protected function generateConstantsLines()
    {
        $code = array();
        foreach ($this->constants as $constant) {
            $constant->setIndentationString($this->getIndentationString());
            $constant->setIndentationLevel($this->getIndentationLevel() + 1);
            $code[] = $constant->generate();
            $code[] = null;
        }

        return $code;
    }