PHP Array Whitelist and Blacklist functions

array-keys.php

<?php

if (!function_exists('array_keys_whitelist')) {
    function array_keys_whitelist(array $array, array $whitelist): array
    {
        return array_intersect_key($array, array_flip($whitelist));
    }
}

if (!function_exists('array_keys_blacklist')) {
    function array_keys_blacklist(array $array, array $blacklist): array
    {
        return array_diff_key($array, array_flip($blacklist));
    }
}