1 // Stream iterators
2
3 // Copyright (C) 2001-2022 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
_GLIBCXX_VISIBILITY(default)37 namespace std _GLIBCXX_VISIBILITY(default)
38 {
39 _GLIBCXX_BEGIN_NAMESPACE_VERSION
40
41 /**
42 * @addtogroup iterators
43 * @{
44 */
45
46 // Ignore warnings about std::iterator.
47 #pragma GCC diagnostic push
48 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
49
50 /// Provides input iterator semantics for streams.
51 template<typename _Tp, typename _CharT = char,
52 typename _Traits = char_traits<_CharT>, typename _Dist = ptrdiff_t>
53 class istream_iterator
54 : public iterator<input_iterator_tag, _Tp, _Dist, const _Tp*, const _Tp&>
55 {
56 public:
57 typedef _CharT char_type;
58 typedef _Traits traits_type;
59 typedef basic_istream<_CharT, _Traits> istream_type;
60
61 private:
62 istream_type* _M_stream;
63 _Tp _M_value;
64 // This bool becomes false at end-of-stream. It should be sufficient to
65 // check _M_stream != nullptr instead, but historically we did not set
66 // _M_stream to null when reaching the end, so we need to keep this flag.
67 bool _M_ok;
68
69 public:
70 /// Construct end of input stream iterator.
71 _GLIBCXX_CONSTEXPR istream_iterator()
72 _GLIBCXX_NOEXCEPT_IF(is_nothrow_default_constructible<_Tp>::value)
73 : _M_stream(0), _M_value(), _M_ok(false) {}
74
75 /// Construct start of input stream iterator.
76 istream_iterator(istream_type& __s)
77 : _M_stream(std::__addressof(__s)), _M_ok(true)
78 { _M_read(); }
79
80 _GLIBCXX_CONSTEXPR
81 istream_iterator(const istream_iterator& __obj)
82 _GLIBCXX_NOEXCEPT_IF(is_nothrow_copy_constructible<_Tp>::value)
83 : _M_stream(__obj._M_stream), _M_value(__obj._M_value),
84 _M_ok(__obj._M_ok)
85 { }
86
87 #if __cplusplus > 201703L && __cpp_lib_concepts
88 constexpr
89 istream_iterator(default_sentinel_t)
90 noexcept(is_nothrow_default_constructible_v<_Tp>)
91 : istream_iterator() { }
92 #endif
93
94 #if __cplusplus >= 201103L
95 istream_iterator& operator=(const istream_iterator&) = default;
96 ~istream_iterator() = default;
97 #endif
98
99 _GLIBCXX_NODISCARD
100 const _Tp&
101 operator*() const _GLIBCXX_NOEXCEPT
102 {
103 __glibcxx_requires_cond(_M_ok,
104 _M_message(__gnu_debug::__msg_deref_istream)
105 ._M_iterator(*this));
106 return _M_value;
107 }
108
109 _GLIBCXX_NODISCARD
110 const _Tp*
111 operator->() const _GLIBCXX_NOEXCEPT
112 { return std::__addressof((operator*())); }
113
114 istream_iterator&
115 operator++()
116 {
117 __glibcxx_requires_cond(_M_ok,
118 _M_message(__gnu_debug::__msg_inc_istream)
119 ._M_iterator(*this));
120 _M_read();
121 return *this;
122 }
123
124 istream_iterator
125 operator++(int)
126 {
127 __glibcxx_requires_cond(_M_ok,
128 _M_message(__gnu_debug::__msg_inc_istream)
129 ._M_iterator(*this));
130 istream_iterator __tmp = *this;
131 _M_read();
132 return __tmp;
133 }
134
135 private:
136 bool
137 _M_equal(const istream_iterator& __x) const _GLIBCXX_NOEXCEPT
138 {
139 // Ideally this would just return _M_stream == __x._M_stream,
140 // but code compiled with old versions never sets _M_stream to null.
141 return (_M_ok == __x._M_ok) && (!_M_ok || _M_stream == __x._M_stream);
142 }
143
144 void
145 _M_read()
146 {
147 if (_M_stream && !(*_M_stream >> _M_value))
148 {
149 _M_stream = 0;
150 _M_ok = false;
151 }
152 }
153
154 /// Return true if the iterators refer to the same stream,
155 /// or are both at end-of-stream.
156 _GLIBCXX_NODISCARD
157 friend bool
158 operator==(const istream_iterator& __x, const istream_iterator& __y)
159 _GLIBCXX_NOEXCEPT
160 { return __x._M_equal(__y); }
161
162 #if __cpp_impl_three_way_comparison < 201907L
163 /// Return true if the iterators refer to different streams,
164 /// or if one is at end-of-stream and the other is not.
165 _GLIBCXX_NODISCARD
166 friend bool
167 operator!=(const istream_iterator& __x, const istream_iterator& __y)
168 _GLIBCXX_NOEXCEPT
169 { return !__x._M_equal(__y); }
170 #endif
171
172 #if __cplusplus > 201703L && __cpp_lib_concepts
173 [[nodiscard]]
174 friend bool
175 operator==(const istream_iterator& __i, default_sentinel_t) noexcept
176 { return !__i._M_stream; }
177 #endif
178 };
179
180 /**
181 * @brief Provides output iterator semantics for streams.
182 *
183 * This class provides an iterator to write to an ostream. The type Tp is
184 * the only type written by this iterator and there must be an
185 * operator<<(Tp) defined.
186 *
187 * @tparam _Tp The type to write to the ostream.
188 * @tparam _CharT The ostream char_type.
189 * @tparam _Traits The ostream char_traits.
190 */
191 template<typename _Tp, typename _CharT = char,
192 typename _Traits = char_traits<_CharT> >
193 class ostream_iterator
194 : public iterator<output_iterator_tag, void, void, void, void>
195 {
196 public:
197 ///@{
198 /// Public typedef
199 #if __cplusplus > 201703L
200 using difference_type = ptrdiff_t;
201 #endif
202 typedef _CharT char_type;
203 typedef _Traits traits_type;
204 typedef basic_ostream<_CharT, _Traits> ostream_type;
205 ///@}
206
207 private:
208 ostream_type* _M_stream;
209 const _CharT* _M_string;
210
211 public:
212 /// Construct from an ostream.
213 ostream_iterator(ostream_type& __s) _GLIBCXX_NOEXCEPT
214 : _M_stream(std::__addressof(__s)), _M_string(0) {}
215
216 /**
217 * Construct from an ostream.
218 *
219 * The delimiter string @a c is written to the stream after every Tp
220 * written to the stream. The delimiter is not copied, and thus must
221 * not be destroyed while this iterator is in use.
222 *
223 * @param __s Underlying ostream to write to.
224 * @param __c CharT delimiter string to insert.
225 */
226 ostream_iterator(ostream_type& __s, const _CharT* __c) _GLIBCXX_NOEXCEPT
227 : _M_stream(std::__addressof(__s)), _M_string(__c) { }
228
229 /// Copy constructor.
230 ostream_iterator(const ostream_iterator& __obj) _GLIBCXX_NOEXCEPT
231 : _M_stream(__obj._M_stream), _M_string(__obj._M_string) { }
232
233 #if __cplusplus >= 201103L
234 ostream_iterator& operator=(const ostream_iterator&) = default;
235 #endif
236
237 /// Writes @a value to underlying ostream using operator<<. If
238 /// constructed with delimiter string, writes delimiter to ostream.
239 ostream_iterator&
240 operator=(const _Tp& __value)
241 {
242 __glibcxx_requires_cond(_M_stream != 0,
243 _M_message(__gnu_debug::__msg_output_ostream)
244 ._M_iterator(*this));
245 *_M_stream << __value;
246 if (_M_string)
247 *_M_stream << _M_string;
248 return *this;
249 }
250
251 _GLIBCXX_NODISCARD
252 ostream_iterator&
253 operator*() _GLIBCXX_NOEXCEPT
254 { return *this; }
255
256 ostream_iterator&
257 operator++() _GLIBCXX_NOEXCEPT
258 { return *this; }
259
260 ostream_iterator&
261 operator++(int) _GLIBCXX_NOEXCEPT
262 { return *this; }
263 };
264 #pragma GCC diagnostic pop
265
266 /// @} group iterators
267
268 _GLIBCXX_END_NAMESPACE_VERSION
269 } // namespace
270
271 #endif
272