1fe6060f1SDimitry Andric // -*- C++ -*- 2fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 3fe6060f1SDimitry Andric // 4fe6060f1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5fe6060f1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 6fe6060f1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7fe6060f1SDimitry Andric // 8fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 9fe6060f1SDimitry Andric 10fe6060f1SDimitry Andric #ifndef _LIBCPP___RANGES_ENABLE_VIEW_H 11fe6060f1SDimitry Andric #define _LIBCPP___RANGES_ENABLE_VIEW_H 12fe6060f1SDimitry Andric 13bdd1243dSDimitry Andric #include <__concepts/derived_from.h> 14bdd1243dSDimitry Andric #include <__concepts/same_as.h> 15fe6060f1SDimitry Andric #include <__config> 16bdd1243dSDimitry Andric #include <__type_traits/is_class.h> 17bdd1243dSDimitry Andric #include <__type_traits/is_convertible.h> 18bdd1243dSDimitry Andric #include <__type_traits/remove_cv.h> 19fe6060f1SDimitry Andric 20fe6060f1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 21fe6060f1SDimitry Andric # pragma GCC system_header 22fe6060f1SDimitry Andric #endif 23fe6060f1SDimitry Andric 24fe6060f1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 25fe6060f1SDimitry Andric 2606c3fb27SDimitry Andric #if _LIBCPP_STD_VER >= 20 27fe6060f1SDimitry Andric 28fe6060f1SDimitry Andric namespace ranges { 29fe6060f1SDimitry Andric 30fe6060f1SDimitry Andric struct view_base {}; 31fe6060f1SDimitry Andric 3204eeddc0SDimitry Andric template <class _Derived> 3304eeddc0SDimitry Andric requires is_class_v<_Derived> && same_as<_Derived, remove_cv_t<_Derived>> 3404eeddc0SDimitry Andric class view_interface; 3504eeddc0SDimitry Andric 3604eeddc0SDimitry Andric template <class _Op, class _Yp> 3704eeddc0SDimitry Andric requires is_convertible_v<_Op*, view_interface<_Yp>*> 3804eeddc0SDimitry Andric void __is_derived_from_view_interface(const _Op*, const view_interface<_Yp>*); 3904eeddc0SDimitry Andric 40fe6060f1SDimitry Andric template <class _Tp> 41*cb14a3feSDimitry Andric inline constexpr bool enable_view = derived_from<_Tp, view_base> || requires { 42*cb14a3feSDimitry Andric ranges::__is_derived_from_view_interface((_Tp*)nullptr, (_Tp*)nullptr); 43*cb14a3feSDimitry Andric }; 44fe6060f1SDimitry Andric 451fd87a68SDimitry Andric } // namespace ranges 46fe6060f1SDimitry Andric 4706c3fb27SDimitry Andric #endif // _LIBCPP_STD_VER >= 20 48fe6060f1SDimitry Andric 49fe6060f1SDimitry Andric _LIBCPP_END_NAMESPACE_STD 50fe6060f1SDimitry Andric 51fe6060f1SDimitry Andric #endif // _LIBCPP___RANGES_ENABLE_VIEW_H 52