public function preFilter($_content)
    {
        // run pre filter if required
        if ($_content != '' &&
            ((isset($this->smarty->autoload_filters[ 'pre' ]) || isset($this->smarty->registered_filters[ 'pre' ])))
        ) {
            return $this->smarty->ext->_filterHandler->runFilter('pre', $_content, $this->template);
        } else {
            return $_content;
        }
    }