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Use fold expressions in mp_plus

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Peter Dimov
2017-05-24 02:50:43 +03:00
parent 3e40aacce5
commit 2bd7393365
1 changed files with 15 additions and 3 deletions
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18
include/boost/mp11/detail/mp_plus.hpp
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@@ -8,7 +8,7 @@
// See accompanying file LICENSE_1_0.txt or copy at // See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt // http://www.boost.org/LICENSE_1_0.txt
#include <boost/config.hpp> #include <boost/mp11/detail/config.hpp>
#include <type_traits> #include <type_traits>
namespace boost namespace boost
@@ -20,6 +20,16 @@ namespace mp11
namespace detail namespace detail
{ {
#if defined( BOOST_MP11_HAS_FOLD_EXPRESSIONS )
template<class... T> struct mp_plus_impl
{
static const auto _v = (T::value + ... + 0);
using type = std::integral_constant<typename std::remove_const<decltype(_v)>::type, _v>;
};
#else
template<class... T> struct mp_plus_impl; template<class... T> struct mp_plus_impl;
template<> struct mp_plus_impl<> template<> struct mp_plus_impl<>
@@ -29,16 +39,18 @@ template<> struct mp_plus_impl<>
template<class T1, class... T> struct mp_plus_impl<T1, T...> template<class T1, class... T> struct mp_plus_impl<T1, T...>
{ {
static const/*expr*/ auto _v = T1::value + mp_plus_impl<T...>::type::value; static const auto _v = T1::value + mp_plus_impl<T...>::type::value;
using type = std::integral_constant<typename std::remove_const<decltype(_v)>::type, _v>; using type = std::integral_constant<typename std::remove_const<decltype(_v)>::type, _v>;
}; };
template<class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class T10, class... T> struct mp_plus_impl<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T...> template<class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class T10, class... T> struct mp_plus_impl<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T...>
{ {
static const/*expr*/ auto _v = T1::value + T2::value + T3::value + T4::value + T5::value + T6::value + T7::value + T8::value + T9::value + T10::value + mp_plus_impl<T...>::type::value; static const auto _v = T1::value + T2::value + T3::value + T4::value + T5::value + T6::value + T7::value + T8::value + T9::value + T10::value + mp_plus_impl<T...>::type::value;
using type = std::integral_constant<typename std::remove_const<decltype(_v)>::type, _v>; using type = std::integral_constant<typename std::remove_const<decltype(_v)>::type, _v>;
}; };
#endif
} // namespace detail } // namespace detail
template<class... T> using mp_plus = typename detail::mp_plus_impl<T...>::type; template<class... T> using mp_plus = typename detail::mp_plus_impl<T...>::type;