//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
*/
//ChangeLog:
//  2013-07-29.0847
//    Converted to use:
//      filtering_estream 
//    instead of:
//      filtering_streambuf
//    after reading post:
/*
From: Stephen Greenfield <StephenG@screenplay.com>
Newsgroups: gmane.comp.lib.boost.user
Subject: Re: [iostreams] How can I use the Stream Insertion
 operator (<<) with a filtering_streambuf?
Date: Mon, 29 Jul 2013 04:28:04 +0000
Lines: 167
 */
//==========================
#include <iostream>
//#define USE_STRINGSTRM //use stringstream instead of fstream.
#ifdef USE_STRINGSTRM
#include <sstream>
#else
#include <fstream>
#endif

#include <boost/iostreams/filtering_stream.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);
          #else
            std::ofstream      myOstrm( filePath );
          #endif
            boost::iostreams::filtering_ostream out;
            out.push(boost::iostreams::gzip_compressor());
            out.push( myOstrm );
            out << "text to be in the file...";
          #ifdef USE_STRINGSTRM
            out.flush();
            strmValue=myOstrm.str();
          #endif
        }
      #ifdef USE_STRINGSTRM
        std::cout<<"strmValue="<<strmValue<<"\n";
      #endif
        {
          #ifdef USE_STRINGSTRM
            std::istringstream myIstrm( strmValue);
          #else
            std::ifstream      myIstrm( filePath );
          #endif
            boost::iostreams::filtering_istream inp;
            inp.push( boost::iostreams::gzip_decompressor() );
            inp.push( myIstrm );
            std::string text;
            while ( inp.good() )
            {
                char ch = inp.get();
                if ( inp.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;
    }
}