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 44namespace 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 49template<typename... Ts> 50struct make_void { typedef void type; }; 51 52template<typename... Ts> 53using 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 58template<typename Predicate> 59struct Not : public std::integral_constant<bool, !Predicate::value> 60{}; 61 62template<typename...> 63struct Or; 64 65template<> 66struct Or<> : public std::false_type 67{}; 68 69template<typename B1> 70struct Or<B1> : public B1 71{}; 72 73template<typename B1, typename B2> 74struct Or<B1, B2> 75 : public std::conditional<B1::value, B1, B2>::type 76{}; 77 78template<typename B1,typename B2,typename B3, typename... Bn> 79struct Or<B1, B2, B3, Bn...> 80 : public std::conditional<B1::value, B1, Or<B2, B3, Bn...>>::type 81{}; 82 83template<typename...> 84struct And; 85 86template<> 87struct And<> : public std::true_type 88{}; 89 90template<typename B1> 91struct And<B1> : public B1 92{}; 93 94template<typename B1, typename B2> 95struct And<B1, B2> 96 : public std::conditional<B1::value, B2, B1>::type 97{}; 98 99template<typename B1, typename B2, typename B3, typename... Bn> 100struct 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. */ 105template<typename Condition> 106using Requires = typename std::enable_if<Condition::value, void>::type; 107} 108 109#endif /* COMMON_TRAITS_H */ 110