1 #ifndef BOOST_MP11_UTILITY_HPP_INCLUDED
2 #define BOOST_MP11_UTILITY_HPP_INCLUDED
4 // Copyright 2015, 2017, 2019 Peter Dimov.
6 // Distributed under the Boost Software License, Version 1.0.
8 // See accompanying file LICENSE_1_0.txt or copy at
9 // http://www.boost.org/LICENSE_1_0.txt
11 #include <boost/mp11/integral.hpp>
12 #include <boost/mp11/detail/config.hpp>
20 template<class T> struct mp_identity
26 template<class T> using mp_identity_t = typename mp_identity<T>::type;
29 template<class... T> struct mp_inherit: T... {};
35 template<bool C, class T, class... E> struct mp_if_c_impl
39 template<class T, class... E> struct mp_if_c_impl<true, T, E...>
44 template<class T, class E> struct mp_if_c_impl<false, T, E>
51 template<bool C, class T, class... E> using mp_if_c = typename detail::mp_if_c_impl<C, T, E...>::type;
52 template<class C, class T, class... E> using mp_if = typename detail::mp_if_c_impl<static_cast<bool>(C::value), T, E...>::type;
56 #if BOOST_MP11_WORKAROUND( BOOST_MP11_INTEL, != 0 ) // tested at 1800
58 // contributed by Roland Schulz in https://github.com/boostorg/mp11/issues/17
63 template<class...> using void_t = void;
65 template<class, template<class...> class F, class... T>
66 struct mp_valid_impl: mp_false {};
68 template<template<class...> class F, class... T>
69 struct mp_valid_impl<void_t<F<T...>>, F, T...>: mp_true {};
73 template<template<class...> class F, class... T> using mp_valid = typename detail::mp_valid_impl<void, F, T...>;
77 // implementation by Bruno Dutra (by the name is_evaluable)
81 template<template<class...> class F, class... T> struct mp_valid_impl
83 template<template<class...> class G, class = G<T...>> static mp_true check(int);
84 template<template<class...> class> static mp_false check(...);
86 using type = decltype(check<F>(0));
91 template<template<class...> class F, class... T> using mp_valid = typename detail::mp_valid_impl<F, T...>::type;
95 template<class Q, class... T> using mp_valid_q = mp_valid<Q::template fn, T...>;
101 template<template<class...> class F, class... T> struct mp_defer_impl
103 using type = F<T...>;
110 #if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )
112 template<template<class...> class F, class... T> struct mp_defer_cuda_workaround
114 using type = mp_if<mp_valid<F, T...>, detail::mp_defer_impl<F, T...>, detail::mp_no_type>;
119 } // namespace detail
121 #if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )
123 template<template<class...> class F, class... T> using mp_defer = typename detail::mp_defer_cuda_workaround< F, T...>::type;
127 template<template<class...> class F, class... T> using mp_defer = mp_if<mp_valid<F, T...>, detail::mp_defer_impl<F, T...>, detail::mp_no_type>;
131 // mp_eval_if, mp_eval_if_c
135 template<bool C, class T, template<class...> class F, class... U> struct mp_eval_if_c_impl;
137 template<class T, template<class...> class F, class... U> struct mp_eval_if_c_impl<true, T, F, U...>
142 template<class T, template<class...> class F, class... U> struct mp_eval_if_c_impl<false, T, F, U...>: mp_defer<F, U...>
146 } // namespace detail
148 template<bool C, class T, template<class...> class F, class... U> using mp_eval_if_c = typename detail::mp_eval_if_c_impl<C, T, F, U...>::type;
149 template<class C, class T, template<class...> class F, class... U> using mp_eval_if = typename detail::mp_eval_if_c_impl<static_cast<bool>(C::value), T, F, U...>::type;
150 template<class C, class T, class Q, class... U> using mp_eval_if_q = typename detail::mp_eval_if_c_impl<static_cast<bool>(C::value), T, Q::template fn, U...>::type;
153 template<class C, class T, template<class...> class F, class... U> using mp_eval_if_not = mp_eval_if<mp_not<C>, T, F, U...>;
154 template<class C, class T, class Q, class... U> using mp_eval_if_not_q = mp_eval_if<mp_not<C>, T, Q::template fn, U...>;
157 template<class T, template<class...> class F, class... U> using mp_eval_or = mp_eval_if_not<mp_valid<F, U...>, T, F, U...>;
158 template<class T, class Q, class... U> using mp_eval_or_q = mp_eval_or<T, Q::template fn, U...>;
162 // so elegant; so doesn't work
163 // template<class C, class T, class... E> using mp_cond = mp_eval_if<C, T, mp_cond, E...>;
168 template<class C, class T, class... E> struct mp_cond_impl;
170 } // namespace detail
172 template<class C, class T, class... E> using mp_cond = typename detail::mp_cond_impl<C, T, E...>::type;
177 template<class C, class T, class... E> using mp_cond_ = mp_eval_if<C, T, mp_cond, E...>;
179 template<class C, class T, class... E> struct mp_cond_impl: mp_defer<mp_cond_, C, T, E...>
183 } // namespace detail
186 template<template<class...> class F> struct mp_quote
188 // the indirection through mp_defer works around the language inability
189 // to expand T... into a fixed parameter list of an alias template
191 template<class... T> using fn = typename mp_defer<F, T...>::type;
195 template<template<class...> class F> struct mp_quote_trait
197 template<class... T> using fn = typename F<T...>::type;
201 #if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
206 template<class Q, class... T> struct mp_invoke_q_impl: mp_defer<Q::template fn, T...> {};
208 } // namespace detail
210 template<class Q, class... T> using mp_invoke_q = typename detail::mp_invoke_q_impl<Q, T...>::type;
212 #elif BOOST_MP11_WORKAROUND( BOOST_MP11_GCC, < 50000 )
214 template<class Q, class... T> using mp_invoke_q = typename mp_defer<Q::template fn, T...>::type;
218 template<class Q, class... T> using mp_invoke_q = typename Q::template fn<T...>;
222 // old name for mp_invoke_q retained for compatibility, but deprecated
223 template<class Q, class... T> using mp_invoke BOOST_MP11_DEPRECATED("please use mp_invoke_q") = mp_invoke_q<Q, T...>;
226 template<template<class...> class P> struct mp_not_fn
228 template<class... T> using fn = mp_not< mp_invoke_q<mp_quote<P>, T...> >;
231 template<class Q> using mp_not_fn_q = mp_not_fn<Q::template fn>;
236 #endif // #ifndef BOOST_MP11_UTILITY_HPP_INCLUDED