text: // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
  // (C) Copyright 2005-2007 Jonathan Turkanis
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
  
  // See http://www.boost.org/libs/iostreams for documentation.
  
  // Based on the work of Christopher Diggins.
  
  #ifndef BOOST_IOSTREAMS_STDIO_FILTER_HPP_INCLUDED
  #define BOOST_IOSTREAMS_STDIO_FILTER_HPP_INCLUDED
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1020)
  # pragma once
  #endif
  
  #include <iostream>
  #include <memory>    // allocator.
  #include <vector>
  #include <boost/iostreams/detail/config/wide_streams.hpp>
  #include <boost/iostreams/detail/char_traits.hpp>
  #include <boost/iostreams/detail/ios.hpp>
  #include <boost/iostreams/device/array.hpp>
  #include <boost/iostreams/device/back_inserter.hpp>
  #include <boost/iostreams/filter/aggregate.hpp>
  #include <boost/iostreams/pipeline.hpp>
  #include <boost/iostreams/stream_buffer.hpp>
  
  namespace boost { namespace iostreams {
  
  namespace detail {
  
  } // End namespace detail.
  
  template<typename Ch, typename Alloc = std::allocator<Ch> >
  class basic_stdio_filter : public aggregate_filter<Ch, Alloc> {
  private:
      typedef aggregate_filter<Ch, Alloc>       base_type;
  public:
      typedef typename base_type::char_type    char_type;
      typedef typename base_type::category     category;
      typedef typename base_type::vector_type  vector_type;
  private:
      static std::istream& standard_input(char*) { return std::cin; }
      static std::ostream& standard_output(char*) { return std::cout; }
  #ifndef BOOST_IOSTREAMS_NO_WIDE_STREAMS
      static std::wistream& standard_input(wchar_t*) { return std::wcin; }
      static std::wostream& standard_output(wchar_t*) { return std::wcout; }
  #endif // BOOST_IOSTREAMS_NO_WIDE_STREAMS
  
      struct scoped_redirector { // Thanks to Maxim Egorushkin.
          typedef BOOST_IOSTREAMS_CHAR_TRAITS(Ch)                  traits_type;
          typedef BOOST_IOSTREAMS_BASIC_IOS(Ch, traits_type)       ios_type;
          typedef BOOST_IOSTREAMS_BASIC_STREAMBUF(Ch, traits_type) streambuf_type;
          scoped_redirector( ios_type& ios,
                             streambuf_type* newbuf )
              : ios_(ios), old_(ios.rdbuf(newbuf))
              { }
          ~scoped_redirector() { ios_.rdbuf(old_); }
          scoped_redirector& operator=(const scoped_redirector&);
          ios_type&        ios_;
          streambuf_type*  old_;
      };
  
      virtual void do_filter() = 0;
      virtual void do_filter(const vector_type& src, vector_type& dest)
      {
          stream_buffer< basic_array_source<Ch> >
                            srcbuf(&src[0], &src[0] + src.size());
          stream_buffer< back_insert_device<vector_type> >
                            destbuf(iostreams::back_inserter(dest));
          scoped_redirector redirect_input(standard_input((Ch*)0), &srcbuf);
          scoped_redirector redirect_output(standard_output((Ch*)0), &destbuf);
          do_filter();
      }
  };
  BOOST_IOSTREAMS_PIPABLE(basic_stdio_filter, 2)
  
  typedef basic_stdio_filter<char>     stdio_filter;
  typedef basic_stdio_filter<wchar_t>  wstdio_wfilter;
  
  } } // End namespaces iostreams, boost.
  
  #endif // #ifndef BOOST_IOSTREAMS_STDIO_FILTER_HPP_INCLUDED
  