Joomla menu list from single-dimention to multi-dimentional array

array_single_to_multi_lvl.php

<?php
/**
 * Refer: https://stackoverflow.com/questions/14961556/convert-one-dimensional-array-into-a-multi-dimensional-array/14963016#14963016
 * 
 * @param mixed $menu_items 
 * @param int $depth 
 * @access public
 * @return array
 */
function array_multi_level($menu_items, $depth = 1) {
    $items = array();
    $in_current_depth = true;

    foreach ($menu_items as $key => $item) {
        if ($item->level < $depth) return $items;
        else if ($item->level == $depth) {
            $in_current_depth = true;
            $items[] = $item;
        }

        if ($in_current_depth && $item->level > $depth) {
            $in_current_depth = false;
            $item_left = array_slice($menu_items, $key);
            @$items[$key - 1]->children = array_multi_level($item_left, $item->level);
        }
    }

    return $items;
}