simple.c revision 290000
1893SN/A#include <stdio.h> 22362SN/A#include <string.h> 3893SN/A#include "../jsmn.h" 4893SN/A 5893SN/A/* 6893SN/A * A small example of jsmn parsing when JSON structure is known and number of 72362SN/A * tokens is predictable. 8893SN/A */ 92362SN/A 10893SN/Aconst char *JSON_STRING = 11893SN/A "{\"user\": \"johndoe\", \"admin\": false, \"uid\": 1000,\n " 12893SN/A "\"groups\": [\"users\", \"wheel\", \"audio\", \"video\"]}"; 13893SN/A 14893SN/Astatic int jsoneq(const char *json, jsmntok_t *tok, const char *s) { 15893SN/A if (tok->type == JSMN_STRING && (int) strlen(s) == tok->end - tok->start && 16893SN/A strncmp(json + tok->start, s, tok->end - tok->start) == 0) { 17893SN/A return 0; 18893SN/A } 19893SN/A return -1; 20893SN/A} 212362SN/A 222362SN/Aint main() { 232362SN/A int i; 24893SN/A int r; 25893SN/A jsmn_parser p; 26893SN/A jsmntok_t t[128]; /* We expect no more than 128 tokens */ 27893SN/A 28893SN/A jsmn_init(&p); 29893SN/A r = jsmn_parse(&p, JSON_STRING, strlen(JSON_STRING), t, sizeof(t)/sizeof(t[0])); 30893SN/A if (r < 0) { 31893SN/A printf("Failed to parse JSON: %d\n", r); 32893SN/A return 1; 33893SN/A } 34893SN/A 35893SN/A /* Assume the top-level element is an object */ 36893SN/A if (r < 1 || t[0].type != JSMN_OBJECT) { 37893SN/A printf("Object expected\n"); 38893SN/A return 1; 39893SN/A } 40893SN/A 41893SN/A /* Loop over all keys of the root object */ 42893SN/A for (i = 1; i < r; i++) { 43893SN/A if (jsoneq(JSON_STRING, &t[i], "user") == 0) { 44893SN/A /* We may use strndup() to fetch string value */ 45893SN/A printf("- User: %.*s\n", t[i+1].end-t[i+1].start, 46893SN/A JSON_STRING + t[i+1].start); 47893SN/A i++; 48893SN/A } else if (jsoneq(JSON_STRING, &t[i], "admin") == 0) { 49908SN/A /* We may additionally check if the value is either "true" or "false" */ 50893SN/A printf("- Admin: %.*s\n", t[i+1].end-t[i+1].start, 51893SN/A JSON_STRING + t[i+1].start); 52893SN/A i++; 53893SN/A } else if (jsoneq(JSON_STRING, &t[i], "uid") == 0) { 54893SN/A /* We may want to do strtol() here to get numeric value */ 55893SN/A printf("- UID: %.*s\n", t[i+1].end-t[i+1].start, 56893SN/A JSON_STRING + t[i+1].start); 57893SN/A i++; 58893SN/A } else if (jsoneq(JSON_STRING, &t[i], "groups") == 0) { 59908SN/A int j; 60893SN/A printf("- Groups:\n"); 61908SN/A if (t[i+1].type != JSMN_ARRAY) { 62893SN/A continue; /* We expect groups to be an array of strings */ 63908SN/A } 64893SN/A for (j = 0; j < t[i+1].size; j++) { 65893SN/A jsmntok_t *g = &t[i+j+2]; 66893SN/A printf(" * %.*s\n", g->end - g->start, JSON_STRING + g->start); 67893SN/A } 68893SN/A i += t[i+1].size + 1; 69 } else { 70 printf("Unexpected key: %.*s\n", t[i].end-t[i].start, 71 JSON_STRING + t[i].start); 72 } 73 } 74 return 0; 75} 76