ar WP $wp */
		global $wp;

		// Non-publicly queryable taxonomies should not register query vars, except in the admin.
		if ( false !== $this->query_var && $wp ) {
			$wp->add_query_var( $this->query_var );
		}

		if ( false !== $this->rewrite && ( is_admin() || get_option( 'permalink_structure' ) ) ) {
			if ( $this->hierarchical && $this->rewrite['hierarchical'] ) {
				$tag = '(.+?)';
			} else {
				$tag = '([^/]+)';
			}

			add_rewrite_tag( "%$this->name%", $tag, $this->query_var ? "{$this->query_var}=" : "taxonomy=$this->name&term=" );
			add_permastruct( $this->name, "{$this->rewrite['slug']}/%$this->name%", $this->rewrite );
		}
	}

	/**
	 * Removes any rewrite rules, permastructs, and rules for the taxonomy.
	 *
	 * @since 4.7.0
	 *
	 * @global WP $wp Current WordPress environment instance.
	 */
	public function remove_rewrite_rules() {
		/* @var WP $wp */
		global $wp;

		// Remove query var.
		if ( false !== $this->query_var ) {
			$wp->remove_query_var( $this->query_var );
		}

		// Remove rewrite tags and permastructs.
		if ( false !== $this->rewrite ) {
			remove_rewrite_tag( "%$this->name%" );
			remove_permastruct( $this->name );
		}
	}

	/**
	 * Registers the ajax callback for the meta box.
	 *
	 * @since 4.7.0
	 */
	public function add_hooks() {
		add_filter( 'wp_ajax_add-' . $this->name, '_wp_ajax_add_hierarchical_term' );
	}

	/**
	 * Removes the ajax callback for the meta box.
	 *
	 * @since 4.7.0
	 */
	public function remove_hooks() {
		remove_filter( 'wp_ajax_add-' . $this->name, '_wp_ajax_add_hierarchical_term' );
	}

	/**
	 * Gets the REST API controller for this taxonomy.
	 *
	 * Will only instantiate the controller class once per request.
	 *
	 * @since 5.5.0
	 *
	 * @return WP_REST_Controller|null The controller instance, or null if the taxonomy
	 *                                 is set not to show in rest.
	 */
	public function get_rest_controller() {
		if ( ! $this->show_in_rest ) {
			return null;
		}

		$class = $this->rest_controller_class ? $this->rest_controller_class : WP_REST_Terms_Controller::class;

		if ( ! class_exists( $class ) ) {
			return null;
		}

		if ( ! is_subclass_of( $class, WP_REST_Controller::class ) ) {
			return null;
		}

		if ( ! $this->rest_controller ) {
			$this->rest_controller = new $class( $this->name );
		}

		if ( ! ( $this->rest_controller instanceof $class ) ) {
			return null;
		}

		return $this->rest_controller;
	}

	/**
	 * Returns the default labels for taxonomies.
	 *
	 * @since 6.0.0
	 *
	 * @return (string|null)[][] The default labels for taxonomies.
	 */
	public static function get_default_labels() {
		if ( ! empty( self::$default_labels ) ) {
			return self::$default_labels;
		}

		$name_field_description   = __( 'The name is how it appears on your site.' );
		$slug_field_description   = __( 'The “slug” is the URL-friendly version of the name. It is usually all lowercase and contains only letters, numbers, and hyphens.' );
		$parent_field_description = __( 'Assign a parent term to create a hierarchy. The term Jazz, for example, would be the parent of Bebop and Big Band.' );
		$desc_field_description   = __( 'The description is not prominent by default; however, some themes may show it.' );

		self::$default_labels = array(
			'name'                       => array( _x( 'Tags', 'taxonomy general name' ), _x( 'Categories', 'taxonomy general name' ) ),
			'singular_name'              => array( _x( 'Tag', 'taxonomy singular name' ), _x( 'Category', 'taxonomy singular name' ) ),
			'search_items'               => array( __( 'Search Tags' ), __( 'Search Categories' ) ),
			'popular_items'              => array( __( 'Popular Tags' ), null ),
			'all_items'                  => array( __( 'All Tags' ), __( 'All Categories' ) ),
			'parent_item'                => array( null, __( 'Parent Category' ) ),
			'parent_item_colon'          => array( null, __( 'Parent Category:' ) ),
			'name_field_description'     => array( $name_field_description, $name_field_description ),
			'slug_field_description'     => array( $slug_field_description, $slug_field_description ),
			'parent_field_description'   => array( null, $parent_field_description ),
			'desc_field_description'     => array( $desc_field_description, $desc_field_description ),
			'edit_item'                  => array( __( 'Edit Tag' ), __( 'Edit Category' ) ),
			'view_item'                  => array( __( 'View Tag' ), __( 'View Category' ) ),
			'update_item'                => array( __( 'Update Tag' ), __( 'Update Category' ) ),
			'add_new_item'               => array( __( 'Add New Tag' ), __( 'Add New Category' ) ),
			'new_item_name'              => array( __( 'New Tag Name' ), __( 'New Category Name' ) ),
			'separate_items_with_commas' => array( __( 'Separate tags with commas' ), null ),
			'add_or_remove_items'        => array( __( 'Add or remove tags' ), null ),
			'choose_from_most_used'      => array( __( 'Choose from the most used tags' ), null ),
			'not_found'                  => array( __( 'No tags found.' ), __( 'No categories found.' ) ),
			'no_terms'                   => array( __( 'No tags' ), __( 'No categories' ) ),
			'filter_by_item'             => array( null, __( 'Filter by category' ) ),
			'items_list_navigation'      => array( __( 'Tags list navigation' ), __( 'Categories list navigation' ) ),
			'items_list'                 => array( __( 'Tags list' ), __( 'Categories list' ) ),
			/* translators: Tab heading when selecting from the most used terms. */
			'most_used'                  => array( _x( 'Most Used', 'tags' ), _x( 'Most Used', 'categories' ) ),
			'back_to_items'              => array( __( '← Go to Tags' ), __( '← Go to Categories' ) ),
			'item_link'                  => array(
				_x( 'Tag Link', 'navigation link block title' ),
				_x( 'Category Link', 'navigation link block title' ),
			),
			'item_link_description'      => array(
				_x( 'A link to a tag.', 'navigation link block description' ),
				_x( 'A link to a category.', 'navigation link block description' ),
			),
		);

		return self::$default_labels;
	}

	/**
	 * Resets the cache for the default labels.
	 *
	 * @since 6.0.0
	 */
	public static function reset_default_labels() {
		self::$default_labels = array();
	}
}