diff core/lib/Drupal/Core/EventSubscriber/HtmlResponsePlaceholderStrategySubscriber.php @ 0:4c8ae668cc8c

Initial import (non-working)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/core/lib/Drupal/Core/EventSubscriber/HtmlResponsePlaceholderStrategySubscriber.php	Wed Nov 29 16:09:58 2017 +0000
@@ -0,0 +1,70 @@
+<?php
+
+namespace Drupal\Core\EventSubscriber;
+
+use Drupal\Core\Render\HtmlResponse;
+use Drupal\Core\Render\Placeholder\PlaceholderStrategyInterface;
+use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
+use Symfony\Component\HttpKernel\KernelEvents;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * HTML response subscriber to allow for different placeholder strategies.
+ *
+ * This allows core and contrib to coordinate how to render placeholders;
+ * e.g. an EsiRenderStrategy could replace the placeholders with ESI tags,
+ * while e.g. a BigPipeRenderStrategy could store the placeholders in a
+ * BigPipe service and render them after the main content has been sent to
+ * the client.
+ */
+class HtmlResponsePlaceholderStrategySubscriber implements EventSubscriberInterface {
+
+  /**
+   * The placeholder strategy to use.
+   *
+   * @var \Drupal\Core\Render\Placeholder\PlaceholderStrategyInterface
+   */
+  protected $placeholderStrategy;
+
+  /**
+   * Constructs a HtmlResponsePlaceholderStrategySubscriber object.
+   *
+   * @param \Drupal\Core\Render\Placeholder\PlaceholderStrategyInterface $placeholder_strategy
+   *   The placeholder strategy to use.
+   */
+  public function __construct(PlaceholderStrategyInterface $placeholder_strategy) {
+    $this->placeholderStrategy = $placeholder_strategy;
+  }
+
+  /**
+   * Processes placeholders for HTML responses.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\FilterResponseEvent $event
+   *   The event to process.
+   */
+  public function onRespond(FilterResponseEvent $event) {
+    $response = $event->getResponse();
+    if (!$response instanceof HtmlResponse) {
+      return;
+    }
+
+    $attachments = $response->getAttachments();
+    if (empty($attachments['placeholders'])) {
+      return;
+    }
+
+    $attachments['placeholders'] = $this->placeholderStrategy->processPlaceholders($attachments['placeholders']);
+
+    $response->setAttachments($attachments);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    // Run shortly before HtmlResponseSubscriber.
+    $events[KernelEvents::RESPONSE][] = ['onRespond', 5];
+    return $events;
+  }
+
+}