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- #include <stdio.h>
- #include <string.h>
- #include "../jsmn.h"
- /*
- * A small example of jsmn parsing when JSON structure is known and number of
- * tokens is predictable.
- */
- //This is the actual JSON string, you could load this with the FS (see ctrulib)
- 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() {
- int i;
- int r;
- jsmn_parser p;
- jsmntok_t t[128]; /* We expect no more than 128 tokens */
- //Initialize the JSMN libary
- jsmn_init(&p);
- //Parses JSON string and fill tokens
- 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++) {
- //jsoneq(FULLSTRING, pointer to t (jsmntok_t), name of "option"/json variable name)
- 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;
- }
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