[Boost-users] Newbie boost::spirit rule semantic action question

Subject: [Boost-users] Newbie boost::spirit rule semantic action question
From: LeMay.Steve (Steve.Lemay_at_[hidden])
Date: 2013-09-20 13:25:20

Brand-newbie boost::spirit::qi question.  MSVS2012, boost 1.54

I have a response from a serial device that provides with 0 or more "profiles" in a given character format.  I want to capture the number of profile responses in the list (semantic action) as well as have the value into the final result (std::vector<std::string>).  How do I properly express this?

Given the input....  (in this case, there are zero profiles returned)

*ARSS:0<CR><LF>OK<CR><LF>

Expect a vector of strings containing "*ARSS" "0" "OK"

This sub-rule fails to return... (Not failing to parse)

boost::spirit::qi::rule<Iter, std::vector<std::string>(), boost::spirit::qi::locals<int, std::string>> service_search_list;

       service_search_list %=                       // %= operator is necessary for attribute propagation when using symantic attributes (anything in [ ])
          string ("*ARSS") >> colon >>               // Initial response
          +digit [qi::_a = qi::_1] >> crlf >>       // Number of discovered devices - save in local qi::_a
          qi::omit [ok [qi::_b = qi::_1]] >>        // Match but don't emit the "OK" here - save it for the end
          qi::repeat (qi::_a)                       // Repeat for each discovered device
          [
                 crlf >>
         (
            qi::hold [profile1]
            | qi::hold [profile2]
            ...
         )
          ] >>
          qi::attr(qi::_b);                         // Emit the "OK" here at the end of the list

Using qi::int_[qi::_a = qi::_1] provides and empty string "" in the result and not "0".

If I omit the numeric input from the result... qi::omit [qi::int_[qi::_a = qi::_1]] the parse will succeed but number of items in the response list is lost in the final result (omitted as requested).

Any suggestion is appreciated, I'm stumped.