UJSON

UJSON is:

• Complete and simple JSON reader and writer written in C
• Produces nice and human readable error messages
• Passes JSONTestSuite

See generated documentation at: https://metan-ucw.github.io/ujson/files.html

The key point of this parser is that:

• works on a buffer in a memory that is not modified during the parsing
• parser does not allocate memory
• nearly stateless, the only state the parser maintains is an offset to the string buffer, recursion depth and error flag
• if error flag is raised all parser functions return immediatelly with error

The parser is started by a call to ujson_start() function in order to determine if first element in the buffer is object or an array.

	switch (ujson_reader_start(reader)) {
	case UJSON_ARR:
		//parse array
	break;
	case UJSON_OBJ:
		//parse object
	break;
	default:
	break;
	}

	if (ujson_reader_err(reader))
		ujson_err_print(reader);

Then you can loop recursively over arrays and objects with:

	char sbuf[128];
	struct ujson_val json = {.buf = sbuf, .buf_size = sizeof(sbuf)};

	UJSON_OBJ_FOREACH(reader, &json) {
		switch (json.type) {
		case UJSON_OBJ:
			//parse object
		break;
		case UJSON_ARR:
			//parse array
		break;
		case UJSON_STR:
		...

		}
	}

The supported types are:

• UJSON_ARR - an array, needs to be parsed recursivelly
• UJSON_OBJ - an object, needs to be parsed recursivelly
• UJSON_INT - an integer number stored as val_int (also sets val_float for convinience)
• UJSON_FLOAT - a floating point number stored as val_float
• UJSON_BOOL - a boolean stored as val_bool
• UJSON_NULL - a null has no value
• UJSON_STR - a string, stored in user supplied buffer