esp-open-rtos/examples/json_jsmn_simple/json_jsmn_simple.c
Drasko DRASKOVIC cc8e8da034 Add JSON support
This commits adds JSON support by adding Jsmn
(http://zserge.com/jsmn.html), a minimalistic JSON parser.

Signed-off-by: Drasko DRASKOVIC <drasko.draskovic@gmail.com>
2016-05-05 01:02:20 +02:00

112 lines
3.6 KiB
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, (signed char *)"jsont", 1024, NULL, 2, NULL);
}