[Boost-users] string algo problem

From: Giampiero Gabbiani (giampiero_gabbiani_at_[hidden])
Date: 2005-08-09 11:55:00

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.