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/* Copyright (C) 2017 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>
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;
/* A few trait helpers, mainly stolen from libstdc++. Uppercase
because "and" is a keyword. */
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
{};
}
#endif /* COMMON_TRAITS_H */
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