Chris@16: // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
Chris@16: // (C) Copyright 2003-2007 Jonathan Turkanis
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
Chris@16: 
Chris@16: // See http://www.boost.org/libs/iostreams for documentation.
Chris@16: 
Chris@16: #ifndef BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED
Chris@16: #define BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1020)
Chris@16: # pragma once
Chris@16: #endif              
Chris@16: 
Chris@16: #include <boost/config.hpp>                             // SFINAE, MSVC.
Chris@16: #include <boost/detail/workaround.hpp>
Chris@16: #include <boost/iostreams/detail/enable_if_stream.hpp>
Chris@16: #include <boost/iostreams/traits_fwd.hpp>               // is_std_io.
Chris@16: #include <boost/mpl/bool.hpp>
Chris@16: #include <boost/mpl/identity.hpp>
Chris@16: #include <boost/mpl/eval_if.hpp>
Chris@16: #include <boost/mpl/if.hpp>
Chris@16: #include <boost/ref.hpp>
Chris@16: 
Chris@16: namespace boost { namespace iostreams { namespace detail {
Chris@16:                     
Chris@16: //------------------Definition of wrap/unwrap traits--------------------------//
Chris@16: 
Chris@16: template<typename T>
Chris@16: struct wrapped_type 
Chris@16:     : mpl::if_<is_std_io<T>, reference_wrapper<T>, T>
Chris@16:     { };
Chris@16: 
Chris@16: template<typename T>
Chris@16: struct unwrapped_type 
Chris@16:     : unwrap_reference<T>
Chris@16:     { };
Chris@16: 
Chris@16: template<typename T>
Chris@16: struct unwrap_ios 
Chris@16:     : mpl::eval_if<
Chris@16:           is_std_io<T>, 
Chris@16:           unwrap_reference<T>, 
Chris@16:           mpl::identity<T>
Chris@16:       >
Chris@16:     { };
Chris@16: 
Chris@16: //------------------Definition of wrap----------------------------------------//
Chris@16: 
Chris@16: #ifndef BOOST_NO_SFINAE //----------------------------------------------------//
Chris@16:     template<typename T>
Chris@16:     inline T wrap(const T& t BOOST_IOSTREAMS_DISABLE_IF_STREAM(T)) 
Chris@16:     { return t; }
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     inline typename wrapped_type<T>::type
Chris@16:     wrap(T& t BOOST_IOSTREAMS_ENABLE_IF_STREAM(T)) { return boost::ref(t); }
Chris@16: #else // #ifndef BOOST_NO_SFINAE //-------------------------------------------//
Chris@16:     template<typename T>
Chris@16:     inline typename wrapped_type<T>::type // BCC 5.x needs namespace qualification.
Chris@16:     wrap_impl(const T& t, mpl::true_) { return boost::ref(const_cast<T&>(t)); }
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     inline typename wrapped_type<T>::type // BCC 5.x needs namespace qualification.
Chris@16:     wrap_impl(T& t, mpl::true_) { return boost::ref(t); }
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     inline typename wrapped_type<T>::type 
Chris@16:     wrap_impl(const T& t, mpl::false_) { return t; }
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     inline typename wrapped_type<T>::type 
Chris@16:     wrap_impl(T& t, mpl::false_) { return t; }
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     inline typename wrapped_type<T>::type 
Chris@16:     wrap(const T& t) { return wrap_impl(t, is_std_io<T>()); }
Chris@16: 
Chris@16:     template<typename T>
Chris@16:     inline typename wrapped_type<T>::type 
Chris@16:     wrap(T& t) { return wrap_impl(t, is_std_io<T>()); }
Chris@16: #endif // #ifndef BOOST_NO_SFINAE //------------------------------------------//
Chris@16: 
Chris@16: //------------------Definition of unwrap--------------------------------------//
Chris@16: 
Chris@16: #if !BOOST_WORKAROUND(BOOST_MSVC, < 1310) //----------------------------------//
Chris@16: 
Chris@16: template<typename T>
Chris@16: typename unwrapped_type<T>::type& 
Chris@16: unwrap(const reference_wrapper<T>& ref) { return ref.get(); }
Chris@16: 
Chris@16: template<typename T>
Chris@16: typename unwrapped_type<T>::type& unwrap(T& t) { return t; }
Chris@16: 
Chris@16: template<typename T>
Chris@16: const typename unwrapped_type<T>::type& unwrap(const T& t) { return t; }
Chris@16: 
Chris@16: #else // #if !BOOST_WORKAROUND(BOOST_MSVC, < 1310) //-------------------------//
Chris@16: 
Chris@16: // Since unwrap is a potential bottleneck, we avoid runtime tag dispatch.
Chris@16: template<bool IsRefWrap>
Chris@16: struct unwrap_impl;
Chris@16: 
Chris@16: template<>
Chris@16: struct unwrap_impl<true> {
Chris@16:     template<typename T>
Chris@16:     static typename unwrapped_type<T>::type& unwrap(const T& t) 
Chris@16:     { return t.get(); }
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct unwrap_impl<false> {
Chris@16:     template<typename T>
Chris@16:     static typename unwrapped_type<T>::type& unwrap(const T& t) 
Chris@16:     { return const_cast<T&>(t); }
Chris@16: };
Chris@16: 
Chris@16: template<typename T>
Chris@16: typename unwrapped_type<T>::type& 
Chris@16: unwrap(const T& t) 
Chris@16: { return unwrap_impl<is_reference_wrapper<T>::value>::unwrap(t); }
Chris@16: 
Chris@16: #endif // #if !BOOST_WORKAROUND(BOOST_MSVC, < 1310) //------------------------//
Chris@16: 
Chris@16: } } } // End namespaces detail, iostreams, boost.
Chris@16: 
Chris@16: #endif // #ifndef BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED