91 lines
2.8 KiB
C++
91 lines
2.8 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___ITERATOR_ITER_MOVE_H
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#define _LIBCPP___ITERATOR_ITER_MOVE_H
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#include <__config>
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#include <__iterator/iterator_traits.h>
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#include <concepts> // __class_or_enum
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#include <type_traits>
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#include <utility>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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#pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if !defined(_LIBCPP_HAS_NO_RANGES)
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namespace ranges::__iter_move {
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void iter_move();
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template<class _Ip>
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concept __unqualified_iter_move = requires(_Ip&& __i) {
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iter_move(_VSTD::forward<_Ip>(__i));
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};
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// [iterator.cust.move]/1
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// The name ranges::iter_move denotes a customization point object.
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// The expression ranges::iter_move(E) for a subexpression E is
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// expression-equivalent to:
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struct __fn {
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// [iterator.cust.move]/1.1
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// iter_move(E), if E has class or enumeration type and iter_move(E) is a
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// well-formed expression when treated as an unevaluated operand, [...]
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template<class _Ip>
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requires __class_or_enum<remove_cvref_t<_Ip>> && __unqualified_iter_move<_Ip>
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[[nodiscard]] constexpr decltype(auto) operator()(_Ip&& __i) const
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noexcept(noexcept(iter_move(_VSTD::forward<_Ip>(__i))))
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{
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return iter_move(_VSTD::forward<_Ip>(__i));
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}
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// [iterator.cust.move]/1.2
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// Otherwise, if the expression *E is well-formed:
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// 1.2.1 if *E is an lvalue, std::move(*E);
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// 1.2.2 otherwise, *E.
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template<class _Ip>
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requires (!(__class_or_enum<remove_cvref_t<_Ip>> && __unqualified_iter_move<_Ip>)) &&
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requires(_Ip&& __i) { *_VSTD::forward<_Ip>(__i); }
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[[nodiscard]] constexpr decltype(auto) operator()(_Ip&& __i) const
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noexcept(noexcept(*_VSTD::forward<_Ip>(__i)))
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{
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if constexpr (is_lvalue_reference_v<decltype(*_VSTD::forward<_Ip>(__i))>) {
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return _VSTD::move(*_VSTD::forward<_Ip>(__i));
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} else {
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return *_VSTD::forward<_Ip>(__i);
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}
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}
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// [iterator.cust.move]/1.3
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// Otherwise, ranges::iter_move(E) is ill-formed.
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};
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} // namespace ranges::__iter_move
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namespace ranges::inline __cpo {
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inline constexpr auto iter_move = __iter_move::__fn{};
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}
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template<__dereferenceable _Tp>
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requires requires(_Tp& __t) { { ranges::iter_move(__t) } -> __referenceable; }
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using iter_rvalue_reference_t = decltype(ranges::iter_move(declval<_Tp&>()));
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#endif // !_LIBCPP_HAS_NO_RANGES
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___ITERATOR_ITER_MOVE_H
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