protected function parseAttributes()
    {
        $parts = explode('; ', $this->value);

        $this->attributes = [];

        foreach ($parts as $part)
        {
            $attrParts = explode('=', $part, 2);

            $type = strtolower($attrParts[0]);

            if ( ! isset($this->attributes[$type]))
            {
                $this->attributes[$type] = [];
            }

            $this->attributes[$type][] = [
                'name' => $attrParts[0],
                'value' => isset($attrParts[1]) ? $attrParts[1] : true
            ];
        }
    }