在PHP中实现多级"迭代器"

function multiLevelIterator($data) {
    $iterator = new RecursiveArrayIterator($data);
    $recursiveIterator = new RecursiveIteratorIterator($iterator);
    $result = [];
    foreach ($recursiveIterator as $value) {
        $result[] = $value;
    }
    return $result;
}

$data = [
    'level1' => [
        'level2' => [
            'level3' => [
                'value1',
                'value2',
                'value3',
            ],
        ],
    ],
];

$result = multiLevelIterator($data);
print_r($result);

Array
(
    [0] => value1
    [1] => value2
    [2] => value3
)