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

core/modules/block/src/BlockPluginCollection.php

@@ -0,0 +1,76 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\block\BlockPluginCollection.
+ */
+
+namespace Drupal\block;
+
+use Drupal\Component\Plugin\Exception\PluginException;
+use Drupal\Component\Plugin\PluginManagerInterface;
+use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Core\Plugin\DefaultSingleLazyPluginCollection;
+
+/**
+ * Provides a collection of block plugins.
+ */
+class BlockPluginCollection extends DefaultSingleLazyPluginCollection {
+
+  /**
+   * The block ID this plugin collection belongs to.
+   *
+   * @var string
+   */
+  protected $blockId;
+
+  /**
+   * Constructs a new BlockPluginCollection.
+   *
+   * @param \Drupal\Component\Plugin\PluginManagerInterface $manager
+   *   The manager to be used for instantiating plugins.
+   * @param string $instance_id
+   *   The ID of the plugin instance.
+   * @param array $configuration
+   *   An array of configuration.
+   * @param string $block_id
+   *   The unique ID of the block entity using this plugin.
+   */
+  public function __construct(PluginManagerInterface $manager, $instance_id, array $configuration, $block_id) {
+    parent::__construct($manager, $instance_id, $configuration);
+
+    $this->blockId = $block_id;
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * @return \Drupal\Core\Block\BlockPluginInterface
+   */
+  public function &get($instance_id) {
+    return parent::get($instance_id);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function initializePlugin($instance_id) {
+    if (!$instance_id) {
+      throw new PluginException(SafeMarkup::format("The block '@block' did not specify a plugin.", array('@block' => $this->blockId)));
+    }
+
+    try {
+      parent::initializePlugin($instance_id);
+    }
+    catch (PluginException $e) {
+      $module = $this->configuration['provider'];
+      // Ignore blocks belonging to uninstalled modules, but re-throw valid
+      // exceptions when the module is installed and the plugin is
+      // misconfigured.
+      if (!$module || \Drupal::moduleHandler()->moduleExists($module)) {
+        throw $e;
+      }
+    }
+  }
+
+}