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