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 #ifndef _LIBCPP___RANGES_EMPTY_VIEW_H 10 #define _LIBCPP___RANGES_EMPTY_VIEW_H 11 12 #include <__config> 13 #include <__ranges/view_interface.h> 14 #include <type_traits> 15 16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17 #pragma GCC system_header 18 #endif 19 20 _LIBCPP_PUSH_MACROS 21 #include <__undef_macros> 22 23 _LIBCPP_BEGIN_NAMESPACE_STD 24 25 #if !defined(_LIBCPP_HAS_NO_RANGES) 26 27 namespace ranges { 28 template<class _Tp> 29 requires is_object_v<_Tp> 30 class empty_view : public view_interface<empty_view<_Tp>> { 31 public: 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 } // namespace ranges 39 40 #endif // !defined(_LIBCPP_HAS_NO_RANGES) 41 42 _LIBCPP_END_NAMESPACE_STD 43 44 _LIBCPP_POP_MACROS 45 46 #endif // _LIBCPP___RANGES_EMPTY_VIEW_H 47