protected function processScalarValue($value)/*# : string */
    {
        if (ClauseInterface::NO_VALUE == $value) {
            return '?';
        } elseif (is_null($value) || is_bool($value)) {
            return strtoupper(var_export($value, true));
        } else {
            return $this->getBuilder()->getParameter()->getPlaceholder($value);
        }
    }