The jsonny JSON scanner is intended to be a simple JSON scanner. All it does is give you tokens and values from the scanning process, not unlike SAX for XML. For example, to parse a single JSON string, you would write:

if (jsonny_scan(js, stream) == JSONNY_STRING)
  printf("%s\n", js->js_str);
else
  printf("error\n");

The value in js->js_str will be the JSON string with no quotes and all escapes processed to their UTF-8 equivalents (including Unicode code point escapes).

The scanner-only model makes for an easy implementation with minimal requirements. The jsonny_scanner_t struct has two buffers: one for the current string value, and one for a delimiter stack. These buffers will expand as necessary to accomodate anything that can fit into memory (note that this means receiving a gigantic string could exaust the memory on your system).

The intended usage model is where you have a struct that you want to populate with JSON data. You simply write a loop that loops over object keys, and copies the scanner's value into your struct. For example:

struct foo {
  int a,
  double b
} f;

if ((token = jsonny_scan(js, stream)) == JSONNY_OBJECT_START) {
  token = jsonny_scan(js, stream);
  while (token != JSONNY_OBJECT_END && token != JSONNY_ERROR) {
    if (token == JSONNY_KEY
	&& strcmp("a", js->js_str) == 0
	&& json_scan(js, stream) == JSONNY_NUMBER)
      f.a = strtol(js->js_str, NULL, 10);
    else if (token == JSONNY_KEY
	     && strcmp("b", js->js_str) == 0
	     && json_scan(js, stream) == JSONNY_NUMBER)
      j.b = strtod(js->js_str, NULL);
    token = jsonny_scan(js, stream);
  }
}