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 |
258 | |