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: Eric Niebler (eric_at_[hidden])
Date: 2010-09-21 09:39:48

On 9/21/2010 4:11 AM, Roland Bock wrote:
> 
> On 09/21/2010 09:49 AM, Joel Falcou wrote:
>> The following code works here:
>>
>> //
>> -----------------------------------------------------------------------
>> [...]
> Yes, I know, but that is not the grammar I need. I want to combine my
> terminal similar to std::string, so that:
> 
> std::string a, b;
> 
> a; // ok
> a + b; // ok
> a == b; // ok
> a == b + b; // ok
> a && a == b; // ERROR
> 
>>
>> Seems proto::or_ wiht *1* condition acts weird.
>> Eric, am I right or am I hallucinating and missing the obvious ?
> 
> You can remove the proto::or_ like
> 
> struct equation:
>       proto::equal_to<addition, addition>
> {};
> 
> It does not change the result. So it does not look like a problem in
> proto::or_, but maybe a bug in how proto determines the operators of
> extensions?

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

?

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com