Re: String encoding problem in R wrappers on Windows

The code in question looks like it comes from the 'out' typemap for char *,
so you are probably wrapping a function returning a char *:

%typemap(out,noblock=1) char *
 {  $result = $1 ? Rf_mkString(%reinterpret_cast($1,char *)) : R_NilValue; }

Just add in your own version with the code you want (your code doesn't
compile for me, but here it is converted into a typemap:)

%typemap(out,noblock=1) char *
// {  $result = $1 ? Rf_mkString(%reinterpret_cast($1,char *)) :
R_NilValue; }
{
  if ( $1 ) {
    PROTECT($result = Rf_mkCharCE((char *)($1), CE_UTF8));
    $result = Rf_mkString($result);
    UNPROTECT(1);
  } else {
    $result = R_NilValue;
  }
}

William



On Thu, 30 Jul 2020 at 21:42, Kevin Smith <[email protected]>
wrote:

> I’m wrapping a library that uses all UTF-8 strings as results.  I noticed
> recently that non-ASCII characters on Windows contained incorrect
> characters.  I tracked it down to the use of Rf_mkString in the wrappers
> which I’m assuming must think the C string is encoded in the native
> encoding for the platform, not necessarily UTF-8.  The lines looks like:
>
>   r_ans = result ? Rf_mkString(result) : R_NilValue;
>
> I’m not sure how to make the wrappers work properly with UTF-8 result
> strings though.  The only thing I can think of is to post-process the
> wrappers to generate code like the following.  It forces the encoding to
> UTF-8.  This approach seems pretty heavy-handed though and I was wondering
> if there was a better solution.
>
>   if ( result ) {
>     PROTECT(r_ans = Rf_mkCharCE((char *)(result), CE_UTF8));
>     r_ans = Rf_mkString(r_ans);
>     UNPROTECT(1);
>   } else {
>     r_ans = R_NilValue;
>   }
>
> Kevin Smith
> [email protected]
>
>
>
>
>
>
> _______________________________________________
> Swig-user mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/swig-user
>

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