注册导航链接区块。

function register_block_core_navigation_link() {
	$post_types = get_post_types( array( 'show_in_nav_menus' => true ), 'objects' );
	$taxonomies = get_taxonomies( array( 'show_in_nav_menus' => true ), 'objects' );

	// Use two separate arrays as a way to order the variations in the UI.
	// Known variations (like Post Link and Page Link) are added to the
	// `built_ins` array. Variations for custom post types and taxonomies are
	// added to the `variations` array and will always appear after `built-ins.
	$built_ins  = array();
	$variations = array();

	if ( $post_types ) {
		foreach ( $post_types as $post_type ) {
			$variation = build_variation_for_navigation_link( $post_type, 'post-type' );
			if ( $post_type->_builtin ) {
				$built_ins[] = $variation;
			} else {
				$variations[] = $variation;
			}
		}
	}
	if ( $taxonomies ) {
		foreach ( $taxonomies as $taxonomy ) {
			$variation = build_variation_for_navigation_link( $taxonomy, 'taxonomy' );
			if ( $taxonomy->_builtin ) {
				$built_ins[] = $variation;
			} else {
				$variations[] = $variation;
			}
		}
	}

	register_block_type_from_metadata(
		__DIR__ . '/navigation-link',
		array(
			'render_callback' => 'render_block_core_navigation_link',
			'variations'      => array_merge( $built_ins, $variations ),
		)
	);
}