//Purpose:
//  Demonstrate that ostream's streambuf can be replaced
//  with boost::iostreams::stream_buffer.
//Reference:
//  http://www.boost.org/doc/libs/1_37_0/libs/iostreams/doc/tutorial/writing_devices.html
//  http://www.boost.org/doc/libs/1_37_0/libs/iostreams/doc/classes/filtering_streambuf.html
//
#include <iostream>
#include <boost/iostreams/filtering_streambuf.hpp>

typedef std::ostream::char_type std_ostrm_char_type;
typedef std::basic_ostream<std_ostrm_char_type> std_ostrm;
typedef std::basic_streambuf<std_ostrm_char_type> std_strmbuf;

namespace io = boost::iostreams;

struct toupper_output_filter 
: public io::output_filter
//Reference:
//  http://www.boost.org/doc/libs/1_37_0/libs/iostreams/doc/concepts/output_filter.html
//
{
    template<typename Sink>
    bool put(Sink& snk, char c) 
    { 
        return io::put(snk, toupper((unsigned char) c)); 
    }
};
    
struct push_filt_strmbuf
: public io::filtering_ostreambuf
{
  push_filt_strmbuf(std_strmbuf& a_buf)
  {
      this->push(my_filter);
      this->push(a_buf);
  }
    toupper_output_filter 
  my_filter
  ;
   
};
int main(void) 
{
    std_ostrm& sout=std::cout;
    sout<<"Hello World!\n";
    std_strmbuf* oldbuf=sout.rdbuf();
    push_filt_strmbuf* ppush_sbuf=new push_filt_strmbuf(*oldbuf);
    sout<<"is_complete="<<ppush_sbuf->is_complete()<<"\n";
    sout.rdbuf(ppush_sbuf);
    sout<<"2nd Hello!\n";
    sout.rdbuf(oldbuf);
    sout<<"3ird Hello!\n";
    return 0;
}