boost/mp11/utility.hpp

0001 #ifndef BOOST_MP11_UTILITY_HPP_INCLUDED
0002 #define BOOST_MP11_UTILITY_HPP_INCLUDED
0003
0004 // Copyright 2015-2020 Peter Dimov.
0005 //
0006 // Distributed under the Boost Software License, Version 1.0.
0007 //
0008 // See accompanying file LICENSE_1_0.txt or copy at
0009 // http://www.boost.org/LICENSE_1_0.txt
0010
0011 #include <boost/mp11/integral.hpp>
0012 #include <boost/mp11/detail/mp_list.hpp>
0013 #include <boost/mp11/detail/mp_fold.hpp>
0014 #include <boost/mp11/detail/mp_front.hpp>
0015 #include <boost/mp11/detail/mp_rename.hpp>
0016 #include <boost/mp11/detail/mp_defer.hpp>
0017 #include <boost/mp11/detail/config.hpp>
0018
0019 namespace boost
0020 {
0021 namespace mp11
0022 {
0023
0024 // mp_identity
0025 template<class T> struct mp_identity
0026 {
0027     using type = T;
0028 };
0029
0030 // mp_identity_t
0031 template<class T> using mp_identity_t = typename mp_identity<T>::type;
0032
0033 // mp_inherit
0034 template<class... T> struct mp_inherit: T... {};
0035
0036 // mp_if, mp_if_c
0037 // mp_valid
0038 // mp_defer
0039 //   moved to detail/mp_defer.hpp
0040
0041 // mp_eval_if, mp_eval_if_c
0042 namespace detail
0043 {
0044
0045 template<bool C, class T, template<class...> class F, class... U> struct mp_eval_if_c_impl;
0046
0047 template<class T, template<class...> class F, class... U> struct mp_eval_if_c_impl<true, T, F, U...>
0048 {
0049     using type = T;
0050 };
0051
0052 template<class T, template<class...> class F, class... U> struct mp_eval_if_c_impl<false, T, F, U...>: mp_defer<F, U...>
0053 {
0054 };
0055
0056 } // namespace detail
0057
0058 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;
0059 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;
0060 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;
0061
0062 // mp_eval_if_not
0063 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...>;
0064 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...>;
0065
0066 // mp_eval_or
0067 template<class T, template<class...> class F, class... U> using mp_eval_or = mp_eval_if_not<mp_valid<F, U...>, T, F, U...>;
0068 template<class T, class Q, class... U> using mp_eval_or_q = mp_eval_or<T, Q::template fn, U...>;
0069
0070 // mp_valid_and_true
0071 template<template<class...> class F, class... T> using mp_valid_and_true = mp_eval_or<mp_false, F, T...>;
0072 template<class Q, class... T> using mp_valid_and_true_q = mp_valid_and_true<Q::template fn, T...>;
0073
0074 // mp_cond
0075
0076 // so elegant; so doesn't work
0077 // template<class C, class T, class... E> using mp_cond = mp_eval_if<C, T, mp_cond, E...>;
0078
0079 namespace detail
0080 {
0081
0082 template<class C, class T, class... E> struct mp_cond_impl;
0083
0084 } // namespace detail
0085
0086 template<class C, class T, class... E> using mp_cond = typename detail::mp_cond_impl<C, T, E...>::type;
0087
0088 namespace detail
0089 {
0090
0091 template<class C, class T, class... E> using mp_cond_ = mp_eval_if<C, T, mp_cond, E...>;
0092
0093 template<class C, class T, class... E> struct mp_cond_impl: mp_defer<mp_cond_, C, T, E...>
0094 {
0095 };
0096
0097 } // namespace detail
0098
0099 // mp_quote
0100 template<template<class...> class F> struct mp_quote
0101 {
0102     // the indirection through mp_defer works around the language inability
0103     // to expand T... into a fixed parameter list of an alias template
0104
0105     template<class... T> using fn = typename mp_defer<F, T...>::type;
0106 };
0107
0108 // mp_quote_trait
0109 template<template<class...> class F> struct mp_quote_trait
0110 {
0111     template<class... T> using fn = typename F<T...>::type;
0112 };
0113
0114 // mp_invoke_q
0115 #if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
0116
0117 namespace detail
0118 {
0119
0120 template<class Q, class... T> struct mp_invoke_q_impl: mp_defer<Q::template fn, T...> {};
0121
0122 } // namespace detail
0123
0124 template<class Q, class... T> using mp_invoke_q = typename detail::mp_invoke_q_impl<Q, T...>::type;
0125
0126 #elif BOOST_MP11_WORKAROUND( BOOST_MP11_GCC, < 50000 )
0127
0128 template<class Q, class... T> using mp_invoke_q = typename mp_defer<Q::template fn, T...>::type;
0129
0130 #else
0131
0132 template<class Q, class... T> using mp_invoke_q = typename Q::template fn<T...>;
0133
0134 #endif
0135
0136 // mp_not_fn<P>
0137 template<template<class...> class P> struct mp_not_fn
0138 {
0139     template<class... T> using fn = mp_not< mp_invoke_q<mp_quote<P>, T...> >;
0140 };
0141
0142 template<class Q> using mp_not_fn_q = mp_not_fn<Q::template fn>;
0143
0144 // mp_compose
0145 namespace detail
0146 {
0147
0148 template<class L, class Q> using mp_compose_helper = mp_list< mp_apply_q<Q, L> >;
0149
0150 } // namespace detail
0151
0152 #if !BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
0153
0154 template<template<class...> class... F> struct mp_compose
0155 {
0156     template<class... T> using fn = mp_front< mp_fold<mp_list<mp_quote<F>...>, mp_list<T...>, detail::mp_compose_helper> >;
0157 };
0158
0159 #endif
0160
0161 template<class... Q> struct mp_compose_q
0162 {
0163     template<class... T> using fn = mp_front< mp_fold<mp_list<Q...>, mp_list<T...>, detail::mp_compose_helper> >;
0164 };
0165
0166 } // namespace mp11
0167 } // namespace boost
0168
0169 #endif // #ifndef BOOST_MP11_UTILITY_HPP_INCLUDED