1 /* Copyright (C) 2017-2018 Free Software Foundation, Inc.
3 This file is part of GDB.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 #ifndef COMMON_TRAITS_H
19 #define COMMON_TRAITS_H
21 #include <type_traits>
23 /* GCC does not understand __has_feature. */
24 #if !defined(__has_feature)
25 # define __has_feature(x) 0
28 /* HAVE_IS_TRIVIALLY_COPYABLE is defined as 1 iff
29 std::is_trivially_copyable is available. GCC only implemented it
31 #if (__has_feature(is_trivially_copyable) \
32 || (defined __GNUC__ && __GNUC__ >= 5))
33 # define HAVE_IS_TRIVIALLY_COPYABLE 1
38 /* Pre C++14-safe (CWG 1558) version of C++17's std::void_t. See
39 <http://en.cppreference.com/w/cpp/types/void_t>. */
41 template<typename
... Ts
>
42 struct make_void
{ typedef void type
; };
44 template<typename
... Ts
>
45 using void_t
= typename make_void
<Ts
...>::type
;
47 /* A few trait helpers, mainly stolen from libstdc++. Uppercase
48 because "and/or", etc. are reserved keywords. */
50 template<typename Predicate
>
51 struct Not
: public std::integral_constant
<bool, !Predicate::value
>
58 struct Or
<> : public std::false_type
62 struct Or
<B1
> : public B1
65 template<typename B1
, typename B2
>
67 : public std::conditional
<B1::value
, B1
, B2
>::type
70 template<typename B1
,typename B2
,typename B3
, typename
... Bn
>
71 struct Or
<B1
, B2
, B3
, Bn
...>
72 : public std::conditional
<B1::value
, B1
, Or
<B2
, B3
, Bn
...>>::type
79 struct And
<> : public std::true_type
83 struct And
<B1
> : public B1
86 template<typename B1
, typename B2
>
88 : public std::conditional
<B1::value
, B2
, B1
>::type
91 template<typename B1
, typename B2
, typename B3
, typename
... Bn
>
92 struct And
<B1
, B2
, B3
, Bn
...>
93 : public std::conditional
<B1::value
, And
<B2
, B3
, Bn
...>, B1
>::type
96 /* Concepts-light-like helper to make SFINAE logic easier to read. */
97 template<typename Condition
>
98 using Requires
= typename
std::enable_if
<Condition::value
, void>::type
;
101 #endif /* COMMON_TRAITS_H */
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