Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/taxonomy/src/TermBreadcrumbBuilder.php

@@ -0,0 +1,75 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\taxonomy\TermBreadcrumbBuilder.
+ */
+
+namespace Drupal\taxonomy;
+
+use Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface;
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Link;
+use Drupal\Core\Routing\RouteMatchInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+
+/**
+ * Provides a custom taxonomy breadcrumb builder that uses the term hierarchy.
+ */
+class TermBreadcrumbBuilder implements BreadcrumbBuilderInterface {
+  use StringTranslationTrait;
+
+  /**
+   * The entity manager.
+   *
+   * @var \Drupal\Core\Entity\EntityManagerInterface
+   */
+  protected $entityManager;
+
+  /**
+   * The taxonomy storage.
+   *
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  protected $termStorage;
+
+  /**
+   * Constructs the TermBreadcrumbBuilder.
+   *
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entityManager
+   *   The entity manager.
+   */
+  public function __construct(EntityManagerInterface $entityManager) {
+    $this->entityManager = $entityManager;
+    $this->termStorage = $entityManager->getStorage('taxonomy_term');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function applies(RouteMatchInterface $route_match) {
+    return $route_match->getRouteName() == 'entity.taxonomy_term.canonical'
+      && $route_match->getParameter('taxonomy_term') instanceof TermInterface;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build(RouteMatchInterface $route_match) {
+    $term = $route_match->getParameter('taxonomy_term');
+    // @todo This overrides any other possible breadcrumb and is a pure
+    //   hard-coded presumption. Make this behavior configurable per
+    //   vocabulary or term.
+    $breadcrumb = array();
+    while ($parents = $this->termStorage->loadParents($term->id())) {
+      $term = array_shift($parents);
+      $term = $this->entityManager->getTranslationFromContext($term);
+      $breadcrumb[] = Link::createFromRoute($term->getName(), 'entity.taxonomy_term.canonical', array('taxonomy_term' => $term->id()));
+    }
+    $breadcrumb[] = Link::createFromRoute($this->t('Home'), '<front>');
+    $breadcrumb = array_reverse($breadcrumb);
+
+    return $breadcrumb;
+  }
+
+}