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RIOT/tests/pkg_jsmn/simple.c 3.87 KB
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  /*
   * Copyright (c) 2010 Serge A. Zaitsev
   *
   * 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.
   *
   * adapted to RIOT by Kaspar Schleiser <kaspar@schleiser.de>
   *
   * changes: - reduced nr of expected tokens to 16, stack would overflow
   *            otherwise with default stacksize on Cortex-M
   */
  
  #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;
  }
  
  int main(void)
  {
      int i;
      int r;
      jsmn_parser p;
      jsmntok_t t[16]; /* We expect no more than 16 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);
          return 1;
      }
  
      /* Assume the top-level element is an object */
      if (r < 1 || t[0].type != JSMN_OBJECT) {
          printf("Object expected\n");
          return 1;
      }
  
      /* 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);
          }
      }
      return 0;
  }