Removed empty attribute about twital HOT 3 CLOSED

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Goetas\Twital\EventDispatcher\SourceEvent;
use Goetas\Twital\EventDispatcher\TemplateEvent;

class CompatibilitySubscriber implements EventSubscriberInterface {
    const PLACEHOLDER = 'placeholderXXX###===';

    public static function getSubscribedEvents() {
        return [
            'compiler.pre_dump' => [
                ['valueAddPlaceholder']
            ],
            'compiler.post_dump' => [
                ['valueRemovePlaceholder']
            ],
        ];
    }

    public function valueAddPlaceholder(TemplateEvent $event) {
        $doc = $event->getTemplate()->getDocument();

        $xp = new \DOMXPath($doc);
        $xp->registerNamespace('xh', 'http://www.w3.org/1999/xhtml');

        /**
         * @var $option \DOMElement
         */
        foreach ($xp->query("//xh:option[@value='']") as $option) {
            $option->setAttribute('value', self::PLACEHOLDER);
        }
    }

    public function valueRemovePlaceholder(SourceEvent $event) {
        $event->setTemplate(str_replace(
                ' value="' . self::PLACEHOLDER . '"',
                ' value=""',
                $event->getTemplate())
        );
    }
}