text: // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
  // (C) Copyright 2003-2007 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.
  
  #ifndef BOOST_IOSTREAMS_DETAIL_LINKED_STREAMBUF_HPP_INCLUDED
  #define BOOST_IOSTREAMS_DETAIL_LINKED_STREAMBUF_HPP_INCLUDED
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1020)
  # pragma once
  #endif
  
  #include <typeinfo>
  #include <boost/config.hpp>                        // member template friends.
  #include <boost/iostreams/detail/char_traits.hpp>
  #include <boost/iostreams/detail/ios.hpp>          // openmode.
  #include <boost/iostreams/detail/streambuf.hpp>
  
  // Must come last.
  #include <boost/iostreams/detail/config/disable_warnings.hpp> // MSVC.
  
  namespace boost { namespace iostreams { namespace detail {
  
  template<typename Self, typename Ch, typename Tr, typename Alloc, typename Mode>
  class chain_base;
  
  template<typename Chain, typename Access, typename Mode> class chainbuf;
  
  #define BOOST_IOSTREAMS_USING_PROTECTED_STREAMBUF_MEMBERS(base) \
      using base::eback; using base::gptr; using base::egptr; \
      using base::setg; using base::gbump; using base::pbase; \
      using base::pptr; using base::epptr; using base::setp; \
      using base::pbump; using base::underflow; using base::pbackfail; \
      using base::xsgetn; using base::overflow; using base::xsputn; \
      using base::sync; using base::seekoff; using base::seekpos; \
      /**/
  
  template<typename Ch, typename Tr = BOOST_IOSTREAMS_CHAR_TRAITS(Ch) >
  class linked_streambuf : public BOOST_IOSTREAMS_BASIC_STREAMBUF(Ch, Tr) {
  protected:
      linked_streambuf() : flags_(0) { }
      void set_true_eof(bool eof) 
      { 
          flags_ = (flags_ & ~f_true_eof) | (eof ? f_true_eof : 0); 
      }
  public:
  
      // Should be called only after receiving an ordinary EOF indication,
      // to confirm that it represents EOF rather than WOULD_BLOCK.
      bool true_eof() const { return (flags_ & f_true_eof) != 0; }
  protected:
  
      //----------grant friendship to chain_base and chainbuf-------------------//
  
  #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
      template< typename Self, typename ChT, typename TrT,
                typename Alloc, typename Mode >
      friend class chain_base;
      template<typename Chain, typename Mode, typename Access>
      friend class chainbuf;
      template<typename U>
      friend class member_close_operation; 
  #else
      public:
          typedef BOOST_IOSTREAMS_BASIC_STREAMBUF(Ch, Tr) base;
          BOOST_IOSTREAMS_USING_PROTECTED_STREAMBUF_MEMBERS(base)
  #endif
      void close(BOOST_IOS::openmode which)
      {
          if ( which == BOOST_IOS::in && 
              (flags_ & f_input_closed) == 0 )
          {
              flags_ |= f_input_closed;
              close_impl(which);
          }
          if ( which == BOOST_IOS::out && 
              (flags_ & f_output_closed) == 0 )
          {
              flags_ |= f_output_closed;
              close_impl(which);
          }
      }
      void set_needs_close()
      {
          flags_ &= ~(f_input_closed | f_output_closed);
      }
      virtual void set_next(linked_streambuf<Ch, Tr>* /* next */) { }
      virtual void close_impl(BOOST_IOS::openmode) = 0;
      virtual bool auto_close() const = 0;
      virtual void set_auto_close(bool) = 0;
      virtual bool strict_sync() = 0;
      virtual const std::type_info& component_type() const = 0;
      virtual void* component_impl() = 0;
  #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
      private:
  #else
      public:
  #endif
  private:
      enum flag_type {
          f_true_eof       = 1,
          f_input_closed   = f_true_eof << 1,
          f_output_closed  = f_input_closed << 1
      };
      int flags_;
  };
  
  } } } // End namespaces detail, iostreams, boost.
  
  #include <boost/iostreams/detail/config/enable_warnings.hpp> // MSVC.
  
  #endif // #ifndef BOOST_IOSTREAMS_DETAIL_LINKED_STREAMBUF_HPP_INCLUDED
  