Apply user functions to both keys and values while recursively walking an associative array

array_walk_recursive_key.php

<?php

function array_walk_recursive_key(array $array, callable $valueCallback, callable $keyCallback = null) {
    foreach ($array as $n => &$v) {
        $n2 = ($keyCallback) ? $keyCallback($n) : $n;
        if ($n != $n2) {
            $array[$n2] = &$array[$n];
            unset($array[$n]);
        }
        if (is_array($v)) {
            $array[$n2] = array_walk_recursive_key($v, $valueCallback, $keyCallback);
        } elseif (is_string($v)) {
            $array[$n2] = $valueCallback($v);
        } elseif (is_array($v)) {
            foreach ($v as &$j) {
                $j = $valueCallback($j);
            }
        }
    }
    return $array;
}