* @param  int    $termId               A term id.
		 * @param  string $taxonomy             The taxonomy name.
		 * @param  array  $termsToFilterAgainst Terms to filter out of the hierarchy.
		 * @return array                        The term's parent hierarchy.
		 */
		public function getFilteredTermHierarchy( $termId, $taxonomy, $termsToFilterAgainst = [] ) {
			$ancestors = $this->getTermHierarchy( $termId, $taxonomy );

			// Keep only selected terms in the hierarchy.
			if ( ! empty( $termsToFilterAgainst ) ) {
				// If it's a WP_Term array make it a term_id array.
				if ( is_a( current( $termsToFilterAgainst ), 'WP_Term' ) ) {
					$termsToFilterAgainst = wp_list_pluck( $termsToFilterAgainst, 'term_id' );
				}

				$ancestors = array_intersect( $ancestors, $termsToFilterAgainst );
			}

			return $ancestors;
		}

		/**
		 * Gets a term's parent hierarchy.
		 *
		 * @since 4.1.1
		 *
		 * @param  int    $termId   A term id.
		 * @param  string $taxonomy A taxonomy name.
		 * @return array            The term parent hierarchy.
		 */
		public function getTermHierarchy( $termId, $taxonomy ) {
			// Return a top to bottom hierarchy.
			return array_reverse( get_ancestors( $termId, $taxonomy, 'taxonomy' ) );
		}

		/**
		 * Gets a post's parent hierarchy.
		 *
		 * @since 4.1.1
		 *
		 * @param  int|\WP_Post $post An ID or a WP_Post object.
		 * @return array              The post parent hierarchy.
		 */
		public function getPostHierarchy( $post ) {
			$postId = ! empty( $post->ID ) ? $post->ID : $post;

			// Return a top to bottom hierarchy.
			return array_reverse( get_ancestors( $postId, '', 'post_type' ) );
		}

		/**
		 * Register our breadcrumb widget.
		 *
		 * @since 4.1.1
		 *
		 * @return void
		 */
		public function registerWidget() {
			register_widget( 'AIOSEO\Plugin\Common\Breadcrumbs\Widget' );
		}
	}
}

namespace {
	// Exit if accessed directly.
	if ( ! defined( 'ABSPATH' ) ) {
		exit;
	}

	if ( ! function_exists( 'aioseo_breadcrumbs' ) ) {
		/**
		 * Global function for breadcrumbs output.
		 *
		 * @since 4.1.1
		 *
		 * @param  boolean     $echo Echo or return the output.
		 * @return string|void       The output.
		 */
		function aioseo_breadcrumbs( $echo = true ) {
			return aioseo()->breadcrumbs->frontend->display( $echo );
		}
	}
}