1// Input streams -*- C++ -*- 
2 
3// Copyright (C) 1997-2019 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 
41namespace 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(&apos;\\n&apos;)). 
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(&apos;\\n&apos;)). 
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(&apos;\\n&apos;)). 
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 /** 
767 * @brief Character string extractors 
768 * @param __in An input stream. 
769 * @param __s A pointer to a character array. 
770 * @return __in 
771 * 
772 * Behaves like one of the formatted arithmetic extractors described in 
773 * std::basic_istream. After constructing a sentry object with good 
774 * status, this function extracts up to @c n characters and stores them 
775 * into the array starting at @a __s. @c n is defined as: 
776 * 
777 * - if @c width() is greater than zero, @c n is width() otherwise 
778 * - @c n is <em>the number of elements of the largest array of * 
779 * - @c char_type that can store a terminating @c eos.</em> 
780 * - [27.6.1.2.3]/6 
781 * 
782 * Characters are extracted and stored until one of the following happens: 
783 * - @c n-1 characters are stored 
784 * - EOF is reached 
785 * - the next character is whitespace according to the current locale 
786 * - the next character is a null byte (i.e., @c charT() ) 
787 * 
788 * @c width(0) is then called for the input stream. 
789 * 
790 * If no characters are extracted, sets failbit. 
791 */ 
792 template<typename _CharT, typename _Traits> 
793 basic_istream<_CharT, _Traits>& 
794 operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s); 
795 
796 // Explicit specialization declaration, defined in src/istream.cc. 
797 template<> 
798 basic_istream<char>& 
799 operator>>(basic_istream<char>& __in, char* __s); 
800 
801 template<class _Traits> 
802 inline basic_istream<char, _Traits>& 
803 operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s) 
804 { return (__in >> reinterpret_cast<char*>(__s)); } 
805 
806 template<class _Traits> 
807 inline basic_istream<char, _Traits>& 
808 operator>>(basic_istream<char, _Traits>& __in, signed char* __s) 
809 { return (__in >> reinterpret_cast<char*>(__s)); } 
810 //@} 
811 
812 /** 
813 * @brief Template class basic_iostream 
814 * @ingroup io 
815 * 
816 * @tparam _CharT Type of character stream. 
817 * @tparam _Traits Traits for character type, defaults to 
818 * char_traits<_CharT>. 
819 * 
820 * This class multiply inherits from the input and output stream classes 
821 * simply to provide a single interface. 
822 */ 
823 template<typename _CharT, typename _Traits> 
824 class basic_iostream 
825 : public basic_istream<_CharT, _Traits>, 
826 public basic_ostream<_CharT, _Traits> 
827 { 
828 public: 
829 // _GLIBCXX_RESOLVE_LIB_DEFECTS 
830 // 271. basic_iostream missing typedefs 
831 // Types (inherited): 
832 typedef _CharT char_type; 
833 typedef typename _Traits::int_type int_type; 
834 typedef typename _Traits::pos_type pos_type; 
835 typedef typename _Traits::off_type off_type; 
836 typedef _Traits traits_type; 
837 
838 // Non-standard Types: 
839 typedef basic_istream<_CharT, _Traits> __istream_type; 
840 typedef basic_ostream<_CharT, _Traits> __ostream_type; 
841 
842 /** 
843 * @brief Constructor does nothing. 
844 * 
845 * Both of the parent classes are initialized with the same 
846 * streambuf pointer passed to this constructor. 
847 */ 
848 explicit 
849 basic_iostream(basic_streambuf<_CharT, _Traits>* __sb) 
850 : __istream_type(__sb), __ostream_type(__sb) { } 
851 
852 /** 
853 * @brief Destructor does nothing. 
854 */ 
855 virtual 
856 ~basic_iostream() { } 
857 
858 protected: 
859 basic_iostream() 
860 : __istream_type(), __ostream_type() { } 
861 
862#if __cplusplus >= 201103L 
863 basic_iostream(const basic_iostream&) = delete; 
864 
865 basic_iostream(basic_iostream&& __rhs) 
866 : __istream_type(std::move(__rhs)), __ostream_type(*this) 
867 { } 
868 
869 // 27.7.3.3 Assign/swap 
870 
871 basic_iostream& operator=(const basic_iostream&) = delete; 
872 
873 basic_iostream& 
874 operator=(basic_iostream&& __rhs) 
875 { 
876 swap(__rhs); 
877 return *this; 
878 } 
879 
880 void 
881 swap(basic_iostream& __rhs) 
882 { __istream_type::swap(__rhs); } 
883#endif 
884 }; 
885 
886 /** 
887 * @brief Quick and easy way to eat whitespace 
888 * 
889 * This manipulator extracts whitespace characters, stopping when the 
890 * next character is non-whitespace, or when the input sequence is empty. 
891 * If the sequence is empty, @c eofbit is set in the stream, but not 
892 * @c failbit. 
893 * 
894 * The current locale is used to distinguish whitespace characters. 
895 * 
896 * Example: 
897 * @code 
898 * MyClass mc; 
899 * 
900 * std::cin >> std::ws >> mc; 
901 * @endcode 
902 * will skip leading whitespace before calling operator>> on cin and your 
903 * object. Note that the same effect can be achieved by creating a 
904 * std::basic_istream::sentry inside your definition of operator>>. 
905 */ 
906 template<typename _CharT, typename _Traits> 
907 basic_istream<_CharT, _Traits>& 
908 ws(basic_istream<_CharT, _Traits>& __is); 
909 
910#if __cplusplus >= 201103L 
911 template<typename _Ch, typename _Up> 
912 basic_istream<_Ch, _Up>& 
913 __is_convertible_to_basic_istream_test(basic_istream<_Ch, _Up>*); 
914 
915 template<typename _Tp, typename = void> 
916 struct __is_convertible_to_basic_istream_impl 
917 { 
918 using __istream_type = void; 
919 }; 
920 
921 template<typename _Tp> 
922 using __do_is_convertible_to_basic_istream_impl = 
923 decltype(__is_convertible_to_basic_istream_test 
924 (declval<typename remove_reference<_Tp>::type*>())); 
925 
926 template<typename _Tp> 
927 struct __is_convertible_to_basic_istream_impl 
928 <_Tp, 
929 __void_t<__do_is_convertible_to_basic_istream_impl<_Tp>>> 
930 { 
931 using __istream_type = 
932 __do_is_convertible_to_basic_istream_impl<_Tp>; 
933 }; 
934 
935 template<typename _Tp> 
936 struct __is_convertible_to_basic_istream 
937 : __is_convertible_to_basic_istream_impl<_Tp> 
938 { 
939 public: 
940 using type = __not_<is_void< 
941 typename __is_convertible_to_basic_istream_impl<_Tp>::__istream_type>>; 
942 constexpr static bool value = type::value; 
943 }; 
944 
945 template<typename _Istream, typename _Tp, typename = void> 
946 struct __is_extractable : false_type {}; 
947 
948 template<typename _Istream, typename _Tp> 
949 struct __is_extractable<_Istream, _Tp, 
950 __void_t<decltype(declval<_Istream&>() 
951 >> declval<_Tp>())>> 
952 : true_type {}; 
953 
954 template<typename _Istream> 
955 using __rvalue_istream_type = 
956 typename __is_convertible_to_basic_istream< 
957 _Istream>::__istream_type; 
958 
959 // [27.7.1.6] Rvalue stream extraction 
960 // _GLIBCXX_RESOLVE_LIB_DEFECTS 
961 // 2328. Rvalue stream extraction should use perfect forwarding 
962 /** 
963 * @brief Generic extractor for rvalue stream 
964 * @param __is An input stream. 
965 * @param __x A reference to the extraction target. 
966 * @return is 
967 * 
968 * This is just a forwarding function to allow extraction from 
969 * rvalue streams since they won't bind to the extractor functions 
970 * that take an lvalue reference. 
971 */ 
972 template<typename _Istream, typename _Tp> 
973 inline 
974 typename enable_if<__and_<__not_<is_lvalue_reference<_Istream>>, 
975 __is_convertible_to_basic_istream<_Istream>, 
976 __is_extractable< 
977 __rvalue_istream_type<_Istream>, 
978 _Tp&&>>::value, 
979 __rvalue_istream_type<_Istream>>::type 
980 operator>>(_Istream&& __is, _Tp&& __x) 
981 { 
982 __rvalue_istream_type<_Istream> __ret_is = __is; 
983 __ret_is >> std::forward<_Tp>(__x); 
984 return __ret_is; 
985 } 
986#endif // C++11 
987 
988_GLIBCXX_END_NAMESPACE_VERSION 
989} // namespace 
990 
991#include <bits/istream.tcc> 
992 
993#endif /* _GLIBCXX_ISTREAM */ 
994