[libcxx-commits] [PATCH] D59178: [libc++] Speedup to_string and to_wstring for integers using stack buffer and SSO

Afanasyev Ivan via Phabricator via libcxx-commits libcxx-commits at lists.llvm.org
Thu Mar 21 08:44:57 PDT 2019

ivafanas added a comment.

In D59178#1436754 <https://reviews.llvm.org/D59178#1436754>, @mclow.lists wrote:

> Now that revision 356585 has landed,  we can use `std::to_chars` to implement `to_string`
> I would suggest something like (untested code):
>   template <class T>
>   string __to_chars(T t)
>   {
>   char buf[numeric_limits<T>::digits10() + 3]; // +1 for '-' +1 for nul, and +1 for extra
>   to_chars_result res(buf, buf + sizeof(buf), t, 10);
>   return string(buf, res.ptr);
>   }
> and then call *that* from the various `to_string` implementations.

Hi, Marshall.

I've started implementing and testing `to_string` via `to_chars` and realized that `to_chars` doesn't support `wchar_t` unlike `to_wstring`.
I'm going to extend `__to_chars_itoa` implementation in order to support `wchar_t` and reuse those internal template function.

Could you please confirm that this way is ok in order not to through away the third attempt on completion.



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