aleph1.co.uk Git - yaffs-website/blob - web/core/lib/Drupal/Core/EventSubscriber/HtmlResponsePlaceholderStrategySubscriber.php

   1 <?php
   2
   3 namespace Drupal\Core\EventSubscriber;
   4
   5 use Drupal\Core\Render\HtmlResponse;
   6 use Drupal\Core\Render\Placeholder\PlaceholderStrategyInterface;
   7 use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
   8 use Symfony\Component\HttpKernel\KernelEvents;
   9 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
  10
  11 /**
  12  * HTML response subscriber to allow for different placeholder strategies.
  13  *
  14  * This allows core and contrib to coordinate how to render placeholders;
  15  * e.g. an EsiRenderStrategy could replace the placeholders with ESI tags,
  16  * while e.g. a BigPipeRenderStrategy could store the placeholders in a
  17  * BigPipe service and render them after the main content has been sent to
  18  * the client.
  19  */
  20 class HtmlResponsePlaceholderStrategySubscriber implements EventSubscriberInterface {
  21
  22   /**
  23    * The placeholder strategy to use.
  24    *
  25    * @var \Drupal\Core\Render\Placeholder\PlaceholderStrategyInterface
  26    */
  27   protected $placeholderStrategy;
  28
  29   /**
  30    * Constructs a HtmlResponsePlaceholderStrategySubscriber object.
  31    *
  32    * @param \Drupal\Core\Render\Placeholder\PlaceholderStrategyInterface $placeholder_strategy
  33    *   The placeholder strategy to use.
  34    */
  35   public function __construct(PlaceholderStrategyInterface $placeholder_strategy) {
  36     $this->placeholderStrategy = $placeholder_strategy;
  37   }
  38
  39   /**
  40    * Processes placeholders for HTML responses.
  41    *
  42    * @param \Symfony\Component\HttpKernel\Event\FilterResponseEvent $event
  43    *   The event to process.
  44    */
  45   public function onRespond(FilterResponseEvent $event) {
  46     $response = $event->getResponse();
  47     if (!$response instanceof HtmlResponse) {
  48       return;
  49     }
  50
  51     $attachments = $response->getAttachments();
  52     if (empty($attachments['placeholders'])) {
  53       return;
  54     }
  55
  56     $attachments['placeholders'] = $this->placeholderStrategy->processPlaceholders($attachments['placeholders']);
  57
  58     $response->setAttachments($attachments);
  59   }
  60
  61   /**
  62    * {@inheritdoc}
  63    */
  64   public static function getSubscribedEvents() {
  65     // Run shortly before HtmlResponseSubscriber.
  66     $events[KernelEvents::RESPONSE][] = ['onRespond', 5];
  67     return $events;
  68   }
  69
  70 }