Re: x3::variant vs boost::variant

Baptiste Wicht <[email protected]> Sat, 20 Feb 2016 10:14:49 +0100
Newsgroups	gmane.comp.parsers.spirit.general
Message-ID	<[email protected]>
On Sat, Feb 20, 2016 at 05:42:14AM +0800, Joel de Guzman wrote:
> On 2/18/16 4:48 AM, Baptiste Wicht wrote:
>
> > The main problem that remains is with x3::variant and x3::forward_ast:
> >
> > I have a type like this:
> >
> >      using Type = boost::spirit::x3::variant<
> >              SimpleType,
> >              boost::spirit::x3::forward_ast<ArrayType>,
> >              boost::spirit::x3::forward_ast<TemplateType>,
> >              boost::spirit::x3::forward_ast<PointerType>
> >          >;
> >
> > And a lot of code resembling this:
> >
> >      if(auto* ptr = boost::get<ast::SimpleType>(&type)){
> >          //Do something on *ptr
> >      } else if(auto* ptr = boost::get<ast::ArrayType>(&type)){
> >          //Do something on *ptr
> >      } else if(auto* ptr = boost::get<ast::PointerType>(&type)){
> >          //...
> >      }
> >      //...
> >
> > But this does not work since ArrayType is not a member of the variant
> > because of the forward_ast and I have an error from boost strict_get.
> >
> > I really have a lot of code like this, I won't be able (neither have the
> > motivation for it) to change all of it. If there is no simple solution,
> > I'll use my old AST with boost::variant and recursive_wrapper.
> >
> > Is there anything I can do to use boost::get with forward_ast ?
>
> There should be a solution. tell you what. Give me a minimal test
> case and I can work on getting it compile and run as expected.

Here it is: http://coliru.stacked-crooked.com/a/641b689346ff322c

Thanks :)

> Regards,
> --
> Joel de Guzman
> http://www.ciere.com
> http://boost-spirit.com
> http://www.cycfi.com/
>
>
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