| //===----------------------------------------------------------------------===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef _LIBCPP___TYPE_TRAITS_CONJUNCTION_H |
| #define _LIBCPP___TYPE_TRAITS_CONJUNCTION_H |
| |
| #include <__config> |
| #include <__type_traits/conditional.h> |
| #include <__type_traits/enable_if.h> |
| #include <__type_traits/integral_constant.h> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| # pragma GCC system_header |
| #endif |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| template <class...> |
| using __expand_to_true = true_type; |
| |
| template <class... _Pred> |
| __expand_to_true<__enable_if_t<_Pred::value>...> __and_helper(int); |
| |
| template <class...> |
| false_type __and_helper(...); |
| |
| // _And always performs lazy evaluation of its arguments. |
| // |
| // However, `_And<_Pred...>` itself will evaluate its result immediately (without having to |
| // be instantiated) since it is an alias, unlike `conjunction<_Pred...>`, which is a struct. |
| // If you want to defer the evaluation of `_And<_Pred...>` itself, use `_Lazy<_And, _Pred...>`. |
| template <class... _Pred> |
| using _And _LIBCPP_NODEBUG = decltype(std::__and_helper<_Pred...>(0)); |
| |
| #if _LIBCPP_STD_VER > 14 |
| |
| template <class...> |
| struct conjunction : true_type {}; |
| |
| template <class _Arg> |
| struct conjunction<_Arg> : _Arg {}; |
| |
| template <class _Arg, class... _Args> |
| struct conjunction<_Arg, _Args...> : conditional_t<!bool(_Arg::value), _Arg, conjunction<_Args...>> {}; |
| |
| template <class... _Args> |
| inline constexpr bool conjunction_v = conjunction<_Args...>::value; |
| |
| #endif // _LIBCPP_STD_VER > 14 |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| #endif // _LIBCPP___TYPE_TRAITS_CONJUNCTION_H |