public function parseMarkup()
    {
        $extension = strtolower(File::extension($this->fileName));

        switch ($extension) {
            case 'txt':
                $result = htmlspecialchars($this->markup);
                break;
            case 'md':
                $result = Markdown::parse($this->markup);
                break;
            default:
                $result = $this->markup;
        }

        return $result;
    }