Custom wordpress menu: Get menu as hierarchical array with children

menu.php

<?php 

	// is child of, recursive

	function is_child_of( $post, $possible_parent_ID ) {
		if ($post->ID == $possible_parent_ID) {
			return true;
		} elseif ($post->post_parent == 0) {
			return false;
		} else {
			return is_child_of( get_post($post->post_parent), $possible_parent_ID );
		}
	}


	// convert relative to absolute URLs

	function relative_to_absolute_URL($rel, $base) {
	    /* return if already absolute URL */
	    if (parse_url($rel, PHP_URL_SCHEME) != '') return $rel;

	    /* queries and anchors */
	    if ($rel[0]=='#' || $rel[0]=='?') return $base.$rel;

	    /* parse base URL and convert to local variables:
	       $scheme, $host, $path */
	    extract(parse_url($base));

	    /* remove non-directory element from path */
	    $path = preg_replace('#/[^/]*$#', '', $path);

	    /* destroy path if relative url points to root */
	    if ($rel[0] == '/') $path = '';

	    /* dirty absolute URL */
	    $abs = "$host$path/$rel";

	    /* replace '//' or '/./' or '/foo/../' with '/' */
	    $re = array('#(/\.?/)#', '#/(?!\.\.)[^/]+/\.\./#');
	    for($n=1; $n>0; $abs=preg_replace($re, '/', $abs, -1, $n)) {}

	    /* absolute URL is ready! */
	    return $scheme.'://'.$abs;
	}


	// custom menu url (e.g. '/custom-archive') – is it current?

	function custom_post_type_menu_current($menuitem) {

		// menu item URL
		$url = $menuitem->url;
		$url = relative_to_absolute_URL($url, site_url());

		// custom post type archive link
		$post_type = get_post_type( get_the_ID() );
		$post_type_archive_link = get_post_type_archive_link($post_type);

		$custom_post_type_archive_link = rtrim($post_type_archive_link,"/");

		if (!$custom_post_type_archive_link) {
			return false;
		}

		if (strpos($url,$custom_post_type_archive_link) !== false) {
			return  true;
		}
		return false;
	}

	function category_menu_current($post, $menuitem) {
		
		if ($menuitem->object !== 'category') {
			return false;
		}

		$categories = get_the_category( $post->ID );
		if (is_category($menuitem->object_id)) {
			return true;
		}

		if ((is_page() || is_single())  && ((int)$menuitem->object_id === $category->term_taxonomy_id)) {
			return true;
		}

		return false;
	}


	// hierarchical menus

	function menu_has_children($item) {
		if (!empty($item->children)) {
			return true;
		} else {
			return false;
		}
	}

	// find id in multidimensional menuitems, recursive

	function find_parent_in_multi_menuitems($id, $menuitems) {	
		foreach ($menuitems as $menuitem) {
			if ((int) $id === (int) $menuitem->ID) {
				// $menuitem->level = $level;
				return $menuitem;
			} else {
				// get children
				if ($children = $menuitem->children) {
					// find parent
					$parent = find_parent_in_multi_menuitems($id, $children);
				}
			}
		}
		return false;
	}

	// for each menuitems, recursive

	function get_heirachical_menu($menu_name, $locations) {

		global $post;
		// get current post object
		
		$the_post_id = false;
		if (!empty($post->ID)) {
			$the_post_id = $post->ID;
		}
		
		if (empty($locations[$menu_name])) {
			return false;
		}

		$menu = wp_get_nav_menu_object( $locations[ $menu_name ] );

		// get wordpress menu items from menu
		$menuitems = wp_get_nav_menu_items( $menu->term_id, array( 'order' => 'DESC' ) );


		$menu_items_multidimensional = array();

		foreach ($menuitems as $menuitem) {

			// add current classes
			$menuitem->current = false;

			// current page is current
			if ($the_post_id === (int)$menuitem->object_id && $menuitem->object === 'page') {
				$menuitem->current = true;
		    }

		    // current post is current
		    if ($the_post_id === (int)$menuitem->object_id && $menuitem->object === 'post') {
				$menuitem->current = true;
		    }

		    // if is child of post
		    if ( is_child_of($post, (int)$menuitem->object_id) && ($menuitem->object === 'page') ) {
		    	$menuitem->current = true;
		    }

			// get parent ID
			$parentID = $menuitem->menu_item_parent;
			// setup childrens array if doesn't exist
			if (!$menuitem->children) {
				$menuitem->children = array();
			} 

			// if menu item is top level
			if ((int) $parentID === 0) {
				// add to multidimensional array;
				$menuitem->level = 0;
				$menu_items_multidimensional[] = $menuitem;
			} else {
				// find parent
				$parent = find_parent_in_multi_menuitems($parentID, $menuitems);
				// add this item to parent->children array();
				if ($menuitem->current) {
					$parent->current = true;
				}

				$menuitem->level = $parent->level + 1;
				$parent->children[] = $menuitem;
			}

			// sort custom post type current classes
			if (custom_post_type_menu_current($menuitem)) {
				$menuitem->current = true;
			}


			if (category_menu_current($post, $menuitem)) {
				$menuitem->current = true;
			}
		}

		return $menu_items_multidimensional;
	}



	// get wordpress menu locations
	$menu_locations = get_nav_menu_locations(); 

	// get menus with $menu = get_heirachical_menu('menu_name', $menu_locations);