A UUID4 String Generator for GML

generate_uuid4_string.gml

function generate_uuid4_string() {
    //As per https://www.cryptosys.net/pki/uuid-rfc4122.html
    //FIXME - Do this without random()/choose() calls
    var _UUID = sha1_string_utf8(string(current_time) + string(date_current_datetime()) + string(random(0xFFFFFF)));
        _UUID = string_set_byte_at(_UUID, 9,  0x2D)
        _UUID = string_set_byte_at(_UUID, 14, 0x2D)
        _UUID = string_set_byte_at(_UUID, 19, 0x2D)
        _UUID = string_set_byte_at(_UUID, 24, 0x2D)
    
        _UUID = string_delete(_UUID, 37, 4)
        _UUID = string_upper(_UUID)
    
        _UUID = string_set_byte_at(_UUID, 15, 0x34);
        _UUID = string_set_byte_at(_UUID, 20, choose(0x38, 0x39, 0x41, 0x42));
    
    return _UUID;
}