esp-open-rtos/examples/json_jsmn_simple/json_jsmn_simple.c

/**
 * Copyright (c) 2010 Serge A. Zaitsev and
 * 2016 Drasko DRASKOVIC <drasko.draskovic@gmail.com>
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "espressif/esp_common.h"
#include "esp/uart.h"
#include "FreeRTOS.h"
#include "task.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "jsmn.h"

/**
 * A small example of jsmn parsing when JSON structure is known and number of
 * tokens is predictable.
 */

const char *JSON_STRING =
	"{\"user\": \"johndoe\", \"admin\": false, \"uid\": 1000,\n  "
	"\"groups\": [\"users\", \"wheel\", \"audio\", \"video\"]}";

static int jsoneq(const char *json, jsmntok_t *tok, const char *s) {
	if (tok->type == JSMN_STRING && (int) strlen(s) == tok->end - tok->start &&
			strncmp(json + tok->start, s, tok->end - tok->start) == 0) {
		return 0;
	}
	return -1;
}

void json_test(void *pvParameters)
{
    int i;
	int r;
	jsmn_parser p;
	jsmntok_t t[128]; /* We expect no more than 128 tokens */

	jsmn_init(&p);
	r = jsmn_parse(&p, JSON_STRING, strlen(JSON_STRING), t, sizeof(t)/sizeof(t[0]));
	if (r < 0) {
		printf("Failed to parse JSON: %d\n", r);
	}

	/* Assume the top-level element is an object */
	if (r < 1 || t[0].type != JSMN_OBJECT) {
		printf("Object expected\n");
	}

	/* Loop over all keys of the root object */
	for (i = 1; i < r; i++) {
		if (jsoneq(JSON_STRING, &t[i], "user") == 0) {
			/* We may use strndup() to fetch string value */
			printf("- User: %.*s\n", t[i+1].end-t[i+1].start,
					JSON_STRING + t[i+1].start);
			i++;
		} else if (jsoneq(JSON_STRING, &t[i], "admin") == 0) {
			/* We may additionally check if the value is either "true" or "false" */
			printf("- Admin: %.*s\n", t[i+1].end-t[i+1].start,
					JSON_STRING + t[i+1].start);
			i++;
		} else if (jsoneq(JSON_STRING, &t[i], "uid") == 0) {
			/* We may want to do strtol() here to get numeric value */
			printf("- UID: %.*s\n", t[i+1].end-t[i+1].start,
					JSON_STRING + t[i+1].start);
			i++;
		} else if (jsoneq(JSON_STRING, &t[i], "groups") == 0) {
			int j;
			printf("- Groups:\n");
			if (t[i+1].type != JSMN_ARRAY) {
				continue; /* We expect groups to be an array of strings */
			}
			for (j = 0; j < t[i+1].size; j++) {
				jsmntok_t *g = &t[i+j+2];
				printf("  * %.*s\n", g->end - g->start, JSON_STRING + g->start);
			}
			i += t[i+1].size + 1;
		} else {
			printf("Unexpected key: %.*s\n", t[i].end-t[i].start,
					JSON_STRING + t[i].start);
		}
	}

    while (1)
        ;
}


void user_init(void)
{
    uart_set_baud(0, 115200);
    printf("SDK version:%s\n", sdk_system_get_sdk_version());
    xTaskCreate(json_test, "jsont", 1024, NULL, 2, NULL);
}