[PHP] Пример рекурсивного вывода меню

menu.php

<?php
$nav = [
    [
        'name' => 'Home',
        'title' => 'Homepage',
        // ...something else...
        'sub' => [
            [
                'name' => 'sub11',
                'title' => null,
                // ...something else...
                'sub' => [
                    [
                        'name' => 'sub111',
                        'title' => 'This is the Sub 111',
                    ],
                ],
            ],
            [
                'name' => '',
                'title' => 'This is the Sub 12',
                'sub' => [
                    [
                        'name' => null,
                        'title' => 'This is the Sub 121',
                    ],
                ],
            ],
        ],
    ],
    [
        'name' => 'sub2',
        'title' => 'This is the Sub 2',
        'sub' => [
            [
                'name' => 'sub21',
                'title' => 'This is the Sub 21',
            ],
        ],
    ],
];

function has_submenu($menu): bool
{
    return is_array($menu)
        && isset($menu['sub'])
        && !empty($menu['sub'])
        && is_array($menu['sub']);
}
function print_menu(array $menu, int $level = 0)
{
    $ident = '';
    foreach ($menu as $element) {
        $ident = str_pad($ident, $level);
        echo $ident.'Name:  '.($element['name'] ?? '(empty)').PHP_EOL;
        echo $ident.'Title: '.($element['title'] ?? '(empty)').PHP_EOL;
        echo $ident.'Url:   '.($element['url'] ?? '(empty)').PHP_EOL;
        echo $ident.'Submenu:'.(has_submenu($element) ? '' : ' (empty)' ).PHP_EOL;
        if (has_submenu($element)) {
            print_menu($element['sub'], $level += 4);
        }
        $level -= 4;
    }
}
print_menu($nav);