < descr_len; i++) {
			void *decode_field = (char *)val + descr[i].offset;

			/* Field has been decoded already, skip */
			if (decoded_fields & ((int64_t)1 << i)) {
				continue;
			}

			/* Check if it's the i-th field */
			if (kv.key_len != descr[i].field_name_len) {
				continue;
			}

			if (memcmp(kv.key, descr[i].field_name,
				   descr[i].field_name_len)) {
				continue;
			}

			/* Store the decoded value */
			ret = decode_value(obj, &descr[i], &kv.value,
					   decode_field, val);
			if (ret < 0) {
				return ret;
			}

			decoded_fields |= (int64_t)1<<i;
			break;
		}

		/* Skip field, if no descriptor was found */
		if (i >= descr_len) {
			ret = skip_field(obj, &kv);
			if (ret < 0) {
				return ret;
			}
		}
	}

	return -EINVAL;
}

int64_t json_obj_parse(char *payload, size_t len,
		       const struct json_obj_descr *descr, size_t descr_len,
		       void *val)
{
	struct json_obj obj;
	int64_t ret;

	__ASSERT_NO_MSG(descr_len < (sizeof(ret) * CHAR_BIT - 1));

	ret = obj_init(&obj, payload, len);
	if (ret < 0) {
		return ret;
	}

	return obj_parse(&obj, descr, descr_len, val);
}

int json_arr_parse(char *payload, size_t len,
		   const struct json_obj_descr *descr, void *val)
{
	struct json_obj arr;
	int ret;

	ret = arr_init(&arr, payload, len);
	if (ret < 0) {
		return ret;
	}

	void *ptr = (char *)val + descr->offset;

	return arr_parse(&arr, descr->array.element_descr,
			 descr->array.n_elements, ptr, val);
}


int json_arr_separate_object_parse_init(struct json_obj *json, char *payload, size_t len)
{
	return arr_init(json, payload, len);
}

int json_arr_separate_parse_object(struct json_obj *json, const struct json_obj_descr *descr,
			  size_t descr_len, void *val)
{
	struct json_token tok;

	if (!lexer_next(&json->lex, &tok)) {
		return -EINVAL;
	}

	if (tok.type == JSON_TOK_ARRAY_END) {
		return 0;
	} else if (tok.type == JSON_TOK_COMMA) {
		if (!lexer_next(&json->lex, &tok)) {
			return -EINVAL;
		}
	}

	if (tok.type != JSON_TOK_OBJECT_START) {
		return -EINVAL;
	}

	return obj_parse(json, descr, descr_len, val);
}

static char escape_as(char chr)
{
	switch (chr) {
	case '"':
		return '"';
	case '\\':
		return '\\';
	case '\b':
		return 'b';
	case '\f':
		return 'f';
	case '\n':
		return 'n';
	case '\r':
		return 'r';
	case '\t':
		return 't';
	}

	return 0;
}

static int json_escape_internal(const char *str,
				json_append_bytes_t append_bytes,
				void *data)
{
	const char *cur;
	int ret = 0;

	if (str == NULL) {
		return ret;
	}

	for (cur = str; ret == 0 && *cur; cur++) {
		char escaped = escape_as(*cur);

		if (escaped) {
			char bytes[2] = { '\\', escaped };

			ret = append_bytes(bytes, 2, data);
		} else {
			ret = append_bytes(cur, 1, data);
		}
	}

	return ret;
}

size_t json_calc_escaped_len(const char *str, size_t len)
{
	size_t escaped_len = len;
	size_t pos;

	for (pos = 0; pos < len; pos++) {
		if (escape_as(str[pos])) {
			escaped_len++;
		}
	}

	return escaped_len;
}

ssize_t json_escape(char *str, size_t *len, size_t buf_size)
{
	char *next; /* Points after next character to escape. */
	char *dest; /* Points after next place to write escaped character. */
	size_t escaped_len = json_calc_escaped_len(str, *len);

	if (escaped_len == *len) {
		/*
		 * If no escape is necessary, there is nothing to do.
		 */
		return 0;
	}

	if (escaped_len >= buf_size) {
		return -ENOMEM;
	}

	/*
	 * By walking backwards in the buffer from the end positions
	 * of both the original and escaped strings, we avoid using
	 * extra space. Characters in the original string are
	 * overwritten only after they have already been escaped.
	 */
	str[escaped_len] = '\0';
	for (next = &str[*len], dest = &str[escaped_len]; next != str;) {
		char next_c = *(--next);
		char escape = escape_as(next_c);

		if (escape) {
			*(--dest) = escape;
			*(--dest) = '\\';
		} else {
			*(--dest) = next_c;
		}
	}
	*len = escaped_len;

	return 0;
}

static int encode(const struct json_obj_descr *descr, const void *val,
		  json_append_bytes_t append_bytes, void *data);

static int arr_encode(const struct json_obj_descr *elem_descr,
		      const void *field, const void *val,
		      json_append_bytes_t append_bytes, void *data)
{
	ptrdiff_t elem_size;
	/*
	 * NOTE: Since an element descriptor's offset isn't meaningful
	 * (array elements occur at multiple offsets in `val'), we use
	 * its space in elem_descr to store the offset to the field
	 * containing the number of elements.
	 */
	size_t n_elem = *(size_t *)((char *)val + elem_descr->offset);
	size_t i;
	int ret;

	ret = append_bytes("[", 1, data);
	if (ret < 0) {
		return ret;
	}

	/* For nested arrays, skip parent descriptor to get elements */
	if (elem_descr->type == JSON_TOK_ARRAY_START) {
		elem_descr = elem_descr->array.element_descr;
	}

	elem_size = get_elem_size(elem_descr);

	for (i = 0; i < n_elem; i++) {
		/*
		 * Though "field" points at the next element in the
		 * array which we need to encode, the value in
		 * elem_descr->offset is actually the offset of the
		 * length field in the "parent" struct containing the
		 * array.
		 *
		 * To patch things up, we lie to encode() about where
		 * the field is by exactly the amount it will offset
		 * it. This is a size optimization for struct
		 * json_obj_descr: the alternative is to keep a
		 * separate field next to element_descr which is an
		 * offset to the length field in the parent struct,
		 * but that would add a size_t to every descriptor.
		 */
		ret = encode(elem_descr, (char *)field - elem_descr->offset,
			     append_bytes, data);
		if (ret < 0) {
			return ret;
		}

		if (i < n_elem - 1) {
			ret = append_bytes(",", 1, data);
			if (ret < 0) {
				return ret;
			}
		}

		field = (char *)field + elem_size;
	}

	return append_bytes("]", 1, data);
}

static int str_encode(const char *str, json_append_bytes_t append_bytes,
		      void *data)
{
	int ret;

	ret = append_bytes("\"", 1, data);
	if (ret < 0) {
		return ret;
	}

	ret = json_escape_internal(str, append_bytes, data);
	if (!ret) {
		return append_bytes("\"", 1, data);
	}

	return ret;
}

static int int32_encode(const int32_t *num, json_append_bytes_t append_bytes,
			void *data)
{
	char buf[3 * sizeof(int32_t)];
	int ret;

	ret = snprintk(buf, sizeof(buf), "%d", *num);
	if (ret < 0) {
		return ret;
	}
	if (ret >= (int)sizeof(buf)) {
		return -ENOMEM;
	}

	return append_bytes(buf, (size_t)ret, data);
}

static int uint32_encode(const uint32_t *num, json_append_bytes_t append_bytes,
			 void *data)
{
	char buf[3 * sizeof(uint32_t)];
	int ret;

	ret = snprintk(buf, sizeof(buf), "%u", *num);
	if (ret < 0) {
		return ret;
	}
	if (ret >= (int)sizeof(buf)) {
		return -ENOMEM;
	}

	return append_bytes(buf, (size_t)ret, data);
}

static int int64_encode(const int64_t *num, json_append_bytes_t append_bytes,
			void *data)
{
	char buf[sizeof("-9223372036854775808")];
	int ret;

	ret = snprintk(buf, sizeof(buf), "%" PRId64, *num);
	if (ret < 0) {
		return ret;
	}
	if (ret >= (int)sizeof(buf)) {
		return -ENOMEM;
	}

	return append_bytes(buf, (size_t)ret, data);
}

static int uint64_encode(const uint64_t *num, json_append_bytes_t append_bytes,
			void *data)
{
	char buf[sizeof("18446744073709551610")];
	int ret;

	ret = snprintk(buf, sizeof(buf), "%" PRIu64, *num);
	if (ret < 0) {
		return ret;
	}
	if (ret >= (int)sizeof(buf)) {
		return -ENOMEM;
	}

	return append_bytes(buf, (size_t)ret, data);
}

static int print_double(char *str, size_t size, const char *fmt, double num)
{
#ifdef CONFIG_JSON_LIBRARY_FP_SUPPORT
	if (isnan(num)) {
		return snprintk(str, size, "NaN");
	}

	if (isinf(num)) {
		if (num < 0) {
			return snprintk(str, size, "-Infinity");
		}
		return snprintk(str, size, "Infinity");
	}

	return snprintk(str, size, fmt, num);

#else
	str[0] = '\0';
	ARG_UNUSED(size);
	ARG_UNUSED(fmt);
	ARG_UNUSED(num);
	return -EINVAL;
#endif
}

static int float_encode(const float *num, json_append_bytes_t append_bytes, void *data)
{
	char buf[sizeof("-3.40282347e+38")];
	int ret;

	ret = print_double(buf, sizeof(buf), "%.9g", (double)*num);

	if (ret < 0) {
		return ret;
	}
	if (ret >= (int)sizeof(buf)) {
		return -ENOMEM;
	}

	return append_bytes(buf, (size_t)ret, data);
}

static int double_encode(const double *num, json_append_bytes_t append_bytes, void *data)
{
	char buf[sizeof("-1.797693134862316e+308")];
	int ret;

	ret = print_double(buf, sizeof(buf), "%.16g", *num);

	if (ret < 0) {
		return ret;
	}
	if (ret >= (int)sizeof(buf)) {
		return -ENOMEM;
	}

	return append_bytes(buf, (size_t)ret, data);
}

static int int_encode(const void *ptr, size_t size, json_append_bytes_t append_bytes,
		      void *data)
{
	switch (size) {
	case 1: {
		const int8_t *num_8 = ptr;
		int32_t num = *num_8;

		return int32_encode(&num, append_bytes, data);
	}
	case 2: {
		const int16_t *num_16 = ptr;
		int32_t num = *num_16;

		return int32_encode(&num, append_bytes, data);
	}
	case 4: {
		const int32_t *num_32 = ptr;
		int32_t num = *num_32;

		return int32_encode(&num, append_bytes, data);
	}
	case 8: {
		const int64_t *num_64 = ptr;
		int64_t num = *num_64;

		return int64_encode(&num, append_bytes, data);
	}
	default:
		return -EINVAL;
	}
}

static int uint_encode(const void *ptr, size_t size, json_append_bytes_t append_bytes,
		       void *data)
{
	switch (size) {
	case 1: {
		const uint8_t *num_8 = ptr;
		uint32_t num = *num_8;

		return uint32_encode(&num, append_bytes, data);
	}
	case 2: {
		const uint16_t *num_16 = ptr;
		uint32_t num = *num_16;

		return uint32_encode(&num, append_bytes, data);
	}
	case 4: {
		const uint32_t *num_32 = ptr;
		uint32_t num = *num_32;

		return uint32_encode(&num, append_bytes, data);
	}
	case 8: {
		const uint64_t *num_64 = ptr;
		uint64_t num = *num_64;

		return uint64_encode(&num, append_bytes, data);
	}
	default:
		return -EINVAL;
	}
}

static int float_ascii_encode(struct json_obj_token *num, json_append_bytes_t append_bytes,
		      void *data)
{

	return append_bytes(num->start, num->length, data);
}

static int opaque_string_encode(struct json_obj_token *opaque, json_append_bytes_t append_bytes,
		      void *data)
{
	int ret;

	ret = append_bytes("\"", 1, data);
	if (ret < 0) {
		return ret;
	}

	ret = append_bytes(opaque->start, opaque->length, data);
	if (ret < 0) {
		return ret;
	}

	return append_bytes("\"", 1, data);
}

static int encoded_obj_encode(const char **str, json_append_bytes_t append_bytes, void *data)
{
	size_t len = strlen(*str);

	return append_bytes(*str, len, data);
}

static int bool_encode(const bool *value, json_append_bytes_t append_bytes,
		       void *data)
{
	if (*value) {
		return append_bytes("true", 4, data);
	}

	return append_bytes("false", 5, data);
}

static int encode(const struct json_obj_descr *descr, const void *val,
		  json_append_bytes_t append_bytes, void *data)
{
	void *ptr = (char *)val + descr->offset;

	switch (descr->type) {
	case JSON_TOK_FALSE:
	case JSON_TOK_TRUE:
		return bool_encode(ptr, append_bytes, data);
	case JSON_TOK_STRING: {
		const char **str = ptr;

		return str_encode(*str, append_bytes, data);
	}
	case JSON_TOK_STRING_BUF:
		return str_encode(ptr, append_bytes, data);
	case JSON_TOK_ARRAY_START:
		return arr_encode(descr->array.element_descr, ptr,
				  val, append_bytes, data);
	case JSON_TOK_OBJECT_START:
		return json_obj_encode(descr->object.sub_descr,
				       descr->object.sub_descr_len,
				       ptr, append_bytes, data);
	case JSON_TOK_NUMBER:
		return int32_encode(ptr, append_bytes, data);
	case JSON_TOK_INT:
		return int_encode(ptr, descr->field.size, append_bytes, data);
	case JSON_TOK_UINT:
		return uint_encode(ptr, descr->field.size, append_bytes, data);
	case JSON_TOK_INT64:
		return int64_encode(ptr, append_bytes, data);
	case JSON_TOK_UINT64:
		return uint64_encode(ptr, append_bytes, data);
	case JSON_TOK_FLOAT_FP:
		return float_encode(ptr, append_bytes, data);
	case JSON_TOK_DOUBLE_FP:
		return double_encode(ptr, append_bytes, data);
	case JSON_TOK_FLOAT:
		return float_ascii_encode(ptr, append_bytes, data);
	case JSON_TOK_OPAQUE:
		return opaque_string_encode(ptr, append_bytes, data);
	case JSON_TOK_ENCODED_OBJ:
		return encoded_obj_encode(ptr, append_bytes, data);
	default:
		return -EINVAL;
	}
}

int json_obj_encode(const struct json_obj_descr *descr, size_t descr_len,
		    const void *val, json_append_bytes_t append_bytes,
		    void *data)
{
	size_t i;
	int ret;

	ret = append_bytes("{", 1, data);
	if (ret < 0) {
		return ret;
	}

	for (i = 0; i < descr_len; i++) {
		ret = str_encode(descr[i].field_name, append_bytes, data);
		if (ret < 0) {
			return ret;
		}

		ret = append_bytes(":", 1, data);
		if (ret < 0) {
			return ret;
		}

		ret = encode(&descr[i], val, append_bytes, data);
		if (ret < 0) {
			return ret;
		}

		if (i < descr_len - 1) {
			ret = append_bytes(",", 1, data);
			if (ret < 0) {
				return ret;
			}
		}
	}

	return append_bytes("}", 1, data);
}

int json_arr_encode(const struct json_obj_descr *descr, const void *val,
		    json_append_bytes_t append_bytes, void *data)
{
	void *ptr = (char *)val + descr->offset;

	return arr_encode(descr->array.element_descr, ptr, val, append_bytes,
			  data);
}

struct appender {
	char *buffer;
	size_t used;
	size_t size;
};

static int append_bytes_to_buf(const char *bytes, size_t len, void *data)
{
	struct appender *appender = data;

	if (len >= appender->size - appender->used) {
		return -ENOMEM;
	}

	memcpy(appender->buffer + appender->used, bytes, len);
	appender->used += len;
	appender->buffer[appender->used] = '\0';

	return 0;
}

int json_obj_encode_buf(const struct json_obj_descr *descr, size_t descr_len,
			const void *val, char *buffer, size_t buf_size)
{
	struct appender appender = { .buffer = buffer, .size = buf_size };

	return json_obj_encode(descr, descr_len, val, append_bytes_to_buf,
			       &appender);
}

int json_arr_encode_buf(const struct json_obj_descr *descr, const void *val,
			char *buffer, size_t buf_size)
{
	struct appender appender = { .buffer = buffer, .size = buf_size };

	return json_arr_encode(descr, val, append_bytes_to_buf, &appender);
}

static int measure_bytes(const char *bytes, size_t len, void *data)
{
	ssize_t *total = data;

	*total += (ssize_t)len;

	ARG_UNUSED(bytes);

	return 0;
}

ssize_t json_calc_encoded_len(const struct json_obj_descr *descr,
			      size_t descr_len, const void *val)
{
	ssize_t total = 0;
	int ret;

	ret = json_obj_encode(descr, descr_len, val, measure_bytes, &total);
	if (ret < 0) {
		return ret;
	}

	return total;
}

ssize_t json_calc_encoded_arr_len(const struct json_obj_descr *descr,
				  const void *val)
{
	ssize_t total = 0;
	int ret;

	ret = json_arr_encode(descr, val, measure_bytes, &total);
	if (ret < 0) {
		return ret;
	}

	return total;
}


static int mixed_arr_parse(struct json_obj *arr,
			   const struct json_mixed_arr_descr *descr,
			   size_t descr_len, void *val);
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);

static int extract_raw_json_data(struct json_obj *obj, struct json_token *value,
				 char **field_ptr)
{
	char *start_pos = value->start;

	switch (value->type) {
	case JSON_TOK_OBJECT_START:
	case JSON_TOK_ARRAY_START: {
	struct json_obj_key_value kv = {
		.key = NULL,
		.key_len = 0,
		.value = *value
	};

	int ret = skip_field(obj, &kv);

	if (ret < 0) {
		return ret;
	}

	char *end_pos = obj->lex.pos;
	*end_pos = '\0';
	*field_ptr = start_pos;

	return 0;
	}

	case JSON_TOK_STRING:
	*value->end = '\0';
	*field_ptr = start_pos;
	return 0;

	default:
	return -EINVAL;
	}
}

static int64_t decode_mixed_value(struct json_obj *obj,
				  const struct json_mixed_arr_descr *elem,
				  struct json_token *value,
				  void *field, void *val)
{
	if (!equivalent_types(value->type, elem->type)) {
		return -EINVAL;
	}

	switch (elem->type) {
	case JSON_TOK_OBJECT_START: {
		return obj_parse(obj, elem->object.sub_descr,
				 elem->object.sub_descr_len, field);
	}
	case JSON_TOK_ARRAY_START: {
		const struct json_obj_descr *actual_elem_descr = elem->array.element_descr;
		size_t actual_n_elements = elem->array.n_elements;

		if (actual_elem_descr->type == JSON_TOK_ARRAY_START) {
			actual_elem_descr = actual_elem_descr->array.element_descr;
		}
		return arr_parse(obj, actual_elem_descr, actual_n_elements, field, val);
	}
	case JSON_TOK_MIXED_ARRAY: {
		return mixed_arr_parse(obj, elem->mixed_array.sub_descr,
				       elem->mixed_array.sub_descr_len,
				       field);
	}
	case JSON_TOK_FALSE:
	case JSON_TOK_TRUE: {
		bool *v = field;

		*v = (value->type == JSON_TOK_TRUE);
		return 0;
	}
	case JSON_TOK_NUMBER: {
		int32_t *num32 = field;

		return decode_int32(value, num32);
	}
	case JSON_TOK_INT: {
		return decode_int(value, field, elem->primitive.size);
	}
	case JSON_TOK_UINT: {
		return decode_uint(value, field, elem->primitive.size);
	}
	case JSON_TOK_INT64: {
		int64_t *num64 = field;

		return decode_int64(value, num64);
	}
	case JSON_TOK_UINT64: {
		uint64_t *unum64 = field;

		return decode_uint64(value, unum64);
	}
	case JSON_TOK_FLOAT_FP: {
		float *f_num = field;

		return decode_float(value, f_num);
	}
	case JSON_TOK_DOUBLE_FP: {
		double *d_num = field;

		return decode_double(value, d_num);
	}
	case JSON_TOK_STRING: {
		char **str_ptr = field;

		*value->end = '\0';
		*str_ptr = value->start;
		return 0;
	}
	case JSON_TOK_STRING_BUF: {
		char *str_buf = field;

		return decode_string_buf(value, str_buf, elem->primitive.size);
	}
	case JSON_TOK_OBJ_ARRAY: {
		struct json_obj_token *obj_token = field;

		obj_token->start = value->start;
		return arr_data_parse(obj, obj_token);
	}
	case JSON_TOK_OPAQUE:
	case JSON_TOK_FLOAT: {
		struct json_obj_token *obj_token = field;

		obj_token->start = value->start;
		obj_token->length = value->end - value->start;
		return 0;
	}
	case JSON_TOK_ENCODED_OBJ: {
		char **str_ptr = field;

		return extract_raw_json_data(obj, value, str_ptr);
	}
	case JSON_TOK_NULL: {
		memset(field, 0, elem->primitive.size);
		return 0;
	}
	default:
		return -EINVAL;
	}
}

static int encode_mixed_value(const struct json_mixed_arr_descr *elem,
			      void *field, void *val,
			      json_append_bytes_t append_bytes, void *data)
{

	switch (elem->type) {
	case JSON_TOK_OBJECT_START: {
		return json_obj_encode(elem->object.sub_descr,
				       elem->object.sub_descr_len,
				       field, append_bytes, data);
	}
	case JSON_TOK_ARRAY_START: {
		const struct json_obj_descr *actual_elem_descr = elem->array.element_descr;

		if (actual_elem_descr->type == JSON_TOK_ARRAY_START) {
			actual_elem_descr = actual_elem_descr->array.element_descr;
		}
		return arr_encode(actual_elem_descr, field, val, append_bytes, data);
	}
	case JSON_TOK_MIXED_ARRAY: {
		return json_mixed_arr_encode(elem->mixed_array.sub_descr,
					   elem->mixed_array.sub_descr_len,
					   field, append_bytes, data);
	}
	case JSON_TOK_FALSE:
	case JSON_TOK_TRUE: {
		return bool_encode(field, append_bytes, data);
	}
	case JSON_TOK_STRING: {
		return str_encode(*((char **)field), append_bytes, data);
	}
	case JSON_TOK_STRING_BUF: {
		return str_encode(field, append_bytes, data);
	}
	case JSON_TOK_NUMBER: {
		return int32_encode(field, append_bytes, data);
	}
	case JSON_TOK_INT: {
		return int_encode(field, elem->primitive.size, append_bytes, data);
	}
	case JSON_TOK_UINT: {
		return uint_encode(field, elem->primitive.size, append_bytes, data);
	}
	case JSON_TOK_INT64: {
		return int64_encode(field, append_bytes, data);
	}
	case JSON_TOK_UINT64: {
		return uint64_encode(field, append_bytes, data);
	}
	case JSON_TOK_FLOAT_FP: {
		return float_encode(field, append_bytes, data);
	}
	case JSON_TOK_DOUBLE_FP: {
		return double_encode(field, append_bytes, data);
	}
	case JSON_TOK_FLOAT: {
		return float_ascii_encode(field, append_bytes, data);
	}
	case JSON_TOK_OPAQUE: {
		return opaque_string_encode(field, append_bytes, data);
	}
	case JSON_TOK_ENCODED_OBJ: {
		return encoded_obj_encode((const char **)field, append_bytes, data);
	}
	default:
		return -EINVAL;
	}
}

static int mixed_arr_parse(struct json_obj *arr,
			   const struct json_mixed_arr_descr *descr,
			   size_t descr_len, void *val)
{
	struct json_token tok;
	size_t elem_idx = 0;
	void *field_ptr;
	int ret;

	if (descr_len == 0) {
		if (!arr_next(arr, &tok) && tok.type == JSON_TOK_ARRAY_END) {
			return 0;
		}
		return -EINVAL;
	}

	while (!arr_next(arr, &tok)) {
		if (tok.type == JSON_TOK_ARRAY_END) {
			return elem_idx;
		}

		if (elem_idx >= descr_len) {
			return -ENOSPC;
		}

		switch (descr[elem_idx].type) {
		case JSON_TOK_OBJECT_START:
			field_ptr = (char *)val + descr[elem_idx].object.offset;
			break;
		case JSON_TOK_ARRAY_START:
			field_ptr = (char *)val + descr[elem_idx].array.offset;
			break;
		case JSON_TOK_MIXED_ARRAY:
			field_ptr = (char *)val + descr[elem_idx].mixed_array.offset;
			break;
		default:
			field_ptr = (char *)val + descr[elem_idx].primitive.offset;
			break;
		}

		ret = decode_mixed_value(arr, &descr[elem_idx], &tok, field_ptr, val);
		if (ret < 0) {
			return ret;
		}

		elem_idx++;
	}

	return elem_idx;
}

int json_mixed_arr_parse(char *json, size_t len,
			 const struct json_mixed_arr_descr *descr,
			 size_t descr_len, void *val)
{
	struct json_obj arr;
	int ret;

	ret = arr_init(&arr, json, len);
	if (ret < 0) {
		return ret;
	}

	return mixed_arr_parse(&arr, descr, descr_len, val);
}

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)
{
	size_t *element_count;
	size_t i;
	int ret;
	void *field_ptr;

	if (descr_len == 0) {
		return append_bytes("[]", 2, data);
	}

	element_count = (size_t *)((char *)val + descr[0].count_offset);

	ret = append_bytes("[", 1, data);
	if (ret < 0) {
		return ret;
	}

	for (i = 0; i < *element_count && i < descr_len; i++) {
		switch (descr[i].type) {
		case JSON_TOK_OBJECT_START:
			field_ptr = (char *)val + descr[i].object.offset;
			break;
		case JSON_TOK_ARRAY_START:
			field_ptr = (char *)val + descr[i].array.offset;
			break;
		case JSON_TOK_MIXED_ARRAY:
			field_ptr = (char *)val + descr[i].mixed_array.offset;
			break;
		default:
			field_ptr = (char *)val + descr[i].primitive.offset;
			break;
		}

		ret = encode_mixed_value(&descr[i], field_ptr, val, append_bytes, data);
		if (ret < 0) {
			return ret;
		}

		if (i < *element_count - 1) {
			ret = append_bytes(",", 1, data);
			if (ret < 0) {
				return ret;
			}
		}
	}

	return append_bytes("]", 1, data);
}

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)
{
	struct appender appender = { .buffer = buffer, .size = buf_size };

	return json_mixed_arr_encode(descr, descr_len, val, append_bytes_to_buf, &appender);
}

ssize_t json_calc_mixed_arr_len(const struct json_mixed_arr_descr *descr,
				size_t descr_len, void *val)
{
	ssize_t total = 0;
	int ret;

	ret = json_mixed_arr_encode(descr, descr_len, val, measure_bytes, &total);
	if (ret < 0) {
		return ret;
	}

	return total;
}