[thirdparty/gcc.git] / libstdc++-v3 / include / bits / streambuf_iterator.h

// Streambuf iterators

// Copyright (C) 1997-2025 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file bits/streambuf_iterator.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{iterator}
 */

#ifndef _STREAMBUF_ITERATOR_H
#define _STREAMBUF_ITERATOR_H 1

#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif

#include <streambuf>
#include <bits/stl_iterator_base_types.h>
#include <debug/debug.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**
   * @addtogroup iterators
   * @{
   */

// Ignore warnings about std::iterator.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
  // 24.5.3 Template class istreambuf_iterator
  /// Provides input iterator semantics for streambufs.
  template<typename _CharT, typename _Traits>
    class istreambuf_iterator
    : public iterator<input_iterator_tag, _CharT, typename _Traits::off_type,
		      _CharT*, _CharT>
    {
    public:
      // Types:
      ///@{
      /// Public typedefs
#if __cplusplus < 201103L
      typedef _CharT& reference; // Changed to _CharT by LWG 445
#elif __cplusplus > 201703L
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 3188. istreambuf_iterator::pointer should not be unspecified
      using pointer = void;
#endif

      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;
      ///@}

      template<typename _CharT2>
	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
				    ostreambuf_iterator<_CharT2> >::__type
	copy(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>,
	     ostreambuf_iterator<_CharT2>);

      template<bool _IsMove, typename _CharT2>
	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
					       _CharT2*>::__type
	__copy_move_a2(istreambuf_iterator<_CharT2>,
		       istreambuf_iterator<_CharT2>, _CharT2*);

      template<typename _CharT2, typename _Size>
	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
					       _CharT2*>::__type
	__copy_n_a(istreambuf_iterator<_CharT2>, _Size, _CharT2*, bool);

      template<typename _CharT2>
	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
				    istreambuf_iterator<_CharT2> >::__type
	find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>,
	     const _CharT2&);

      template<typename _CharT2, typename _Distance>
	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
					       void>::__type
	advance(istreambuf_iterator<_CharT2>&, _Distance);

    private:
      // 24.5.3 istreambuf_iterator
      // p 1
      // If the end of stream is reached (streambuf_type::sgetc()
      // returns traits_type::eof()), the iterator becomes equal to
      // the "end of stream" iterator value.
      // NB: This implementation assumes the "end of stream" value
      // is EOF, or -1.
      mutable streambuf_type*	_M_sbuf;
      int_type			_M_c;

    public:
      ///  Construct end of input stream iterator.
      _GLIBCXX_CONSTEXPR istreambuf_iterator() _GLIBCXX_USE_NOEXCEPT
      : _M_sbuf(0), _M_c(traits_type::eof()) { }

#if __cplusplus > 201703L && __cpp_lib_concepts
      constexpr istreambuf_iterator(default_sentinel_t) noexcept
      : istreambuf_iterator() { }
#endif

#if __cplusplus >= 201103L
      istreambuf_iterator(const istreambuf_iterator&) noexcept = default;

      ~istreambuf_iterator() = default;
#endif

      ///  Construct start of input stream iterator.
      istreambuf_iterator(istream_type& __s) _GLIBCXX_USE_NOEXCEPT
      : _M_sbuf(__s.rdbuf()), _M_c(traits_type::eof()) { }

      ///  Construct start of streambuf iterator.
      istreambuf_iterator(streambuf_type* __s) _GLIBCXX_USE_NOEXCEPT
      : _M_sbuf(__s), _M_c(traits_type::eof()) { }

#if __cplusplus >= 201103L
      istreambuf_iterator&
      operator=(const istreambuf_iterator&) noexcept = default;
#endif

      ///  Return the current character pointed to by iterator.  This returns
      ///  streambuf.sgetc().  It cannot be assigned.  NB: The result of
      ///  operator*() on an end of stream is undefined.
      _GLIBCXX_NODISCARD
      char_type
      operator*() const
      {
	int_type __c = _M_get();

#ifdef _GLIBCXX_DEBUG_PEDANTIC
	// Dereferencing a past-the-end istreambuf_iterator is a
	// libstdc++ extension
	__glibcxx_requires_cond(!_S_is_eof(__c),
				_M_message(__gnu_debug::__msg_deref_istreambuf)
				._M_iterator(*this));
#endif
	return traits_type::to_char_type(__c);
      }

      /// Advance the iterator.  Calls streambuf.sbumpc().
      istreambuf_iterator&
      operator++()
      {
	__glibcxx_requires_cond(_M_sbuf &&
				(!_S_is_eof(_M_c) || !_S_is_eof(_M_sbuf->sgetc())),
				_M_message(__gnu_debug::__msg_inc_istreambuf)
				._M_iterator(*this));

	_M_sbuf->sbumpc();
	_M_c = traits_type::eof();
	return *this;
      }

      /// Advance the iterator.  Calls streambuf.sbumpc().
      istreambuf_iterator
      operator++(int)
      {
	__glibcxx_requires_cond(_M_sbuf &&
				(!_S_is_eof(_M_c) || !_S_is_eof(_M_sbuf->sgetc())),
				_M_message(__gnu_debug::__msg_inc_istreambuf)
				._M_iterator(*this));

	istreambuf_iterator __old = *this;
	__old._M_c = _M_sbuf->sbumpc();
	_M_c = traits_type::eof();
	return __old;
      }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 110 istreambuf_iterator::equal not const
      // NB: there is also number 111 (NAD) relevant to this function.
      /// Return true both iterators are end or both are not end.
      _GLIBCXX_NODISCARD
      bool
      equal(const istreambuf_iterator& __b) const
      { return _M_at_eof() == __b._M_at_eof(); }

    private:
      int_type
      _M_get() const
      {
	int_type __ret = _M_c;
	if (_M_sbuf && _S_is_eof(__ret) && _S_is_eof(__ret = _M_sbuf->sgetc()))
	  _M_sbuf = 0;
	return __ret;
      }

      bool
      _M_at_eof() const
      { return _S_is_eof(_M_get()); }

      static bool
      _S_is_eof(int_type __c)
      {
	const int_type __eof = traits_type::eof();
	return traits_type::eq_int_type(__c, __eof);
      }

#if __cplusplus > 201703L && __cpp_lib_concepts
      [[nodiscard]]
      friend bool
      operator==(const istreambuf_iterator& __i, default_sentinel_t)
      { return __i._M_at_eof(); }
#endif
    };

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

#if __cpp_impl_three_way_comparison < 201907L
  template<typename _CharT, typename _Traits>
    _GLIBCXX_NODISCARD
    inline bool
    operator!=(const istreambuf_iterator<_CharT, _Traits>& __a,
	       const istreambuf_iterator<_CharT, _Traits>& __b)
    { return !__a.equal(__b); }
#endif

  /// Provides output iterator semantics for streambufs.
  template<typename _CharT, typename _Traits>
    class ostreambuf_iterator
    : public iterator<output_iterator_tag, void, void, void, void>
    {
    public:
      // Types:
      ///@{
      /// Public typedefs
#if __cplusplus > 201703L
      using difference_type = ptrdiff_t;
#endif
      typedef _CharT			       char_type;
      typedef _Traits			       traits_type;
      typedef basic_streambuf<_CharT, _Traits> streambuf_type;
      typedef basic_ostream<_CharT, _Traits>   ostream_type;
      ///@}

      template<typename _CharT2>
	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
				    ostreambuf_iterator<_CharT2> >::__type
	copy(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>,
	     ostreambuf_iterator<_CharT2>);

    private:
      streambuf_type*	_M_sbuf;
      bool		_M_failed;

    public:

#if __cplusplus > 201703L
      constexpr
      ostreambuf_iterator() noexcept
      : _M_sbuf(nullptr), _M_failed(true) { }
#endif

      ///  Construct output iterator from ostream.
      ostreambuf_iterator(ostream_type& __s) _GLIBCXX_USE_NOEXCEPT
      : _M_sbuf(__s.rdbuf()), _M_failed(!_M_sbuf) { }

      ///  Construct output iterator from streambuf.
      ostreambuf_iterator(streambuf_type* __s) _GLIBCXX_USE_NOEXCEPT
      : _M_sbuf(__s), _M_failed(!_M_sbuf) { }

      ///  Write character to streambuf.  Calls streambuf.sputc().
      ostreambuf_iterator&
      operator=(_CharT __c)
      {
	if (!_M_failed &&
	    _Traits::eq_int_type(_M_sbuf->sputc(__c), _Traits::eof()))
	  _M_failed = true;
	return *this;
      }

      /// Return *this.
      _GLIBCXX_NODISCARD
      ostreambuf_iterator&
      operator*()
      { return *this; }

      /// Return *this.
      ostreambuf_iterator&
      operator++(int)
      { return *this; }

      /// Return *this.
      ostreambuf_iterator&
      operator++()
      { return *this; }

      /// Return true if previous operator=() failed.
      _GLIBCXX_NODISCARD
      bool
      failed() const _GLIBCXX_USE_NOEXCEPT
      { return _M_failed; }

      ostreambuf_iterator&
      _M_put(const _CharT* __ws, streamsize __len)
      {
	if (__builtin_expect(!_M_failed, true)
	    && __builtin_expect(this->_M_sbuf->sputn(__ws, __len) != __len,
				false))
	  _M_failed = true;
	return *this;
      }
    };
#pragma GCC diagnostic pop

  // Overloads for streambuf iterators.
  template<typename _CharT>
    typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
				    ostreambuf_iterator<_CharT> >::__type
    copy(istreambuf_iterator<_CharT> __first,
	 istreambuf_iterator<_CharT> __last,
	 ostreambuf_iterator<_CharT> __result)
    {
      if (__first._M_sbuf && !__last._M_sbuf && !__result._M_failed)
	{
	  bool __ineof;
	  __copy_streambufs_eof(__first._M_sbuf, __result._M_sbuf, __ineof);
	  if (!__ineof)
	    __result._M_failed = true;
	}
      return __result;
    }

  template<bool _IsMove, typename _CharT>
    typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
				    ostreambuf_iterator<_CharT> >::__type
    __copy_move_a2(_CharT* __first, _CharT* __last,
		   ostreambuf_iterator<_CharT> __result)
    {
      const streamsize __num = __last - __first;
      if (__num > 0)
	__result._M_put(__first, __num);
      return __result;
    }

  template<bool _IsMove, typename _CharT>
    typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
				    ostreambuf_iterator<_CharT> >::__type
    __copy_move_a2(const _CharT* __first, const _CharT* __last,
		   ostreambuf_iterator<_CharT> __result)
    {
      const streamsize __num = __last - __first;
      if (__num > 0)
	__result._M_put(__first, __num);
      return __result;
    }

  template<bool _IsMove, typename _CharT>
    typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
				    _CharT*>::__type
    __copy_move_a2(istreambuf_iterator<_CharT> __first,
		   istreambuf_iterator<_CharT> __last, _CharT* __result)
    {
      typedef istreambuf_iterator<_CharT>		   __is_iterator_type;
      typedef typename __is_iterator_type::traits_type	   traits_type;
      typedef typename __is_iterator_type::streambuf_type  streambuf_type;
      typedef typename traits_type::int_type		   int_type;

      if (__first._M_sbuf && !__last._M_sbuf)
	{
	  streambuf_type* __sb = __first._M_sbuf;
	  int_type __c = __sb->sgetc();
	  while (!traits_type::eq_int_type(__c, traits_type::eof()))
	    {
	      const streamsize __n = __sb->egptr() - __sb->gptr();
	      if (__n > 1)
		{
		  traits_type::copy(__result, __sb->gptr(), __n);
		  __sb->__safe_gbump(__n);
		  __result += __n;
		  __c = __sb->underflow();
		}
	      else
		{
		  *__result++ = traits_type::to_char_type(__c);
		  __c = __sb->snextc();
		}
	    }
	}
      return __result;
    }

  template<typename _CharT, typename _Size>
    typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
				    _CharT*>::__type
    __copy_n_a(istreambuf_iterator<_CharT> __it, _Size __n, _CharT* __result,
	       bool __strict __attribute__((__unused__)))
    {
      if (__n == 0)
	return __result;

      __glibcxx_requires_cond(__it._M_sbuf,
			      _M_message(__gnu_debug::__msg_inc_istreambuf)
			      ._M_iterator(__it));
      _CharT* __beg = __result;
      __result += __it._M_sbuf->sgetn(__beg, __n);
      __glibcxx_requires_cond(!__strict || __result - __beg == __n,
			      _M_message(__gnu_debug::__msg_inc_istreambuf)
			      ._M_iterator(__it));
      return __result;
    }

  template<typename _CharT>
    typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
		  		    istreambuf_iterator<_CharT> >::__type
    find(istreambuf_iterator<_CharT> __first,
	 istreambuf_iterator<_CharT> __last, const _CharT& __val)
    {
      typedef istreambuf_iterator<_CharT>		   __is_iterator_type;
      typedef typename __is_iterator_type::traits_type     traits_type;
      typedef typename __is_iterator_type::streambuf_type  streambuf_type;
      typedef typename traits_type::int_type		   int_type;
      const int_type __eof = traits_type::eof();

      if (__first._M_sbuf && !__last._M_sbuf)
	{
	  const int_type __ival = traits_type::to_int_type(__val);
	  streambuf_type* __sb = __first._M_sbuf;
	  int_type __c = __sb->sgetc();
	  while (!traits_type::eq_int_type(__c, __eof)
		 && !traits_type::eq_int_type(__c, __ival))
	    {
	      streamsize __n = __sb->egptr() - __sb->gptr();
	      if (__n > 1)
		{
		  const _CharT* __p = traits_type::find(__sb->gptr(),
							__n, __val);
		  if (__p)
		    __n = __p - __sb->gptr();
		  __sb->__safe_gbump(__n);
		  __c = __sb->sgetc();
		}
	      else
		__c = __sb->snextc();
	    }

	  __first._M_c = __eof;
	}

      return __first;
    }

  template<typename _CharT, typename _Distance>
    typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
				    void>::__type
    advance(istreambuf_iterator<_CharT>& __i, _Distance __n)
    {
      if (__n == 0)
	return;

      __glibcxx_assert(__n > 0);
      __glibcxx_requires_cond(!__i._M_at_eof(),
			      _M_message(__gnu_debug::__msg_inc_istreambuf)
			      ._M_iterator(__i));

      typedef istreambuf_iterator<_CharT>		   __is_iterator_type;
      typedef typename __is_iterator_type::traits_type	   traits_type;
      typedef typename __is_iterator_type::streambuf_type  streambuf_type;
      typedef typename traits_type::int_type		   int_type;
      const int_type __eof = traits_type::eof();

      streambuf_type* __sb = __i._M_sbuf;
      while (__n > 0)
	{
	  streamsize __size = __sb->egptr() - __sb->gptr();
	  if (__size > __n)
	    {
	      __sb->__safe_gbump(__n);
	      break;
	    }

	  __sb->__safe_gbump(__size);
	  __n -= __size;
	  if (traits_type::eq_int_type(__sb->underflow(), __eof))
	    {
	      __glibcxx_requires_cond(__n == 0,
				_M_message(__gnu_debug::__msg_inc_istreambuf)
				._M_iterator(__i));
	      break;
	    }
	}

      __i._M_c = __eof;
    }

/// @} group iterators

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif
Commit	Line	Data
	1	// Streambuf iterators
	2
	3	// Copyright (C) 1997-2025 Free Software Foundation, Inc.
	4	//
	5	// This file is part of the GNU ISO C++ Library. This library is free
	6	// software; you can redistribute it and/or modify it under the
	7	// terms of the GNU General Public License as published by the
	8	// Free Software Foundation; either version 3, or (at your option)
	9	// any later version.
	10
	11	// This library is distributed in the hope that it will be useful,
	12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	// GNU General Public License for more details.
	15
	16	// Under Section 7 of GPL version 3, you are granted additional
	17	// permissions described in the GCC Runtime Library Exception, version
	18	// 3.1, as published by the Free Software Foundation.
	19
	20	// You should have received a copy of the GNU General Public License and
	21	// a copy of the GCC Runtime Library Exception along with this program;
	22	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
	23	// <http://www.gnu.org/licenses/>.
	24
	25	/** @file bits/streambuf_iterator.h
	26	* This is an internal header file, included by other library headers.
	27	* Do not attempt to use it directly. @headername{iterator}
	28	*/
	29
	30	#ifndef _STREAMBUF_ITERATOR_H
	31	#define _STREAMBUF_ITERATOR_H 1
	32
	33	#ifdef _GLIBCXX_SYSHDR
	34	#pragma GCC system_header
	35	#endif
	36
	37	#include <streambuf>
	38	#include <bits/stl_iterator_base_types.h>
	39	#include <debug/debug.h>
	40
	41	namespace std _GLIBCXX_VISIBILITY(default)
	42	{
	43	_GLIBCXX_BEGIN_NAMESPACE_VERSION
	44
	45	/**
	46	* @addtogroup iterators
	47	* @{
	48	*/
	49
	50	// Ignore warnings about std::iterator.
	51	#pragma GCC diagnostic push
	52	#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
	53	// 24.5.3 Template class istreambuf_iterator
	54	/// Provides input iterator semantics for streambufs.
	55	template<typename _CharT, typename _Traits>
	56	class istreambuf_iterator
	57	: public iterator<input_iterator_tag, _CharT, typename _Traits::off_type,
	58	_CharT*, _CharT>
	59	{
	60	public:
	61	// Types:
	62	///@{
	63	/// Public typedefs
	64	#if __cplusplus < 201103L
	65	typedef _CharT& reference; // Changed to _CharT by LWG 445
	66	#elif __cplusplus > 201703L
	67	// _GLIBCXX_RESOLVE_LIB_DEFECTS
	68	// 3188. istreambuf_iterator::pointer should not be unspecified
	69	using pointer = void;
	70	#endif
	71
	72	typedef _CharT char_type;
	73	typedef _Traits traits_type;
	74	typedef typename _Traits::int_type int_type;
	75	typedef basic_streambuf<_CharT, _Traits> streambuf_type;
	76	typedef basic_istream<_CharT, _Traits> istream_type;
	77	///@}
	78
	79	template<typename _CharT2>
	80	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
	81	ostreambuf_iterator<_CharT2> >::__type
	82	copy(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>,
	83	ostreambuf_iterator<_CharT2>);
	84
	85	template<bool _IsMove, typename _CharT2>
	86	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
	87	_CharT2*>::__type
	88	__copy_move_a2(istreambuf_iterator<_CharT2>,
	89	istreambuf_iterator<_CharT2>, _CharT2*);
	90
	91	template<typename _CharT2, typename _Size>
	92	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
	93	_CharT2*>::__type
	94	__copy_n_a(istreambuf_iterator<_CharT2>, _Size, _CharT2*, bool);
	95
	96	template<typename _CharT2>
	97	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
	98	istreambuf_iterator<_CharT2> >::__type
	99	find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>,
	100	const _CharT2&);
	101
	102	template<typename _CharT2, typename _Distance>
	103	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
	104	void>::__type
	105	advance(istreambuf_iterator<_CharT2>&, _Distance);
	106
	107	private:
	108	// 24.5.3 istreambuf_iterator
	109	// p 1
	110	// If the end of stream is reached (streambuf_type::sgetc()
	111	// returns traits_type::eof()), the iterator becomes equal to
	112	// the "end of stream" iterator value.
	113	// NB: This implementation assumes the "end of stream" value
	114	// is EOF, or -1.
	115	mutable streambuf_type* _M_sbuf;
	116	int_type _M_c;
	117
	118	public:
	119	/// Construct end of input stream iterator.
	120	_GLIBCXX_CONSTEXPR istreambuf_iterator() _GLIBCXX_USE_NOEXCEPT
	121	: _M_sbuf(0), _M_c(traits_type::eof()) { }
	122
	123	#if __cplusplus > 201703L && __cpp_lib_concepts
	124	constexpr istreambuf_iterator(default_sentinel_t) noexcept
	125	: istreambuf_iterator() { }
	126	#endif
	127
	128	#if __cplusplus >= 201103L
	129	istreambuf_iterator(const istreambuf_iterator&) noexcept = default;
	130
	131	~istreambuf_iterator() = default;
	132	#endif
	133
	134	/// Construct start of input stream iterator.
	135	istreambuf_iterator(istream_type& __s) _GLIBCXX_USE_NOEXCEPT
	136	: _M_sbuf(__s.rdbuf()), _M_c(traits_type::eof()) { }
	137
	138	/// Construct start of streambuf iterator.
	139	istreambuf_iterator(streambuf_type* __s) _GLIBCXX_USE_NOEXCEPT
	140	: _M_sbuf(__s), _M_c(traits_type::eof()) { }
	141
	142	#if __cplusplus >= 201103L
	143	istreambuf_iterator&
	144	operator=(const istreambuf_iterator&) noexcept = default;
	145	#endif
	146
	147	/// Return the current character pointed to by iterator. This returns
	148	/// streambuf.sgetc(). It cannot be assigned. NB: The result of
	149	/// operator*() on an end of stream is undefined.
	150	_GLIBCXX_NODISCARD
	151	char_type
	152	operator*() const
	153	{
	154	int_type __c = _M_get();
	155
	156	#ifdef _GLIBCXX_DEBUG_PEDANTIC
	157	// Dereferencing a past-the-end istreambuf_iterator is a
	158	// libstdc++ extension
	159	__glibcxx_requires_cond(!_S_is_eof(__c),
	160	_M_message(__gnu_debug::__msg_deref_istreambuf)
	161	._M_iterator(*this));
	162	#endif
	163	return traits_type::to_char_type(__c);
	164	}
	165
	166	/// Advance the iterator. Calls streambuf.sbumpc().
	167	istreambuf_iterator&
	168	operator++()
	169	{
	170	__glibcxx_requires_cond(_M_sbuf &&
	171	(!_S_is_eof(_M_c) \|\| !_S_is_eof(_M_sbuf->sgetc())),
	172	_M_message(__gnu_debug::__msg_inc_istreambuf)
	173	._M_iterator(*this));
	174
	175	_M_sbuf->sbumpc();
	176	_M_c = traits_type::eof();
	177	return *this;
	178	}
	179
	180	/// Advance the iterator. Calls streambuf.sbumpc().
	181	istreambuf_iterator
	182	operator++(int)
	183	{
	184	__glibcxx_requires_cond(_M_sbuf &&
	185	(!_S_is_eof(_M_c) \|\| !_S_is_eof(_M_sbuf->sgetc())),
	186	_M_message(__gnu_debug::__msg_inc_istreambuf)
	187	._M_iterator(*this));
	188
	189	istreambuf_iterator __old = *this;
	190	__old._M_c = _M_sbuf->sbumpc();
	191	_M_c = traits_type::eof();
	192	return __old;
	193	}
	194
	195	// _GLIBCXX_RESOLVE_LIB_DEFECTS
	196	// 110 istreambuf_iterator::equal not const
	197	// NB: there is also number 111 (NAD) relevant to this function.
	198	/// Return true both iterators are end or both are not end.
	199	_GLIBCXX_NODISCARD
	200	bool
	201	equal(const istreambuf_iterator& __b) const
	202	{ return _M_at_eof() == __b._M_at_eof(); }
	203
	204	private:
	205	int_type
	206	_M_get() const
	207	{
	208	int_type __ret = _M_c;
	209	if (_M_sbuf && _S_is_eof(__ret) && _S_is_eof(__ret = _M_sbuf->sgetc()))
	210	_M_sbuf = 0;
	211	return __ret;
	212	}
	213
	214	bool
	215	_M_at_eof() const
	216	{ return _S_is_eof(_M_get()); }
	217
	218	static bool
	219	_S_is_eof(int_type __c)
	220	{
	221	const int_type __eof = traits_type::eof();
	222	return traits_type::eq_int_type(__c, __eof);
	223	}
	224
	225	#if __cplusplus > 201703L && __cpp_lib_concepts
	226	[[nodiscard]]
	227	friend bool
	228	operator==(const istreambuf_iterator& __i, default_sentinel_t)
	229	{ return __i._M_at_eof(); }
	230	#endif
	231	};
	232
	233	template<typename _CharT, typename _Traits>
	234	_GLIBCXX_NODISCARD
	235	inline bool
	236	operator==(const istreambuf_iterator<_CharT, _Traits>& __a,
	237	const istreambuf_iterator<_CharT, _Traits>& __b)
	238	{ return __a.equal(__b); }
	239
	240	#if __cpp_impl_three_way_comparison < 201907L
	241	template<typename _CharT, typename _Traits>
	242	_GLIBCXX_NODISCARD
	243	inline bool
	244	operator!=(const istreambuf_iterator<_CharT, _Traits>& __a,
	245	const istreambuf_iterator<_CharT, _Traits>& __b)
	246	{ return !__a.equal(__b); }
	247	#endif
	248
	249	/// Provides output iterator semantics for streambufs.
	250	template<typename _CharT, typename _Traits>
	251	class ostreambuf_iterator
	252	: public iterator<output_iterator_tag, void, void, void, void>
	253	{
	254	public:
	255	// Types:
	256	///@{
	257	/// Public typedefs
	258	#if __cplusplus > 201703L
	259	using difference_type = ptrdiff_t;
	260	#endif
	261	typedef _CharT char_type;
	262	typedef _Traits traits_type;
	263	typedef basic_streambuf<_CharT, _Traits> streambuf_type;
	264	typedef basic_ostream<_CharT, _Traits> ostream_type;
	265	///@}
	266
	267	template<typename _CharT2>
	268	friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
	269	ostreambuf_iterator<_CharT2> >::__type
	270	copy(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>,
	271	ostreambuf_iterator<_CharT2>);
	272
	273	private:
	274	streambuf_type* _M_sbuf;
	275	bool _M_failed;
	276
	277	public:
	278
	279	#if __cplusplus > 201703L
	280	constexpr
	281	ostreambuf_iterator() noexcept
	282	: _M_sbuf(nullptr), _M_failed(true) { }
	283	#endif
	284
	285	/// Construct output iterator from ostream.
	286	ostreambuf_iterator(ostream_type& __s) _GLIBCXX_USE_NOEXCEPT
	287	: _M_sbuf(__s.rdbuf()), _M_failed(!_M_sbuf) { }
	288
	289	/// Construct output iterator from streambuf.
	290	ostreambuf_iterator(streambuf_type* __s) _GLIBCXX_USE_NOEXCEPT
	291	: _M_sbuf(__s), _M_failed(!_M_sbuf) { }
	292
	293	/// Write character to streambuf. Calls streambuf.sputc().
	294	ostreambuf_iterator&
	295	operator=(_CharT __c)
	296	{
	297	if (!_M_failed &&
	298	_Traits::eq_int_type(_M_sbuf->sputc(__c), _Traits::eof()))
	299	_M_failed = true;
	300	return *this;
	301	}
	302
	303	/// Return *this.
	304	_GLIBCXX_NODISCARD
	305	ostreambuf_iterator&
	306	operator*()
	307	{ return *this; }
	308
	309	/// Return *this.
	310	ostreambuf_iterator&
	311	operator++(int)
	312	{ return *this; }
	313
	314	/// Return *this.
	315	ostreambuf_iterator&
	316	operator++()
	317	{ return *this; }
	318
	319	/// Return true if previous operator=() failed.
	320	_GLIBCXX_NODISCARD
	321	bool
	322	failed() const _GLIBCXX_USE_NOEXCEPT
	323	{ return _M_failed; }
	324
	325	ostreambuf_iterator&
	326	_M_put(const _CharT* __ws, streamsize __len)
	327	{
	328	if (__builtin_expect(!_M_failed, true)
	329	&& __builtin_expect(this->_M_sbuf->sputn(__ws, __len) != __len,
	330	false))
	331	_M_failed = true;
	332	return *this;
	333	}
	334	};
	335	#pragma GCC diagnostic pop
	336
	337	// Overloads for streambuf iterators.
	338	template<typename _CharT>
	339	typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
	340	ostreambuf_iterator<_CharT> >::__type
	341	copy(istreambuf_iterator<_CharT> __first,
	342	istreambuf_iterator<_CharT> __last,
	343	ostreambuf_iterator<_CharT> __result)
	344	{
	345	if (__first._M_sbuf && !__last._M_sbuf && !__result._M_failed)
	346	{
	347	bool __ineof;
	348	__copy_streambufs_eof(__first._M_sbuf, __result._M_sbuf, __ineof);
	349	if (!__ineof)
	350	__result._M_failed = true;
	351	}
	352	return __result;
	353	}
	354
	355	template<bool _IsMove, typename _CharT>
	356	typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
	357	ostreambuf_iterator<_CharT> >::__type
	358	__copy_move_a2(_CharT* __first, _CharT* __last,
	359	ostreambuf_iterator<_CharT> __result)
	360	{
	361	const streamsize __num = __last - __first;
	362	if (__num > 0)
	363	__result._M_put(__first, __num);
	364	return __result;
	365	}
	366
	367	template<bool _IsMove, typename _CharT>
	368	typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
	369	ostreambuf_iterator<_CharT> >::__type
	370	__copy_move_a2(const _CharT* __first, const _CharT* __last,
	371	ostreambuf_iterator<_CharT> __result)
	372	{
	373	const streamsize __num = __last - __first;
	374	if (__num > 0)
	375	__result._M_put(__first, __num);
	376	return __result;
	377	}
	378
	379	template<bool _IsMove, typename _CharT>
	380	typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
	381	_CharT*>::__type
	382	__copy_move_a2(istreambuf_iterator<_CharT> __first,
	383	istreambuf_iterator<_CharT> __last, _CharT* __result)
	384	{
	385	typedef istreambuf_iterator<_CharT> __is_iterator_type;
	386	typedef typename __is_iterator_type::traits_type traits_type;
	387	typedef typename __is_iterator_type::streambuf_type streambuf_type;
	388	typedef typename traits_type::int_type int_type;
	389
	390	if (__first._M_sbuf && !__last._M_sbuf)
	391	{
	392	streambuf_type* __sb = __first._M_sbuf;
	393	int_type __c = __sb->sgetc();
	394	while (!traits_type::eq_int_type(__c, traits_type::eof()))
	395	{
	396	const streamsize __n = __sb->egptr() - __sb->gptr();
	397	if (__n > 1)
	398	{
	399	traits_type::copy(__result, __sb->gptr(), __n);
	400	__sb->__safe_gbump(__n);
	401	__result += __n;
	402	__c = __sb->underflow();
	403	}
	404	else
	405	{
	406	*__result++ = traits_type::to_char_type(__c);
	407	__c = __sb->snextc();
	408	}
	409	}
	410	}
	411	return __result;
	412	}
	413
	414	template<typename _CharT, typename _Size>
	415	typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
	416	_CharT*>::__type
	417	__copy_n_a(istreambuf_iterator<_CharT> __it, _Size __n, _CharT* __result,
	418	bool __strict __attribute__((__unused__)))
	419	{
	420	if (__n == 0)
	421	return __result;
	422
	423	__glibcxx_requires_cond(__it._M_sbuf,
	424	_M_message(__gnu_debug::__msg_inc_istreambuf)
	425	._M_iterator(__it));
	426	_CharT* __beg = __result;
	427	__result += __it._M_sbuf->sgetn(__beg, __n);
	428	__glibcxx_requires_cond(!__strict \|\| __result - __beg == __n,
	429	_M_message(__gnu_debug::__msg_inc_istreambuf)
	430	._M_iterator(__it));
	431	return __result;
	432	}
	433
	434	template<typename _CharT>
	435	typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
	436	istreambuf_iterator<_CharT> >::__type
	437	find(istreambuf_iterator<_CharT> __first,
	438	istreambuf_iterator<_CharT> __last, const _CharT& __val)
	439	{
	440	typedef istreambuf_iterator<_CharT> __is_iterator_type;
	441	typedef typename __is_iterator_type::traits_type traits_type;
	442	typedef typename __is_iterator_type::streambuf_type streambuf_type;
	443	typedef typename traits_type::int_type int_type;
	444	const int_type __eof = traits_type::eof();
	445
	446	if (__first._M_sbuf && !__last._M_sbuf)
	447	{
	448	const int_type __ival = traits_type::to_int_type(__val);
	449	streambuf_type* __sb = __first._M_sbuf;
	450	int_type __c = __sb->sgetc();
	451	while (!traits_type::eq_int_type(__c, __eof)
	452	&& !traits_type::eq_int_type(__c, __ival))
	453	{
	454	streamsize __n = __sb->egptr() - __sb->gptr();
	455	if (__n > 1)
	456	{
	457	const _CharT* __p = traits_type::find(__sb->gptr(),
	458	__n, __val);
	459	if (__p)
	460	__n = __p - __sb->gptr();
	461	__sb->__safe_gbump(__n);
	462	__c = __sb->sgetc();
	463	}
	464	else
	465	__c = __sb->snextc();
	466	}
	467
	468	__first._M_c = __eof;
	469	}
	470
	471	return __first;
	472	}
	473
	474	template<typename _CharT, typename _Distance>
	475	typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
	476	void>::__type
	477	advance(istreambuf_iterator<_CharT>& __i, _Distance __n)
	478	{
	479	if (__n == 0)
	480	return;
	481
	482	__glibcxx_assert(__n > 0);
	483	__glibcxx_requires_cond(!__i._M_at_eof(),
	484	_M_message(__gnu_debug::__msg_inc_istreambuf)
	485	._M_iterator(__i));
	486
	487	typedef istreambuf_iterator<_CharT> __is_iterator_type;
	488	typedef typename __is_iterator_type::traits_type traits_type;
	489	typedef typename __is_iterator_type::streambuf_type streambuf_type;
	490	typedef typename traits_type::int_type int_type;
	491	const int_type __eof = traits_type::eof();
	492
	493	streambuf_type* __sb = __i._M_sbuf;
	494	while (__n > 0)
	495	{
	496	streamsize __size = __sb->egptr() - __sb->gptr();
	497	if (__size > __n)
	498	{
	499	__sb->__safe_gbump(__n);
	500	break;
	501	}
	502
	503	__sb->__safe_gbump(__size);
	504	__n -= __size;
	505	if (traits_type::eq_int_type(__sb->underflow(), __eof))
	506	{
	507	__glibcxx_requires_cond(__n == 0,
	508	_M_message(__gnu_debug::__msg_inc_istreambuf)
	509	._M_iterator(__i));
	510	break;
	511	}
	512	}
	513
	514	__i._M_c = __eof;
	515	}
	516
	517	/// @} group iterators
	518
	519	_GLIBCXX_END_NAMESPACE_VERSION
	520	} // namespace
	521
	522	#endif