component_library-1.0.x-dev/src/EventSubscriber/PrepareOverrideBase.php

<?php

declare(strict_types=1);

namespace Drupal\component_library\EventSubscriber;

use Drupal\component_library\Event\PrepareOverrideEvent;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * Prepare override base.
 */
abstract class PrepareOverrideBase implements EventSubscriberInterface {

  /**
   * Has been processed.
   *
   * @var bool
   *   Whether this event has been processed.
   */
  protected bool $hasBeenProcessed = FALSE;

  /**
   * On Prepare Override.
   *
   * This event is dispatched multiple times. EventSubscribers should call
   * overridePrepared() once the event has been completed to prevent subsequent
   * executions.
   *
   * @param \Drupal\component_library\Event\PrepareOverrideEvent $event
   *   The prepare override event.
   */
  abstract protected function onPrepareOverride(PrepareOverrideEvent $event): void;

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents(): array {
    $events = [];
    $events[PrepareOverrideEvent::class][] = ['runOnce'];
    return $events;
  }

  /**
   * Override prepared.
   *
   * Flags that this event has been processed to prevent subsequent executions.
   */
  protected function overridePrepared(): void {
    $this->hasBeenProcessed = TRUE;
  }

  /**
   * Run once.
   *
   * Ensure that onPrepareOverride is only computed once for each event since it
   * is dispatched multiple times.
   *
   * @param \Drupal\component_library\Event\PrepareOverrideEvent $event
   *   The event.
   */
  public function runOnce(PrepareOverrideEvent $event): void {
    if (!$this->hasBeenProcessed) {
      $this->onPrepareOverride($event);
    }
  }

}