private function _getCombination($sourceDataSet, $setKeyList, Pointer $pointer)
    {
        $combination = array();

        $indexPointerList = $pointer->getPointerList();
        foreach ($indexPointerList as $indexPointer) {
            $namedKey = $setKeyList[$indexPointer];
            
            $combination[$namedKey] = $sourceDataSet[$namedKey];
        }

        return $combination;
    }