| // -*- 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_ENABLE_VIEW_H |
| #define _LIBCPP___RANGES_ENABLE_VIEW_H |
| |
| #include <__config> |
| #include <concepts> |
| #include <type_traits> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| #pragma GCC system_header |
| #endif |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| #if !defined(_LIBCPP_HAS_NO_RANGES) |
| |
| namespace ranges { |
| |
| struct view_base { }; |
| |
| template<class _Derived> |
| requires is_class_v<_Derived> && same_as<_Derived, remove_cv_t<_Derived>> |
| class view_interface; |
| |
| template<class _Op, class _Yp> |
| requires is_convertible_v<_Op*, view_interface<_Yp>*> |
| void __is_derived_from_view_interface(const _Op*, const view_interface<_Yp>*); |
| |
| template <class _Tp> |
| inline constexpr bool enable_view = derived_from<_Tp, view_base> || |
| requires { ranges::__is_derived_from_view_interface((_Tp*)nullptr, (_Tp*)nullptr); }; |
| |
| } // end namespace ranges |
| |
| #endif // !_LIBCPP_HAS_NO_RANGES |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| #endif // _LIBCPP___RANGES_ENABLE_VIEW_H |
