protected function inAtRuleStringState()
    {
        $char = $this->getCurrentChar();

        if ($char === self::CHAR_DOUBLEQUOTE && $this->isEscaping() === false) {
            $this->cleanBuffer();
            $this->setState(self::IN_ATRULE);
        } elseif ($char === self::CHAR_ESCAPE) {
            $this->bufferize($char);
        } else {
            $this->cleanBuffer();
        }

        $this->output($char);
    }