Generates a random UUID string; version 4 as specified in RFC 4122.

uuid4.nut

function uuid4() {
	local fn = function(c) {
		local r = (((1.0 * rand() / RAND_MAX) * 16) + 1).tointeger();
		local v = (c == "x") ? r : (r & 0x3 | 0x8);
		return format("%x", r);
	}

	local string = "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx";
	local expression = regexp(@"[xy]");
	local captures = expression.capture(string);

	local result = "";
	local position = 0;

	// thank you, m0pey
	// http://www.squirrel-lang.org/forums/default.aspx?g=posts&m=6523

	while (captures != null) {
		foreach (i, capture in captures) {
			result += string.slice(position, capture.begin);
			result += fn(result);
			position = capture.end;
		}

	    captures = expression.capture(string, position);
	}

	result += string.slice(position);
	return result;
}