public function export(array &$rows)
    {
        $config     = $this->getConfiguration('export');
        $fieldNames = isset($config['fields']) ? $config['fields'] : null;
        $result     = array();

        if ($fieldNames) {
            foreach ($rows as &$row) {
                $exportRow = array();
                foreach ($fieldNames as $fieldName => $fieldCode) {
                    $exportRow[ $fieldName ] = $this->evaluateField($row, $fieldCode);
                }
                $result[] = $exportRow;
            }
        } else {
            $result = &$rows;
        }

        return $result;
    }