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1 : // Input streams -*- C++ -*-
2 :
3 : // Copyright (C) 1997-2021 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 : //
26 : // ISO C++ 14882: 27.6.1 Input streams
27 : //
28 :
29 : /** @file include/istream
30 : * This is a Standard C++ Library header.
31 : */
32 :
33 : #ifndef _GLIBCXX_ISTREAM
34 : #define _GLIBCXX_ISTREAM 1
35 :
36 : #pragma GCC system_header
37 :
38 : #include <ios>
39 : #include <ostream>
40 :
41 : namespace std _GLIBCXX_VISIBILITY(default)
42 : {
43 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
44 :
45 : /**
46 : * @brief Template class basic_istream.
47 : * @ingroup io
48 : *
49 : * @tparam _CharT Type of character stream.
50 : * @tparam _Traits Traits for character type, defaults to
51 : * char_traits<_CharT>.
52 : *
53 : * This is the base class for all input streams. It provides text
54 : * formatting of all builtin types, and communicates with any class
55 : * derived from basic_streambuf to do the actual input.
56 : */
57 : template<typename _CharT, typename _Traits>
58 : class basic_istream : virtual public basic_ios<_CharT, _Traits>
59 : {
60 : public:
61 : // Types (inherited from basic_ios (27.4.4)):
62 : typedef _CharT char_type;
63 : typedef typename _Traits::int_type int_type;
64 : typedef typename _Traits::pos_type pos_type;
65 : typedef typename _Traits::off_type off_type;
66 : typedef _Traits traits_type;
67 :
68 : // Non-standard Types:
69 : typedef basic_streambuf<_CharT, _Traits> __streambuf_type;
70 : typedef basic_ios<_CharT, _Traits> __ios_type;
71 : typedef basic_istream<_CharT, _Traits> __istream_type;
72 : typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >
73 : __num_get_type;
74 : typedef ctype<_CharT> __ctype_type;
75 :
76 : protected:
77 : // Data Members:
78 : /**
79 : * The number of characters extracted in the previous unformatted
80 : * function; see gcount().
81 : */
82 : streamsize _M_gcount;
83 :
84 : public:
85 : /**
86 : * @brief Base constructor.
87 : *
88 : * This ctor is almost never called by the user directly, rather from
89 : * derived classes' initialization lists, which pass a pointer to
90 : * their own stream buffer.
91 : */
92 : explicit
93 : basic_istream(__streambuf_type* __sb)
94 : : _M_gcount(streamsize(0))
95 : { this->init(__sb); }
96 :
97 : /**
98 : * @brief Base destructor.
99 : *
100 : * This does very little apart from providing a virtual base dtor.
101 : */
102 : virtual
103 : ~basic_istream()
104 : { _M_gcount = streamsize(0); }
105 :
106 : /// Safe prefix/suffix operations.
107 : class sentry;
108 : friend class sentry;
109 :
110 : ///@{
111 : /**
112 : * @brief Interface for manipulators.
113 : *
114 : * Manipulators such as @c std::ws and @c std::dec use these
115 : * functions in constructs like
116 : * <code>std::cin >> std::ws</code>.
117 : * For more information, see the iomanip header.
118 : */
119 : __istream_type&
120 : operator>>(__istream_type& (*__pf)(__istream_type&))
121 : { return __pf(*this); }
122 :
123 : __istream_type&
124 : operator>>(__ios_type& (*__pf)(__ios_type&))
125 : {
126 : __pf(*this);
127 : return *this;
128 : }
129 :
130 : __istream_type&
131 : operator>>(ios_base& (*__pf)(ios_base&))
132 : {
133 : __pf(*this);
134 : return *this;
135 : }
136 : ///@}
137 :
138 : ///@{
139 : /**
140 : * @name Extractors
141 : *
142 : * All the @c operator>> functions (aka <em>formatted input
143 : * functions</em>) have some common behavior. Each starts by
144 : * constructing a temporary object of type std::basic_istream::sentry
145 : * with the second argument (noskipws) set to false. This has several
146 : * effects, concluding with the setting of a status flag; see the
147 : * sentry documentation for more.
148 : *
149 : * If the sentry status is good, the function tries to extract
150 : * whatever data is appropriate for the type of the argument.
151 : *
152 : * If an exception is thrown during extraction, ios_base::badbit
153 : * will be turned on in the stream's error state (without causing an
154 : * ios_base::failure to be thrown) and the original exception will
155 : * be rethrown if badbit is set in the exceptions mask.
156 : */
157 :
158 : ///@{
159 : /**
160 : * @brief Integer arithmetic extractors
161 : * @param __n A variable of builtin integral type.
162 : * @return @c *this if successful
163 : *
164 : * These functions use the stream's current locale (specifically, the
165 : * @c num_get facet) to parse the input data.
166 : */
167 : __istream_type&
168 : operator>>(bool& __n)
169 : { return _M_extract(__n); }
170 :
171 : __istream_type&
172 : operator>>(short& __n);
173 :
174 : __istream_type&
175 : operator>>(unsigned short& __n)
176 : { return _M_extract(__n); }
177 :
178 : __istream_type&
179 : operator>>(int& __n);
180 :
181 : __istream_type&
182 : operator>>(unsigned int& __n)
183 : { return _M_extract(__n); }
184 :
185 : __istream_type&
186 : operator>>(long& __n)
187 : { return _M_extract(__n); }
188 :
189 : __istream_type&
190 : operator>>(unsigned long& __n)
191 : { return _M_extract(__n); }
192 :
193 : #ifdef _GLIBCXX_USE_LONG_LONG
194 : __istream_type&
195 : operator>>(long long& __n)
196 : { return _M_extract(__n); }
197 :
198 : __istream_type&
199 : operator>>(unsigned long long& __n)
200 : { return _M_extract(__n); }
201 : #endif
202 : ///@}
203 :
204 : ///@{
205 : /**
206 : * @brief Floating point arithmetic extractors
207 : * @param __f A variable of builtin floating point type.
208 : * @return @c *this if successful
209 : *
210 : * These functions use the stream's current locale (specifically, the
211 : * @c num_get facet) to parse the input data.
212 : */
213 : __istream_type&
214 : operator>>(float& __f)
215 : { return _M_extract(__f); }
216 :
217 : __istream_type&
218 : operator>>(double& __f)
219 : { return _M_extract(__f); }
220 :
221 : __istream_type&
222 : operator>>(long double& __f)
223 : { return _M_extract(__f); }
224 : ///@}
225 :
226 : /**
227 : * @brief Basic arithmetic extractors
228 : * @param __p A variable of pointer type.
229 : * @return @c *this if successful
230 : *
231 : * These functions use the stream's current locale (specifically, the
232 : * @c num_get facet) to parse the input data.
233 : */
234 : __istream_type&
235 : operator>>(void*& __p)
236 : { return _M_extract(__p); }
237 :
238 : /**
239 : * @brief Extracting into another streambuf.
240 : * @param __sb A pointer to a streambuf
241 : *
242 : * This function behaves like one of the basic arithmetic extractors,
243 : * in that it also constructs a sentry object and has the same error
244 : * handling behavior.
245 : *
246 : * If @p __sb is NULL, the stream will set failbit in its error state.
247 : *
248 : * Characters are extracted from this stream and inserted into the
249 : * @p __sb streambuf until one of the following occurs:
250 : *
251 : * - the input stream reaches end-of-file,
252 : * - insertion into the output buffer fails (in this case, the
253 : * character that would have been inserted is not extracted), or
254 : * - an exception occurs (and in this case is caught)
255 : *
256 : * If the function inserts no characters, failbit is set.
257 : */
258 : __istream_type&
259 : operator>>(__streambuf_type* __sb);
260 : ///@}
261 :
262 : // [27.6.1.3] unformatted input
263 : /**
264 : * @brief Character counting
265 : * @return The number of characters extracted by the previous
266 : * unformatted input function dispatched for this stream.
267 : */
268 : streamsize
269 : gcount() const
270 : { return _M_gcount; }
271 :
272 : ///@{
273 : /**
274 : * @name Unformatted Input Functions
275 : *
276 : * All the unformatted input functions have some common behavior.
277 : * Each starts by constructing a temporary object of type
278 : * std::basic_istream::sentry with the second argument (noskipws)
279 : * set to true. This has several effects, concluding with the
280 : * setting of a status flag; see the sentry documentation for more.
281 : *
282 : * If the sentry status is good, the function tries to extract
283 : * whatever data is appropriate for the type of the argument.
284 : *
285 : * The number of characters extracted is stored for later retrieval
286 : * by gcount().
287 : *
288 : * If an exception is thrown during extraction, ios_base::badbit
289 : * will be turned on in the stream's error state (without causing an
290 : * ios_base::failure to be thrown) and the original exception will
291 : * be rethrown if badbit is set in the exceptions mask.
292 : */
293 :
294 : /**
295 : * @brief Simple extraction.
296 : * @return A character, or eof().
297 : *
298 : * Tries to extract a character. If none are available, sets failbit
299 : * and returns traits::eof().
300 : */
301 : int_type
302 : get();
303 :
304 : /**
305 : * @brief Simple extraction.
306 : * @param __c The character in which to store data.
307 : * @return *this
308 : *
309 : * Tries to extract a character and store it in @a __c. If none are
310 : * available, sets failbit and returns traits::eof().
311 : *
312 : * @note This function is not overloaded on signed char and
313 : * unsigned char.
314 : */
315 : __istream_type&
316 : get(char_type& __c);
317 :
318 : /**
319 : * @brief Simple multiple-character extraction.
320 : * @param __s Pointer to an array.
321 : * @param __n Maximum number of characters to store in @a __s.
322 : * @param __delim A "stop" character.
323 : * @return *this
324 : *
325 : * Characters are extracted and stored into @a __s until one of the
326 : * following happens:
327 : *
328 : * - @c __n-1 characters are stored
329 : * - the input sequence reaches EOF
330 : * - the next character equals @a __delim, in which case the character
331 : * is not extracted
332 : *
333 : * If no characters are stored, failbit is set in the stream's error
334 : * state.
335 : *
336 : * In any case, a null character is stored into the next location in
337 : * the array.
338 : *
339 : * @note This function is not overloaded on signed char and
340 : * unsigned char.
341 : */
342 : __istream_type&
343 : get(char_type* __s, streamsize __n, char_type __delim);
344 :
345 : /**
346 : * @brief Simple multiple-character extraction.
347 : * @param __s Pointer to an array.
348 : * @param __n Maximum number of characters to store in @a s.
349 : * @return *this
350 : *
351 : * Returns @c get(__s,__n,widen('\\n')).
352 : */
353 : __istream_type&
354 : get(char_type* __s, streamsize __n)
355 : { return this->get(__s, __n, this->widen('\n')); }
356 :
357 : /**
358 : * @brief Extraction into another streambuf.
359 : * @param __sb A streambuf in which to store data.
360 : * @param __delim A "stop" character.
361 : * @return *this
362 : *
363 : * Characters are extracted and inserted into @a __sb until one of the
364 : * following happens:
365 : *
366 : * - the input sequence reaches EOF
367 : * - insertion into the output buffer fails (in this case, the
368 : * character that would have been inserted is not extracted)
369 : * - the next character equals @a __delim (in this case, the character
370 : * is not extracted)
371 : * - an exception occurs (and in this case is caught)
372 : *
373 : * If no characters are stored, failbit is set in the stream's error
374 : * state.
375 : */
376 : __istream_type&
377 : get(__streambuf_type& __sb, char_type __delim);
378 :
379 : /**
380 : * @brief Extraction into another streambuf.
381 : * @param __sb A streambuf in which to store data.
382 : * @return *this
383 : *
384 : * Returns @c get(__sb,widen('\\n')).
385 : */
386 : __istream_type&
387 : get(__streambuf_type& __sb)
388 : { return this->get(__sb, this->widen('\n')); }
389 :
390 : /**
391 : * @brief String extraction.
392 : * @param __s A character array in which to store the data.
393 : * @param __n Maximum number of characters to extract.
394 : * @param __delim A "stop" character.
395 : * @return *this
396 : *
397 : * Extracts and stores characters into @a __s until one of the
398 : * following happens. Note that these criteria are required to be
399 : * tested in the order listed here, to allow an input line to exactly
400 : * fill the @a __s array without setting failbit.
401 : *
402 : * -# the input sequence reaches end-of-file, in which case eofbit
403 : * is set in the stream error state
404 : * -# the next character equals @c __delim, in which case the character
405 : * is extracted (and therefore counted in @c gcount()) but not stored
406 : * -# @c __n-1 characters are stored, in which case failbit is set
407 : * in the stream error state
408 : *
409 : * If no characters are extracted, failbit is set. (An empty line of
410 : * input should therefore not cause failbit to be set.)
411 : *
412 : * In any case, a null character is stored in the next location in
413 : * the array.
414 : */
415 : __istream_type&
416 : getline(char_type* __s, streamsize __n, char_type __delim);
417 :
418 : /**
419 : * @brief String extraction.
420 : * @param __s A character array in which to store the data.
421 : * @param __n Maximum number of characters to extract.
422 : * @return *this
423 : *
424 : * Returns @c getline(__s,__n,widen('\\n')).
425 : */
426 : __istream_type&
427 : getline(char_type* __s, streamsize __n)
428 : { return this->getline(__s, __n, this->widen('\n')); }
429 :
430 : /**
431 : * @brief Discarding characters
432 : * @param __n Number of characters to discard.
433 : * @param __delim A "stop" character.
434 : * @return *this
435 : *
436 : * Extracts characters and throws them away until one of the
437 : * following happens:
438 : * - if @a __n @c != @c std::numeric_limits<int>::max(), @a __n
439 : * characters are extracted
440 : * - the input sequence reaches end-of-file
441 : * - the next character equals @a __delim (in this case, the character
442 : * is extracted); note that this condition will never occur if
443 : * @a __delim equals @c traits::eof().
444 : *
445 : * NB: Provide three overloads, instead of the single function
446 : * (with defaults) mandated by the Standard: this leads to a
447 : * better performing implementation, while still conforming to
448 : * the Standard.
449 : */
450 : __istream_type&
451 : ignore(streamsize __n, int_type __delim);
452 :
453 : __istream_type&
454 : ignore(streamsize __n);
455 :
456 : __istream_type&
457 : ignore();
458 :
459 : /**
460 : * @brief Looking ahead in the stream
461 : * @return The next character, or eof().
462 : *
463 : * If, after constructing the sentry object, @c good() is false,
464 : * returns @c traits::eof(). Otherwise reads but does not extract
465 : * the next input character.
466 : */
467 : int_type
468 : peek();
469 :
470 : /**
471 : * @brief Extraction without delimiters.
472 : * @param __s A character array.
473 : * @param __n Maximum number of characters to store.
474 : * @return *this
475 : *
476 : * If the stream state is @c good(), extracts characters and stores
477 : * them into @a __s until one of the following happens:
478 : * - @a __n characters are stored
479 : * - the input sequence reaches end-of-file, in which case the error
480 : * state is set to @c failbit|eofbit.
481 : *
482 : * @note This function is not overloaded on signed char and
483 : * unsigned char.
484 : */
485 : __istream_type&
486 : read(char_type* __s, streamsize __n);
487 :
488 : /**
489 : * @brief Extraction until the buffer is exhausted, but no more.
490 : * @param __s A character array.
491 : * @param __n Maximum number of characters to store.
492 : * @return The number of characters extracted.
493 : *
494 : * Extracts characters and stores them into @a __s depending on the
495 : * number of characters remaining in the streambuf's buffer,
496 : * @c rdbuf()->in_avail(), called @c A here:
497 : * - if @c A @c == @c -1, sets eofbit and extracts no characters
498 : * - if @c A @c == @c 0, extracts no characters
499 : * - if @c A @c > @c 0, extracts @c min(A,n)
500 : *
501 : * The goal is to empty the current buffer, and to not request any
502 : * more from the external input sequence controlled by the streambuf.
503 : */
504 : streamsize
505 : readsome(char_type* __s, streamsize __n);
506 :
507 : /**
508 : * @brief Unextracting a single character.
509 : * @param __c The character to push back into the input stream.
510 : * @return *this
511 : *
512 : * If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c).
513 : *
514 : * If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in
515 : * the error state.
516 : *
517 : * @note This function first clears eofbit. Since no characters
518 : * are extracted, the next call to @c gcount() will return 0,
519 : * as required by DR 60.
520 : */
521 : __istream_type&
522 : putback(char_type __c);
523 :
524 : /**
525 : * @brief Unextracting the previous character.
526 : * @return *this
527 : *
528 : * If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c).
529 : *
530 : * If @c rdbuf() is null or if @c sungetc() fails, sets badbit in
531 : * the error state.
532 : *
533 : * @note This function first clears eofbit. Since no characters
534 : * are extracted, the next call to @c gcount() will return 0,
535 : * as required by DR 60.
536 : */
537 : __istream_type&
538 : unget();
539 :
540 : /**
541 : * @brief Synchronizing the stream buffer.
542 : * @return 0 on success, -1 on failure
543 : *
544 : * If @c rdbuf() is a null pointer, returns -1.
545 : *
546 : * Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
547 : * sets badbit and returns -1.
548 : *
549 : * Otherwise, returns 0.
550 : *
551 : * @note This function does not count the number of characters
552 : * extracted, if any, and therefore does not affect the next
553 : * call to @c gcount().
554 : */
555 : int
556 : sync();
557 :
558 : /**
559 : * @brief Getting the current read position.
560 : * @return A file position object.
561 : *
562 : * If @c fail() is not false, returns @c pos_type(-1) to indicate
563 : * failure. Otherwise returns @c rdbuf()->pubseekoff(0,cur,in).
564 : *
565 : * @note This function does not count the number of characters
566 : * extracted, if any, and therefore does not affect the next
567 : * call to @c gcount(). At variance with putback, unget and
568 : * seekg, eofbit is not cleared first.
569 : */
570 : pos_type
571 : tellg();
572 :
573 : /**
574 : * @brief Changing the current read position.
575 : * @param __pos A file position object.
576 : * @return *this
577 : *
578 : * If @c fail() is not true, calls @c rdbuf()->pubseekpos(__pos). If
579 : * that function fails, sets failbit.
580 : *
581 : * @note This function first clears eofbit. It does not count the
582 : * number of characters extracted, if any, and therefore does
583 : * not affect the next call to @c gcount().
584 : */
585 : __istream_type&
586 : seekg(pos_type);
587 :
588 : /**
589 : * @brief Changing the current read position.
590 : * @param __off A file offset object.
591 : * @param __dir The direction in which to seek.
592 : * @return *this
593 : *
594 : * If @c fail() is not true, calls @c rdbuf()->pubseekoff(__off,__dir).
595 : * If that function fails, sets failbit.
596 : *
597 : * @note This function first clears eofbit. It does not count the
598 : * number of characters extracted, if any, and therefore does
599 : * not affect the next call to @c gcount().
600 : */
601 : __istream_type&
602 : seekg(off_type, ios_base::seekdir);
603 : ///@}
604 :
605 : protected:
606 : basic_istream()
607 : : _M_gcount(streamsize(0))
608 : { this->init(0); }
609 :
610 : #if __cplusplus >= 201103L
611 : basic_istream(const basic_istream&) = delete;
612 :
613 : basic_istream(basic_istream&& __rhs)
614 : : __ios_type(), _M_gcount(__rhs._M_gcount)
615 : {
616 : __ios_type::move(__rhs);
617 : __rhs._M_gcount = 0;
618 : }
619 :
620 : // 27.7.3.3 Assign/swap
621 :
622 : basic_istream& operator=(const basic_istream&) = delete;
623 :
624 : basic_istream&
625 : operator=(basic_istream&& __rhs)
626 : {
627 : swap(__rhs);
628 : return *this;
629 : }
630 :
631 : void
632 : swap(basic_istream& __rhs)
633 : {
634 : __ios_type::swap(__rhs);
635 : std::swap(_M_gcount, __rhs._M_gcount);
636 : }
637 : #endif
638 :
639 : template<typename _ValueT>
640 : __istream_type&
641 : _M_extract(_ValueT& __v);
642 : };
643 :
644 : /// Explicit specialization declarations, defined in src/istream.cc.
645 : template<>
646 : basic_istream<char>&
647 : basic_istream<char>::
648 : getline(char_type* __s, streamsize __n, char_type __delim);
649 :
650 : template<>
651 : basic_istream<char>&
652 : basic_istream<char>::
653 : ignore(streamsize __n);
654 :
655 : template<>
656 : basic_istream<char>&
657 : basic_istream<char>::
658 : ignore(streamsize __n, int_type __delim);
659 :
660 : #ifdef _GLIBCXX_USE_WCHAR_T
661 : template<>
662 : basic_istream<wchar_t>&
663 : basic_istream<wchar_t>::
664 : getline(char_type* __s, streamsize __n, char_type __delim);
665 :
666 : template<>
667 : basic_istream<wchar_t>&
668 : basic_istream<wchar_t>::
669 : ignore(streamsize __n);
670 :
671 : template<>
672 : basic_istream<wchar_t>&
673 : basic_istream<wchar_t>::
674 : ignore(streamsize __n, int_type __delim);
675 : #endif
676 :
677 : /**
678 : * @brief Performs setup work for input streams.
679 : *
680 : * Objects of this class are created before all of the standard
681 : * extractors are run. It is responsible for <em>exception-safe
682 : * prefix and suffix operations,</em> although only prefix actions
683 : * are currently required by the standard.
684 : */
685 : template<typename _CharT, typename _Traits>
686 : class basic_istream<_CharT, _Traits>::sentry
687 : {
688 : // Data Members.
689 : bool _M_ok;
690 :
691 : public:
692 : /// Easy access to dependent types.
693 : typedef _Traits traits_type;
694 : typedef basic_streambuf<_CharT, _Traits> __streambuf_type;
695 : typedef basic_istream<_CharT, _Traits> __istream_type;
696 : typedef typename __istream_type::__ctype_type __ctype_type;
697 : typedef typename _Traits::int_type __int_type;
698 :
699 : /**
700 : * @brief The constructor performs all the work.
701 : * @param __is The input stream to guard.
702 : * @param __noskipws Whether to consume whitespace or not.
703 : *
704 : * If the stream state is good (@a __is.good() is true), then the
705 : * following actions are performed, otherwise the sentry state
706 : * is false (<em>not okay</em>) and failbit is set in the
707 : * stream state.
708 : *
709 : * The sentry's preparatory actions are:
710 : *
711 : * -# if the stream is tied to an output stream, @c is.tie()->flush()
712 : * is called to synchronize the output sequence
713 : * -# if @a __noskipws is false, and @c ios_base::skipws is set in
714 : * @c is.flags(), the sentry extracts and discards whitespace
715 : * characters from the stream. The currently imbued locale is
716 : * used to determine whether each character is whitespace.
717 : *
718 : * If the stream state is still good, then the sentry state becomes
719 : * true (@a okay).
720 : */
721 : explicit
722 : sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false);
723 :
724 : /**
725 : * @brief Quick status checking.
726 : * @return The sentry state.
727 : *
728 : * For ease of use, sentries may be converted to booleans. The
729 : * return value is that of the sentry state (true == okay).
730 : */
731 : #if __cplusplus >= 201103L
732 : explicit
733 : #endif
734 : operator bool() const
735 : { return _M_ok; }
736 : };
737 :
738 : ///@{
739 : /**
740 : * @brief Character extractors
741 : * @param __in An input stream.
742 : * @param __c A character reference.
743 : * @return in
744 : *
745 : * Behaves like one of the formatted arithmetic extractors described in
746 : * std::basic_istream. After constructing a sentry object with good
747 : * status, this function extracts a character (if one is available) and
748 : * stores it in @a __c. Otherwise, sets failbit in the input stream.
749 : */
750 : template<typename _CharT, typename _Traits>
751 : basic_istream<_CharT, _Traits>&
752 : operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c);
753 :
754 : template<class _Traits>
755 : inline basic_istream<char, _Traits>&
756 : operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
757 : { return (__in >> reinterpret_cast<char&>(__c)); }
758 :
759 : template<class _Traits>
760 : inline basic_istream<char, _Traits>&
761 : operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
762 : { return (__in >> reinterpret_cast<char&>(__c)); }
763 : ///@}
764 :
765 :
766 : template<typename _CharT, typename _Traits>
767 : void
768 : __istream_extract(basic_istream<_CharT, _Traits>&, _CharT*, streamsize);
769 :
770 : void __istream_extract(istream&, char*, streamsize);
771 :
772 : ///@{
773 : /**
774 : * @brief Character string extractors
775 : * @param __in An input stream.
776 : * @param __s A character array (or a pointer to an array before C++20).
777 : * @return __in
778 : *
779 : * Behaves like one of the formatted arithmetic extractors described in
780 : * `std::basic_istream`. After constructing a sentry object with good
781 : * status, this function extracts up to `n` characters and stores them
782 : * into the array `__s`. `n` is defined as:
783 : *
784 : * - if `width()` is greater than zero, `n` is `min(width(), n)`
785 : * - otherwise `n` is the number of elements of the array
786 : * - (before C++20 the pointer is assumed to point to an array of
787 : * the largest possible size for an array of `char_type`).
788 : *
789 : * Characters are extracted and stored until one of the following happens:
790 : * - `n - 1` characters are stored
791 : * - EOF is reached
792 : * - the next character is whitespace according to the current locale
793 : *
794 : * `width(0)` is then called for the input stream.
795 : *
796 : * If no characters are extracted, sets failbit.
797 : */
798 :
799 : #if __cplusplus <= 201703L
800 : template<typename _CharT, typename _Traits>
801 : __attribute__((__nonnull__(2), __access__(__write_only__, 2)))
802 : inline basic_istream<_CharT, _Traits>&
803 : operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s)
804 : {
805 : #ifdef __OPTIMIZE__
806 : // Function inlining might make the buffer size known, allowing us to
807 : // prevent overflow.
808 : size_t __n = __builtin_object_size(__s, 0);
809 : if (__n < sizeof(_CharT))
810 : {
811 : // There is not even space for the required null terminator.
812 : __glibcxx_assert(__n >= sizeof(_CharT));
813 : // No point calling __istream_extract, but still need to reset width.
814 : __in.width(0);
815 : __in.setstate(ios_base::failbit);
816 : }
817 : else if (__n != (size_t)-1)
818 : {
819 : __n /= sizeof(_CharT);
820 : streamsize __w = __in.width();
821 : std::__istream_extract(__in, __s, __n);
822 : if (__in.good() && (__w <= 0 || __n < __w))
823 : {
824 : // Stopped extracting early to avoid overflowing the buffer,
825 : // but might have stopped anyway (and set eofbit) if at EOF.
826 : const typename _Traits::int_type __c = __in.rdbuf()->sgetc();
827 : const bool __eof = _Traits::eq_int_type(__c, _Traits::eof());
828 : if (__builtin_expect(__eof, true)) // Assume EOF, not overflow.
829 : __in.setstate(ios_base::eofbit);
830 : }
831 : }
832 : else
833 : #endif // __OPTIMIZE
834 : {
835 : // Buffer size is unknown, have to assume it's huge.
836 : streamsize __n = __gnu_cxx::__numeric_traits<streamsize>::__max;
837 : __n /= sizeof(_CharT);
838 : std::__istream_extract(__in, __s, __n);
839 : }
840 : return __in;
841 : }
842 :
843 : template<class _Traits>
844 : __attribute__((__nonnull__(2), __access__(__write_only__, 2)))
845 : inline basic_istream<char, _Traits>&
846 : operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
847 : { return __in >> reinterpret_cast<char*>(__s); }
848 :
849 : template<class _Traits>
850 : __attribute__((__nonnull__(2), __access__(__write_only__, 2)))
851 : inline basic_istream<char, _Traits>&
852 : operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
853 : { return __in >> reinterpret_cast<char*>(__s); }
854 : #else
855 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
856 : // 2499. operator>>(istream&, char*) makes it hard to avoid buffer overflows
857 : template<typename _CharT, typename _Traits, size_t _Num>
858 : inline basic_istream<_CharT, _Traits>&
859 : operator>>(basic_istream<_CharT, _Traits>& __in, _CharT (&__s)[_Num])
860 : {
861 : static_assert(_Num <= __gnu_cxx::__numeric_traits<streamsize>::__max);
862 : std::__istream_extract(__in, __s, _Num);
863 : return __in;
864 : }
865 :
866 : template<class _Traits, size_t _Num>
867 : inline basic_istream<char, _Traits>&
868 : operator>>(basic_istream<char, _Traits>& __in, unsigned char (&__s)[_Num])
869 : { return __in >> reinterpret_cast<char(&)[_Num]>(__s); }
870 :
871 : template<class _Traits, size_t _Num>
872 : inline basic_istream<char, _Traits>&
873 : operator>>(basic_istream<char, _Traits>& __in, signed char (&__s)[_Num])
874 : { return __in >> reinterpret_cast<char(&)[_Num]>(__s); }
875 : #endif
876 : ///@}
877 :
878 : /**
879 : * @brief Template class basic_iostream
880 : * @ingroup io
881 : *
882 : * @tparam _CharT Type of character stream.
883 : * @tparam _Traits Traits for character type, defaults to
884 : * char_traits<_CharT>.
885 : *
886 : * This class multiply inherits from the input and output stream classes
887 : * simply to provide a single interface.
888 : */
889 : template<typename _CharT, typename _Traits>
890 : class basic_iostream
891 : : public basic_istream<_CharT, _Traits>,
892 : public basic_ostream<_CharT, _Traits>
893 : {
894 : public:
895 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
896 : // 271. basic_iostream missing typedefs
897 : // Types (inherited):
898 : typedef _CharT char_type;
899 : typedef typename _Traits::int_type int_type;
900 : typedef typename _Traits::pos_type pos_type;
901 : typedef typename _Traits::off_type off_type;
902 : typedef _Traits traits_type;
903 :
904 : // Non-standard Types:
905 : typedef basic_istream<_CharT, _Traits> __istream_type;
906 : typedef basic_ostream<_CharT, _Traits> __ostream_type;
907 :
908 : /**
909 : * @brief Constructor does nothing.
910 : *
911 : * Both of the parent classes are initialized with the same
912 : * streambuf pointer passed to this constructor.
913 : */
914 : explicit
915 : basic_iostream(basic_streambuf<_CharT, _Traits>* __sb)
916 : : __istream_type(__sb), __ostream_type(__sb) { }
917 :
918 : /**
919 : * @brief Destructor does nothing.
920 : */
921 : virtual
922 : ~basic_iostream() { }
923 :
924 : protected:
925 : basic_iostream()
926 : : __istream_type(), __ostream_type() { }
927 :
928 : #if __cplusplus >= 201103L
929 : basic_iostream(const basic_iostream&) = delete;
930 :
931 : basic_iostream(basic_iostream&& __rhs)
932 : : __istream_type(std::move(__rhs)), __ostream_type(*this)
933 : { }
934 :
935 : // 27.7.3.3 Assign/swap
936 :
937 : basic_iostream& operator=(const basic_iostream&) = delete;
938 :
939 : basic_iostream&
940 : operator=(basic_iostream&& __rhs)
941 : {
942 : swap(__rhs);
943 : return *this;
944 : }
945 :
946 : void
947 : swap(basic_iostream& __rhs)
948 : { __istream_type::swap(__rhs); }
949 : #endif
950 : };
951 :
952 : /**
953 : * @brief Quick and easy way to eat whitespace
954 : *
955 : * This manipulator extracts whitespace characters, stopping when the
956 : * next character is non-whitespace, or when the input sequence is empty.
957 : * If the sequence is empty, @c eofbit is set in the stream, but not
958 : * @c failbit.
959 : *
960 : * The current locale is used to distinguish whitespace characters.
961 : *
962 : * Example:
963 : * @code
964 : * MyClass mc;
965 : *
966 : * std::cin >> std::ws >> mc;
967 : * @endcode
968 : * will skip leading whitespace before calling operator>> on cin and your
969 : * object. Note that the same effect can be achieved by creating a
970 : * std::basic_istream::sentry inside your definition of operator>>.
971 : */
972 : template<typename _CharT, typename _Traits>
973 : basic_istream<_CharT, _Traits>&
974 : ws(basic_istream<_CharT, _Traits>& __is);
975 :
976 : #if __cplusplus >= 201103L
977 : // C++11 27.7.2.6 Rvalue stream extraction [istream.rvalue]
978 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
979 : // 2328. Rvalue stream extraction should use perfect forwarding
980 : // 1203. More useful rvalue stream insertion
981 :
982 : #if __cpp_lib_concepts
983 : template<typename _Is, typename _Tp>
984 : requires __derived_from_ios_base<_Is>
985 : && requires (_Is& __is, _Tp&& __t) { __is >> std::forward<_Tp>(__t); }
986 : using __rvalue_stream_extraction_t = _Is&&;
987 : #else
988 : template<typename _Is, typename _Tp,
989 : typename = _Require_derived_from_ios_base<_Is>,
990 : typename = decltype(std::declval<_Is&>() >> std::declval<_Tp>())>
991 : using __rvalue_stream_extraction_t = _Is&&;
992 : #endif
993 :
994 : /**
995 : * @brief Generic extractor for rvalue stream
996 : * @param __is An input stream.
997 : * @param __x A reference to the extraction target.
998 : * @return __is
999 : *
1000 : * This is just a forwarding function to allow extraction from
1001 : * rvalue streams since they won't bind to the extractor functions
1002 : * that take an lvalue reference.
1003 : */
1004 : template<typename _Istream, typename _Tp>
1005 : inline __rvalue_stream_extraction_t<_Istream, _Tp>
1006 0 : operator>>(_Istream&& __is, _Tp&& __x)
1007 : {
1008 0 : __is >> std::forward<_Tp>(__x);
1009 0 : return std::move(__is);
1010 : }
1011 : #endif // C++11
1012 :
1013 : _GLIBCXX_END_NAMESPACE_VERSION
1014 : } // namespace
1015 :
1016 : #include <bits/istream.tcc>
1017 :
1018 : #endif /* _GLIBCXX_ISTREAM */
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