boost/core/exchange.hpp

0001 /*
0002 Copyright 2018 Glen Joseph Fernandes
0003 (glenjofe@gmail.com)
0004
0005 Distributed under the Boost Software License, Version 1.0.
0006 (http://www.boost.org/LICENSE_1_0.txt)
0007 */
0008 #ifndef BOOST_CORE_EXCHANGE_HPP
0009 #define BOOST_CORE_EXCHANGE_HPP
0010
0011 #include <boost/config.hpp>
0012 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
0013 #include <boost/config/workaround.hpp>
0014 #include <utility>
0015 #endif
0016
0017 namespace boost {
0018
0019 #if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
0020 template<class T, class U>
0021 inline T exchange(T& t, const U& u)
0022 {
0023     T v = t;
0024     t = u;
0025     return v;
0026 }
0027 #else
0028 #if BOOST_WORKAROUND(BOOST_MSVC, < 1800)
0029 template<class T, class U>
0030 inline T exchange(T& t, U&& u)
0031 {
0032     T v = std::move(t);
0033     t = std::forward<U>(u);
0034     return v;
0035 }
0036 #else
0037 template<class T, class U = T>
0038 BOOST_CXX14_CONSTEXPR inline T exchange(T& t, U&& u)
0039 {
0040     T v = std::move(t);
0041     t = std::forward<U>(u);
0042     return v;
0043 }
0044 #endif
0045 #endif
0046
0047 } /* boost */
0048
0049 #endif