Polyfill for `call_user_func` and `call_user_func_array` in hack lang

polyfill.hh

<?hh // strict

namespace Polyfill;

use type ReflectionMethod;
use type ReflectionFunction;

function call_user_func(mixed $callable, mixed ...$args): mixed {
    return call_user_func_array($callable, $args);
}

function call_user_func_array(mixed $callable, varray<mixed> $args): mixed {
    if (\is_object($callable)) {
        $reflection = new ReflectionMethod($callable, '__invoke');
        return $reflection->invokeArgs($callable, $args);
    } elseif ($callable is string) {
        $reflection = new ReflectionFunction($callable);
        return $reflection->invokeArgs($args);
    } elseif ($callable is (string, string)) {
        $reflection = new ReflectionMethod($callable[0], $callable[1]);
        return $reflection->invokeArgs(null, $args);
    } elseif ($callable is (mixed, string)) {
        $reflection = new ReflectionMethod($callable[0], $callable[1]);
        return $reflection->invokeArgs($callable[0], $args);
    } else {
        $reflection = new ReflectionFunction($callable);
        return $reflection->invokeArgs($args);
    }
}