Re: [Boost-users] string algo problem

From: Pavol Droba (droba_at_[hidden])
Date: 2005-08-09 15:58:27

Hi,

to_upper algorithm is using locales to perform the conversion. By defualt, default
locales are used. AFAIK locales in the standar library support only char and wchar_t
data types. So you need to provide your own conversion facet to the locales
(the one, that will work with UTF16:Char) and provide this locales as a parameter
to the to_upper algorithm. (or you can modify the default locales).

Unless so you do so, to_upper will not be able to work with your string class.

Best Regards,
Pavol.

On Tue, Aug 09, 2005 at 06:55:00PM +0200, Giampiero Gabbiani wrote:
> hi to all,
> I'm trying to implementing a string class as a std::list of elements that
> can be common char, wchar_t or something else (as utf-16 chars, for
> example).
> In order to obtain this, I've defined a collection as a template class, and
> used with different value_type(s).
> When I try to use the collection with char or wchar_t, the boost algo
> to_upper works fine but, when I use the collection template with a
> UTF16::Char (a class that implements the UTF-16 encoding) I obtain the
> following exception:
> 
> Exception catch:St8bad_cast
> 
> The following code is the definition of the Char class and an example of its
> use with the standard list and the boost algo:
> 
> namespace UTF16 {
> 
> class Char {
> public:
>   Char();
>   Char(const char c);
>   // UTF-16 encoding constructor
>   Char(wchar_t v);
>   bool operator == (const Char& c) const;  
>   bool operator != (const Char& c) const;
>   operator wchar_t () const;
>   Char(const Char& chr);
>   Char(Char& chr);
>   ~Char();
>   Char& operator = (const Char& chr);
>   Char& operator = (Char& chr);
> private:
>   u_int16_t* _value;
>   size_t _size;
> };
> 
> }
> 
> 
> int main(int argc, char *argv[]) {
>   try {
>     list<UTF16::Char> l;
>     l.push_back(UTF16::Char('a'));
> 
>     // THE FOLLOWING LINE PRODUCES A 'bad_cast' exception...
>     boost::algorithm::to_upper(l);
> 
>   } catch(const exception& error) {
>     cout << "Exception catch:" << error.what() << endl;
>   } catch(...) {
>     cerr << "Unhandled exception.\n";
>   }
>   return EXIT_SUCCESS;
> }
> 
> Is there something wrong/missing in the definition of the Char class?
> Or maybe the boost string algos are usable only with char and wchar_t?
> 
> Thanks in advance
> Giampiero.
> 
> 
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