SystemBreadcrumbBlock.php

<?php

namespace Drupal\system\Plugin\Block;

use Drupal\Core\Block\BlockBase;
use Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface;
use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
use Drupal\Core\Routing\RouteMatchInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Provides a block to display the breadcrumbs.
 *
 * @Block(
 *   id = "system_breadcrumb_block",
 *   admin_label = @Translation("Breadcrumbs")
 * )
 */
class SystemBreadcrumbBlock extends BlockBase implements ContainerFactoryPluginInterface {
    
    /**
     * The breadcrumb manager.
     *
     * @var \Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface
     */
    protected $breadcrumbManager;
    
    /**
     * The current route match.
     *
     * @var \Drupal\Core\Routing\RouteMatchInterface
     */
    protected $routeMatch;
    
    /**
     * Constructs a new SystemBreadcrumbBlock object.
     *
     * @param array $configuration
     *   A configuration array containing information about the plugin instance.
     * @param string $plugin_id
     *   The plugin_id for the plugin instance.
     * @param mixed $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface $breadcrumb_manager
     *   The breadcrumb manager.
     * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
     *   The current route match.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, BreadcrumbBuilderInterface $breadcrumb_manager, RouteMatchInterface $route_match) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->breadcrumbManager = $breadcrumb_manager;
        $this->routeMatch = $route_match;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('breadcrumb'), $container->get('current_route_match'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function build() {
        return $this->breadcrumbManager
            ->build($this->routeMatch)
            ->toRenderable();
    }

}