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Joel Falcou | 11 Oct 17:45
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[Proto] Strange behavior with semantic action and custom tag function

I'm stuck on some problem that may en dup silly.
I have a DSL defined by the following grammar :

struct dimen_grammar : bp::or_<

//////////////////////////////////////////////////////////////////////////
    // Terminals are dimensional values or integral values

//////////////////////////////////////////////////////////////////////////
   bp::or_< bp::terminal< dimensions<bp::_,bp::_> >
           , integer_grammar
           >

//////////////////////////////////////////////////////////////////////////
    // dimen can be added together or scaled by an integer
   // or shifted left or right by an integer

////////////////////////////////////////////////////////////////////////// 

   ,bp::or_< bp::plus<dimen_grammar,dimen_grammar>
        ,bp::multiplies<dimen_grammar,integer_grammar>
            ,bp::multiplies<integer_grammar,dimen_grammar>
         ,bp::shift_left<dimen_grammar,integer_grammar>
           ,bp::shift_right<dimen_grammar,integer_grammar>
           >
    > {};

I've defined a proper callable_context that take care of my special
terminals and built
a terminal class. At this point, everythign works perfect : i can build
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Eric Niebler | 11 Oct 18:04

Re: [Proto] Strange behavior with semantic action and custom tag function

Joel Falcou wrote:
> I'm stuck on some problem that may en dup silly.

<snip very beautifully written transform>

> This works. If I remove the bp::when<bp::_, bm::size_t<0>()>, it fails
> to compile when I try to use a hand-overloaded operator<< for
> displaying expression values on standard output.

Could you post the code? The problem is probably pretty simple.

> So, is there anything I missed (like deactivating operator<< in the
> grammar somehow ?) ?
> 
> Other question :
> When defining custom tag to build new function, why does the make_expr
> tempalte doesn't do check on its argument
> to see if it's match the grammar of the domain it's bound to use ? Seems
> I'm forced to add additional layer of SFINAE to prevent those
> function to get called on w/e types.

It's true, with make_expr you can create expressions that don't conform 
to the grammar for your domain. But a call to make_expr is pretty 
explicit -- it can't happen by accident. And make_expr is to be used by 
DSEL designers such as yourself who may use it to build an expression 
template piecemeal ... the intermediate pieces of which may not conform 
to the grammar, while the whole might. Does that make sense?

--

-- 
Eric Niebler
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Joel Falcou | 11 Oct 18:22
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Re: [Proto] Strange behavior with semantic action and custom tag function

Eric Niebler a écrit :
> <snip very beautifully written transform>
>
I take this as a compliment :D
> Could you post the code? The problem is probably pretty simple.
The complete code ? Wow, it may end up rather large. I'll pack it in 
some archive
of only the DSL related part and attach it to this mail. It won't be 
compilable though
as it has large roots into a even larger project.
> It's true, with make_expr you can create expressions that don't 
> conform to the grammar for your domain. But a call to make_expr is 
> pretty explicit -- it can't happen by accident. And make_expr is to be 
> used by DSEL designers such as yourself who may use it to build an 
> expression template piecemeal ... the intermediate pieces of which may 
> not conform to the grammar, while the whole might. Does that make sense?
I see. So it's my responsibility to write correct make_expr code then to 
SFINAE them out if I need it.
The current problem arise with a simple complex number DSL I'm writing 
as an introductory example
for a master degree 'Generic Programming in C++' lesson I'm building up. 
I have a conj_ tag which
represents taking the conjugate of a complex number.

The function itself is :

  template<class X>
  typename proto::result_of::make_expr<conj_, complex_domain,X const 
&>::type
  conj( X const& x )
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Joel Falcou | 11 Oct 18:26
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Re: [Proto] Strange behavior with semantic action and custom tag function

Well ofc I have to fail and forgot the zip v_v
Here it is.
It contains folder : dimen, which have all the context,expression,entity 
and grammar
&  ast which contains some helper I wrote

--

-- 
___________________________________________
Joel Falcou - Assistant Professor
PARALL Team - LRI - Universite Paris Sud XI
Tel : (+33)1 69 15 66 35
Attachment (error_dsl.zip): application/zip, 10 KiB
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Eric Niebler | 12 Oct 16:47

Re: [Proto] Strange behavior with semantic action and custom tag function

Joel Falcou wrote:
> Well ofc I have to fail and forgot the zip v_v Here it is. It
> contains folder : dimen, which have all the context,expression,entity
> and grammar &  ast which contains some helper I wrote

This is a bug in Proto. The following small program reproduces the error:

   #include <iostream>
   #include <boost/proto/proto.hpp>

   namespace mpl = boost::mpl;
   namespace proto = boost::proto;
   using proto::_;

   template<class E>
   struct e;

   struct g
     : proto::or_<
           proto::terminal<int>
         , proto::plus<g,g>
       >
   {};

   struct d
     : proto::domain<proto::generator<e>, g>
   {};

   template<class E>
   struct e
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Joel Falcou | 12 Oct 16:59
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Re: [Proto] Strange behavior with semantic action and custom tag function

Eric Niebler a écrit :
> This is a bug in Proto. The following small program reproduces the error:
> <snip>
> I'll see about fixing this bug. Please open a track ticket. Thanks.
Ok , ticket is :

http://svn.boost.org/trac/boost/ticket/2407

Thanks for the head up :)
I'll keep the work-around for now on and wait for a bug fix :)

--

-- 
___________________________________________
Joel Falcou - Assistant Professor
PARALL Team - LRI - Universite Paris Sud XI
Tel : (+33)1 69 15 66 35
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Eric Niebler | 17 Nov 00:25

Re: [Proto] Strange behavior with semantic action and custom tag function

Joel Falcou wrote:
> Eric Niebler a écrit :
>> This is a bug in Proto. The following small program reproduces the error:
>> <snip>
>> I'll see about fixing this bug. Please open a track ticket. Thanks.
> Ok , ticket is :
> 
> http://svn.boost.org/trac/boost/ticket/2407
> 
> Thanks for the head up :)
> I'll keep the work-around for now on and wait for a bug fix :)

This bug is now fixed in trunk as of revision 49812. Sorry for the delay.

https://svn.boost.org/trac/boost/changeset/49812

--

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