simple.c revision 284990
1284990Scy#include <stdio.h> 2284990Scy#include <string.h> 3284990Scy#include "../jsmn.h" 4284990Scy 5284990Scy/* 6284990Scy * A small example of jsmn parsing when JSON structure is known and number of 7284990Scy * tokens is predictable. 8284990Scy */ 9284990Scy 10284990Scyconst char *JSON_STRING = 11284990Scy "{\"user\": \"johndoe\", \"admin\": false, \"uid\": 1000,\n " 12284990Scy "\"groups\": [\"users\", \"wheel\", \"audio\", \"video\"]}"; 13284990Scy 14284990Scystatic int jsoneq(const char *json, jsmntok_t *tok, const char *s) { 15284990Scy if (tok->type == JSMN_STRING && (int) strlen(s) == tok->end - tok->start && 16284990Scy strncmp(json + tok->start, s, tok->end - tok->start) == 0) { 17284990Scy return 0; 18284990Scy } 19284990Scy return -1; 20284990Scy} 21284990Scy 22284990Scyint main() { 23284990Scy int i; 24284990Scy int r; 25284990Scy jsmn_parser p; 26284990Scy jsmntok_t t[128]; /* We expect no more than 128 tokens */ 27284990Scy 28284990Scy jsmn_init(&p); 29284990Scy r = jsmn_parse(&p, JSON_STRING, strlen(JSON_STRING), t, sizeof(t)/sizeof(t[0])); 30284990Scy if (r < 0) { 31284990Scy printf("Failed to parse JSON: %d\n", r); 32284990Scy return 1; 33284990Scy } 34284990Scy 35284990Scy /* Assume the top-level element is an object */ 36284990Scy if (r < 1 || t[0].type != JSMN_OBJECT) { 37284990Scy printf("Object expected\n"); 38284990Scy return 1; 39284990Scy } 40284990Scy 41284990Scy /* Loop over all keys of the root object */ 42284990Scy for (i = 1; i < r; i++) { 43284990Scy if (jsoneq(JSON_STRING, &t[i], "user") == 0) { 44284990Scy /* We may use strndup() to fetch string value */ 45284990Scy printf("- User: %.*s\n", t[i+1].end-t[i+1].start, 46284990Scy JSON_STRING + t[i+1].start); 47284990Scy i++; 48284990Scy } else if (jsoneq(JSON_STRING, &t[i], "admin") == 0) { 49284990Scy /* We may additionally check if the value is either "true" or "false" */ 50284990Scy printf("- Admin: %.*s\n", t[i+1].end-t[i+1].start, 51284990Scy JSON_STRING + t[i+1].start); 52284990Scy i++; 53284990Scy } else if (jsoneq(JSON_STRING, &t[i], "uid") == 0) { 54284990Scy /* We may want to do strtol() here to get numeric value */ 55284990Scy printf("- UID: %.*s\n", t[i+1].end-t[i+1].start, 56284990Scy JSON_STRING + t[i+1].start); 57284990Scy i++; 58284990Scy } else if (jsoneq(JSON_STRING, &t[i], "groups") == 0) { 59284990Scy int j; 60284990Scy printf("- Groups:\n"); 61284990Scy if (t[i+1].type != JSMN_ARRAY) { 62284990Scy continue; /* We expect groups to be an array of strings */ 63284990Scy } 64284990Scy for (j = 0; j < t[i+1].size; j++) { 65284990Scy jsmntok_t *g = &t[i+j+2]; 66284990Scy printf(" * %.*s\n", g->end - g->start, JSON_STRING + g->start); 67284990Scy } 68284990Scy i += t[i+1].size + 1; 69284990Scy } else { 70284990Scy printf("Unexpected key: %.*s\n", t[i].end-t[i].start, 71284990Scy JSON_STRING + t[i].start); 72284990Scy } 73284990Scy } 74284990Scy return 0; 75284990Scy} 76