public function isCronDue($expr, $time = null)
    {
        list($expr, $times) = $this->process($expr, $time);

        foreach ($expr as $pos => $segment) {
            if ($segment === '*' || $segment === '?') {
                continue;
            }

            if (!$this->checker->checkDue($segment, $pos, $times)) {
                return false;
            }
        }

        return true;
    }