Re: [Boost-users] Boost.Proto embedding a function calls into expressions

Subject: Re: [Boost-users] Boost.Proto embedding a function calls into expressions
From: Kim Kuen Tang (kuentang_at_[hidden])
Date: 2010-03-25 12:05:18

Hi Stefan,

Stefan Frehse schrieb:
> Hello Boost.Proto,
> 
> firstly, thank you very much for your great work for providing such a 
> powerful framework.
> 
> My Setup: I defined  a grammar, like  grammar * grammar, a domain and so on.
> Based on the domain two evaluator for different contexts are provided. 
> For standard operators that works great.
> For  expression evaluation I have a function defined as follow:
> 
> template<typename T, typename Expr, typename Arg0, typename Arg1, ... >
> generate (T& t, Expr const& expr, Arg0 const& arg0, ... )
> {
>    call the first or the second evaluator switched by T and passes the 
> value arg0, ...
> }
> Therewith, I can write for example, generate (foo,  _1 * _2,  a, b);
> 
> Coming to my problem. I would like to  write, generate (foo, _1 * func 
> (_2, _3), a ,b, c); Overall I would like to embedd function
> calls into the expression and the pass them to the generate function.
> 
> I tried to implement a make_expr based on func, but that does not work 
> for me, i.e., compiler error for fmi::ite (_0, _1, _2) (a,b,c);
> 
> error: invalid use of incomplete type 'struct 
> fmi::ite_::result<fmi::ite_(boost::fusion::vector1<const fmi::bv&>, 
> boost::fusion::vector1<const fmi::bv&>, 
> boost::fusion::vector1<mpl_::void_&>)>'
> 
> error: declaration of 'struct 
> fmi::ite_::result<fmi::ite_(boost::fusion::vector1<const fmi::bv&>, 
> boost::fusion::vector1<const fmi::bv&>, 
> boost::fusion::vector1<mpl_::void_&>)>'
> cpp:7:
> 
> Can you imaging what the problem is? Otherwise I will attach further 
> cleaned code.

It will be more easier to understand if you can provide a standalone 
example.

Cheers,
Kim

> 
> 
> 
> Best wishes,
> sfrehse
> 
> 
> 
> 
> 
> 
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