//Purpose:
//  Explore differences in ways iostreams filtering is done
//  with different device types.
//Acknowledgements:
//  Original code from post:
/*
From: Ken Appleby <ken.appleby@btopenworld.com>
Newsgroups: gmane.comp.lib.boost.user
Subject: Re: [iostreams] How can I use the Stream Insertion
 operator (<<) with a filtering_streambuf?
Date: Fri, 26 Jul 2013 18:06:47 +0100
Lines: 94
*/
//==========================
#include <iostream>
#define USE_STRINGSTRM //use stringstream instead of fstream.
#ifdef USE_STRINGSTRM
#include <sstream>
#else
#include <fstream>
#endif

#include <boost/iostreams/filtering_streambuf.hpp>
#include <boost/iostreams/copy.hpp>
#include <boost/iostreams/filter/gzip.hpp>

int main()
{
    try
    {
      #ifdef USE_STRINGSTRM
        std::string strmValue;
      #else
        char const*filePath="hello.gz";
      #endif
        {
          #ifdef USE_STRINGSTRM
            std::ostringstream myOstrm( strmValue, std::ios_base::out | std::ios_base::binary );
          #else
            std::ofstream      myOstrm( filePath , std::ios_base::out | std::ios_base::binary );
          #endif
            boost::iostreams::filtering_streambuf<boost::iostreams::output> out;
          //#define USE_FILT
          #ifdef USE_FILT
            out.push(boost::iostreams::gzip_compressor());
          #endif
            out.push( myOstrm );
            std::ostream os(&out);
            os << "text I want to be compressed and end up in the file...";
            os.flush();
            strmValue=myOstrm.str();
        }
      #ifdef USE_STRINGSTRM
        std::cout<<"strmValue="<<strmValue<<"\n";
      #endif
        {
          #ifdef USE_STRINGSTRM
            std::istringstream myIstrm( strmValue, std::ios::in | std::ios::binary );
          #else
            std::ifstream      myIstrm( filePath , std::ios::in | std::ios::binary );
          #endif
            boost::iostreams::filtering_streambuf< boost::iostreams::input > in;
          #ifdef USE_FILT
            in.push( boost::iostreams::gzip_decompressor() );
          #endif
            in.push( myIstrm );
            std::istream is( &in );
            std::string text;
            while ( is.good() )
            {
                char ch = is.get();
                if ( is.good() )
                    text.push_back( ch );
            }
            std::cout << "text from file is \"" << text << "\"" << std::endl << std::flush;
        }
    } catch ( std::exception& e )
    {
        std::cerr << e.what() << std::endl;
    }
}