while (!empty($stack)) {
            foreach ($stack as $curKey => &$curMerge) {
                foreach ($curMerge[0] as $key => &$val) {
                    if (!empty($curMerge[1][$key]) && (array)$curMerge[1][$key] === $curMerge[1][$key] && (array)$val === $val) {
                        $stack[] = array(&$val, &$curMerge[1][$key]);