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