exchange.hpp

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#ifndef SILICIUM_REACTIVE_EXCHANGE_HPP
#define SILICIUM_REACTIVE_EXCHANGE_HPP

#include <silicium/move_if_noexcept.hpp>
#include <utility>
#include <boost/config.hpp>

namespace Si
{
    namespace detail
    {
        template <class T, class U>
        T exchange_impl(T &dest, U &&source, std::true_type)
        {
            auto old = Si::move_if_noexcept(dest);
            dest = std::forward<U>(source);
            return old;
        }

        template <class T, class U>
        T exchange_impl(T &dest, U &&source, std::false_type)
        {
            auto old = dest;
            dest = std::forward<U>(source);
            return old;
        }
    }

    template <class T, class U>
    T exchange(T &dest, U &&source)
    {
        return detail::exchange_impl(
            dest,
            std::forward<U>(source),
            std::integral_constant<bool,
#ifdef _MSC_VER
                true
#else
                BOOST_NOEXCEPT_EXPR(dest = std::forward<U>(source))
#endif
            >()
        );
    }
}

#endif