/**
  * @param FOLDER $obj
  * @return boolean
  * @access private
  */
 protected function _is_indexable_object($obj)
 {
     $Result = !isset($this->_filter_by_sets);
     if (!$Result) {
         $Result = $obj->defines_security();
         if ($Result) {
             $idx_set = 0;
             while ($Result && $idx_set < sizeof($this->_filter_by_sets)) {
                 $Result = $this->_user->is_allowed($this->_filter_by_sets[$idx_set], $this->_filter_by_types[$idx_set], $obj);
                 $idx_set += 1;
             }
         }
     }
     return $Result;
 }