// -*- 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
// SPDX-FileCopyrightText: Copyright (c) 2023 NVIDIA CORPORATION & AFFILIATES.
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCUDACXX___ITERATOR_ISTREAMBUF_ITERATOR_H
#define _LIBCUDACXX___ITERATOR_ISTREAMBUF_ITERATOR_H

#include <cuda/std/detail/__config>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <cuda/std/__iterator/default_sentinel.h>
#include <cuda/std/__iterator/iterator.h>
#include <cuda/std/__iterator/iterator_traits.h>
#include <cuda/std/detail/libcxx/include/iosfwd>

_LIBCUDACXX_BEGIN_NAMESPACE_STD

_CCCL_SUPPRESS_DEPRECATED_PUSH
template <class _CharT, class _Traits>
class _LIBCUDACXX_TEMPLATE_VIS istreambuf_iterator
#if _CCCL_STD_VER <= 2014 || !defined(_LIBCUDACXX_ABI_NO_ITERATOR_BASES)
    : public iterator<input_iterator_tag, _CharT, typename _Traits::off_type, _CharT*, _CharT>
#endif
{
  _CCCL_SUPPRESS_DEPRECATED_POP

public:
  typedef input_iterator_tag iterator_category;
  typedef _CharT value_type;
  typedef typename _Traits::off_type difference_type;
  typedef _CharT* pointer;
  typedef _CharT reference;
  typedef _CharT char_type;
  typedef _Traits traits_type;
  typedef typename _Traits::int_type int_type;
  typedef basic_streambuf<_CharT, _Traits> streambuf_type;
  typedef basic_istream<_CharT, _Traits> istream_type;

private:
  mutable streambuf_type* __sbuf_;

  class __proxy
  {
    char_type __keep_;
    streambuf_type* __sbuf_;
    _LIBCUDACXX_INLINE_VISIBILITY explicit __proxy(char_type __c, streambuf_type* __s)
        : __keep_(__c)
        , __sbuf_(__s)
    {}
    friend class istreambuf_iterator;

  public:
    _LIBCUDACXX_INLINE_VISIBILITY char_type operator*() const
    {
      return __keep_;
    }
  };

  _LIBCUDACXX_INLINE_VISIBILITY bool __test_for_eof() const
  {
    if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sgetc(), traits_type::eof()))
    {
      __sbuf_ = nullptr;
    }
    return __sbuf_ == nullptr;
  }

public:
  _LIBCUDACXX_INLINE_VISIBILITY constexpr istreambuf_iterator() noexcept
      : __sbuf_(nullptr)
  {}
#if _CCCL_STD_VER > 2017
  _LIBCUDACXX_INLINE_VISIBILITY constexpr istreambuf_iterator(default_sentinel_t) noexcept
      : istreambuf_iterator()
  {}
#endif // _CCCL_STD_VER > 2017
  _LIBCUDACXX_INLINE_VISIBILITY istreambuf_iterator(istream_type& __s) noexcept
      : __sbuf_(__s.rdbuf())
  {}
  _LIBCUDACXX_INLINE_VISIBILITY istreambuf_iterator(streambuf_type* __s) noexcept
      : __sbuf_(__s)
  {}
  _LIBCUDACXX_INLINE_VISIBILITY istreambuf_iterator(const __proxy& __p) noexcept
      : __sbuf_(__p.__sbuf_)
  {}

  _LIBCUDACXX_INLINE_VISIBILITY char_type operator*() const
  {
    return static_cast<char_type>(__sbuf_->sgetc());
  }
  _LIBCUDACXX_INLINE_VISIBILITY istreambuf_iterator& operator++()
  {
    __sbuf_->sbumpc();
    return *this;
  }
  _LIBCUDACXX_INLINE_VISIBILITY __proxy operator++(int)
  {
    return __proxy(__sbuf_->sbumpc(), __sbuf_);
  }

  _LIBCUDACXX_INLINE_VISIBILITY bool equal(const istreambuf_iterator& __b) const
  {
    return __test_for_eof() == __b.__test_for_eof();
  }

#if _CCCL_STD_VER > 2014
  friend _LIBCUDACXX_HIDE_FROM_ABI bool operator==(const istreambuf_iterator& __i, default_sentinel_t)
  {
    return __i.__test_for_eof();
  }
#  if _CCCL_STD_VER < 2020
  friend _LIBCUDACXX_HIDE_FROM_ABI bool operator==(default_sentinel_t, const istreambuf_iterator& __i)
  {
    return __i.__test_for_eof();
  }
  friend _LIBCUDACXX_HIDE_FROM_ABI bool operator!=(const istreambuf_iterator& __i, default_sentinel_t)
  {
    return !__i.__test_for_eof();
  }
  friend _LIBCUDACXX_HIDE_FROM_ABI bool operator!=(default_sentinel_t, const istreambuf_iterator& __i)
  {
    return !__i.__test_for_eof();
  }
#  endif // _CCCL_STD_VER < 2020
#endif // _CCCL_STD_VER > 2014
};

template <class _CharT, class _Traits>
inline _LIBCUDACXX_INLINE_VISIBILITY bool
operator==(const istreambuf_iterator<_CharT, _Traits>& __a, const istreambuf_iterator<_CharT, _Traits>& __b)
{
  return __a.equal(__b);
}

#if _CCCL_STD_VER <= 2017
template <class _CharT, class _Traits>
inline _LIBCUDACXX_INLINE_VISIBILITY bool
operator!=(const istreambuf_iterator<_CharT, _Traits>& __a, const istreambuf_iterator<_CharT, _Traits>& __b)
{
  return !__a.equal(__b);
}
#endif // _CCCL_STD_VER <= 2017

_LIBCUDACXX_END_NAMESPACE_STD

#endif // _LIBCUDACXX___ITERATOR_ISTREAMBUF_ITERATOR_H
