1 | // Iostreams base classes -*- C++ -*- |
2 | |
3 | // Copyright (C) 1997-2017 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/basic_ios.h |
26 | * This is an internal header file, included by other library headers. |
27 | * Do not attempt to use it directly. @headername{ios} |
28 | */ |
29 | |
30 | #ifndef _BASIC_IOS_H |
31 | #define _BASIC_IOS_H 1 |
32 | |
33 | #pragma GCC system_header |
34 | |
35 | #include <bits/localefwd.h> |
36 | #include <bits/locale_classes.h> |
37 | #include <bits/locale_facets.h> |
38 | #include <bits/streambuf_iterator.h> |
39 | #include <bits/move.h> |
40 | |
41 | namespace std _GLIBCXX_VISIBILITY(default) |
42 | { |
43 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
44 | |
45 | template<typename _Facet> |
46 | inline const _Facet& |
47 | __check_facet(const _Facet* __f) |
48 | { |
49 | if (!__f) |
50 | __throw_bad_cast(); |
51 | return *__f; |
52 | } |
53 | |
54 | /** |
55 | * @brief Template class basic_ios, virtual base class for all |
56 | * stream classes. |
57 | * @ingroup io |
58 | * |
59 | * @tparam _CharT Type of character stream. |
60 | * @tparam _Traits Traits for character type, defaults to |
61 | * char_traits<_CharT>. |
62 | * |
63 | * Most of the member functions called dispatched on stream objects |
64 | * (e.g., @c std::cout.foo(bar);) are consolidated in this class. |
65 | */ |
66 | template<typename _CharT, typename _Traits> |
67 | class basic_ios : public ios_base |
68 | { |
69 | public: |
70 | //@{ |
71 | /** |
72 | * These are standard types. They permit a standardized way of |
73 | * referring to names of (or names dependent on) the template |
74 | * parameters, which are specific to the implementation. |
75 | */ |
76 | typedef _CharT char_type; |
77 | typedef typename _Traits::int_type int_type; |
78 | typedef typename _Traits::pos_type pos_type; |
79 | typedef typename _Traits::off_type off_type; |
80 | typedef _Traits traits_type; |
81 | //@} |
82 | |
83 | //@{ |
84 | /** |
85 | * These are non-standard types. |
86 | */ |
87 | typedef ctype<_CharT> __ctype_type; |
88 | typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> > |
89 | __num_put_type; |
90 | typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> > |
91 | __num_get_type; |
92 | //@} |
93 | |
94 | // Data members: |
95 | protected: |
96 | basic_ostream<_CharT, _Traits>* _M_tie; |
97 | mutable char_type _M_fill; |
98 | mutable bool _M_fill_init; |
99 | basic_streambuf<_CharT, _Traits>* _M_streambuf; |
100 | |
101 | // Cached use_facet<ctype>, which is based on the current locale info. |
102 | const __ctype_type* _M_ctype; |
103 | // For ostream. |
104 | const __num_put_type* _M_num_put; |
105 | // For istream. |
106 | const __num_get_type* _M_num_get; |
107 | |
108 | public: |
109 | //@{ |
110 | /** |
111 | * @brief The quick-and-easy status check. |
112 | * |
113 | * This allows you to write constructs such as |
114 | * <code>if (!a_stream) ...</code> and <code>while (a_stream) ...</code> |
115 | */ |
116 | #if __cplusplus >= 201103L |
117 | explicit operator bool() const |
118 | { return !this->fail(); } |
119 | #else |
120 | operator void*() const |
121 | { return this->fail() ? 0 : const_cast<basic_ios*>(this); } |
122 | #endif |
123 | |
124 | bool |
125 | operator!() const |
126 | { return this->fail(); } |
127 | //@} |
128 | |
129 | /** |
130 | * @brief Returns the error state of the stream buffer. |
131 | * @return A bit pattern (well, isn't everything?) |
132 | * |
133 | * See std::ios_base::iostate for the possible bit values. Most |
134 | * users will call one of the interpreting wrappers, e.g., good(). |
135 | */ |
136 | iostate |
137 | rdstate() const |
138 | { return _M_streambuf_state; } |
139 | |
140 | /** |
141 | * @brief [Re]sets the error state. |
142 | * @param __state The new state flag(s) to set. |
143 | * |
144 | * See std::ios_base::iostate for the possible bit values. Most |
145 | * users will not need to pass an argument. |
146 | */ |
147 | void |
148 | clear(iostate __state = goodbit); |
149 | |
150 | /** |
151 | * @brief Sets additional flags in the error state. |
152 | * @param __state The additional state flag(s) to set. |
153 | * |
154 | * See std::ios_base::iostate for the possible bit values. |
155 | */ |
156 | void |
157 | setstate(iostate __state) |
158 | { this->clear(this->rdstate() | __state); } |
159 | |
160 | // Flip the internal state on for the proper state bits, then |
161 | // rethrows the propagated exception if bit also set in |
162 | // exceptions(). |
163 | void |
164 | _M_setstate(iostate __state) |
165 | { |
166 | // 27.6.1.2.1 Common requirements. |
167 | // Turn this on without causing an ios::failure to be thrown. |
168 | _M_streambuf_state |= __state; |
169 | if (this->exceptions() & __state) |
170 | __throw_exception_again; |
171 | } |
172 | |
173 | /** |
174 | * @brief Fast error checking. |
175 | * @return True if no error flags are set. |
176 | * |
177 | * A wrapper around rdstate. |
178 | */ |
179 | bool |
180 | good() const |
181 | { return this->rdstate() == 0; } |
182 | |
183 | /** |
184 | * @brief Fast error checking. |
185 | * @return True if the eofbit is set. |
186 | * |
187 | * Note that other iostate flags may also be set. |
188 | */ |
189 | bool |
190 | eof() const |
191 | { return (this->rdstate() & eofbit) != 0; } |
192 | |
193 | /** |
194 | * @brief Fast error checking. |
195 | * @return True if either the badbit or the failbit is set. |
196 | * |
197 | * Checking the badbit in fail() is historical practice. |
198 | * Note that other iostate flags may also be set. |
199 | */ |
200 | bool |
201 | fail() const |
202 | { return (this->rdstate() & (badbit | failbit)) != 0; } |
203 | |
204 | /** |
205 | * @brief Fast error checking. |
206 | * @return True if the badbit is set. |
207 | * |
208 | * Note that other iostate flags may also be set. |
209 | */ |
210 | bool |
211 | bad() const |
212 | { return (this->rdstate() & badbit) != 0; } |
213 | |
214 | /** |
215 | * @brief Throwing exceptions on errors. |
216 | * @return The current exceptions mask. |
217 | * |
218 | * This changes nothing in the stream. See the one-argument version |
219 | * of exceptions(iostate) for the meaning of the return value. |
220 | */ |
221 | iostate |
222 | exceptions() const |
223 | { return _M_exception; } |
224 | |
225 | /** |
226 | * @brief Throwing exceptions on errors. |
227 | * @param __except The new exceptions mask. |
228 | * |
229 | * By default, error flags are set silently. You can set an |
230 | * exceptions mask for each stream; if a bit in the mask becomes set |
231 | * in the error flags, then an exception of type |
232 | * std::ios_base::failure is thrown. |
233 | * |
234 | * If the error flag is already set when the exceptions mask is |
235 | * added, the exception is immediately thrown. Try running the |
236 | * following under GCC 3.1 or later: |
237 | * @code |
238 | * #include <iostream> |
239 | * #include <fstream> |
240 | * #include <exception> |
241 | * |
242 | * int main() |
243 | * { |
244 | * std::set_terminate (__gnu_cxx::__verbose_terminate_handler); |
245 | * |
246 | * std::ifstream f ("/etc/motd"); |
247 | * |
248 | * std::cerr << "Setting badbit\n"; |
249 | * f.setstate (std::ios_base::badbit); |
250 | * |
251 | * std::cerr << "Setting exception mask\n"; |
252 | * f.exceptions (std::ios_base::badbit); |
253 | * } |
254 | * @endcode |
255 | */ |
256 | void |
257 | exceptions(iostate __except) |
258 | { |
259 | _M_exception = __except; |
260 | this->clear(_M_streambuf_state); |
261 | } |
262 | |
263 | // Constructor/destructor: |
264 | /** |
265 | * @brief Constructor performs initialization. |
266 | * |
267 | * The parameter is passed by derived streams. |
268 | */ |
269 | explicit |
270 | basic_ios(basic_streambuf<_CharT, _Traits>* __sb) |
271 | : ios_base(), _M_tie(0), _M_fill(), _M_fill_init(false), _M_streambuf(0), |
272 | _M_ctype(0), _M_num_put(0), _M_num_get(0) |
273 | { this->init(__sb); } |
274 | |
275 | /** |
276 | * @brief Empty. |
277 | * |
278 | * The destructor does nothing. More specifically, it does not |
279 | * destroy the streambuf held by rdbuf(). |
280 | */ |
281 | virtual |
282 | ~basic_ios() { } |
283 | |
284 | // Members: |
285 | /** |
286 | * @brief Fetches the current @e tied stream. |
287 | * @return A pointer to the tied stream, or NULL if the stream is |
288 | * not tied. |
289 | * |
290 | * A stream may be @e tied (or synchronized) to a second output |
291 | * stream. When this stream performs any I/O, the tied stream is |
292 | * first flushed. For example, @c std::cin is tied to @c std::cout. |
293 | */ |
294 | basic_ostream<_CharT, _Traits>* |
295 | tie() const |
296 | { return _M_tie; } |
297 | |
298 | /** |
299 | * @brief Ties this stream to an output stream. |
300 | * @param __tiestr The output stream. |
301 | * @return The previously tied output stream, or NULL if the stream |
302 | * was not tied. |
303 | * |
304 | * This sets up a new tie; see tie() for more. |
305 | */ |
306 | basic_ostream<_CharT, _Traits>* |
307 | tie(basic_ostream<_CharT, _Traits>* __tiestr) |
308 | { |
309 | basic_ostream<_CharT, _Traits>* __old = _M_tie; |
310 | _M_tie = __tiestr; |
311 | return __old; |
312 | } |
313 | |
314 | /** |
315 | * @brief Accessing the underlying buffer. |
316 | * @return The current stream buffer. |
317 | * |
318 | * This does not change the state of the stream. |
319 | */ |
320 | basic_streambuf<_CharT, _Traits>* |
321 | rdbuf() const |
322 | { return _M_streambuf; } |
323 | |
324 | /** |
325 | * @brief Changing the underlying buffer. |
326 | * @param __sb The new stream buffer. |
327 | * @return The previous stream buffer. |
328 | * |
329 | * Associates a new buffer with the current stream, and clears the |
330 | * error state. |
331 | * |
332 | * Due to historical accidents which the LWG refuses to correct, the |
333 | * I/O library suffers from a design error: this function is hidden |
334 | * in derived classes by overrides of the zero-argument @c rdbuf(), |
335 | * which is non-virtual for hysterical raisins. As a result, you |
336 | * must use explicit qualifications to access this function via any |
337 | * derived class. For example: |
338 | * |
339 | * @code |
340 | * std::fstream foo; // or some other derived type |
341 | * std::streambuf* p = .....; |
342 | * |
343 | * foo.ios::rdbuf(p); // ios == basic_ios<char> |
344 | * @endcode |
345 | */ |
346 | basic_streambuf<_CharT, _Traits>* |
347 | rdbuf(basic_streambuf<_CharT, _Traits>* __sb); |
348 | |
349 | /** |
350 | * @brief Copies fields of __rhs into this. |
351 | * @param __rhs The source values for the copies. |
352 | * @return Reference to this object. |
353 | * |
354 | * All fields of __rhs are copied into this object except that rdbuf() |
355 | * and rdstate() remain unchanged. All values in the pword and iword |
356 | * arrays are copied. Before copying, each callback is invoked with |
357 | * erase_event. After copying, each (new) callback is invoked with |
358 | * copyfmt_event. The final step is to copy exceptions(). |
359 | */ |
360 | basic_ios& |
361 | copyfmt(const basic_ios& __rhs); |
362 | |
363 | /** |
364 | * @brief Retrieves the @a empty character. |
365 | * @return The current fill character. |
366 | * |
367 | * It defaults to a space (' ') in the current locale. |
368 | */ |
369 | char_type |
370 | fill() const |
371 | { |
372 | if (!_M_fill_init) |
373 | { |
374 | _M_fill = this->widen(' '); |
375 | _M_fill_init = true; |
376 | } |
377 | return _M_fill; |
378 | } |
379 | |
380 | /** |
381 | * @brief Sets a new @a empty character. |
382 | * @param __ch The new character. |
383 | * @return The previous fill character. |
384 | * |
385 | * The fill character is used to fill out space when P+ characters |
386 | * have been requested (e.g., via setw), Q characters are actually |
387 | * used, and Q<P. It defaults to a space (' ') in the current locale. |
388 | */ |
389 | char_type |
390 | fill(char_type __ch) |
391 | { |
392 | char_type __old = this->fill(); |
393 | _M_fill = __ch; |
394 | return __old; |
395 | } |
396 | |
397 | // Locales: |
398 | /** |
399 | * @brief Moves to a new locale. |
400 | * @param __loc The new locale. |
401 | * @return The previous locale. |
402 | * |
403 | * Calls @c ios_base::imbue(loc), and if a stream buffer is associated |
404 | * with this stream, calls that buffer's @c pubimbue(loc). |
405 | * |
406 | * Additional l10n notes are at |
407 | * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html |
408 | */ |
409 | locale |
410 | imbue(const locale& __loc); |
411 | |
412 | /** |
413 | * @brief Squeezes characters. |
414 | * @param __c The character to narrow. |
415 | * @param __dfault The character to narrow. |
416 | * @return The narrowed character. |
417 | * |
418 | * Maps a character of @c char_type to a character of @c char, |
419 | * if possible. |
420 | * |
421 | * Returns the result of |
422 | * @code |
423 | * std::use_facet<ctype<char_type> >(getloc()).narrow(c,dfault) |
424 | * @endcode |
425 | * |
426 | * Additional l10n notes are at |
427 | * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html |
428 | */ |
429 | char |
430 | narrow(char_type __c, char __dfault) const |
431 | { return __check_facet(_M_ctype).narrow(__c, __dfault); } |
432 | |
433 | /** |
434 | * @brief Widens characters. |
435 | * @param __c The character to widen. |
436 | * @return The widened character. |
437 | * |
438 | * Maps a character of @c char to a character of @c char_type. |
439 | * |
440 | * Returns the result of |
441 | * @code |
442 | * std::use_facet<ctype<char_type> >(getloc()).widen(c) |
443 | * @endcode |
444 | * |
445 | * Additional l10n notes are at |
446 | * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html |
447 | */ |
448 | char_type |
449 | widen(char __c) const |
450 | { return __check_facet(_M_ctype).widen(__c); } |
451 | |
452 | protected: |
453 | // 27.4.5.1 basic_ios constructors |
454 | /** |
455 | * @brief Empty. |
456 | * |
457 | * The default constructor does nothing and is not normally |
458 | * accessible to users. |
459 | */ |
460 | basic_ios() |
461 | : ios_base(), _M_tie(0), _M_fill(char_type()), _M_fill_init(false), |
462 | _M_streambuf(0), _M_ctype(0), _M_num_put(0), _M_num_get(0) |
463 | { } |
464 | |
465 | /** |
466 | * @brief All setup is performed here. |
467 | * |
468 | * This is called from the public constructor. It is not virtual and |
469 | * cannot be redefined. |
470 | */ |
471 | void |
472 | init(basic_streambuf<_CharT, _Traits>* __sb); |
473 | |
474 | #if __cplusplus >= 201103L |
475 | basic_ios(const basic_ios&) = delete; |
476 | basic_ios& operator=(const basic_ios&) = delete; |
477 | |
478 | void |
479 | move(basic_ios& __rhs) |
480 | { |
481 | ios_base::_M_move(__rhs); |
482 | _M_cache_locale(_M_ios_locale); |
483 | this->tie(__rhs.tie(nullptr)); |
484 | _M_fill = __rhs._M_fill; |
485 | _M_fill_init = __rhs._M_fill_init; |
486 | _M_streambuf = nullptr; |
487 | } |
488 | |
489 | void |
490 | move(basic_ios&& __rhs) |
491 | { this->move(__rhs); } |
492 | |
493 | void |
494 | swap(basic_ios& __rhs) noexcept |
495 | { |
496 | ios_base::_M_swap(__rhs); |
497 | _M_cache_locale(_M_ios_locale); |
498 | __rhs._M_cache_locale(__rhs._M_ios_locale); |
499 | std::swap(_M_tie, __rhs._M_tie); |
500 | std::swap(_M_fill, __rhs._M_fill); |
501 | std::swap(_M_fill_init, __rhs._M_fill_init); |
502 | } |
503 | |
504 | void |
505 | set_rdbuf(basic_streambuf<_CharT, _Traits>* __sb) |
506 | { _M_streambuf = __sb; } |
507 | #endif |
508 | |
509 | void |
510 | _M_cache_locale(const locale& __loc); |
511 | }; |
512 | |
513 | _GLIBCXX_END_NAMESPACE_VERSION |
514 | } // namespace |
515 | |
516 | #include <bits/basic_ios.tcc> |
517 | |
518 | #endif /* _BASIC_IOS_H */ |
519 | |