| 1 | /* Copyright (C) 2017-2020 Free Software Foundation, Inc. |
| 2 | |
| 3 | This file is part of GDB. |
| 4 | |
| 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. |
| 9 | |
| 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. |
| 14 | |
| 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/>. */ |
| 17 | |
| 18 | #ifndef COMMON_TRAITS_H |
| 19 | #define COMMON_TRAITS_H |
| 20 | |
| 21 | #include <type_traits> |
| 22 | |
| 23 | /* GCC does not understand __has_feature. */ |
| 24 | #if !defined(__has_feature) |
| 25 | # define __has_feature(x) 0 |
| 26 | #endif |
| 27 | |
| 28 | /* HAVE_IS_TRIVIALLY_COPYABLE is defined as 1 iff |
| 29 | std::is_trivially_copyable is available. GCC only implemented it |
| 30 | in GCC 5. */ |
| 31 | #if (__has_feature(is_trivially_copyable) \ |
| 32 | || (defined __GNUC__ && __GNUC__ >= 5)) |
| 33 | # define HAVE_IS_TRIVIALLY_COPYABLE 1 |
| 34 | #endif |
| 35 | |
| 36 | /* HAVE_IS_TRIVIALLY_CONSTRUCTIBLE is defined as 1 iff |
| 37 | std::is_trivially_constructible is available. GCC only implemented it |
| 38 | in GCC 5. */ |
| 39 | #if (__has_feature(is_trivially_constructible) \ |
| 40 | || (defined __GNUC__ && __GNUC__ >= 5)) |
| 41 | # define HAVE_IS_TRIVIALLY_CONSTRUCTIBLE 1 |
| 42 | #endif |
| 43 | |
| 44 | namespace gdb { |
| 45 | |
| 46 | /* Pre C++14-safe (CWG 1558) version of C++17's std::void_t. See |
| 47 | <http://en.cppreference.com/w/cpp/types/void_t>. */ |
| 48 | |
| 49 | template<typename... Ts> |
| 50 | struct make_void { typedef void type; }; |
| 51 | |
| 52 | template<typename... Ts> |
| 53 | using void_t = typename make_void<Ts...>::type; |
| 54 | |
| 55 | /* A few trait helpers, mainly stolen from libstdc++. Uppercase |
| 56 | because "and/or", etc. are reserved keywords. */ |
| 57 | |
| 58 | template<typename Predicate> |
| 59 | struct Not : public std::integral_constant<bool, !Predicate::value> |
| 60 | {}; |
| 61 | |
| 62 | template<typename...> |
| 63 | struct Or; |
| 64 | |
| 65 | template<> |
| 66 | struct Or<> : public std::false_type |
| 67 | {}; |
| 68 | |
| 69 | template<typename B1> |
| 70 | struct Or<B1> : public B1 |
| 71 | {}; |
| 72 | |
| 73 | template<typename B1, typename B2> |
| 74 | struct Or<B1, B2> |
| 75 | : public std::conditional<B1::value, B1, B2>::type |
| 76 | {}; |
| 77 | |
| 78 | template<typename B1,typename B2,typename B3, typename... Bn> |
| 79 | struct Or<B1, B2, B3, Bn...> |
| 80 | : public std::conditional<B1::value, B1, Or<B2, B3, Bn...>>::type |
| 81 | {}; |
| 82 | |
| 83 | template<typename...> |
| 84 | struct And; |
| 85 | |
| 86 | template<> |
| 87 | struct And<> : public std::true_type |
| 88 | {}; |
| 89 | |
| 90 | template<typename B1> |
| 91 | struct And<B1> : public B1 |
| 92 | {}; |
| 93 | |
| 94 | template<typename B1, typename B2> |
| 95 | struct And<B1, B2> |
| 96 | : public std::conditional<B1::value, B2, B1>::type |
| 97 | {}; |
| 98 | |
| 99 | template<typename B1, typename B2, typename B3, typename... Bn> |
| 100 | struct And<B1, B2, B3, Bn...> |
| 101 | : public std::conditional<B1::value, And<B2, B3, Bn...>, B1>::type |
| 102 | {}; |
| 103 | |
| 104 | /* Concepts-light-like helper to make SFINAE logic easier to read. */ |
| 105 | template<typename Condition> |
| 106 | using Requires = typename std::enable_if<Condition::value, void>::type; |
| 107 | } |
| 108 | |
| 109 | #endif /* COMMON_TRAITS_H */ |