[Swig-user] Odp: wstring in Ruby

[<von...@am...>]

Hello Dan,

I faced the same issue some time ago. The problem is that Ruby does not 
know too much about wide characters, however it can works well with UTF-8 
encoding. Since there are no conversion routines in Ruby C interface which 
would allowed you to convert wide chars to UTF-8 encoded characters, you 
have to provide this conversion by yourself at now.

I have placed following implementation (which mimics Python implementation 
of the same swig fragments) on top of my .i file:

%fragment("SWIG_AsWCharPtrAndSize","header",fragment="<wchar.h>",fragment="SWIG_pwchar_descriptor") 
{
SWIGINTERN int
SWIG_AsWCharPtrAndSize(VALUE obj, wchar_t **cptr, size_t *psize, int 
*alloc)
{
  if (TYPE(obj) == T_STRING) {
    %#if defined(StringValuePtr)
    char *cstr = StringValuePtr(obj); 
    %#else
    char *cstr = STR2CSTR(obj);
    %#endif

        std::wstring tempStr = WcsServices::aswcs(cstr, 
WcsServices::cp_utf8);

    size_t size = tempStr.size() + 1;
    if (cptr)  {
      if (alloc) { 
                *cptr = %new_copy_array(tempStr.c_str(), size, wchar_t);
                *alloc = SWIG_NEWOBJ;
      }
    }
    if (psize) *psize = size;
    return SWIG_OK;
  } else {
    swig_type_info* pwchar_descriptor = SWIG_pwchar_descriptor();
    if (pwchar_descriptor) {
      void* vptr = 0;
      if (SWIG_ConvertPtr(obj, &vptr, pwchar_descriptor, 0) == SWIG_OK) {
        if (cptr) *cptr = (wchar_t *)vptr;
        if (psize) *psize = vptr ? (wcslen((wchar_t*)vptr) + 1) : 0;
        if (alloc) *alloc = SWIG_OLDOBJ;
        return SWIG_OK;
      }
    }
  } 
  return SWIG_TypeError;
}
}

%fragment("SWIG_FromWCharPtrAndSize","header",fragment="<wchar.h>",fragment="SWIG_pwchar_descriptor") 
{
SWIGINTERNINLINE VALUE
SWIG_FromWCharPtrAndSize(const wchar_t * carray, size_t size)
{
  if (carray) {
        std::string tempStr(WcsServices::asmbs(carray, 
WcsServices::cp_utf8));

    if (tempStr.size() > LONG_MAX) {
      swig_type_info* pwchar_descriptor = SWIG_pwchar_descriptor();
      return pwchar_descriptor ? 
                SWIG_NewPointerObj(%const_cast(carray,wchar_t *), 
pwchar_descriptor, 0) : Qnil;
    } else {
      return rb_str_new(tempStr.c_str(), 
%numeric_cast(tempStr.size(),long));
    }
  } else {
    return Qnil;
  }
}
}

%include <typemaps/cwstring.swg>
%include <typemaps/std_wstring.swg>


Note that WcsServices class is the class which is responsible for 
conversions between wide chars and chars. You have replace it by your own 
code. Also note that you should not include %include <cwstring.i> and 
%include <std_wstring.i> since they are useless yet. 

Anyway I feel this is ugly workaround, so I would be glad to see some 
better solution soon. Hopefully Ruby 2.0 will bring more light into this 
issue.



Vit
 



"Macumber, Daniel" <Dan...@nr...> 
08.05.2009 20:25

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[Swig-user] wstring in Ruby






I am able to SWIG, compile, and successfully run the test case 
"li_std_string.i" for Ruby 1.8 using SWIG 1.3.39.  However, when I try to 
do this with "li_std_wstring.i" I get the following errors:

1>c:\working\test\li_std_wstring_wrap.cxx(2834) : error C3861: 
'SWIG_AsCharPtrAndSize': identifier not found

1>c:\working\test\li_std_wstring_wrap.cxx(2915) : error C3861: 
'SWIG_FromCharPtrAndSize': identifier not found

I noticed that there is a "li_std_string_runme.rb" in the test-suite\ruby 
directory but no "li_std_wstring_runme.rb".  Does this imply that wstring 
is not supported in Ruby?  There is a "std_wstring.i" in the Lib\ruby 
directory which made me think wstring should be supported?

Thanks a lot,
Dan


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