Re: [boost] [metaparse] performance comparisons?

Subject: Re: [boost] [metaparse] performance comparisons?
From: Evgeny Panasyuk (evgeny.panasyuk_at_[hidden])
Date: 2015-06-07 06:40:31

07.06.2015 12:07, Roland Bock:
> However, this is limited in the way that the type cannot be based on a
> literal outside a struct/class. There also is a macro that can be
> employed to create such types, e.g:
>
> SQLPP_ALIAS_PROVIDER(hello);

By the way, I saw sqlpp11 earlier, and I think that alias/field provider 
is a useful meta-programming tool on it's own.
https://github.com/rbock/sqlpp11/blob/master/include/sqlpp11/alias_provider.h#L33-L48

For example it can be used in transformation of vector of structs into 
structs of vectors - such macro would provide names for fields in 
synthesized struct of references.

Perhaps it could be embedded by default into BOOST_FUSION_DEFINE_STRUCT 
and others.

Also I think following template intrinsic can be useful addition to C++ ISO:

template<char...> struct names_provider;

Which would be automatically specialized by compiler on usage, for 
example something like:

template<>
struct names_provider<'f', 'o', 'o'>
{
     template<typename T>
     struct field
     {
         T foo;
     };
     template<typename F>
     struct method
     {
         template<typename ...Ts>
         auto foo(Ts... args)
         {
             return F{}(args...);
         }
     };
     // ...
};

With help of such intrinsic it is possible to parse string with some 
EDSL at compile time, and based only on this generate all required 
structures defined by language embedded in string.

Best Regards,
Evgeny Panasyuk