| // -*- 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 |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H |
| #define _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H |
| |
| #include <__compare/synth_three_way.h> |
| #include <__concepts/boolean_testable.h> |
| #include <__config> |
| #include <__functional/weak_result_type.h> |
| #include <__memory/addressof.h> |
| #include <__type_traits/desugars_to.h> |
| #include <__type_traits/enable_if.h> |
| #include <__type_traits/invoke.h> |
| #include <__type_traits/is_const.h> |
| #include <__type_traits/remove_cvref.h> |
| #include <__type_traits/void_t.h> |
| #include <__utility/declval.h> |
| #include <__utility/forward.h> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| # pragma GCC system_header |
| #endif |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| template <class _Tp> |
| class reference_wrapper : public __weak_result_type<_Tp> { |
| public: |
| // types |
| typedef _Tp type; |
| |
| private: |
| type* __f_; |
| |
| static void __fun(_Tp&) _NOEXCEPT; |
| static void __fun(_Tp&&) = delete; // NOLINT(modernize-use-equals-delete) ; This is llvm.org/PR54276 |
| |
| public: |
| template <class _Up, |
| class = __void_t<decltype(__fun(std::declval<_Up>()))>, |
| __enable_if_t<!__is_same_uncvref<_Up, reference_wrapper>::value, int> = 0> |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reference_wrapper(_Up&& __u) |
| _NOEXCEPT_(noexcept(__fun(std::declval<_Up>()))) { |
| type& __f = static_cast<_Up&&>(__u); |
| __f_ = std::addressof(__f); |
| } |
| |
| // access |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 operator type&() const _NOEXCEPT { return *__f_; } |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 type& get() const _NOEXCEPT { return *__f_; } |
| |
| // invoke |
| template <class... _ArgTypes> |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __invoke_result_t<type&, _ArgTypes...> |
| operator()(_ArgTypes&&... __args) const |
| #if _LIBCPP_STD_VER >= 17 |
| // Since is_nothrow_invocable requires C++17 LWG3764 is not backported |
| // to earlier versions. |
| noexcept(is_nothrow_invocable_v<_Tp&, _ArgTypes...>) |
| #endif |
| { |
| return std::__invoke(get(), std::forward<_ArgTypes>(__args)...); |
| } |
| |
| #if _LIBCPP_STD_VER >= 26 |
| |
| // [refwrap.comparisons], comparisons |
| |
| _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(reference_wrapper __x, reference_wrapper __y) |
| requires requires { |
| { __x.get() == __y.get() } -> __boolean_testable; |
| } |
| { |
| return __x.get() == __y.get(); |
| } |
| |
| _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(reference_wrapper __x, const _Tp& __y) |
| requires requires { |
| { __x.get() == __y } -> __boolean_testable; |
| } |
| { |
| return __x.get() == __y; |
| } |
| |
| _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(reference_wrapper __x, reference_wrapper<const _Tp> __y) |
| requires(!is_const_v<_Tp>) && requires { |
| { __x.get() == __y.get() } -> __boolean_testable; |
| } |
| { |
| return __x.get() == __y.get(); |
| } |
| |
| _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(reference_wrapper __x, reference_wrapper __y) |
| requires requires { std::__synth_three_way(__x.get(), __y.get()); } |
| { |
| return std::__synth_three_way(__x.get(), __y.get()); |
| } |
| |
| _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(reference_wrapper __x, const _Tp& __y) |
| requires requires { std::__synth_three_way(__x.get(), __y); } |
| { |
| return std::__synth_three_way(__x.get(), __y); |
| } |
| |
| _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(reference_wrapper __x, reference_wrapper<const _Tp> __y) |
| requires(!is_const_v<_Tp>) && requires { std::__synth_three_way(__x.get(), __y.get()); } |
| { |
| return std::__synth_three_way(__x.get(), __y.get()); |
| } |
| |
| #endif // _LIBCPP_STD_VER >= 26 |
| }; |
| |
| #if _LIBCPP_STD_VER >= 17 |
| template <class _Tp> |
| reference_wrapper(_Tp&) -> reference_wrapper<_Tp>; |
| #endif |
| |
| template <class _Tp> |
| inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reference_wrapper<_Tp> ref(_Tp& __t) _NOEXCEPT { |
| return reference_wrapper<_Tp>(__t); |
| } |
| |
| template <class _Tp> |
| inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reference_wrapper<_Tp> |
| ref(reference_wrapper<_Tp> __t) _NOEXCEPT { |
| return __t; |
| } |
| |
| template <class _Tp> |
| inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reference_wrapper<const _Tp> cref(const _Tp& __t) _NOEXCEPT { |
| return reference_wrapper<const _Tp>(__t); |
| } |
| |
| template <class _Tp> |
| inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reference_wrapper<const _Tp> |
| cref(reference_wrapper<_Tp> __t) _NOEXCEPT { |
| return __t; |
| } |
| |
| template <class _Tp> |
| void ref(const _Tp&&) = delete; |
| template <class _Tp> |
| void cref(const _Tp&&) = delete; |
| |
| // Let desugars-to pass through std::reference_wrapper |
| template <class _CanonicalTag, class _Operation, class... _Args> |
| inline const bool __desugars_to_v<_CanonicalTag, reference_wrapper<_Operation>, _Args...> = |
| __desugars_to_v<_CanonicalTag, _Operation, _Args...>; |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| #endif // _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H |