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___FUNCTIONAL_PERFECT_FORWARD_H 11 #define _LIBCPP___FUNCTIONAL_PERFECT_FORWARD_H 12 13 #include <__config> 14 #include <__type_traits/enable_if.h> 15 #include <__type_traits/invoke.h> 16 #include <__type_traits/is_constructible.h> 17 #include <__utility/declval.h> 18 #include <__utility/forward.h> 19 #include <__utility/integer_sequence.h> 20 #include <__utility/move.h> 21 #include <tuple> 22 23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 24 # pragma GCC system_header 25 #endif 26 27 _LIBCPP_PUSH_MACROS 28 #include <__undef_macros> 29 30 _LIBCPP_BEGIN_NAMESPACE_STD 31 32 #if _LIBCPP_STD_VER >= 17 33 34 template <class _Op, class _Indices, class... _BoundArgs> 35 struct __perfect_forward_impl; 36 37 template <class _Op, size_t... _Idx, class... _BoundArgs> 38 struct __perfect_forward_impl<_Op, index_sequence<_Idx...>, _BoundArgs...> { 39 private: 40 tuple<_BoundArgs...> __bound_args_; 41 42 public: 43 template <class... _Args, class = enable_if_t< is_constructible_v<tuple<_BoundArgs...>, _Args&&...> >> 44 _LIBCPP_HIDE_FROM_ABI explicit constexpr __perfect_forward_impl(_Args&&... __bound_args) 45 : __bound_args_(std::forward<_Args>(__bound_args)...) {} 46 47 _LIBCPP_HIDE_FROM_ABI __perfect_forward_impl(__perfect_forward_impl const&) = default; 48 _LIBCPP_HIDE_FROM_ABI __perfect_forward_impl(__perfect_forward_impl&&) = default; 49 50 _LIBCPP_HIDE_FROM_ABI __perfect_forward_impl& operator=(__perfect_forward_impl const&) = default; 51 _LIBCPP_HIDE_FROM_ABI __perfect_forward_impl& operator=(__perfect_forward_impl&&) = default; 52 53 template <class... _Args, class = enable_if_t<is_invocable_v<_Op, _BoundArgs&..., _Args...>>> 54 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) & noexcept( 55 noexcept(_Op()(std::get<_Idx>(__bound_args_)..., std::forward<_Args>(__args)...))) 56 -> decltype(_Op()(std::get<_Idx>(__bound_args_)..., std::forward<_Args>(__args)...)) { 57 return _Op()(std::get<_Idx>(__bound_args_)..., std::forward<_Args>(__args)...); 58 } 59 60 template <class... _Args, class = enable_if_t<!is_invocable_v<_Op, _BoundArgs&..., _Args...>>> 61 auto operator()(_Args&&...) & = delete; 62 63 template <class... _Args, class = enable_if_t<is_invocable_v<_Op, _BoundArgs const&..., _Args...>>> 64 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) const& noexcept( 65 noexcept(_Op()(std::get<_Idx>(__bound_args_)..., std::forward<_Args>(__args)...))) 66 -> decltype(_Op()(std::get<_Idx>(__bound_args_)..., std::forward<_Args>(__args)...)) { 67 return _Op()(std::get<_Idx>(__bound_args_)..., std::forward<_Args>(__args)...); 68 } 69 70 template <class... _Args, class = enable_if_t<!is_invocable_v<_Op, _BoundArgs const&..., _Args...>>> 71 auto operator()(_Args&&...) const& = delete; 72 73 template <class... _Args, class = enable_if_t<is_invocable_v<_Op, _BoundArgs..., _Args...>>> 74 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) && noexcept( 75 noexcept(_Op()(std::get<_Idx>(std::move(__bound_args_))..., std::forward<_Args>(__args)...))) 76 -> decltype(_Op()(std::get<_Idx>(std::move(__bound_args_))..., std::forward<_Args>(__args)...)) { 77 return _Op()(std::get<_Idx>(std::move(__bound_args_))..., std::forward<_Args>(__args)...); 78 } 79 80 template <class... _Args, class = enable_if_t<!is_invocable_v<_Op, _BoundArgs..., _Args...>>> 81 auto operator()(_Args&&...) && = delete; 82 83 template <class... _Args, class = enable_if_t<is_invocable_v<_Op, _BoundArgs const..., _Args...>>> 84 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) const&& noexcept( 85 noexcept(_Op()(std::get<_Idx>(std::move(__bound_args_))..., std::forward<_Args>(__args)...))) 86 -> decltype(_Op()(std::get<_Idx>(std::move(__bound_args_))..., std::forward<_Args>(__args)...)) { 87 return _Op()(std::get<_Idx>(std::move(__bound_args_))..., std::forward<_Args>(__args)...); 88 } 89 90 template <class... _Args, class = enable_if_t<!is_invocable_v<_Op, _BoundArgs const..., _Args...>>> 91 auto operator()(_Args&&...) const&& = delete; 92 }; 93 94 // __perfect_forward implements a perfect-forwarding call wrapper as explained in [func.require]. 95 template <class _Op, class... _Args> 96 using __perfect_forward = __perfect_forward_impl<_Op, index_sequence_for<_Args...>, _Args...>; 97 98 #endif // _LIBCPP_STD_VER >= 17 99 100 _LIBCPP_END_NAMESPACE_STD 101 102 _LIBCPP_POP_MACROS 103 104 #endif // _LIBCPP___FUNCTIONAL_PERFECT_FORWARD_H 105