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 ..._Bound> 29 struct __perfect_forward_impl; 30 31 template <class _Op, size_t ..._Idx, class ..._Bound> 32 struct __perfect_forward_impl<_Op, index_sequence<_Idx...>, _Bound...> { 33 private: 34 tuple<_Bound...> __bound_; 35 36 public: 37 template <class ..._BoundArgs, class = enable_if_t< 38 is_constructible_v<tuple<_Bound...>, _BoundArgs&&...> 39 >> 40 explicit constexpr __perfect_forward_impl(_BoundArgs&& ...__bound) 41 : __bound_(_VSTD::forward<_BoundArgs>(__bound)...) 42 { } 43 44 __perfect_forward_impl(__perfect_forward_impl const&) = default; 45 __perfect_forward_impl(__perfect_forward_impl&&) = default; 46 47 __perfect_forward_impl& operator=(__perfect_forward_impl const&) = default; 48 __perfect_forward_impl& operator=(__perfect_forward_impl&&) = default; 49 50 template <class ..._Args, class = enable_if_t<is_invocable_v<_Op, _Bound&..., _Args...>>> 51 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) & 52 noexcept(noexcept(_Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...))) 53 -> decltype( _Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...)) 54 { return _Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...); } 55 56 template <class ..._Args, class = enable_if_t<!is_invocable_v<_Op, _Bound&..., _Args...>>> 57 auto operator()(_Args&&...) & = delete; 58 59 template <class ..._Args, class = enable_if_t<is_invocable_v<_Op, _Bound const&..., _Args...>>> 60 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) const& 61 noexcept(noexcept(_Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...))) 62 -> decltype( _Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...)) 63 { return _Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...); } 64 65 template <class ..._Args, class = enable_if_t<!is_invocable_v<_Op, _Bound const&..., _Args...>>> 66 auto operator()(_Args&&...) const& = delete; 67 68 template <class ..._Args, class = enable_if_t<is_invocable_v<_Op, _Bound..., _Args...>>> 69 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) && 70 noexcept(noexcept(_Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...))) 71 -> decltype( _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...)) 72 { return _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...); } 73 74 template <class ..._Args, class = enable_if_t<!is_invocable_v<_Op, _Bound..., _Args...>>> 75 auto operator()(_Args&&...) && = delete; 76 77 template <class ..._Args, class = enable_if_t<is_invocable_v<_Op, _Bound const..., _Args...>>> 78 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) const&& 79 noexcept(noexcept(_Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...))) 80 -> decltype( _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...)) 81 { return _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...); } 82 83 template <class ..._Args, class = enable_if_t<!is_invocable_v<_Op, _Bound const..., _Args...>>> 84 auto operator()(_Args&&...) const&& = delete; 85 }; 86 87 // __perfect_forward implements a perfect-forwarding call wrapper as explained in [func.require]. 88 template <class _Op, class ..._Args> 89 using __perfect_forward = __perfect_forward_impl<_Op, index_sequence_for<_Args...>, _Args...>; 90 91 #endif // _LIBCPP_STD_VER > 14 92 93 _LIBCPP_END_NAMESPACE_STD 94 95 #endif // _LIBCPP___FUNCTIONAL_PERFECT_FORWARD_H 96