1 #ifndef BOOST_MP11_DETAIL_MP_FOLD_HPP_INCLUDED 2 #define BOOST_MP11_DETAIL_MP_FOLD_HPP_INCLUDED 3 4 // Copyright 2015-2017 Peter Dimov. 5 // 6 // Distributed under the Boost Software License, Version 1.0. 7 // 8 // See accompanying file LICENSE_1_0.txt or copy at 9 // http://www.boost.org/LICENSE_1_0.txt 10 11 #include <boost/mp11/detail/config.hpp> 12 13 namespace boost 14 { 15 namespace mp11 16 { 17 18 // mp_fold<L, V, F> 19 namespace detail 20 { 21 22 template<class L, class V, template<class...> class F> struct mp_fold_impl 23 { 24 // An error "no type named 'type'" here means that the first argument to mp_fold is not a list 25 }; 26 27 #if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 ) 28 29 template<template<class...> class L, class... T, class V, template<class...> class F> struct mp_fold_impl<L<T...>, V, F> 30 { 31 static_assert( sizeof...(T) == 0, "T... must be empty" ); 32 using type = V; 33 }; 34 35 #else 36 37 template<template<class...> class L, class V, template<class...> class F> struct mp_fold_impl<L<>, V, F> 38 { 39 using type = V; 40 }; 41 42 #endif 43 44 template<template<class...> class L, class T1, class... T, class V, template<class...> class F> struct mp_fold_impl<L<T1, T...>, V, F> 45 { 46 using type = typename mp_fold_impl<L<T...>, F<V, T1>, F>::type; 47 }; 48 49 template<template<class...> class L, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class T10, class... T, class V, template<class...> class F> struct mp_fold_impl<L<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T...>, V, F> 50 { 51 using type = typename mp_fold_impl<L<T...>, F<F<F<F<F<F<F<F<F<F<V, T1>, T2>, T3>, T4>, T5>, T6>, T7>, T8>, T9>, T10>, F>::type; 52 }; 53 54 } // namespace detail 55 56 template<class L, class V, template<class...> class F> using mp_fold = typename detail::mp_fold_impl<L, V, F>::type; 57 template<class L, class V, class Q> using mp_fold_q = mp_fold<L, V, Q::template fn>; 58 59 } // namespace mp11 60 } // namespace boost 61 62 #endif // #ifndef BOOST_MP11_DETAIL_MP_FOLD_HPP_INCLUDED 63