1#ifndef BOOST_MP11_UTILITY_HPP_INCLUDED
2#define BOOST_MP11_UTILITY_HPP_INCLUDED
3
4// Copyright 2015-2020 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/integral.hpp>
12#include <boost/mp11/detail/mp_list.hpp>
13#include <boost/mp11/detail/mp_fold.hpp>
14#include <boost/mp11/detail/config.hpp>
15
16namespace boost
17{
18namespace mp11
19{
20
21// mp_identity
22template<class T> struct mp_identity
23{
24 using type = T;
25};
26
27// mp_identity_t
28template<class T> using mp_identity_t = typename mp_identity<T>::type;
29
30// mp_inherit
31template<class... T> struct mp_inherit: T... {};
32
33// mp_if, mp_if_c
34namespace detail
35{
36
37template<bool C, class T, class... E> struct mp_if_c_impl
38{
39};
40
41template<class T, class... E> struct mp_if_c_impl<true, T, E...>
42{
43 using type = T;
44};
45
46template<class T, class E> struct mp_if_c_impl<false, T, E>
47{
48 using type = E;
49};
50
51} // namespace detail
52
53template<bool C, class T, class... E> using mp_if_c = typename detail::mp_if_c_impl<C, T, E...>::type;
54template<class C, class T, class... E> using mp_if = typename detail::mp_if_c_impl<static_cast<bool>(C::value), T, E...>::type;
55
56// mp_valid
57
58#if BOOST_MP11_WORKAROUND( BOOST_MP11_INTEL, != 0 ) // tested at 1800
59
60// contributed by Roland Schulz in https://github.com/boostorg/mp11/issues/17
61
62namespace detail
63{
64
65template<class...> using void_t = void;
66
67template<class, template<class...> class F, class... T>
68struct mp_valid_impl: mp_false {};
69
70template<template<class...> class F, class... T>
71struct mp_valid_impl<void_t<F<T...>>, F, T...>: mp_true {};
72
73} // namespace detail
74
75template<template<class...> class F, class... T> using mp_valid = typename detail::mp_valid_impl<void, F, T...>;
76
77#else
78
79// implementation by Bruno Dutra (by the name is_evaluable)
80namespace detail
81{
82
83template<template<class...> class F, class... T> struct mp_valid_impl
84{
85 template<template<class...> class G, class = G<T...>> static mp_true check(int);
86 template<template<class...> class> static mp_false check(...);
87
88 using type = decltype(check<F>(0));
89};
90
91} // namespace detail
92
93template<template<class...> class F, class... T> using mp_valid = typename detail::mp_valid_impl<F, T...>::type;
94
95#endif
96
97template<class Q, class... T> using mp_valid_q = mp_valid<Q::template fn, T...>;
98
99// mp_defer
100namespace detail
101{
102
103template<template<class...> class F, class... T> struct mp_defer_impl
104{
105 using type = F<T...>;
106};
107
108struct mp_no_type
109{
110};
111
112#if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )
113
114template<template<class...> class F, class... T> struct mp_defer_cuda_workaround
115{
116 using type = mp_if<mp_valid<F, T...>, detail::mp_defer_impl<F, T...>, detail::mp_no_type>;
117};
118
119#endif
120
121} // namespace detail
122
123#if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )
124
125template<template<class...> class F, class... T> using mp_defer = typename detail::mp_defer_cuda_workaround< F, T...>::type;
126
127#else
128
129template<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>;
130
131#endif
132
133// mp_eval_if, mp_eval_if_c
134namespace detail
135{
136
137template<bool C, class T, template<class...> class F, class... U> struct mp_eval_if_c_impl;
138
139template<class T, template<class...> class F, class... U> struct mp_eval_if_c_impl<true, T, F, U...>
140{
141 using type = T;
142};
143
144template<class T, template<class...> class F, class... U> struct mp_eval_if_c_impl<false, T, F, U...>: mp_defer<F, U...>
145{
146};
147
148} // namespace detail
149
150template<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;
151template<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;
152template<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
154// mp_eval_if_not
155template<class C, class T, template<class...> class F, class... U> using mp_eval_if_not = mp_eval_if<mp_not<C>, T, F, U...>;
156template<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
158// mp_eval_or
159template<class T, template<class...> class F, class... U> using mp_eval_or = mp_eval_if_not<mp_valid<F, U...>, T, F, U...>;
160template<class T, class Q, class... U> using mp_eval_or_q = mp_eval_or<T, Q::template fn, U...>;
161
162// mp_cond
163
164// so elegant; so doesn't work
165// template<class C, class T, class... E> using mp_cond = mp_eval_if<C, T, mp_cond, E...>;
166
167namespace detail
168{
169
170template<class C, class T, class... E> struct mp_cond_impl;
171
172} // namespace detail
173
174template<class C, class T, class... E> using mp_cond = typename detail::mp_cond_impl<C, T, E...>::type;
175
176namespace detail
177{
178
179template<class C, class T, class... E> using mp_cond_ = mp_eval_if<C, T, mp_cond, E...>;
180
181template<class C, class T, class... E> struct mp_cond_impl: mp_defer<mp_cond_, C, T, E...>
182{
183};
184
185} // namespace detail
186
187// mp_quote
188template<template<class...> class F> struct mp_quote
189{
190 // the indirection through mp_defer works around the language inability
191 // to expand T... into a fixed parameter list of an alias template
192
193 template<class... T> using fn = typename mp_defer<F, T...>::type;
194};
195
196// mp_quote_trait
197template<template<class...> class F> struct mp_quote_trait
198{
199 template<class... T> using fn = typename F<T...>::type;
200};
201
202// mp_invoke_q
203#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
204
205namespace detail
206{
207
208template<class Q, class... T> struct mp_invoke_q_impl: mp_defer<Q::template fn, T...> {};
209
210} // namespace detail
211
212template<class Q, class... T> using mp_invoke_q = typename detail::mp_invoke_q_impl<Q, T...>::type;
213
214#elif BOOST_MP11_WORKAROUND( BOOST_MP11_GCC, < 50000 )
215
216template<class Q, class... T> using mp_invoke_q = typename mp_defer<Q::template fn, T...>::type;
217
218#else
219
220template<class Q, class... T> using mp_invoke_q = typename Q::template fn<T...>;
221
222#endif
223
224// old name for mp_invoke_q retained for compatibility, but deprecated
225#if !defined(__clang__)
226
227template<class Q, class... T> using mp_invoke BOOST_MP11_DEPRECATED("please use mp_invoke_q") = mp_invoke_q<Q, T...>;
228
229#else
230
231// Clang doesn't warn on deprecated alias templates
232
233template<class Q, class... T> struct BOOST_MP11_DEPRECATED("please use mp_invoke_q") mp_invoke_
234{
235 using type = mp_invoke_q<Q, T...>;
236};
237
238template<class Q, class... T> using mp_invoke = typename mp_invoke_<Q, T...>::type;
239
240#endif
241
242// mp_not_fn<P>
243template<template<class...> class P> struct mp_not_fn
244{
245 template<class... T> using fn = mp_not< mp_invoke_q<mp_quote<P>, T...> >;
246};
247
248template<class Q> using mp_not_fn_q = mp_not_fn<Q::template fn>;
249
250// mp_compose
251namespace detail
252{
253
254template<class T, class Q> using mp_reverse_invoke_q = mp_invoke_q<Q, T>;
255
256} // namespace detail
257
258#if !BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
259
260template<template<class...> class... F> struct mp_compose
261{
262 template<class T> using fn = mp_fold<mp_list<mp_quote<F>...>, T, detail::mp_reverse_invoke_q>;
263};
264
265#endif
266
267template<class... Q> struct mp_compose_q
268{
269 template<class T> using fn = mp_fold<mp_list<Q...>, T, detail::mp_reverse_invoke_q>;
270};
271
272} // namespace mp11
273} // namespace boost
274
275#endif // #ifndef BOOST_MP11_UTILITY_HPP_INCLUDED
276

source code of include/boost/mp11/utility.hpp