class BreadcrumbManager in Drupal 9

Provides a breadcrumb manager.

Can be assigned any number of BreadcrumbBuilderInterface objects by calling the addBuilder() method. When build() is called it iterates over the objects in priority order and uses the first one that returns TRUE from BreadcrumbBuilderInterface::applies() to build the breadcrumbs.

Hierarchy

• class \Drupal\Core\Breadcrumb\BreadcrumbManager implements ChainBreadcrumbBuilderInterface

See also

\Drupal\Core\DependencyInjection\Compiler\RegisterBreadcrumbBuilderPass

1 file declares its use of BreadcrumbManager

BreadcrumbManagerTest.php in core/tests/Drupal/Tests/Core/Breadcrumb/BreadcrumbManagerTest.php

1 string reference to 'BreadcrumbManager'

core.services.yml in core/core.services.yml

core/core.services.yml

1 service uses BreadcrumbManager

breadcrumb in core/core.services.yml

Drupal\Core\Breadcrumb\BreadcrumbManager

File

core/lib/Drupal/Core/Breadcrumb/BreadcrumbManager.php, line 18

Namespace

Drupal\Core\Breadcrumb

class BreadcrumbManager implements ChainBreadcrumbBuilderInterface {

  /**
   * The module handler to invoke the alter hook.
   *
   * @var \Drupal\Core\Extension\ModuleHandlerInterface
   */
  protected $moduleHandler;

  /**
   * Holds arrays of breadcrumb builders, keyed by priority.
   *
   * @var array
   */
  protected $builders = [];

  /**
   * Holds the array of breadcrumb builders sorted by priority.
   *
   * Set to NULL if the array needs to be re-calculated.
   *
   * @var \Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface[]|null
   */
  protected $sortedBuilders;

  /**
   * Constructs a \Drupal\Core\Breadcrumb\BreadcrumbManager object.
   *
   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
   *   The module handler.
   */
  public function __construct(ModuleHandlerInterface $module_handler) {
    $this->moduleHandler = $module_handler;
  }

  /**
   * {@inheritdoc}
   */
  public function addBuilder(BreadcrumbBuilderInterface $builder, $priority) {
    $this->builders[$priority][] = $builder;

    // Force the builders to be re-sorted.
    $this->sortedBuilders = NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function applies(RouteMatchInterface $route_match) {
    return TRUE;
  }

  /**
   * {@inheritdoc}
   */
  public function build(RouteMatchInterface $route_match) {
    $breadcrumb = new Breadcrumb();
    $context = [
      'builder' => NULL,
    ];

    // Call the build method of registered breadcrumb builders,
    // until one of them returns an array.
    foreach ($this
      ->getSortedBuilders() as $builder) {
      if (!$builder
        ->applies($route_match)) {

        // The builder does not apply, so we continue with the other builders.
        continue;
      }
      $breadcrumb = $builder
        ->build($route_match);
      if ($breadcrumb instanceof Breadcrumb) {
        $context['builder'] = $builder;
        break;
      }
      else {
        throw new \UnexpectedValueException('Invalid breadcrumb returned by ' . get_class($builder) . '::build().');
      }
    }

    // Allow modules to alter the breadcrumb.
    $this->moduleHandler
      ->alter('system_breadcrumb', $breadcrumb, $route_match, $context);
    return $breadcrumb;
  }

  /**
   * Returns the sorted array of breadcrumb builders.
   *
   * @return \Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface[]
   *   An array of breadcrumb builder objects.
   */
  protected function getSortedBuilders() {
    if (!isset($this->sortedBuilders)) {

      // Sort the builders according to priority.
      krsort($this->builders);

      // Merge nested builders from $this->builders into $this->sortedBuilders.
      $this->sortedBuilders = [];
      foreach ($this->builders as $builders) {
        $this->sortedBuilders = array_merge($this->sortedBuilders, $builders);
      }
    }
    return $this->sortedBuilders;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
BreadcrumbManager::$builders	protected	property	Holds arrays of breadcrumb builders, keyed by priority.
BreadcrumbManager::$moduleHandler	protected	property	The module handler to invoke the alter hook.
BreadcrumbManager::$sortedBuilders	protected	property	Holds the array of breadcrumb builders sorted by priority.
BreadcrumbManager::addBuilder	public	function	Adds another breadcrumb builder. Overrides ChainBreadcrumbBuilderInterface::addBuilder
BreadcrumbManager::applies	public	function	Whether this breadcrumb builder should be used to build the breadcrumb. Overrides BreadcrumbBuilderInterface::applies
BreadcrumbManager::build	public	function	Builds the breadcrumb. Overrides BreadcrumbBuilderInterface::build
BreadcrumbManager::getSortedBuilders	protected	function	Returns the sorted array of breadcrumb builders.
BreadcrumbManager::__construct	public	function	Constructs a \Drupal\Core\Breadcrumb\BreadcrumbManager object.