// -*- 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
//
//===----------------------------------------------------------------------===//
//==============================================================================
// NOTICE: This file has been modified by Green Hills Software, Inc.  Such
// modifications are subject to copyright by Green Hills Software, Inc.  See the
// "Green Hills Software Modifications" section in the LICENSE.txt included with
// this distribution for more information.
//==============================================================================

#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

#if defined(__ghs__)
  #pragma ghs start_cxx_lib_header
  #pragma ghs startdata
  #if defined(__ghs_max_pack_value)
    #pragma pack (push, __ghs_max_pack_value)
  #endif
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER > 17

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

_LIBCPP_END_NAMESPACE_STD

#if defined(__ghs__)
  #if defined(__ghs_max_pack_value)
    #pragma pack(pop)
  #endif
  #pragma ghs enddata
  #pragma ghs end_cxx_lib_header
#endif

#endif // _LIBCPP___RANGES_EMPTY_VIEW_H