1 // Input streams -*- C++ -*-
2
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
4 // Free Software Foundation, Inc.
5 //
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 2, or (at your option)
10 // any later version.
11
12 // This library is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
16
17 // You should have received a copy of the GNU General Public License along
18 // with this library; see the file COPYING. If not, write to the Free
19 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
20 // USA.
21
22 // As a special exception, you may use this file as part of a free software
23 // library without restriction. Specifically, if other files instantiate
24 // templates or use macros or inline functions from this file, or you compile
25 // this file and link it with other files to produce an executable, this
26 // file does not by itself cause the resulting executable to be covered by
27 // the GNU General Public License. This exception does not however
28 // invalidate any other reasons why the executable file might be covered by
29 // the GNU General Public License.
30
31 //
32 // ISO C++ 14882: 27.6.1 Input streams
33 //
34
35 /** @file istream
36 * This is a Standard C++ Library header.
37 */
38
39 #ifndef _GLIBCXX_ISTREAM
40 #define _GLIBCXX_ISTREAM 1
41
42 #pragma GCC system_header
43
44 #include <ios>
45 #include <limits> // For numeric_limits
46
_GLIBCXX_BEGIN_NAMESPACE(std)47 _GLIBCXX_BEGIN_NAMESPACE(std)
48
49 // [27.6.1.1] Template class basic_istream
50 /**
51 * @brief Controlling input.
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 template<typename _CharT2, typename _Traits2>
77 friend basic_istream<_CharT2, _Traits2>&
78 operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2&);
79
80 template<typename _CharT2, typename _Traits2>
81 friend basic_istream<_CharT2, _Traits2>&
82 operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*);
83
84 protected:
85 // Data Members:
86 /**
87 * @if maint
88 * The number of characters extracted in the previous unformatted
89 * function; see gcount().
90 * @endif
91 */
92 streamsize _M_gcount;
93
94 public:
95 // [27.6.1.1.1] constructor/destructor
96 /**
97 * @brief Base constructor.
98 *
99 * This ctor is almost never called by the user directly, rather from
100 * derived classes' initialization lists, which pass a pointer to
101 * their own stream buffer.
102 */
103 explicit
104 basic_istream(__streambuf_type* __sb): _M_gcount(streamsize(0))
105 { this->init(__sb); }
106
107 /**
108 * @brief Base destructor.
109 *
110 * This does very little apart from providing a virtual base dtor.
111 */
112 virtual
113 ~basic_istream()
114 { _M_gcount = streamsize(0); }
115
116 // [27.6.1.1.2] prefix/suffix
117 class sentry;
118 friend class sentry;
119
120 // [27.6.1.2] formatted input
121 // [27.6.1.2.3] basic_istream::operator>>
122 //@{
123 /**
124 * @brief Interface for manipulators.
125 *
126 * Manuipulators such as @c std::ws and @c std::dec use these
127 * functions in constructs like "std::cin >> std::ws". For more
128 * information, see the iomanip header.
129 */
130 __istream_type&
131 operator>>(__istream_type& (*__pf)(__istream_type&))
132 { return __pf(*this); }
133
134 __istream_type&
135 operator>>(__ios_type& (*__pf)(__ios_type&))
136 {
137 __pf(*this);
138 return *this;
139 }
140
141 __istream_type&
142 operator>>(ios_base& (*__pf)(ios_base&))
143 {
144 __pf(*this);
145 return *this;
146 }
147 //@}
148
149 // [27.6.1.2.2] arithmetic extractors
150 /**
151 * @name Arithmetic Extractors
152 *
153 * All the @c operator>> functions (aka <em>formatted input
154 * functions</em>) have some common behavior. Each starts by
155 * constructing a temporary object of type std::basic_istream::sentry
156 * with the second argument (noskipws) set to false. This has several
157 * effects, concluding with the setting of a status flag; see the
158 * sentry documentation for more.
159 *
160 * If the sentry status is good, the function tries to extract
161 * whatever data is appropriate for the type of the argument.
162 *
163 * If an exception is thrown during extraction, ios_base::badbit
164 * will be turned on in the stream's error state without causing an
165 * ios_base::failure to be thrown. The original exception will then
166 * be rethrown.
167 */
168 //@{
169 /**
170 * @brief Basic arithmetic extractors
171 * @param A variable of builtin type.
172 * @return @c *this if successful
173 *
174 * These functions use the stream's current locale (specifically, the
175 * @c num_get facet) to parse the input data.
176 */
177 __istream_type&
178 operator>>(bool& __n)
179 { return _M_extract(__n); }
180
181 __istream_type&
182 operator>>(short& __n);
183
184 __istream_type&
185 operator>>(unsigned short& __n)
186 { return _M_extract(__n); }
187
188 __istream_type&
189 operator>>(int& __n);
190
191 __istream_type&
192 operator>>(unsigned int& __n)
193 { return _M_extract(__n); }
194
195 __istream_type&
196 operator>>(long& __n)
197 { return _M_extract(__n); }
198
199 __istream_type&
200 operator>>(unsigned long& __n)
201 { return _M_extract(__n); }
202
203 #ifdef _GLIBCXX_USE_LONG_LONG
204 __istream_type&
205 operator>>(long long& __n)
206 { return _M_extract(__n); }
207
208 __istream_type&
209 operator>>(unsigned long long& __n)
210 { return _M_extract(__n); }
211 #endif
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 __istream_type&
226 operator>>(void*& __p)
227 { return _M_extract(__p); }
228
229 /**
230 * @brief Extracting into another streambuf.
231 * @param sb A pointer to a streambuf
232 *
233 * This function behaves like one of the basic arithmetic extractors,
234 * in that it also constructs a sentry object and has the same error
235 * handling behavior.
236 *
237 * If @a sb is NULL, the stream will set failbit in its error state.
238 *
239 * Characters are extracted from this stream and inserted into the
240 * @a sb streambuf until one of the following occurs:
241 *
242 * - the input stream reaches end-of-file,
243 * - insertion into the output buffer fails (in this case, the
244 * character that would have been inserted is not extracted), or
245 * - an exception occurs (and in this case is caught)
246 *
247 * If the function inserts no characters, failbit is set.
248 */
249 __istream_type&
250 operator>>(__streambuf_type* __sb);
251 //@}
252
253 // [27.6.1.3] unformatted input
254 /**
255 * @brief Character counting
256 * @return The number of characters extracted by the previous
257 * unformatted input function dispatched for this stream.
258 */
259 streamsize
260 gcount() const
261 { return _M_gcount; }
262
263 /**
264 * @name Unformatted Input Functions
265 *
266 * All the unformatted input functions have some common behavior.
267 * Each starts by constructing a temporary object of type
268 * std::basic_istream::sentry with the second argument (noskipws)
269 * set to true. This has several effects, concluding with the
270 * setting of a status flag; see the sentry documentation for more.
271 *
272 * If the sentry status is good, the function tries to extract
273 * whatever data is appropriate for the type of the argument.
274 *
275 * The number of characters extracted is stored for later retrieval
276 * by gcount().
277 *
278 * If an exception is thrown during extraction, ios_base::badbit
279 * will be turned on in the stream's error state without causing an
280 * ios_base::failure to be thrown. The original exception will then
281 * be rethrown.
282 */
283 //@{
284 /**
285 * @brief Simple extraction.
286 * @return A character, or eof().
287 *
288 * Tries to extract a character. If none are available, sets failbit
289 * and returns traits::eof().
290 */
291 int_type
292 get();
293
294 /**
295 * @brief Simple extraction.
296 * @param c The character in which to store data.
297 * @return *this
298 *
299 * Tries to extract a character and store it in @a c. If none are
300 * available, sets failbit and returns traits::eof().
301 *
302 * @note This function is not overloaded on signed char and
303 * unsigned char.
304 */
305 __istream_type&
306 get(char_type& __c);
307
308 /**
309 * @brief Simple multiple-character extraction.
310 * @param s Pointer to an array.
311 * @param n Maximum number of characters to store in @a s.
312 * @param delim A "stop" character.
313 * @return *this
314 *
315 * Characters are extracted and stored into @a s until one of the
316 * following happens:
317 *
318 * - @c n-1 characters are stored
319 * - the input sequence reaches EOF
320 * - the next character equals @a delim, in which case the character
321 * is not extracted
322 *
323 * If no characters are stored, failbit is set in the stream's error
324 * state.
325 *
326 * In any case, a null character is stored into the next location in
327 * the array.
328 *
329 * @note This function is not overloaded on signed char and
330 * unsigned char.
331 */
332 __istream_type&
333 get(char_type* __s, streamsize __n, char_type __delim);
334
335 /**
336 * @brief Simple multiple-character extraction.
337 * @param s Pointer to an array.
338 * @param n Maximum number of characters to store in @a s.
339 * @return *this
340 *
341 * Returns @c get(s,n,widen('\n')).
342 */
343 __istream_type&
344 get(char_type* __s, streamsize __n)
345 { return this->get(__s, __n, this->widen('\n')); }
346
347 /**
348 * @brief Extraction into another streambuf.
349 * @param sb A streambuf in which to store data.
350 * @param delim A "stop" character.
351 * @return *this
352 *
353 * Characters are extracted and inserted into @a sb until one of the
354 * following happens:
355 *
356 * - the input sequence reaches EOF
357 * - insertion into the output buffer fails (in this case, the
358 * character that would have been inserted is not extracted)
359 * - the next character equals @a delim (in this case, the character
360 * is not extracted)
361 * - an exception occurs (and in this case is caught)
362 *
363 * If no characters are stored, failbit is set in the stream's error
364 * state.
365 */
366 __istream_type&
367 get(__streambuf_type& __sb, char_type __delim);
368
369 /**
370 * @brief Extraction into another streambuf.
371 * @param sb A streambuf in which to store data.
372 * @return *this
373 *
374 * Returns @c get(sb,widen('\n')).
375 */
376 __istream_type&
377 get(__streambuf_type& __sb)
378 { return this->get(__sb, this->widen('\n')); }
379
380 /**
381 * @brief String extraction.
382 * @param s A character array in which to store the data.
383 * @param n Maximum number of characters to extract.
384 * @param delim A "stop" character.
385 * @return *this
386 *
387 * Extracts and stores characters into @a s until one of the
388 * following happens. Note that these criteria are required to be
389 * tested in the order listed here, to allow an input line to exactly
390 * fill the @a s array without setting failbit.
391 *
392 * -# the input sequence reaches end-of-file, in which case eofbit
393 * is set in the stream error state
394 * -# the next character equals @c delim, in which case the character
395 * is extracted (and therefore counted in @c gcount()) but not stored
396 * -# @c n-1 characters are stored, in which case failbit is set
397 * in the stream error state
398 *
399 * If no characters are extracted, failbit is set. (An empty line of
400 * input should therefore not cause failbit to be set.)
401 *
402 * In any case, a null character is stored in the next location in
403 * the array.
404 */
405 __istream_type&
406 getline(char_type* __s, streamsize __n, char_type __delim);
407
408 /**
409 * @brief String extraction.
410 * @param s A character array in which to store the data.
411 * @param n Maximum number of characters to extract.
412 * @return *this
413 *
414 * Returns @c getline(s,n,widen('\n')).
415 */
416 __istream_type&
417 getline(char_type* __s, streamsize __n)
418 { return this->getline(__s, __n, this->widen('\n')); }
419
420 /**
421 * @brief Discarding characters
422 * @param n Number of characters to discard.
423 * @param delim A "stop" character.
424 * @return *this
425 *
426 * Extracts characters and throws them away until one of the
427 * following happens:
428 * - if @a n @c != @c std::numeric_limits<int>::max(), @a n
429 * characters are extracted
430 * - the input sequence reaches end-of-file
431 * - the next character equals @a delim (in this case, the character
432 * is extracted); note that this condition will never occur if
433 * @a delim equals @c traits::eof().
434 *
435 * NB: Provide three overloads, instead of the single function
436 * (with defaults) mandated by the Standard: this leads to a
437 * better performing implementation, while still conforming to
438 * the Standard.
439 */
440 __istream_type&
441 ignore();
442
443 __istream_type&
444 ignore(streamsize __n);
445
446 __istream_type&
447 ignore(streamsize __n, int_type __delim);
448
449 /**
450 * @brief Looking ahead in the stream
451 * @return The next character, or eof().
452 *
453 * If, after constructing the sentry object, @c good() is false,
454 * returns @c traits::eof(). Otherwise reads but does not extract
455 * the next input character.
456 */
457 int_type
458 peek();
459
460 /**
461 * @brief Extraction without delimiters.
462 * @param s A character array.
463 * @param n Maximum number of characters to store.
464 * @return *this
465 *
466 * If the stream state is @c good(), extracts characters and stores
467 * them into @a s until one of the following happens:
468 * - @a n characters are stored
469 * - the input sequence reaches end-of-file, in which case the error
470 * state is set to @c failbit|eofbit.
471 *
472 * @note This function is not overloaded on signed char and
473 * unsigned char.
474 */
475 __istream_type&
476 read(char_type* __s, streamsize __n);
477
478 /**
479 * @brief Extraction until the buffer is exhausted, but no more.
480 * @param s A character array.
481 * @param n Maximum number of characters to store.
482 * @return The number of characters extracted.
483 *
484 * Extracts characters and stores them into @a s depending on the
485 * number of characters remaining in the streambuf's buffer,
486 * @c rdbuf()->in_avail(), called @c A here:
487 * - if @c A @c == @c -1, sets eofbit and extracts no characters
488 * - if @c A @c == @c 0, extracts no characters
489 * - if @c A @c > @c 0, extracts @c min(A,n)
490 *
491 * The goal is to empty the current buffer, and to not request any
492 * more from the external input sequence controlled by the streambuf.
493 */
494 streamsize
495 readsome(char_type* __s, streamsize __n);
496
497 /**
498 * @brief Unextracting a single character.
499 * @param c The character to push back into the input stream.
500 * @return *this
501 *
502 * If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c).
503 *
504 * If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in
505 * the error state.
506 *
507 * @note Since no characters are extracted, the next call to
508 * @c gcount() will return 0, as required by DR 60.
509 */
510 __istream_type&
511 putback(char_type __c);
512
513 /**
514 * @brief Unextracting the previous character.
515 * @return *this
516 *
517 * If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c).
518 *
519 * If @c rdbuf() is null or if @c sungetc() fails, sets badbit in
520 * the error state.
521 *
522 * @note Since no characters are extracted, the next call to
523 * @c gcount() will return 0, as required by DR 60.
524 */
525 __istream_type&
526 unget();
527
528 /**
529 * @brief Synchronizing the stream buffer.
530 * @return 0 on success, -1 on failure
531 *
532 * If @c rdbuf() is a null pointer, returns -1.
533 *
534 * Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
535 * sets badbit and returns -1.
536 *
537 * Otherwise, returns 0.
538 *
539 * @note This function does not count the number of characters
540 * extracted, if any, and therefore does not affect the next
541 * call to @c gcount().
542 */
543 int
544 sync();
545
546 /**
547 * @brief Getting the current read position.
548 * @return A file position object.
549 *
550 * If @c fail() is not false, returns @c pos_type(-1) to indicate
551 * failure. Otherwise returns @c rdbuf()->pubseekoff(0,cur,in).
552 *
553 * @note This function does not count the number of characters
554 * extracted, if any, and therefore does not affect the next
555 * call to @c gcount().
556 */
557 pos_type
558 tellg();
559
560 /**
561 * @brief Changing the current read position.
562 * @param pos A file position object.
563 * @return *this
564 *
565 * If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos). If
566 * that function fails, sets failbit.
567 *
568 * @note This function does not count the number of characters
569 * extracted, if any, and therefore does not affect the next
570 * call to @c gcount().
571 */
572 __istream_type&
573 seekg(pos_type);
574
575 /**
576 * @brief Changing the current read position.
577 * @param off A file offset object.
578 * @param dir The direction in which to seek.
579 * @return *this
580 *
581 * If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir).
582 * If that function fails, sets failbit.
583 *
584 * @note This function does not count the number of characters
585 * extracted, if any, and therefore does not affect the next
586 * call to @c gcount().
587 */
588 __istream_type&
589 seekg(off_type, ios_base::seekdir);
590 //@}
591
592 protected:
593 explicit
594 basic_istream(): _M_gcount(streamsize(0)) { }
595
596 template<typename _ValueT>
597 __istream_type&
598 _M_extract(_ValueT& __v);
599 };
600
601 // Explicit specialization declarations, defined in src/istream.cc.
602 template<>
603 basic_istream<char>&
604 basic_istream<char>::
605 getline(char_type* __s, streamsize __n, char_type __delim);
606
607 template<>
608 basic_istream<char>&
609 basic_istream<char>::
610 ignore(streamsize __n);
611
612 template<>
613 basic_istream<char>&
614 basic_istream<char>::
615 ignore(streamsize __n, int_type __delim);
616
617 #ifdef _GLIBCXX_USE_WCHAR_T
618 template<>
619 basic_istream<wchar_t>&
620 basic_istream<wchar_t>::
621 getline(char_type* __s, streamsize __n, char_type __delim);
622
623 template<>
624 basic_istream<wchar_t>&
625 basic_istream<wchar_t>::
626 ignore(streamsize __n);
627
628 template<>
629 basic_istream<wchar_t>&
630 basic_istream<wchar_t>::
631 ignore(streamsize __n, int_type __delim);
632 #endif
633
634 /**
635 * @brief Performs setup work for input streams.
636 *
637 * Objects of this class are created before all of the standard
638 * extractors are run. It is responsible for "exception-safe prefix and
639 * suffix operations," although only prefix actions are currently required
640 * by the standard. Additional actions may be added by the
641 * implementation, and we list them in
642 * http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#5
643 * under [27.6] notes.
644 */
645 template<typename _CharT, typename _Traits>
646 class basic_istream<_CharT, _Traits>::sentry
647 {
648 public:
649 /// Easy access to dependant types.
650 typedef _Traits traits_type;
651 typedef basic_streambuf<_CharT, _Traits> __streambuf_type;
652 typedef basic_istream<_CharT, _Traits> __istream_type;
653 typedef typename __istream_type::__ctype_type __ctype_type;
654 typedef typename _Traits::int_type __int_type;
655
656 /**
657 * @brief The constructor performs all the work.
658 * @param is The input stream to guard.
659 * @param noskipws Whether to consume whitespace or not.
660 *
661 * If the stream state is good (@a is.good() is true), then the
662 * following actions are performed, otherwise the sentry state is
663 * false ("not okay") and failbit is set in the stream state.
664 *
665 * The sentry's preparatory actions are:
666 *
667 * -# if the stream is tied to an output stream, @c is.tie()->flush()
668 * is called to synchronize the output sequence
669 * -# if @a noskipws is false, and @c ios_base::skipws is set in
670 * @c is.flags(), the sentry extracts and discards whitespace
671 * characters from the stream. The currently imbued locale is
672 * used to determine whether each character is whitespace.
673 *
674 * If the stream state is still good, then the sentry state becomes
675 * true ("okay").
676 */
677 explicit
678 sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false);
679
680 /**
681 * @brief Quick status checking.
682 * @return The sentry state.
683 *
684 * For ease of use, sentries may be converted to booleans. The
685 * return value is that of the sentry state (true == okay).
686 */
687 operator bool() const
688 { return _M_ok; }
689
690 private:
691 bool _M_ok;
692 };
693
694 // [27.6.1.2.3] character extraction templates
695 //@{
696 /**
697 * @brief Character extractors
698 * @param in An input stream.
699 * @param c A character reference.
700 * @return in
701 *
702 * Behaves like one of the formatted arithmetic extractors described in
703 * std::basic_istream. After constructing a sentry object with good
704 * status, this function extracts a character (if one is available) and
705 * stores it in @a c. Otherwise, sets failbit in the input stream.
706 */
707 template<typename _CharT, typename _Traits>
708 basic_istream<_CharT, _Traits>&
709 operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c);
710
711 template<class _Traits>
712 inline basic_istream<char, _Traits>&
713 operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
714 { return (__in >> reinterpret_cast<char&>(__c)); }
715
716 template<class _Traits>
717 inline basic_istream<char, _Traits>&
718 operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
719 { return (__in >> reinterpret_cast<char&>(__c)); }
720 //@}
721
722 //@{
723 /**
724 * @brief Character string extractors
725 * @param in An input stream.
726 * @param s A pointer to a character array.
727 * @return in
728 *
729 * Behaves like one of the formatted arithmetic extractors described in
730 * std::basic_istream. After constructing a sentry object with good
731 * status, this function extracts up to @c n characters and stores them
732 * into the array starting at @a s. @c n is defined as:
733 *
734 * - if @c width() is greater than zero, @c n is width()
735 * - otherwise @c n is "the number of elements of the largest array of
736 * @c char_type that can store a terminating @c eos." [27.6.1.2.3]/6
737 *
738 * Characters are extracted and stored until one of the following happens:
739 * - @c n-1 characters are stored
740 * - EOF is reached
741 * - the next character is whitespace according to the current locale
742 * - the next character is a null byte (i.e., @c charT() )
743 *
744 * @c width(0) is then called for the input stream.
745 *
746 * If no characters are extracted, sets failbit.
747 */
748 template<typename _CharT, typename _Traits>
749 basic_istream<_CharT, _Traits>&
750 operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s);
751
752 // Explicit specialization declaration, defined in src/istream.cc.
753 template<>
754 basic_istream<char>&
755 operator>>(basic_istream<char>& __in, char* __s);
756
757 template<class _Traits>
758 inline basic_istream<char, _Traits>&
759 operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
760 { return (__in >> reinterpret_cast<char*>(__s)); }
761
762 template<class _Traits>
763 inline basic_istream<char, _Traits>&
764 operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
765 { return (__in >> reinterpret_cast<char*>(__s)); }
766 //@}
767
768 // 27.6.1.5 Template class basic_iostream
769 /**
770 * @brief Merging istream and ostream capabilities.
771 *
772 * This class multiply inherits from the input and output stream classes
773 * simply to provide a single interface.
774 */
775 template<typename _CharT, typename _Traits>
776 class basic_iostream
777 : public basic_istream<_CharT, _Traits>,
778 public basic_ostream<_CharT, _Traits>
779 {
780 public:
781 // _GLIBCXX_RESOLVE_LIB_DEFECTS
782 // 271. basic_iostream missing typedefs
783 // Types (inherited):
784 typedef _CharT char_type;
785 typedef typename _Traits::int_type int_type;
786 typedef typename _Traits::pos_type pos_type;
787 typedef typename _Traits::off_type off_type;
788 typedef _Traits traits_type;
789
790 // Non-standard Types:
791 typedef basic_istream<_CharT, _Traits> __istream_type;
792 typedef basic_ostream<_CharT, _Traits> __ostream_type;
793
794 /**
795 * @brief Constructor does nothing.
796 *
797 * Both of the parent classes are initialized with the same
798 * streambuf pointer passed to this constructor.
799 */
800 explicit
basic_iostream(basic_streambuf<_CharT,_Traits> * __sb)801 basic_iostream(basic_streambuf<_CharT, _Traits>* __sb)
802 : __istream_type(), __ostream_type()
803 { this->init(__sb); }
804
805 /**
806 * @brief Destructor does nothing.
807 */
808 virtual
~basic_iostream()809 ~basic_iostream() { }
810
811 protected:
812 explicit
basic_iostream()813 basic_iostream() : __istream_type(), __ostream_type()
814 { }
815 };
816
817 // [27.6.1.4] standard basic_istream manipulators
818 /**
819 * @brief Quick and easy way to eat whitespace
820 *
821 * This manipulator extracts whitespace characters, stopping when the
822 * next character is non-whitespace, or when the input sequence is empty.
823 * If the sequence is empty, @c eofbit is set in the stream, but not
824 * @c failbit.
825 *
826 * The current locale is used to distinguish whitespace characters.
827 *
828 * Example:
829 * @code
830 * MyClass mc;
831 *
832 * std::cin >> std::ws >> mc;
833 * @endcode
834 * will skip leading whitespace before calling operator>> on cin and your
835 * object. Note that the same effect can be achieved by creating a
836 * std::basic_istream::sentry inside your definition of operator>>.
837 */
838 template<typename _CharT, typename _Traits>
839 basic_istream<_CharT, _Traits>&
840 ws(basic_istream<_CharT, _Traits>& __is);
841
842 _GLIBCXX_END_NAMESPACE
843
844 #ifndef _GLIBCXX_EXPORT_TEMPLATE
845 # include <bits/istream.tcc>
846 #endif
847
848 #endif /* _GLIBCXX_ISTREAM */
849