Re: [Boost-users] [Proto]: How to use complex grammars in a domain/extension

Subject: Re: [Boost-users] [Proto]: How to use complex grammars in a domain/extension
From: Roland Bock (rbock_at_[hidden])
Date: 2010-09-21 03:15:10

On 09/21/2010 08:54 AM, Joel Falcou wrote:
> On 20/09/10 22:57, Roland Bock wrote:
>> typedef proto::terminal<proto::_>::type terminal;
>>
>> struct addition:
>>     proto::or_
>> <
>>        terminal,
>>        proto::plus<addition, addition>
>> >
>> {};
>
> terminal is a terminal type, not a terminal grammar:
>
> struct addition :
>    proto::or_< proto::terminal<proto::_>
>          , proto::plus<addition,addition>
> > {};
That did not make a difference:

// -----------------------------------------------------------------
#include<complex>
#include<boost/proto/proto.hpp>

using namespace boost;

struct addition :
    proto::or_
    <
       proto::terminal<proto::_>
     , proto::plus<addition,addition>
    >
{};

struct equation:
    proto::or_
    <
       proto::equal_to<addition, addition>
    >
{};

template<class Expr>
struct extension;

struct my_domain
   : proto::domain<
         proto::pod_generator<  extension>
       , equation
     >
{};

template<class Expr>
struct extension
{
     BOOST_PROTO_EXTENDS(
         Expr
       , extension<Expr>
       , my_domain
     )
};

int main()
{
     extension<proto::terminal<int>::type>  i;

     i == i; // ERROR
}
// -----------------------------------------------------------------

Regards,

Roland