Re: [Spirit-general] How to call tupel/variant/optional/vector object methods in phoenix/qi

[Jeffrey L. H. Jr. <jef...@gm...>]

On Fri, Aug 19, 2011 at 3:20 PM, Marc Wäckerlin <ma...@wa...> wrote:

> Hi there
>
> If I use a rule like:
>
>  a>>b
>
> The attibute is a «tuple<A, B>» according to the documentation.
>
> How do I access the tupel in phoenix? According to tupel-documentation, I
> should be able to access the first tupel part «a» using «get<0>()»:
>
>  (a>>b)[qi::_1.get<0>()]
>
> But this fails, because «qi::_1» is not a tupel, but a:
>
>  const struct boost::phoenix::actor<boost::spirit::argument<0> >
>
> So, how to get «a» (and «b») using phoenix in «(a>>b)[...]»?
>

#include <boost\spirit\home\phoenix\fusion\at.hpp>

and then

phoenix::at_c<qi::_1>

should work.  (Unfortunately, I don't think the above header is
documented...yet :)

[...]

> Another example:
>
> Parse a line of string:
>
>  std::string res;
>  Rule r = (+qi::char_)[phoenix::ref(res)=std::string(qi::_1.begin(),
> qi::_1.end())];
>
> Which does not work for the same reason, how to access the methods
> «begin()» and «end()» of the matched vector?
>

This might help:

http://www.boost.org/doc/libs/1_47_0/libs/spirit/phoenix/doc/html/phoenix/container.html

- Jeff