1*4bdff4beSrobert // -*- C++ -*- 2*4bdff4beSrobert //===----------------------------------------------------------------------===// 3*4bdff4beSrobert // 4*4bdff4beSrobert // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5*4bdff4beSrobert // See https://llvm.org/LICENSE.txt for license information. 6*4bdff4beSrobert // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7*4bdff4beSrobert // 8*4bdff4beSrobert //===----------------------------------------------------------------------===// 9*4bdff4beSrobert 10*4bdff4beSrobert #ifndef _LIBCPP___UTILITY_FORWARD_LIKE_H 11*4bdff4beSrobert #define _LIBCPP___UTILITY_FORWARD_LIKE_H 12*4bdff4beSrobert 13*4bdff4beSrobert #include <__config> 14*4bdff4beSrobert #include <__type_traits/conditional.h> 15*4bdff4beSrobert #include <__type_traits/is_const.h> 16*4bdff4beSrobert #include <__type_traits/is_reference.h> 17*4bdff4beSrobert #include <__type_traits/remove_reference.h> 18*4bdff4beSrobert 19*4bdff4beSrobert #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20*4bdff4beSrobert # pragma GCC system_header 21*4bdff4beSrobert #endif 22*4bdff4beSrobert 23*4bdff4beSrobert _LIBCPP_BEGIN_NAMESPACE_STD 24*4bdff4beSrobert 25*4bdff4beSrobert #if _LIBCPP_STD_VER > 20 26*4bdff4beSrobert 27*4bdff4beSrobert template <class _Ap, class _Bp> 28*4bdff4beSrobert using _CopyConst = _If<is_const_v<_Ap>, const _Bp, _Bp>; 29*4bdff4beSrobert 30*4bdff4beSrobert template <class _Ap, class _Bp> 31*4bdff4beSrobert using _OverrideRef = _If<is_rvalue_reference_v<_Ap>, remove_reference_t<_Bp>&&, _Bp&>; 32*4bdff4beSrobert 33*4bdff4beSrobert template <class _Ap, class _Bp> 34*4bdff4beSrobert using _ForwardLike = _OverrideRef<_Ap&&, _CopyConst<remove_reference_t<_Ap>, remove_reference_t<_Bp>>>; 35*4bdff4beSrobert 36*4bdff4beSrobert template <class _Tp, class _Up> 37*4bdff4beSrobert [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto forward_like(_LIBCPP_LIFETIMEBOUND _Up&& __ux) noexcept 38*4bdff4beSrobert -> _ForwardLike<_Tp, _Up> { 39*4bdff4beSrobert return static_cast<_ForwardLike<_Tp, _Up>>(__ux); 40*4bdff4beSrobert } 41*4bdff4beSrobert 42*4bdff4beSrobert #endif // _LIBCPP_STD_VER > 20 43*4bdff4beSrobert 44*4bdff4beSrobert _LIBCPP_END_NAMESPACE_STD 45*4bdff4beSrobert 46*4bdff4beSrobert #endif // _LIBCPP___UTILITY_FORWARD_LIKE_H 47