--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/class-wp-classic-to-block-menu-converter.php	Fri Sep 05 18:40:08 2025 +0200
@@ -0,0 +1,132 @@
+<?php
+/**
+ * WP_Classic_To_Block_Menu_Converter class
+ *
+ * @package WordPress
+ * @since 6.3.0
+ */
+
+/**
+ * Converts a Classic Menu to Block Menu blocks.
+ *
+ * @since 6.3.0
+ * @access public
+ */
+class WP_Classic_To_Block_Menu_Converter {
+
+	/**
+	 * Converts a Classic Menu to blocks.
+	 *
+	 * @since 6.3.0
+	 *
+	 * @param WP_Term $menu The Menu term object of the menu to convert.
+	 * @return string|WP_Error The serialized and normalized parsed blocks on success,
+	 *                         an empty string when there are no menus to convert,
+	 *                         or WP_Error on invalid menu.
+	 */
+	public static function convert( $menu ) {
+
+		if ( ! is_nav_menu( $menu ) ) {
+			return new WP_Error(
+				'invalid_menu',
+				__( 'The menu provided is not a valid menu.' )
+			);
+		}
+
+		$menu_items = wp_get_nav_menu_items( $menu->term_id, array( 'update_post_term_cache' => false ) );
+
+		if ( empty( $menu_items ) ) {
+			return '';
+		}
+
+		// Set up the $menu_item variables.
+		// Adds the class property classes for the current context, if applicable.
+		_wp_menu_item_classes_by_context( $menu_items );
+
+		$menu_items_by_parent_id = static::group_by_parent_id( $menu_items );
+
+		$first_menu_item = isset( $menu_items_by_parent_id[0] )
+			? $menu_items_by_parent_id[0]
+			: array();
+
+		$inner_blocks = static::to_blocks(
+			$first_menu_item,
+			$menu_items_by_parent_id
+		);
+
+		return serialize_blocks( $inner_blocks );
+	}
+
+	/**
+	 * Returns an array of menu items grouped by the id of the parent menu item.
+	 *
+	 * @since 6.3.0
+	 *
+	 * @param array $menu_items An array of menu items.
+	 * @return array
+	 */
+	private static function group_by_parent_id( $menu_items ) {
+		$menu_items_by_parent_id = array();
+
+		foreach ( $menu_items as $menu_item ) {
+			$menu_items_by_parent_id[ $menu_item->menu_item_parent ][] = $menu_item;
+		}
+
+		return $menu_items_by_parent_id;
+	}
+
+	/**
+	 * Turns menu item data into a nested array of parsed blocks
+	 *
+	 * @since 6.3.0
+	 *
+	 * @param array $menu_items              An array of menu items that represent
+	 *                                       an individual level of a menu.
+	 * @param array $menu_items_by_parent_id An array keyed by the id of the
+	 *                                       parent menu where each element is an
+	 *                                       array of menu items that belong to
+	 *                                       that parent.
+	 * @return array An array of parsed block data.
+	 */
+	private static function to_blocks( $menu_items, $menu_items_by_parent_id ) {
+
+		if ( empty( $menu_items ) ) {
+			return array();
+		}
+
+		$blocks = array();
+
+		foreach ( $menu_items as $menu_item ) {
+			$class_name       = ! empty( $menu_item->classes ) ? implode( ' ', (array) $menu_item->classes ) : null;
+			$id               = ( null !== $menu_item->object_id && 'custom' !== $menu_item->object ) ? $menu_item->object_id : null;
+			$opens_in_new_tab = null !== $menu_item->target && '_blank' === $menu_item->target;
+			$rel              = ( null !== $menu_item->xfn && '' !== $menu_item->xfn ) ? $menu_item->xfn : null;
+			$kind             = null !== $menu_item->type ? str_replace( '_', '-', $menu_item->type ) : 'custom';
+
+			$block = array(
+				'blockName' => isset( $menu_items_by_parent_id[ $menu_item->ID ] ) ? 'core/navigation-submenu' : 'core/navigation-link',
+				'attrs'     => array(
+					'className'     => $class_name,
+					'description'   => $menu_item->description,
+					'id'            => $id,
+					'kind'          => $kind,
+					'label'         => $menu_item->title,
+					'opensInNewTab' => $opens_in_new_tab,
+					'rel'           => $rel,
+					'title'         => $menu_item->attr_title,
+					'type'          => $menu_item->object,
+					'url'           => $menu_item->url,
+				),
+			);
+
+			$block['innerBlocks']  = isset( $menu_items_by_parent_id[ $menu_item->ID ] )
+			? static::to_blocks( $menu_items_by_parent_id[ $menu_item->ID ], $menu_items_by_parent_id )
+			: array();
+			$block['innerContent'] = array_map( 'serialize_block', $block['innerBlocks'] );
+
+			$blocks[] = $block;
+		}
+
+		return $blocks;
+	}
+}