#ifndef BOOST_CORE_EXCHANGE_HPP
#define BOOST_CORE_EXCHANGE_HPP
#include <boost/config.hpp>
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
#include <boost/config/workaround.hpp>
#include <utility>
#endif
namespace boost {
#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
template<class T, class U>
inline T exchange(T& t, const U& u)
{
T v = t;
t = u;
return v;
}
#else
#if BOOST_WORKAROUND(BOOST_MSVC, < 1800)
template<class T, class U>
inline T exchange(T& t, U&& u)
{
T v = std::move(t);
t = std::forward<U>(u);
return v;
}
#else
template<class T, class U = T>
BOOST_CXX14_CONSTEXPR inline T exchange(T& t, U&& u)
{
T v = std::move(t);
t = std::forward<U>(u);
return v;
}
#endif
#endif
}
#endif