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