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< 44 is_constructible_v<tuple<_BoundArgs...>, _Args&&...> 45 >> 46 _LIBCPP_HIDE_FROM_ABI explicit constexpr __perfect_forward_impl(_Args&&... __bound_args) 47 : __bound_args_(_VSTD::forward<_Args>(__bound_args)...) {} 48 49 _LIBCPP_HIDE_FROM_ABI __perfect_forward_impl(__perfect_forward_impl const&) = default; 50 _LIBCPP_HIDE_FROM_ABI __perfect_forward_impl(__perfect_forward_impl&&) = default; 51 52 _LIBCPP_HIDE_FROM_ABI __perfect_forward_impl& operator=(__perfect_forward_impl const&) = default; 53 _LIBCPP_HIDE_FROM_ABI __perfect_forward_impl& operator=(__perfect_forward_impl&&) = default; 54 55 template <class... _Args, class = enable_if_t<is_invocable_v<_Op, _BoundArgs&..., _Args...>>> 56 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) & 57 noexcept(noexcept(_Op()(_VSTD::get<_Idx>(__bound_args_)..., _VSTD::forward<_Args>(__args)...))) 58 -> decltype( _Op()(_VSTD::get<_Idx>(__bound_args_)..., _VSTD::forward<_Args>(__args)...)) 59 { return _Op()(_VSTD::get<_Idx>(__bound_args_)..., _VSTD::forward<_Args>(__args)...); } 60 61 template <class... _Args, class = enable_if_t<!is_invocable_v<_Op, _BoundArgs&..., _Args...>>> 62 auto operator()(_Args&&...) & = delete; 63 64 template <class... _Args, class = enable_if_t<is_invocable_v<_Op, _BoundArgs const&..., _Args...>>> 65 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) const& 66 noexcept(noexcept(_Op()(_VSTD::get<_Idx>(__bound_args_)..., _VSTD::forward<_Args>(__args)...))) 67 -> decltype( _Op()(_VSTD::get<_Idx>(__bound_args_)..., _VSTD::forward<_Args>(__args)...)) 68 { return _Op()(_VSTD::get<_Idx>(__bound_args_)..., _VSTD::forward<_Args>(__args)...); } 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) && 75 noexcept(noexcept(_Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_args_))..., _VSTD::forward<_Args>(__args)...))) 76 -> decltype( _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_args_))..., _VSTD::forward<_Args>(__args)...)) 77 { return _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_args_))..., _VSTD::forward<_Args>(__args)...); } 78 79 template <class... _Args, class = enable_if_t<!is_invocable_v<_Op, _BoundArgs..., _Args...>>> 80 auto operator()(_Args&&...) && = delete; 81 82 template <class... _Args, class = enable_if_t<is_invocable_v<_Op, _BoundArgs const..., _Args...>>> 83 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) const&& 84 noexcept(noexcept(_Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_args_))..., _VSTD::forward<_Args>(__args)...))) 85 -> decltype( _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_args_))..., _VSTD::forward<_Args>(__args)...)) 86 { return _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_args_))..., _VSTD::forward<_Args>(__args)...); } 87 88 template <class... _Args, class = enable_if_t<!is_invocable_v<_Op, _BoundArgs const..., _Args...>>> 89 auto operator()(_Args&&...) const&& = delete; 90 }; 91 92 // __perfect_forward implements a perfect-forwarding call wrapper as explained in [func.require]. 93 template <class _Op, class ..._Args> 94 using __perfect_forward = __perfect_forward_impl<_Op, index_sequence_for<_Args...>, _Args...>; 95 96 #endif // _LIBCPP_STD_VER >= 17 97 98 _LIBCPP_END_NAMESPACE_STD 99 100 _LIBCPP_POP_MACROS 101 102 #endif // _LIBCPP___FUNCTIONAL_PERFECT_FORWARD_H 103