STLForwardCompat.h

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//===- STLForwardCompat.h - Library features from future STLs ------C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file contains library features backported from future STL versions.
///
/// These should be replaced with their STL counterparts as the C++ version LLVM
/// is compiled with is updated.
///
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_ADT_STLFORWARDCOMPAT_H
#define LLVM_ADT_STLFORWARDCOMPAT_H
 
#include <type_traits>
 
namespace llvm {
 
//===----------------------------------------------------------------------===//
//     Features from C++17
//===----------------------------------------------------------------------===//
 
template <typename T>
struct negation // NOLINT(readability-identifier-naming)
    : std::integral_constant<bool, !bool(T::value)> {};
 
template <typename...>
struct conjunction // NOLINT(readability-identifier-naming)
    : std::true_type {};
template <typename B1> struct conjunction<B1> : B1 {};
template <typename B1, typename... Bn>
struct conjunction<B1, Bn...>
    : std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
 
template <typename...>
struct disjunction // NOLINT(readability-identifier-naming)
    : std::false_type {};
template <typename B1> struct disjunction<B1> : B1 {};
template <typename B1, typename... Bn>
struct disjunction<B1, Bn...>
    : std::conditional<bool(B1::value), B1, disjunction<Bn...>>::type {};
 
struct in_place_t // NOLINT(readability-identifier-naming)
{
  explicit in_place_t() = default;
};
/// \warning This must not be odr-used, as it cannot be made \c inline in C++14.
constexpr in_place_t in_place; // NOLINT(readability-identifier-naming)
 
template <typename T>
struct in_place_type_t // NOLINT(readability-identifier-naming)
{
  explicit in_place_type_t() = default;
};
 
template <std::size_t I>
struct in_place_index_t // NOLINT(readability-identifier-naming)
{
  explicit in_place_index_t() = default;
};
 
//===----------------------------------------------------------------------===//
//     Features from C++20
//===----------------------------------------------------------------------===//
 
template <typename T>
struct remove_cvref // NOLINT(readability-identifier-naming)
{
  using type = std::remove_cv_t<std::remove_reference_t<T>>;
};
 
template <typename T>
using remove_cvref_t // NOLINT(readability-identifier-naming)
    = typename llvm::remove_cvref<T>::type;
 
} // namespace llvm
 
#endif // LLVM_ADT_STLFORWARDCOMPAT_H