public function getLiteralLength()
    {
        if ($this->_stream->substring(-1, 1) === '}') {
            $literal_data = $this->_stream->getString(
                $this->_stream->search('{', true) - 1
            );
            $literal_len = substr($literal_data, 2, -1);

            if (is_numeric($literal_len)) {
                return array(
                    'binary' => ($literal_data[0] === '~'),
                    'length' => intval($literal_len)
                );
            }
        }

        return null;
    }