SystemMenuBlock.php

<?php

namespace Drupal\system\Plugin\Derivative;

use Drupal\Component\Plugin\Derivative\DeriverBase;
use Drupal\Core\Entity\EntityStorageInterface;
use Drupal\Core\Plugin\Discovery\ContainerDeriverInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Provides block plugin definitions for custom menus.
 *
 * @see \Drupal\system\Plugin\Block\SystemMenuBlock
 */
class SystemMenuBlock extends DeriverBase implements ContainerDeriverInterface {
    
    /**
     * The menu storage.
     *
     * @var \Drupal\Core\Entity\EntityStorageInterface
     */
    protected $menuStorage;
    
    /**
     * Constructs new SystemMenuBlock.
     *
     * @param \Drupal\Core\Entity\EntityStorageInterface $menu_storage
     *   The menu storage.
     */
    public function __construct(EntityStorageInterface $menu_storage) {
        $this->menuStorage = $menu_storage;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, $base_plugin_id) {
        return new static($container->get('entity_type.manager')
            ->getStorage('menu'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDerivativeDefinitions($base_plugin_definition) {
        foreach ($this->menuStorage
            ->loadMultiple() as $menu => $entity) {
            $this->derivatives[$menu] = $base_plugin_definition;
            $this->derivatives[$menu]['admin_label'] = $entity->label();
            $this->derivatives[$menu]['config_dependencies']['config'] = [
                $entity->getConfigDependencyName(),
            ];
        }
        return $this->derivatives;
    }

}