// -*- C++ -*- //===----------------------------------------------------------------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// #ifndef _LIBCPP___RANGES_EMPTY_VIEW_H #define _LIBCPP___RANGES_EMPTY_VIEW_H #include <__config> #include <__ranges/enable_borrowed_range.h> #include <__ranges/view_interface.h> #include <type_traits> #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) # pragma GCC system_header #endif _LIBCPP_BEGIN_NAMESPACE_STD #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) namespace ranges { template<class _Tp> requires is_object_v<_Tp> class empty_view : public view_interface<empty_view<_Tp>> { public: _LIBCPP_HIDE_FROM_ABI static constexpr _Tp* begin() noexcept { return nullptr; } _LIBCPP_HIDE_FROM_ABI static constexpr _Tp* end() noexcept { return nullptr; } _LIBCPP_HIDE_FROM_ABI static constexpr _Tp* data() noexcept { return nullptr; } _LIBCPP_HIDE_FROM_ABI static constexpr size_t size() noexcept { return 0; } _LIBCPP_HIDE_FROM_ABI static constexpr bool empty() noexcept { return true; } }; template<class _Tp> inline constexpr bool enable_borrowed_range<empty_view<_Tp>> = true; namespace views { template <class _Tp> inline constexpr empty_view<_Tp> empty{}; } // namespace views } // namespace ranges #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) _LIBCPP_END_NAMESPACE_STD #endif // _LIBCPP___RANGES_EMPTY_VIEW_H