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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-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___FUNCTIONAL_BIND_BACK_H11#define _LIBCPP___FUNCTIONAL_BIND_BACK_H12 13#include <__config>14#include <__functional/invoke.h>15#include <__functional/perfect_forward.h>16#include <__type_traits/decay.h>17#include <__utility/forward.h>18#include <__utility/integer_sequence.h>19#include <tuple>20 21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)22# pragma GCC system_header23#endif24 25_LIBCPP_BEGIN_NAMESPACE_STD26 27#if _LIBCPP_STD_VER >= 2028 29template <size_t _NBound, class = make_index_sequence<_NBound>>30struct __bind_back_op;31 32template <size_t _NBound, size_t... _Ip>33struct __bind_back_op<_NBound, index_sequence<_Ip...>> {34 template <class _Fn, class _BoundArgs, class... _Args>35 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Fn&& __f, _BoundArgs&& __bound_args, _Args&&... __args) const36 noexcept(noexcept(std::invoke(std::forward<_Fn>(__f),37 std::forward<_Args>(__args)...,38 std::get<_Ip>(std::forward<_BoundArgs>(__bound_args))...)))39 -> decltype(std::invoke(std::forward<_Fn>(__f),40 std::forward<_Args>(__args)...,41 std::get<_Ip>(std::forward<_BoundArgs>(__bound_args))...)) {42 return std::invoke(std::forward<_Fn>(__f),43 std::forward<_Args>(__args)...,44 std::get<_Ip>(std::forward<_BoundArgs>(__bound_args))...);45 }46};47 48template <class _Fn, class _BoundArgs>49struct __bind_back_t : __perfect_forward<__bind_back_op<tuple_size_v<_BoundArgs>>, _Fn, _BoundArgs> {50 using __perfect_forward<__bind_back_op<tuple_size_v<_BoundArgs>>, _Fn, _BoundArgs>::__perfect_forward;51};52 53template <class _Fn, class... _Args>54 requires is_constructible_v<decay_t<_Fn>, _Fn> && is_move_constructible_v<decay_t<_Fn>> &&55 (is_constructible_v<decay_t<_Args>, _Args> && ...) && (is_move_constructible_v<decay_t<_Args>> && ...)56_LIBCPP_HIDE_FROM_ABI constexpr auto __bind_back(_Fn&& __f, _Args&&... __args) noexcept(57 noexcept(__bind_back_t<decay_t<_Fn>, tuple<decay_t<_Args>...>>(58 std::forward<_Fn>(__f), std::forward_as_tuple(std::forward<_Args>(__args)...))))59 -> decltype(__bind_back_t<decay_t<_Fn>, tuple<decay_t<_Args>...>>(60 std::forward<_Fn>(__f), std::forward_as_tuple(std::forward<_Args>(__args)...))) {61 return __bind_back_t<decay_t<_Fn>, tuple<decay_t<_Args>...>>(62 std::forward<_Fn>(__f), std::forward_as_tuple(std::forward<_Args>(__args)...));63}64 65# if _LIBCPP_STD_VER >= 2366template <class _Fn, class... _Args>67[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto bind_back(_Fn&& __f, _Args&&... __args) {68 static_assert(is_constructible_v<decay_t<_Fn>, _Fn>, "bind_back requires decay_t<F> to be constructible from F");69 static_assert(is_move_constructible_v<decay_t<_Fn>>, "bind_back requires decay_t<F> to be move constructible");70 static_assert((is_constructible_v<decay_t<_Args>, _Args> && ...),71 "bind_back requires all decay_t<Args> to be constructible from respective Args");72 static_assert((is_move_constructible_v<decay_t<_Args>> && ...),73 "bind_back requires all decay_t<Args> to be move constructible");74 return __bind_back_t<decay_t<_Fn>, tuple<decay_t<_Args>...>>(75 std::forward<_Fn>(__f), std::forward_as_tuple(std::forward<_Args>(__args)...));76}77# endif // _LIBCPP_STD_VER >= 2378 79#endif // _LIBCPP_STD_VER >= 2080 81_LIBCPP_END_NAMESPACE_STD82 83#endif // _LIBCPP___FUNCTIONAL_BIND_BACK_H84