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_BIND_BACK_H 11 #define _LIBCPP___FUNCTIONAL_BIND_BACK_H 12 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_header 23 #endif 24 25 _LIBCPP_BEGIN_NAMESPACE_STD 26 27 #if _LIBCPP_STD_VER >= 20 28 29 template <size_t _NBound, class = make_index_sequence<_NBound>> 30 struct __bind_back_op; 31 32 template <size_t _NBound, size_t... _Ip> 33 struct __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) const 36 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 48 template <class _Fn, class _BoundArgs> 49 struct __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 53 template <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 >= 23 66 template <class _Fn, class... _Args> 67 _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 >= 23 78 79 #endif // _LIBCPP_STD_VER >= 20 80 81 _LIBCPP_END_NAMESPACE_STD 82 83 #endif // _LIBCPP___FUNCTIONAL_BIND_BACK_H 84