A function to retrieve the bare structure of a WordPress menu.

gistfile1.php

<?php
/**
 * Retrieve the bare structure of a nav menu instead of the formatted output.
 *
 * @param unknown $args - the same arguments you pass into wp_nav_menu (the fallback and output arguments do not apply)
 */
function prefix_get_nav_menu( $args=array() ) {
  $args = wp_parse_args( $args, array() );
	$args = apply_filters( 'wp_nav_menu_args', $args );
	$args = (object) $args;

	// Get the nav menu based on the requested menu
	$menu = wp_get_nav_menu_object( $args->menu );

	// Get the nav menu based on the theme_location
	if ( ! $menu && $args->theme_location && ( $locations = get_nav_menu_locations() ) && isset( $locations[ $args->theme_location ] ) ) {
		$menu = wp_get_nav_menu_object( $locations[ $args->theme_location ] );
	}

	// Bail if nothing was found
	if ( !$menu ) {
		return array();
	}

	// If the menu exists, get its items.
	if ( $menu && ! is_wp_error( $menu ) && !isset( $menu_items ) ) {
		$menu_items = wp_get_nav_menu_items( $menu->term_id );
	}

	// Set up the $menu_item variables
	_wp_menu_item_classes_by_context( $menu_items );

	// Sort the menu items
	$sorted_menu_items = array();
	foreach ( (array) $menu_items as $key => $menu_item ) {
		$sorted_menu_items[$menu_item->menu_order] = $menu_item;
	}
	$sorted_menu_items = apply_filters( 'wp_nav_menu_objects', $sorted_menu_items, $args );

	// Build lookup from parent to child
	$parent_to_children = array();
	foreach ( $sorted_menu_items as $item ) {
		// Make sure an array exists to add to
		if ( !isset( $parent_to_children[$item->menu_item_parent] ) ) {
			$parent_to_children[$item->menu_item_parent] = array();
		}

		$parent_to_children[$item->menu_item_parent][] = $item;
	}


	$menu_tree = _prefix_get_nav_menu_walk( $sorted_menu_items, $parent_to_children, 0 );

	return $menu_tree;
}


/**
 *
 *
 * @private
 *
 * The recursive callback for walking the menu for prefix_get_nav_menu_walk
 *
 * @param unknown_type $menu_items
 * @param unknown_type $parent_to_children
 * @param unknown_type $current_id
 */
function _prefix_get_nav_menu_walk( &$menu_items, &$parent_to_children, $current_id ) {
	if ( isset( $parent_to_children[$current_id] ) ) {
		$tree = $parent_to_children[$current_id];

		foreach ( $tree as $item ) {
			$item->children = _prefix_get_nav_menu_walk( $menu_items, $parent_to_children, $item->ID );
		}

		return $tree;
	}

	return array();
}