Re: [Boost-users] [Proto] Stuck turning a complex gramamr action to a primitive trasnform

Subject: Re: [Boost-users] [Proto] Stuck turning a complex gramamr action to a primitive trasnform
From: Eric Niebler (eric_at_[hidden])
Date: 2009-10-28 15:41:27

joel wrote:
> I tried to turn a complex grammar transform
> :
> struct grammar :
> or_< ...
> 
>   ,bp::when< bp::nary_expr< bp::_, bp::vararg< grammar > >
>                          , bp::_default< grammar >
>                            (
>                               
> _bp::functional::unpack_expr<bp::tag::function>(
>                                        push_front( bp::_
>                                                  , bp::_make_terminal
>                                                    (
>                                                       some_type< 
> bp::tag_of<bp::_> >()
>                                                    )
>                                                  )
>                                       )
>                            )
>                          >
> 
> into a single primitive transform but I end up stuck cause it seems some 
> of those transform (make_terminal) don't follow
> the classic proto::result_of/proto namespace acces to compute it's 
> return type and calling it. 

I don't know what you mean. Are you referring to the fact that 
_make_terminal is not a primitive transform? It is a callable function 
object. Unfortunately, the _make_terminal name follows Proto's naming 
conventions for primitive transforms, even though it isn't. Is that what 
has thrown you off?

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