public function reverseOrderBy()
    {
        $order = $this->getOrderBy();
        $this->orderby = array();

        foreach ($order as $clause => $dir) {
            $dir = (strtoupper($dir) == 'DESC') ? 'ASC' : 'DESC';
            $this->addOrderBy($clause, $dir);
        }

        return $this;
    }