protected function transformItems()
    {
        $this->leftItems = array();
        $this->rightItems = array();
        
        foreach ($this->items as $hash => $value) {
            if (array_search($value->getKey(), $this->value) !== false) {
                $this->rightItems[] = $value;
            } else {
                $this->leftItems[] = $value;
            }
        }
    }