llvm-project/libcxx/include/__ranges/enable_view.h

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// -*- 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>
#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 _Tp>
inline constexpr bool enable_view = derived_from<_Tp, view_base>;
} // end namespace ranges
#endif // !_LIBCPP_HAS_NO_RANGES
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___RANGES_ENABLE_VIEW_H