DisplayPluginCollection.php

<?php

namespace Drupal\views;

use Drupal\Component\Plugin\Exception\PluginException;
use Drupal\Component\Plugin\PluginManagerInterface;
use Drupal\Core\Plugin\DefaultLazyPluginCollection;

/**
 * A class which wraps the displays of a view so you can lazy-initialize them.
 */
class DisplayPluginCollection extends DefaultLazyPluginCollection {

  /**
   * Stores a reference to the view which has this displays attached.
   *
   * @var \Drupal\views\ViewExecutable
   */
  protected $view;

  /**
   * {@inheritdoc}
   */
  protected $pluginKey = 'display_plugin';

  /**
   * Constructs a DisplayPluginCollection object.
   *
   * @param \Drupal\views\ViewExecutable $view
   *   The view which has this displays attached.
   * @param \Drupal\Component\Plugin\PluginManagerInterface $manager
   *   The manager to be used for instantiating plugins.
   */
  public function __construct(ViewExecutable $view, PluginManagerInterface $manager) {
    parent::__construct($manager, $view->storage
      ->get('display'));
    $this->view = $view;
    $this
      ->initializePlugin('default');
  }

  /**
   * Destructs a DisplayPluginCollection object.
   */
  public function __destruct() {
    $this
      ->clear();
  }

  /**
   * {@inheritdoc}
   *
   * @return \Drupal\views\Plugin\views\display\DisplayPluginBase
   */
  public function &get($instance_id) {
    return parent::get($instance_id);
  }

  /**
   * {@inheritdoc}
   */
  public function clear() {
    foreach (array_filter($this->pluginInstances) as $display) {
      $display
        ->destroy();
    }
    parent::clear();
  }

  /**
   * {@inheritdoc}
   */
  protected function initializePlugin($display_id) {

    // Retrieve and initialize the new display handler with data.
    $display =& $this->view->storage
      ->getDisplay($display_id);
    try {
      $this->configurations[$display_id] = $display;
      parent::initializePlugin($display_id);
    } catch (PluginException $e) {
      $message = $e
        ->getMessage();
      \Drupal::messenger()
        ->addWarning(t('@message', [
        '@message' => $message,
      ]));
    }

    // If no plugin instance has been created, return NULL.
    if (empty($this->pluginInstances[$display_id])) {
      return NULL;
    }
    $this->pluginInstances[$display_id]
      ->initDisplay($this->view, $display);

    // If this is not the default display handler, let it know which is since
    // it may well use some data from the default.
    if ($display_id != 'default') {
      $this->pluginInstances[$display_id]->default_display = $this->pluginInstances['default'];
    }
  }

  /**
   * {@inheritdoc}
   */
  public function remove($instance_id) {
    $this
      ->get($instance_id)
      ->remove();
    parent::remove($instance_id);
  }

}