Re: [boost] Compile Time String in C++11/C++14

Subject: Re: [boost] Compile Time String in C++11/C++14
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 2014-08-26 07:43:17

Tongari J wrote:
> Hi Louis,
>
> 2014-08-26 0:01 GMT+08:00 Louis Dionne <ldionne.2_at_[hidden]>:
>> This is genius, thanks a lot for posting. I've been searching for a
>> way to do this to implement compile-time strings in Boost.Hana[1].
>>
> Glad to hear :)
>
> Actually I've found an even simpler way:

Nice! And with some small tweaks it works in C++11, assuming you have 
some implementation of index_sequence:

```
     template<char...>

     struct  str  {};

     template<std::size_t...  Ns,  class  S>

     auto  make_str_impl(index_sequence<Ns...>,  S)  ->  decltype(str<S::get()[Ns]...>())

     {

          return  str<S::get()[Ns]...>();

     }

     template<class  S>

     auto  make_str(S)  ->  decltype(make_str_impl(make_index_sequence<sizeof(S::get())  -  1>(),  S()))

     {

          return  make_str_impl(make_index_sequence<sizeof(S::get())  -  1>(),  S());

     }

     #define  LIT(s)  make_str([]()  \

     {  \

          struct  \

          {  \

              static  constexpr  decltype(s)  get()  \

              {  \

                  return  s;  \

              }  \

          }  _;  \

          return  _;  \

     }())

```

Well VS2013 complains about a static data member in locally defined 
class but I assume it's a VS bug.

Regards,
Adam