sclass UTF8Processor {
  byte[] buffer = new byte[5];
  int count = 0;

  S processByte(byte nextByte) ctex {
    buffer[count++] = nextByte;
    if(count == expectedBytes()) {
        S result = new S(buffer, 0, count, "UTF-8");
        count = 0;
        return result;
    }
    return "";
  }

  int expectedBytes() {
    int num = buffer[0] & 255;
    if(num < 0x80) return 1;
    if(num < 0xe0) return 2;
    if(num < 0xf0) return 3;
    if(num < 0xf8) return 4;
    return 5;
  }
}