102 lines
2.7 KiB
C++
102 lines
2.7 KiB
C++
/* Copyright (C) 2017-2018 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef COMMON_TRAITS_H
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#define COMMON_TRAITS_H
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#include <type_traits>
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/* GCC does not understand __has_feature. */
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#if !defined(__has_feature)
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# define __has_feature(x) 0
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#endif
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/* HAVE_IS_TRIVIALLY_COPYABLE is defined as 1 iff
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std::is_trivially_copyable is available. GCC only implemented it
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in GCC 5. */
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#if (__has_feature(is_trivially_copyable) \
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|| (defined __GNUC__ && __GNUC__ >= 5))
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# define HAVE_IS_TRIVIALLY_COPYABLE 1
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#endif
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namespace gdb {
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/* Pre C++14-safe (CWG 1558) version of C++17's std::void_t. See
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<http://en.cppreference.com/w/cpp/types/void_t>. */
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template<typename... Ts>
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struct make_void { typedef void type; };
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template<typename... Ts>
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using void_t = typename make_void<Ts...>::type;
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/* A few trait helpers, mainly stolen from libstdc++. Uppercase
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because "and/or", etc. are reserved keywords. */
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template<typename Predicate>
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struct Not : public std::integral_constant<bool, !Predicate::value>
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{};
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template<typename...>
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struct Or;
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template<>
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struct Or<> : public std::false_type
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{};
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template<typename B1>
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struct Or<B1> : public B1
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{};
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template<typename B1, typename B2>
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struct Or<B1, B2>
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: public std::conditional<B1::value, B1, B2>::type
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{};
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template<typename B1,typename B2,typename B3, typename... Bn>
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struct Or<B1, B2, B3, Bn...>
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: public std::conditional<B1::value, B1, Or<B2, B3, Bn...>>::type
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{};
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template<typename...>
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struct And;
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template<>
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struct And<> : public std::true_type
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{};
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template<typename B1>
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struct And<B1> : public B1
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{};
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template<typename B1, typename B2>
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struct And<B1, B2>
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: public std::conditional<B1::value, B2, B1>::type
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{};
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template<typename B1, typename B2, typename B3, typename... Bn>
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struct And<B1, B2, B3, Bn...>
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: public std::conditional<B1::value, And<B2, B3, Bn...>, B1>::type
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{};
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/* Concepts-light-like helper to make SFINAE logic easier to read. */
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template<typename Condition>
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using Requires = typename std::enable_if<Condition::value, void>::type;
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}
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#endif /* COMMON_TRAITS_H */
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