protected function scanComment()
    {
        if (preg_match('/^ *\/\/(-)?([^\n]*)/', $this->input, $matches)) {
            $this->consume($matches[0]);
            $token         = $this->token('comment', isset($matches[2]) ? $matches[2] : '');
            $token->buffer = '-' !== $matches[1];

            return $token;
        }
    }