11.2.0/bits/stream_iterator.h

// Stream iterators

// Copyright (C) 2001-2021 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/stream_iterator.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{iterator}
 */

#ifndef _STREAM_ITERATOR_H
#define _STREAM_ITERATOR_H 1

#pragma GCC system_header

#include <debug/debug.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

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

  /// Provides input iterator semantics for streams.
  template<typename _Tp, typename _CharT = char,
           typename _Traits = char_traits<_CharT>, typename _Dist = ptrdiff_t>
    class istream_iterator
    : public iterator<input_iterator_tag, _Tp, _Dist, const _Tp*, const _Tp&>
    {
    public:
      typedef _CharT                         char_type;
      typedef _Traits                        traits_type;
      typedef basic_istream<_CharT, _Traits> istream_type;

    private:
      istream_type*     _M_stream;
      _Tp               _M_value;
      // This bool becomes false at end-of-stream. It should be sufficient to
      // check _M_stream != nullptr instead, but historically we did not set
      // _M_stream to null when reaching the end, so we need to keep this flag.
      bool              _M_ok;

    public:
      ///  Construct end of input stream iterator.
      _GLIBCXX_CONSTEXPR istream_iterator()
      : _M_stream(0), _M_value(), _M_ok(false) {}

      ///  Construct start of input stream iterator.
      istream_iterator(istream_type& __s)
      : _M_stream(std::__addressof(__s)), _M_ok(true)
      { _M_read(); }

      istream_iterator(const istream_iterator& __obj)
      : _M_stream(__obj._M_stream), _M_value(__obj._M_value),
        _M_ok(__obj._M_ok)
      { }

#if __cplusplus > 201703L && __cpp_lib_concepts
      constexpr
      istream_iterator(default_sentinel_t)
      noexcept(is_nothrow_default_constructible_v<_Tp>)
      : istream_iterator() { }
#endif

#if __cplusplus >= 201103L
      istream_iterator& operator=(const istream_iterator&) = default;
      ~istream_iterator() = default;
#endif

      const _Tp&
      operator*() const
      {
        __glibcxx_requires_cond(_M_ok,
                                _M_message(__gnu_debug::__msg_deref_istream)
                                ._M_iterator(*this));
        return _M_value;
      }

      const _Tp*
      operator->() const { return std::__addressof((operator*())); }

      istream_iterator&
      operator++()
      {
        __glibcxx_requires_cond(_M_ok,
                                _M_message(__gnu_debug::__msg_inc_istream)
                                ._M_iterator(*this));
        _M_read();
        return *this;
      }

      istream_iterator
      operator++(int)
      {
        __glibcxx_requires_cond(_M_ok,
                                _M_message(__gnu_debug::__msg_inc_istream)
                                ._M_iterator(*this));
        istream_iterator __tmp = *this;
        _M_read();
        return __tmp;
      }

    private:
      bool
      _M_equal(const istream_iterator& __x) const
      {
        // Ideally this would just return _M_stream == __x._M_stream,
        // but code compiled with old versions never sets _M_stream to null.
        return (_M_ok == __x._M_ok) && (!_M_ok || _M_stream == __x._M_stream);
      }

      void
      _M_read()
      {
        if (_M_stream && !(*_M_stream >> _M_value))
          {
            _M_stream = 0;
            _M_ok = false;
          }
      }

      /// Return true if the iterators refer to the same stream,
      /// or are both at end-of-stream.
      friend bool
      operator==(const istream_iterator& __x, const istream_iterator& __y)
      { return __x._M_equal(__y); }

      /// Return true if the iterators refer to different streams,
      /// or if one is at end-of-stream and the other is not.
      friend bool
      operator!=(const istream_iterator& __x, const istream_iterator& __y)
      { return !__x._M_equal(__y); }

#if __cplusplus > 201703L && __cpp_lib_concepts
      friend bool
      operator==(const istream_iterator& __i, default_sentinel_t)
      { return !__i._M_stream; }
#endif
    };

  /**
   *  @brief  Provides output iterator semantics for streams.
   *
   *  This class provides an iterator to write to an ostream.  The type Tp is
   *  the only type written by this iterator and there must be an
   *  operator<<(Tp) defined.
   *
   *  @tparam  _Tp  The type to write to the ostream.
   *  @tparam  _CharT  The ostream char_type.
   *  @tparam  _Traits  The ostream char_traits.
  */
  template<typename _Tp, typename _CharT = char,
           typename _Traits = char_traits<_CharT> >
    class ostream_iterator
    : public iterator<output_iterator_tag, void, void, void, void>
    {
    public:
      ///@{
      /// Public typedef
#if __cplusplus > 201703L
      using difference_type = ptrdiff_t;
#endif
      typedef _CharT                         char_type;
      typedef _Traits                        traits_type;
      typedef basic_ostream<_CharT, _Traits> ostream_type;
      ///@}

    private:
      ostream_type*     _M_stream;
      const _CharT*     _M_string;

    public:
#if __cplusplus > 201703L
      constexpr ostream_iterator() noexcept
      : _M_stream(nullptr), _M_string(nullptr) { }
#endif

      /// Construct from an ostream.
      ostream_iterator(ostream_type& __s)
      : _M_stream(std::__addressof(__s)), _M_string(0) {}

      /**
       *  Construct from an ostream.
       *
       *  The delimiter string @a c is written to the stream after every Tp
       *  written to the stream.  The delimiter is not copied, and thus must
       *  not be destroyed while this iterator is in use.
       *
       *  @param  __s  Underlying ostream to write to.
       *  @param  __c  CharT delimiter string to insert.
      */
      ostream_iterator(ostream_type& __s, const _CharT* __c)
      : _M_stream(std::__addressof(__s)), _M_string(__c)  { }

      /// Copy constructor.
      ostream_iterator(const ostream_iterator& __obj)
      : _M_stream(__obj._M_stream), _M_string(__obj._M_string)  { }

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

      /// Writes @a value to underlying ostream using operator<<.  If
      /// constructed with delimiter string, writes delimiter to ostream.
      ostream_iterator&
      operator=(const _Tp& __value)
      {
        __glibcxx_requires_cond(_M_stream != 0,
                                _M_message(__gnu_debug::__msg_output_ostream)
                                ._M_iterator(*this));
        *_M_stream << __value;
        if (_M_string)
          *_M_stream << _M_string;
        return *this;
      }

      ostream_iterator&
      operator*()
      { return *this; }

      ostream_iterator&
      operator++()
      { return *this; }

      ostream_iterator&
      operator++(int)
      { return *this; }
    };

  /// @} group iterators

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif
Revision:	1166
Committed:	Tue Oct 26 14:22:36 2021 UTC (4 years ago) by rossy
Content type:	text/x-chdr
File size:	7697 byte(s)
Log Message:	Daodan: Replace MinGW build env with an up-to-date MSYS2 env
#	Content
1	// Stream iterators
2
3	// Copyright (C) 2001-2021 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/stream_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 _STREAM_ITERATOR_H
31	#define _STREAM_ITERATOR_H 1
32
33	#pragma GCC system_header
34
35	#include <debug/debug.h>
36
37	namespace std _GLIBCXX_VISIBILITY(default)
38	{
39	_GLIBCXX_BEGIN_NAMESPACE_VERSION
40
41	/**
42	* @addtogroup iterators
43	* @{
44	*/
45
46	/// Provides input iterator semantics for streams.
47	template<typename _Tp, typename _CharT = char,
48	typename _Traits = char_traits<_CharT>, typename _Dist = ptrdiff_t>
49	class istream_iterator
50	: public iterator<input_iterator_tag, _Tp, _Dist, const _Tp*, const _Tp&>
51	{
52	public:
53	typedef _CharT char_type;
54	typedef _Traits traits_type;
55	typedef basic_istream<_CharT, _Traits> istream_type;
56
57	private:
58	istream_type* _M_stream;
59	_Tp _M_value;
60	// This bool becomes false at end-of-stream. It should be sufficient to
61	// check _M_stream != nullptr instead, but historically we did not set
62	// _M_stream to null when reaching the end, so we need to keep this flag.
63	bool _M_ok;
64
65	public:
66	/// Construct end of input stream iterator.
67	_GLIBCXX_CONSTEXPR istream_iterator()
68	: _M_stream(0), _M_value(), _M_ok(false) {}
69
70	/// Construct start of input stream iterator.
71	istream_iterator(istream_type& __s)
72	: _M_stream(std::__addressof(__s)), _M_ok(true)
73	{ _M_read(); }
74
75	istream_iterator(const istream_iterator& __obj)
76	: _M_stream(__obj._M_stream), _M_value(__obj._M_value),
77	_M_ok(__obj._M_ok)
78	{ }
79
80	#if __cplusplus > 201703L && __cpp_lib_concepts
81	constexpr
82	istream_iterator(default_sentinel_t)
83	noexcept(is_nothrow_default_constructible_v<_Tp>)
84	: istream_iterator() { }
85	#endif
86
87	#if __cplusplus >= 201103L
88	istream_iterator& operator=(const istream_iterator&) = default;
89	~istream_iterator() = default;
90	#endif
91
92	const _Tp&
93	operator*() const
94	{
95	__glibcxx_requires_cond(_M_ok,
96	_M_message(__gnu_debug::__msg_deref_istream)
97	._M_iterator(*this));
98	return _M_value;
99	}
100
101	const _Tp*
102	operator->() const { return std::__addressof((operator*())); }
103
104	istream_iterator&
105	operator++()
106	{
107	__glibcxx_requires_cond(_M_ok,
108	_M_message(__gnu_debug::__msg_inc_istream)
109	._M_iterator(*this));
110	_M_read();
111	return *this;
112	}
113
114	istream_iterator
115	operator++(int)
116	{
117	__glibcxx_requires_cond(_M_ok,
118	_M_message(__gnu_debug::__msg_inc_istream)
119	._M_iterator(*this));
120	istream_iterator __tmp = *this;
121	_M_read();
122	return __tmp;
123	}
124
125	private:
126	bool
127	_M_equal(const istream_iterator& __x) const
128	{
129	// Ideally this would just return _M_stream == __x._M_stream,
130	// but code compiled with old versions never sets _M_stream to null.
131	return (_M_ok == __x._M_ok) && (!_M_ok \|\| _M_stream == __x._M_stream);
132	}
133
134	void
135	_M_read()
136	{
137	if (_M_stream && !(*_M_stream >> _M_value))
138	{
139	_M_stream = 0;
140	_M_ok = false;
141	}
142	}
143
144	/// Return true if the iterators refer to the same stream,
145	/// or are both at end-of-stream.
146	friend bool
147	operator==(const istream_iterator& __x, const istream_iterator& __y)
148	{ return __x._M_equal(__y); }
149
150	/// Return true if the iterators refer to different streams,
151	/// or if one is at end-of-stream and the other is not.
152	friend bool
153	operator!=(const istream_iterator& __x, const istream_iterator& __y)
154	{ return !__x._M_equal(__y); }
155
156	#if __cplusplus > 201703L && __cpp_lib_concepts
157	friend bool
158	operator==(const istream_iterator& __i, default_sentinel_t)
159	{ return !__i._M_stream; }
160	#endif
161	};
162
163	/**
164	* @brief Provides output iterator semantics for streams.
165	*
166	* This class provides an iterator to write to an ostream. The type Tp is
167	* the only type written by this iterator and there must be an
168	* operator<<(Tp) defined.
169	*
170	* @tparam _Tp The type to write to the ostream.
171	* @tparam _CharT The ostream char_type.
172	* @tparam _Traits The ostream char_traits.
173	*/
174	template<typename _Tp, typename _CharT = char,
175	typename _Traits = char_traits<_CharT> >
176	class ostream_iterator
177	: public iterator<output_iterator_tag, void, void, void, void>
178	{
179	public:
180	///@{
181	/// Public typedef
182	#if __cplusplus > 201703L
183	using difference_type = ptrdiff_t;
184	#endif
185	typedef _CharT char_type;
186	typedef _Traits traits_type;
187	typedef basic_ostream<_CharT, _Traits> ostream_type;
188	///@}
189
190	private:
191	ostream_type* _M_stream;
192	const _CharT* _M_string;
193
194	public:
195	#if __cplusplus > 201703L
196	constexpr ostream_iterator() noexcept
197	: _M_stream(nullptr), _M_string(nullptr) { }
198	#endif
199
200	/// Construct from an ostream.
201	ostream_iterator(ostream_type& __s)
202	: _M_stream(std::__addressof(__s)), _M_string(0) {}
203
204	/**
205	* Construct from an ostream.
206	*
207	* The delimiter string @a c is written to the stream after every Tp
208	* written to the stream. The delimiter is not copied, and thus must
209	* not be destroyed while this iterator is in use.
210	*
211	* @param __s Underlying ostream to write to.
212	* @param __c CharT delimiter string to insert.
213	*/
214	ostream_iterator(ostream_type& __s, const _CharT* __c)
215	: _M_stream(std::__addressof(__s)), _M_string(__c) { }
216
217	/// Copy constructor.
218	ostream_iterator(const ostream_iterator& __obj)
219	: _M_stream(__obj._M_stream), _M_string(__obj._M_string) { }
220
221	#if __cplusplus >= 201103L
222	ostream_iterator& operator=(const ostream_iterator&) = default;
223	#endif
224
225	/// Writes @a value to underlying ostream using operator<<. If
226	/// constructed with delimiter string, writes delimiter to ostream.
227	ostream_iterator&
228	operator=(const _Tp& __value)
229	{
230	__glibcxx_requires_cond(_M_stream != 0,
231	_M_message(__gnu_debug::__msg_output_ostream)
232	._M_iterator(*this));
233	*_M_stream << __value;
234	if (_M_string)
235	*_M_stream << _M_string;
236	return *this;
237	}
238
239	ostream_iterator&
240	operator*()
241	{ return *this; }
242
243	ostream_iterator&
244	operator++()
245	{ return *this; }
246
247	ostream_iterator&
248	operator++(int)
249	{ return *this; }
250	};
251
252	/// @} group iterators
253
254	_GLIBCXX_END_NAMESPACE_VERSION
255	} // namespace
256
257	#endif