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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___RANGES_EMPTY_VIEW_H11#define _LIBCPP___RANGES_EMPTY_VIEW_H12 13#include <__config>14#include <__cstddef/size_t.h>15#include <__ranges/enable_borrowed_range.h>16#include <__ranges/view_interface.h>17#include <__type_traits/is_object.h>18 19#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)20# pragma GCC system_header21#endif22 23_LIBCPP_BEGIN_NAMESPACE_STD24 25#if _LIBCPP_STD_VER >= 2026 27namespace ranges {28template <class _Tp>29 requires is_object_v<_Tp>30class empty_view : public view_interface<empty_view<_Tp>> {31public:32 _LIBCPP_HIDE_FROM_ABI static constexpr _Tp* begin() noexcept { return nullptr; }33 _LIBCPP_HIDE_FROM_ABI static constexpr _Tp* end() noexcept { return nullptr; }34 _LIBCPP_HIDE_FROM_ABI static constexpr _Tp* data() noexcept { return nullptr; }35 _LIBCPP_HIDE_FROM_ABI static constexpr size_t size() noexcept { return 0; }36 _LIBCPP_HIDE_FROM_ABI static constexpr bool empty() noexcept { return true; }37};38 39template <class _Tp>40inline constexpr bool enable_borrowed_range<empty_view<_Tp>> = true;41 42namespace views {43 44template <class _Tp>45inline constexpr empty_view<_Tp> empty{};46 47} // namespace views48} // namespace ranges49 50#endif // _LIBCPP_STD_VER >= 2051 52_LIBCPP_END_NAMESPACE_STD53 54#endif // _LIBCPP___RANGES_EMPTY_VIEW_H55