Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/block/src/BlockViewBuilder.php

@@ -0,0 +1,151 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\block\BlockViewBuilder.
+ */
+
+namespace Drupal\block;
+
+use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Cache\CacheableMetadata;
+use Drupal\Core\Entity\EntityViewBuilder;
+use Drupal\Core\Entity\EntityViewBuilderInterface;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Render\Element;
+
+/**
+ * Provides a Block view builder.
+ */
+class BlockViewBuilder extends EntityViewBuilder {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildComponents(array &$build, array $entities, array $displays, $view_mode, $langcode = NULL) {
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function view(EntityInterface $entity, $view_mode = 'full', $langcode = NULL) {
+    $build = $this->viewMultiple(array($entity), $view_mode, $langcode);
+    return reset($build);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function viewMultiple(array $entities = array(), $view_mode = 'full', $langcode = NULL) {
+    /** @var \Drupal\block\BlockInterface[] $entities */
+    $build = array();
+    foreach ($entities as  $entity) {
+      $entity_id = $entity->id();
+      $plugin = $entity->getPlugin();
+      $plugin_id = $plugin->getPluginId();
+      $base_id = $plugin->getBaseId();
+      $derivative_id = $plugin->getDerivativeId();
+      $configuration = $plugin->getConfiguration();
+
+      // Create the render array for the block as a whole.
+      // @see template_preprocess_block().
+      $build[$entity_id] = array(
+        '#theme' => 'block',
+        '#attributes' => array(),
+        // All blocks get a "Configure block" contextual link.
+        '#contextual_links' => array(
+          'block' => array(
+            'route_parameters' => array('block' => $entity->id()),
+          ),
+        ),
+        '#weight' => $entity->getWeight(),
+        '#configuration' => $configuration,
+        '#plugin_id' => $plugin_id,
+        '#base_plugin_id' => $base_id,
+        '#derivative_plugin_id' => $derivative_id,
+        '#id' => $entity->id(),
+        '#cache' => [
+          'keys' => ['entity_view', 'block', $entity->id()],
+          'contexts' => $plugin->getCacheContexts(),
+          'tags' => Cache::mergeTags(
+            $this->getCacheTags(), // Block view builder cache tag.
+            $entity->getCacheTags(), // Block entity cache tag.
+            $plugin->getCacheTags() // Block plugin cache tags.
+          ),
+          'max-age' => $plugin->getCacheMaxAge(),
+        ],
+        '#pre_render' => [
+          [$this, 'buildBlock'],
+        ],
+        // Add the entity so that it can be used in the #pre_render method.
+        '#block' => $entity,
+      );
+      $build[$entity_id]['#configuration']['label'] = SafeMarkup::checkPlain($configuration['label']);
+
+      // Don't run in ::buildBlock() to ensure cache keys can be altered. If an
+      // alter hook wants to modify the block contents, it can append another
+      // #pre_render hook.
+      $this->moduleHandler()->alter(array('block_view', "block_view_$base_id"), $build[$entity_id], $plugin);
+    }
+    return $build;
+  }
+
+  /**
+   * #pre_render callback for building a block.
+   *
+   * Renders the content using the provided block plugin, and then:
+   * - if there is no content, aborts rendering, and makes sure the block won't
+   *   be rendered.
+   * - if there is content, moves the contextual links from the block content to
+   *   the block itself.
+   */
+  public function buildBlock($build) {
+    $content = $build['#block']->getPlugin()->build();
+    // Remove the block entity from the render array, to ensure that blocks
+    // can be rendered without the block config entity.
+    unset($build['#block']);
+    if ($content !== NULL && !Element::isEmpty($content)) {
+      // Place the $content returned by the block plugin into a 'content' child
+      // element, as a way to allow the plugin to have complete control of its
+      // properties and rendering (e.g., its own #theme) without conflicting
+      // with the properties used above, or alternate ones used by alternate
+      // block rendering approaches in contrib (e.g., Panels). However, the use
+      // of a child element is an implementation detail of this particular block
+      // rendering approach. Semantically, the content returned by the plugin
+      // "is the" block, and in particular, #attributes and #contextual_links is
+      // information about the *entire* block. Therefore, we must move these
+      // properties from $content and merge them into the top-level element.
+      foreach (array('#attributes', '#contextual_links') as $property) {
+        if (isset($content[$property])) {
+          $build[$property] += $content[$property];
+          unset($content[$property]);
+        }
+      }
+      $build['content'] = $content;
+    }
+    // Either the block's content is completely empty, or it consists only of
+    // cacheability metadata.
+    else {
+      // Abort rendering: render as the empty string and ensure this block is
+      // render cached, so we can avoid the work of having to repeatedly
+      // determine whether the block is empty. E.g. modifying or adding entities
+      // could cause the block to no longer be empty.
+      $build = array(
+        '#markup' => '',
+        '#cache' => $build['#cache'],
+      );
+      // If $content is not empty, then it contains cacheability metadata, and
+      // we must merge it with the existing cacheability metadata. This allows
+      // blocks to be empty, yet still bubble cacheability metadata, to indicate
+      // why they are empty.
+      if (!empty($content)) {
+        CacheableMetadata::createFromRenderArray($build)
+          ->merge(CacheableMetadata::createFromRenderArray($content))
+          ->applyTo($build);
+      }
+    }
+    return $build;
+   }
+
+}