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- /* Copyright (C) 2017-2022 Free Software Foundation, Inc.
- This file is part of GDB.
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
- #ifndef COMMON_TRAITS_H
- #define COMMON_TRAITS_H
- #include <type_traits>
- /* GCC does not understand __has_feature. */
- #if !defined(__has_feature)
- # define __has_feature(x) 0
- #endif
- /* HAVE_IS_TRIVIALLY_COPYABLE is defined as 1 iff
- std::is_trivially_copyable is available. GCC only implemented it
- in GCC 5. */
- #if (__has_feature(is_trivially_copyable) \
- || (defined __GNUC__ && __GNUC__ >= 5))
- # define HAVE_IS_TRIVIALLY_COPYABLE 1
- #endif
- /* HAVE_IS_TRIVIALLY_CONSTRUCTIBLE is defined as 1 iff
- std::is_trivially_constructible is available. GCC only implemented it
- in GCC 5. */
- #if (__has_feature(is_trivially_constructible) \
- || (defined __GNUC__ && __GNUC__ >= 5))
- # define HAVE_IS_TRIVIALLY_CONSTRUCTIBLE 1
- #endif
- namespace gdb {
- /* Pre C++14-safe (CWG 1558) version of C++17's std::void_t. See
- <http://en.cppreference.com/w/cpp/types/void_t>. */
- template<typename... Ts>
- struct make_void { typedef void type; };
- template<typename... Ts>
- using void_t = typename make_void<Ts...>::type;
- /* Implementation of the detection idiom:
- - http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4502.pdf
- - http://en.cppreference.com/w/cpp/experimental/is_detected
- */
- struct nonesuch
- {
- nonesuch () = delete;
- ~nonesuch () = delete;
- nonesuch (const nonesuch &) = delete;
- void operator= (const nonesuch &) = delete;
- };
- namespace detection_detail {
- /* Implementation of the detection idiom (negative case). */
- template<typename Default, typename AlwaysVoid,
- template<typename...> class Op, typename... Args>
- struct detector
- {
- using value_t = std::false_type;
- using type = Default;
- };
- /* Implementation of the detection idiom (positive case). */
- template<typename Default, template<typename...> class Op, typename... Args>
- struct detector<Default, void_t<Op<Args...>>, Op, Args...>
- {
- using value_t = std::true_type;
- using type = Op<Args...>;
- };
- /* Detect whether Op<Args...> is a valid type, use Default if not. */
- template<typename Default, template<typename...> class Op,
- typename... Args>
- using detected_or = detector<Default, void, Op, Args...>;
- /* Op<Args...> if that is a valid type, otherwise Default. */
- template<typename Default, template<typename...> class Op,
- typename... Args>
- using detected_or_t
- = typename detected_or<Default, Op, Args...>::type;
- } /* detection_detail */
- template<template<typename...> class Op, typename... Args>
- using is_detected
- = typename detection_detail::detector<nonesuch, void, Op, Args...>::value_t;
- template<template<typename...> class Op, typename... Args>
- using detected_t
- = typename detection_detail::detector<nonesuch, void, Op, Args...>::type;
- template<typename Default, template<typename...> class Op, typename... Args>
- using detected_or = detection_detail::detected_or<Default, Op, Args...>;
- template<typename Default, template<typename...> class Op, typename... Args>
- using detected_or_t = typename detected_or<Default, Op, Args...>::type;
- template<typename Expected, template<typename...> class Op, typename... Args>
- using is_detected_exact = std::is_same<Expected, detected_t<Op, Args...>>;
- template<typename To, template<typename...> class Op, typename... Args>
- using is_detected_convertible
- = std::is_convertible<detected_t<Op, Args...>, To>;
- /* A few trait helpers, mainly stolen from libstdc++. Uppercase
- because "and/or", etc. are reserved keywords. */
- template<typename Predicate>
- struct Not : public std::integral_constant<bool, !Predicate::value>
- {};
- template<typename...>
- struct Or;
- template<>
- struct Or<> : public std::false_type
- {};
- template<typename B1>
- struct Or<B1> : public B1
- {};
- template<typename B1, typename B2>
- struct Or<B1, B2>
- : public std::conditional<B1::value, B1, B2>::type
- {};
- template<typename B1,typename B2,typename B3, typename... Bn>
- struct Or<B1, B2, B3, Bn...>
- : public std::conditional<B1::value, B1, Or<B2, B3, Bn...>>::type
- {};
- template<typename...>
- struct And;
- template<>
- struct And<> : public std::true_type
- {};
- template<typename B1>
- struct And<B1> : public B1
- {};
- template<typename B1, typename B2>
- struct And<B1, B2>
- : public std::conditional<B1::value, B2, B1>::type
- {};
- template<typename B1, typename B2, typename B3, typename... Bn>
- struct And<B1, B2, B3, Bn...>
- : public std::conditional<B1::value, And<B2, B3, Bn...>, B1>::type
- {};
- /* Concepts-light-like helper to make SFINAE logic easier to read. */
- template<typename Condition>
- using Requires = typename std::enable_if<Condition::value, void>::type;
- }
- #endif /* COMMON_TRAITS_H */
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