src/boost/iostreams/detail/streambuf/chainbuf.hpp
72fef926
 // (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_CHAINBUF_HPP_INCLUDED
 #define BOOST_IOSTREAMS_DETAIL_CHAINBUF_HPP_INCLUDED
 
 #if defined(_MSC_VER)
 # pragma once
 #endif      
 
 #include <boost/config.hpp>                    // BOOST_MSVC, template friends.
 #include <boost/detail/workaround.hpp>
 #include <boost/iostreams/chain.hpp>
 #include <boost/iostreams/detail/access_control.hpp>
 #include <boost/iostreams/detail/config/wide_streams.hpp>
 #include <boost/iostreams/detail/streambuf.hpp>
 #include <boost/iostreams/detail/streambuf/linked_streambuf.hpp>
 #include <boost/iostreams/detail/translate_int_type.hpp>
 #include <boost/iostreams/traits.hpp>
 #include <boost/noncopyable.hpp>
 
 namespace boost { namespace iostreams { namespace detail {
 
 //--------------Definition of chainbuf----------------------------------------//
 
 //
 // Template name: chainbuf.
 // Description: Stream buffer which operates by delegating to the first
 //      linked_streambuf in a chain.
 // Template parameters:
 //      Chain - The chain type.
 //
 template<typename Chain, typename Mode, typename Access>
 class chainbuf
     : public BOOST_IOSTREAMS_BASIC_STREAMBUF(
                  typename Chain::char_type,
                  typename Chain::traits_type
              ),
       public access_control<typename Chain::client_type, Access>,
       private noncopyable
 {
 private:
     typedef access_control<chain_client<Chain>, Access>      client_type;
 public:
     typedef typename Chain::char_type                        char_type;
     BOOST_IOSTREAMS_STREAMBUF_TYPEDEFS(typename Chain::traits_type)
 protected:
     typedef linked_streambuf<char_type, traits_type>         delegate_type;
     chainbuf() { client_type::set_chain(&chain_); }
     int_type underflow() 
         { sentry t(this); return translate(delegate().underflow()); }
     int_type pbackfail(int_type c)
         { sentry t(this); return translate(delegate().pbackfail(c)); }
     std::streamsize xsgetn(char_type* s, std::streamsize n)
         { sentry t(this); return delegate().xsgetn(s, n); }
     int_type overflow(int_type c)
         { sentry t(this); return translate(delegate().overflow(c)); }
     std::streamsize xsputn(const char_type* s, std::streamsize n)
         { sentry t(this); return delegate().xsputn(s, n); }
     int sync() { sentry t(this); return delegate().sync(); }
     pos_type seekoff( off_type off, BOOST_IOS::seekdir way,
                       BOOST_IOS::openmode which =
                           BOOST_IOS::in | BOOST_IOS::out )
         { sentry t(this); return delegate().seekoff(off, way, which); }
     pos_type seekpos( pos_type sp,
                       BOOST_IOS::openmode which =
                           BOOST_IOS::in | BOOST_IOS::out )
         { sentry t(this); return delegate().seekpos(sp, which); }
 protected:
     typedef BOOST_IOSTREAMS_BASIC_STREAMBUF(
                  typename Chain::char_type,
                  typename Chain::traits_type
              )                                               base_type;
 private:
 
     // Translate from std int_type to chain's int_type.
     typedef BOOST_IOSTREAMS_CHAR_TRAITS(char_type)           std_traits;
     typedef typename Chain::traits_type                      chain_traits;
     static typename chain_traits::int_type 
     translate(typename std_traits::int_type c)
         { return translate_int_type<std_traits, chain_traits>(c); }
 
     delegate_type& delegate() 
         { return static_cast<delegate_type&>(chain_.front()); }
     void get_pointers()
         {
             this->setg(delegate().eback(), delegate().gptr(), delegate().egptr());
             this->setp(delegate().pbase(), delegate().epptr());
             this->pbump((int) (delegate().pptr() - delegate().pbase()));
         }
     void set_pointers()
         {
             delegate().setg(this->eback(), this->gptr(), this->egptr());
             delegate().setp(this->pbase(), this->epptr());
             delegate().pbump((int) (this->pptr() - this->pbase()));
         }
     struct sentry {
         sentry(chainbuf<Chain, Mode, Access>* buf) : buf_(buf)
             { buf_->set_pointers(); }
         ~sentry() { buf_->get_pointers(); }
         chainbuf<Chain, Mode, Access>* buf_;
     };
     friend struct sentry;
     Chain chain_;
 };
 
 } } } // End namespaces detail, iostreams, boost.
 
 #endif // #ifndef BOOST_IOSTREAMS_DETAIL_CHAINBUF_HPP_INCLUDED