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___ITERATOR_ITER_MOVE_H 11 #define _LIBCPP___ITERATOR_ITER_MOVE_H 12 13 #include <__config> 14 #include <__iterator/iterator_traits.h> 15 #include <__utility/forward.h> 16 #include <concepts> // __class_or_enum 17 #include <type_traits> 18 #include <utility> 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 !defined(_LIBCPP_HAS_NO_CONCEPTS) 27 28 // [iterator.cust.move] 29 30 namespace ranges { 31 namespace __iter_move { 32 33 void iter_move(); 34 35 template <class _Tp> 36 concept __unqualified_iter_move = 37 __class_or_enum<remove_cvref_t<_Tp>> && 38 requires (_Tp&& __t) { 39 iter_move(_VSTD::forward<_Tp>(__t)); 40 }; 41 42 // [iterator.cust.move]/1 43 // The name ranges::iter_move denotes a customization point object. 44 // The expression ranges::iter_move(E) for a subexpression E is 45 // expression-equivalent to: 46 struct __fn { 47 // [iterator.cust.move]/1.1 48 // iter_move(E), if E has class or enumeration type and iter_move(E) is a 49 // well-formed expression when treated as an unevaluated operand, [...] 50 template<class _Ip> 51 requires __class_or_enum<remove_cvref_t<_Ip>> && __unqualified_iter_move<_Ip> 52 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Ip&& __i) const 53 noexcept(noexcept(iter_move(_VSTD::forward<_Ip>(__i)))) 54 { 55 return iter_move(_VSTD::forward<_Ip>(__i)); 56 } 57 58 // [iterator.cust.move]/1.2 59 // Otherwise, if the expression *E is well-formed: 60 // 1.2.1 if *E is an lvalue, std::move(*E); 61 // 1.2.2 otherwise, *E. 62 template<class _Ip> 63 requires (!(__class_or_enum<remove_cvref_t<_Ip>> && __unqualified_iter_move<_Ip>)) && 64 requires(_Ip&& __i) { *_VSTD::forward<_Ip>(__i); } 65 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Ip&& __i) const 66 noexcept(noexcept(*_VSTD::forward<_Ip>(__i))) 67 { 68 if constexpr (is_lvalue_reference_v<decltype(*_VSTD::forward<_Ip>(__i))>) { 69 return _VSTD::move(*_VSTD::forward<_Ip>(__i)); 70 } else { 71 return *_VSTD::forward<_Ip>(__i); 72 } 73 } 74 75 // [iterator.cust.move]/1.3 76 // Otherwise, ranges::iter_move(E) is ill-formed. 77 }; 78 } // namespace __iter_move 79 80 inline namespace __cpo { 81 inline constexpr auto iter_move = __iter_move::__fn{}; 82 } // namespace __cpo 83 } // namespace ranges 84 85 template<__dereferenceable _Tp> 86 requires requires(_Tp& __t) { { ranges::iter_move(__t) } -> __referenceable; } 87 using iter_rvalue_reference_t = decltype(ranges::iter_move(declval<_Tp&>())); 88 89 #endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) 90 91 _LIBCPP_END_NAMESPACE_STD 92 93 #endif // _LIBCPP___ITERATOR_ITER_MOVE_H 94