public function parseDelimiter()
    {
        $idx = 0;

        while ($idx < $this->delimiterLen && $this->last + $idx < $this->len) {
            if ($this->delimiter[$idx] !== $this->str[$this->last + $idx]) {
                return null;
            }
            ++$idx;
        }

        $this->last += $this->delimiterLen - 1;

        return new Token($this->delimiter, Token::TYPE_DELIMITER);
    }