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

Subject: Re: [Boost-users] Newbie boost::spirit rule semantic action question
From: TONGARI J (tongari95_at_[hidden])
Date: 2013-09-21 00:50:01

2013/9/21 LeMay.Steve <Steve.Lemay_at_[hidden]>

> 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”.
>

Because int_ returns "int" which is not comatible with "string".
>
> ****
>
> ** **
>
> 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).
>

Try qi::raw[], it'll give you a range which is string-compatible.

HTH