1 // Stream iterators
2
3 // Copyright (C) 2001-2023 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 <iosfwd>
36 #include <bits/move.h>
37 #include <bits/stl_iterator_base_types.h>
38 #include <debug/debug.h>
39
40 namespace std _GLIBCXX_VISIBILITY(default)
41 {
42 _GLIBCXX_BEGIN_NAMESPACE_VERSION
43
44 /**
45 * @addtogroup iterators
46 * @{
47 */
48
49 // Ignore warnings about std::iterator.
50 #pragma GCC diagnostic push
51 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
52
53 /// Provides input iterator semantics for streams.
54 template<typename _Tp, typename _CharT = char,
55 typename _Traits = char_traits<_CharT>, typename _Dist = ptrdiff_t>
56 class istream_iterator
57 : public iterator<input_iterator_tag, _Tp, _Dist, const _Tp*, const _Tp&>
58 {
59 public:
60 typedef _CharT char_type;
61 typedef _Traits traits_type;
62 typedef basic_istream<_CharT, _Traits> istream_type;
63
64 private:
65 istream_type* _M_stream;
66 _Tp _M_value;
67 // This bool becomes false at end-of-stream. It should be sufficient to
68 // check _M_stream != nullptr instead, but historically we did not set
69 // _M_stream to null when reaching the end, so we need to keep this flag.
70 bool _M_ok;
71
72 public:
73 /// Construct end of input stream iterator.
74 _GLIBCXX_CONSTEXPR istream_iterator()
75 _GLIBCXX_NOEXCEPT_IF(is_nothrow_default_constructible<_Tp>::value)
76 : _M_stream(0), _M_value(), _M_ok(false) {}
77
78 /// Construct start of input stream iterator.
79 istream_iterator(istream_type& __s)
80 : _M_stream(std::__addressof(__s)), _M_ok(true)
81 { _M_read(); }
82
83 _GLIBCXX_CONSTEXPR
84 istream_iterator(const istream_iterator& __obj)
85 _GLIBCXX_NOEXCEPT_IF(is_nothrow_copy_constructible<_Tp>::value)
86 : _M_stream(__obj._M_stream), _M_value(__obj._M_value),
87 _M_ok(__obj._M_ok)
88 { }
89
90 #if __cplusplus > 201703L && __cpp_lib_concepts
91 constexpr
92 istream_iterator(default_sentinel_t)
93 noexcept(is_nothrow_default_constructible_v<_Tp>)
94 : istream_iterator() { }
95 #endif
96
97 #if __cplusplus >= 201103L
98 istream_iterator& operator=(const istream_iterator&) = default;
99 ~istream_iterator() = default;
100 #endif
101
102 _GLIBCXX_NODISCARD
103 const _Tp&
104 operator*() const _GLIBCXX_NOEXCEPT
105 {
106 __glibcxx_requires_cond(_M_ok,
107 _M_message(__gnu_debug::__msg_deref_istream)
108 ._M_iterator(*this));
109 return _M_value;
110 }
111
112 _GLIBCXX_NODISCARD
113 const _Tp*
114 operator->() const _GLIBCXX_NOEXCEPT
115 { return std::__addressof((operator*())); }
116
117 istream_iterator&
118 operator++()
119 {
120 __glibcxx_requires_cond(_M_ok,
121 _M_message(__gnu_debug::__msg_inc_istream)
122 ._M_iterator(*this));
123 _M_read();
124 return *this;
125 }
126
127 istream_iterator
128 operator++(int)
129 {
130 __glibcxx_requires_cond(_M_ok,
131 _M_message(__gnu_debug::__msg_inc_istream)
132 ._M_iterator(*this));
133 istream_iterator __tmp = *this;
134 _M_read();
135 return __tmp;
136 }
137
138 private:
139 bool
140 _M_equal(const istream_iterator& __x) const _GLIBCXX_NOEXCEPT
141 {
142 // Ideally this would just return _M_stream == __x._M_stream,
143 // but code compiled with old versions never sets _M_stream to null.
144 return (_M_ok == __x._M_ok) && (!_M_ok || _M_stream == __x._M_stream);
145 }
146
147 void
148 _M_read()
149 {
150 if (_M_stream && !(*_M_stream >> _M_value))
151 {
152 _M_stream = 0;
153 _M_ok = false;
154 }
155 }
156
157 /// Return true if the iterators refer to the same stream,
158 /// or are both at end-of-stream.
159 _GLIBCXX_NODISCARD
160 friend bool
161 operator==(const istream_iterator& __x, const istream_iterator& __y)
162 _GLIBCXX_NOEXCEPT
163 { return __x._M_equal(__y); }
164
165 #if __cpp_impl_three_way_comparison < 201907L
166 /// Return true if the iterators refer to different streams,
167 /// or if one is at end-of-stream and the other is not.
168 _GLIBCXX_NODISCARD
169 friend bool
170 operator!=(const istream_iterator& __x, const istream_iterator& __y)
171 _GLIBCXX_NOEXCEPT
172 { return !__x._M_equal(__y); }
173 #endif
174
175 #if __cplusplus > 201703L && __cpp_lib_concepts
176 [[nodiscard]]
177 friend bool
178 operator==(const istream_iterator& __i, default_sentinel_t) noexcept
179 { return !__i._M_stream; }
180 #endif
181 };
182
183 /**
184 * @brief Provides output iterator semantics for streams.
185 *
186 * This class provides an iterator to write to an ostream. The type Tp is
187 * the only type written by this iterator and there must be an
188 * operator<<(Tp) defined.
189 *
190 * @tparam _Tp The type to write to the ostream.
191 * @tparam _CharT The ostream char_type.
192 * @tparam _Traits The ostream char_traits.
193 */
194 template<typename _Tp, typename _CharT = char,
195 typename _Traits = char_traits<_CharT> >
196 class ostream_iterator
197 : public iterator<output_iterator_tag, void, void, void, void>
198 {
199 public:
200 ///@{
201 /// Public typedef
202 #if __cplusplus > 201703L
203 using difference_type = ptrdiff_t;
204 #endif
205 typedef _CharT char_type;
206 typedef _Traits traits_type;
207 typedef basic_ostream<_CharT, _Traits> ostream_type;
208 ///@}
209
210 private:
211 ostream_type* _M_stream;
212 const _CharT* _M_string;
213
214 public:
215 /// Construct from an ostream.
216 ostream_iterator(ostream_type& __s) _GLIBCXX_NOEXCEPT
217 : _M_stream(std::__addressof(__s)), _M_string(0) {}
218
219 /**
220 * Construct from an ostream.
221 *
222 * The delimiter string @a c is written to the stream after every Tp
223 * written to the stream. The delimiter is not copied, and thus must
224 * not be destroyed while this iterator is in use.
225 *
226 * @param __s Underlying ostream to write to.
227 * @param __c CharT delimiter string to insert.
228 */
229 ostream_iterator(ostream_type& __s, const _CharT* __c) _GLIBCXX_NOEXCEPT
230 : _M_stream(std::__addressof(__s)), _M_string(__c) { }
231
232 /// Copy constructor.
233 ostream_iterator(const ostream_iterator& __obj) _GLIBCXX_NOEXCEPT
234 : _M_stream(__obj._M_stream), _M_string(__obj._M_string) { }
235
236 #if __cplusplus >= 201103L
237 ostream_iterator& operator=(const ostream_iterator&) = default;
238 #endif
239
240 /// Writes @a value to underlying ostream using operator<<. If
241 /// constructed with delimiter string, writes delimiter to ostream.
242 ostream_iterator&
243 operator=(const _Tp& __value)
244 {
245 __glibcxx_requires_cond(_M_stream != 0,
246 _M_message(__gnu_debug::__msg_output_ostream)
247 ._M_iterator(*this));
248 *_M_stream << __value;
249 if (_M_string)
250 *_M_stream << _M_string;
251 return *this;
252 }
253
254 _GLIBCXX_NODISCARD
255 ostream_iterator&
256 operator*() _GLIBCXX_NOEXCEPT
257 { return *this; }
258
259 ostream_iterator&
260 operator++() _GLIBCXX_NOEXCEPT
261 { return *this; }
262
263 ostream_iterator&
264 operator++(int) _GLIBCXX_NOEXCEPT
265 { return *this; }
266 };
267 #pragma GCC diagnostic pop
268
269 /// @} group iterators
270
271 _GLIBCXX_END_NAMESPACE_VERSION
272 } // namespace
273
274 #endif