typename boost::spirit::classic::parser_result<this_t, ScannerT>::type parse(ScannerT const& scan) const { scan.first.clear_queue(); return scan.empty_match(); }
typename cl::parser_result<quickbook_range, ScannerT>::type parse(ScannerT const& scan) const { return in_range() ? scan.empty_match() : scan.no_match(); }