1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___CXX03___FUNCTIONAL_REFERENCE_WRAPPER_H 11 #define _LIBCPP___CXX03___FUNCTIONAL_REFERENCE_WRAPPER_H 12 13 #include <__cxx03/__config> 14 #include <__cxx03/__functional/weak_result_type.h> 15 #include <__cxx03/__memory/addressof.h> 16 #include <__cxx03/__type_traits/enable_if.h> 17 #include <__cxx03/__type_traits/invoke.h> 18 #include <__cxx03/__type_traits/is_const.h> 19 #include <__cxx03/__type_traits/remove_cvref.h> 20 #include <__cxx03/__type_traits/void_t.h> 21 #include <__cxx03/__utility/declval.h> 22 #include <__cxx03/__utility/forward.h> 23 24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 25 # pragma GCC system_header 26 #endif 27 28 _LIBCPP_BEGIN_NAMESPACE_STD 29 30 template <class _Tp> 31 class _LIBCPP_TEMPLATE_VIS reference_wrapper : public __weak_result_type<_Tp> { 32 public: 33 // types 34 typedef _Tp type; 35 36 private: 37 type* __f_; 38 39 static void __fun(_Tp&) _NOEXCEPT; 40 static void __fun(_Tp&&) = delete; // NOLINT(modernize-use-equals-delete) ; This is llvm.org/PR54276 41 42 public: 43 template <class _Up, 44 class = __void_t<decltype(__fun(std::declval<_Up>()))>, 45 __enable_if_t<!__is_same_uncvref<_Up, reference_wrapper>::value, int> = 0> reference_wrapper(_Up && __u)46 _LIBCPP_HIDE_FROM_ABI reference_wrapper(_Up&& __u) { 47 type& __f = static_cast<_Up&&>(__u); 48 __f_ = std::addressof(__f); 49 } 50 51 // access 52 _LIBCPP_HIDE_FROM_ABI operator type&() const _NOEXCEPT { return *__f_; } get()53 _LIBCPP_HIDE_FROM_ABI type& get() const _NOEXCEPT { return *__f_; } 54 55 // invoke 56 template <class... _ArgTypes> operator()57 _LIBCPP_HIDE_FROM_ABI typename __invoke_of<type&, _ArgTypes...>::type operator()(_ArgTypes&&... __args) const { 58 return std::__invoke(get(), std::forward<_ArgTypes>(__args)...); 59 } 60 }; 61 62 template <class _Tp> ref(_Tp & __t)63inline _LIBCPP_HIDE_FROM_ABI reference_wrapper<_Tp> ref(_Tp& __t) _NOEXCEPT { 64 return reference_wrapper<_Tp>(__t); 65 } 66 67 template <class _Tp> ref(reference_wrapper<_Tp> __t)68inline _LIBCPP_HIDE_FROM_ABI reference_wrapper<_Tp> ref(reference_wrapper<_Tp> __t) _NOEXCEPT { 69 return __t; 70 } 71 72 template <class _Tp> cref(const _Tp & __t)73inline _LIBCPP_HIDE_FROM_ABI reference_wrapper<const _Tp> cref(const _Tp& __t) _NOEXCEPT { 74 return reference_wrapper<const _Tp>(__t); 75 } 76 77 template <class _Tp> cref(reference_wrapper<_Tp> __t)78inline _LIBCPP_HIDE_FROM_ABI reference_wrapper<const _Tp> cref(reference_wrapper<_Tp> __t) _NOEXCEPT { 79 return __t; 80 } 81 82 template <class _Tp> 83 void ref(const _Tp&&) = delete; 84 template <class _Tp> 85 void cref(const _Tp&&) = delete; 86 87 _LIBCPP_END_NAMESPACE_STD 88 89 #endif // _LIBCPP___CXX03___FUNCTIONAL_REFERENCE_WRAPPER_H 90