template<typename CharT, typename Device> 
class wide_adaptor {
public:
  // types
  typedef CharT                  char_type;
  typedef implementation defined category; 

  // construct/copy/destruct
  explicit wide_adaptor(const Device&);
  wide_adaptor(const Device&, std::streamsize);

  // Boost.Iostreams implementation
  std::streamsize read(CharT*, std::streamsize);
  std::streamsize write(const CharT*, std::streamsize);
  void close();
  std::streamsize optimal_buffer_size() const;
};

// creation
template<typename CharT, typename Device> 
  wide_adaptor<CharT, Device> widen(const Device&);