// (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_WRAP_UNWRAP_HPP_INCLUDED #define BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED #if defined(_MSC_VER) && (_MSC_VER >= 1020) # pragma once #endif #include <boost/config.hpp> // SFINAE, MSVC. #include <boost/detail/workaround.hpp> #include <boost/iostreams/detail/enable_if_stream.hpp> #include <boost/iostreams/traits_fwd.hpp> // is_std_io. #include <boost/mpl/bool.hpp> #include <boost/mpl/identity.hpp> #include <boost/mpl/eval_if.hpp> #include <boost/mpl/if.hpp> #include <boost/ref.hpp> namespace boost { namespace iostreams { namespace detail { //------------------Definition of wrap/unwrap traits--------------------------// template<typename T> struct wrapped_type : mpl::if_<is_std_io<T>, reference_wrapper<T>, T> { }; template<typename T> struct unwrapped_type : unwrap_reference<T> { }; template<typename T> struct unwrap_ios : mpl::eval_if< is_std_io<T>, unwrap_reference<T>, mpl::identity<T> > { }; //------------------Definition of wrap----------------------------------------// #ifndef BOOST_NO_SFINAE //----------------------------------------------------// template<typename T> inline T wrap(const T& t BOOST_IOSTREAMS_DISABLE_IF_STREAM(T)) { return t; } template<typename T> inline typename wrapped_type<T>::type wrap(T& t BOOST_IOSTREAMS_ENABLE_IF_STREAM(T)) { return boost::ref(t); } #else // #ifndef BOOST_NO_SFINAE //-------------------------------------------// template<typename T> inline typename wrapped_type<T>::type // BCC 5.x needs namespace qualification. wrap_impl(const T& t, mpl::true_) { return boost::ref(const_cast<T&>(t)); } template<typename T> inline typename wrapped_type<T>::type // BCC 5.x needs namespace qualification. wrap_impl(T& t, mpl::true_) { return boost::ref(t); } template<typename T> inline typename wrapped_type<T>::type wrap_impl(const T& t, mpl::false_) { return t; } template<typename T> inline typename wrapped_type<T>::type wrap_impl(T& t, mpl::false_) { return t; } template<typename T> inline typename wrapped_type<T>::type wrap(const T& t) { return wrap_impl(t, is_std_io<T>()); } template<typename T> inline typename wrapped_type<T>::type wrap(T& t) { return wrap_impl(t, is_std_io<T>()); } #endif // #ifndef BOOST_NO_SFINAE //------------------------------------------// //------------------Definition of unwrap--------------------------------------// #if !BOOST_WORKAROUND(BOOST_MSVC, < 1310) //----------------------------------// template<typename T> typename unwrapped_type<T>::type& unwrap(const reference_wrapper<T>& ref) { return ref.get(); } template<typename T> typename unwrapped_type<T>::type& unwrap(T& t) { return t; } template<typename T> const typename unwrapped_type<T>::type& unwrap(const T& t) { return t; } #else // #if !BOOST_WORKAROUND(BOOST_MSVC, < 1310) //-------------------------// // Since unwrap is a potential bottleneck, we avoid runtime tag dispatch. template<bool IsRefWrap> struct unwrap_impl; template<> struct unwrap_impl<true> { template<typename T> static typename unwrapped_type<T>::type& unwrap(const T& t) { return t.get(); } }; template<> struct unwrap_impl<false> { template<typename T> static typename unwrapped_type<T>::type& unwrap(const T& t) { return const_cast<T&>(t); } }; template<typename T> typename unwrapped_type<T>::type& unwrap(const T& t) { return unwrap_impl<is_reference_wrapper<T>::value>::unwrap(t); } #endif // #if !BOOST_WORKAROUND(BOOST_MSVC, < 1310) //------------------------// } } } // End namespaces detail, iostreams, boost. #endif // #ifndef BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED