libstdc++
streambuf
Go to the documentation of this file.
1 // Stream buffer classes -*- C++ -*-
2 
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
4 // 2006, 2007, 2008, 2009, 2010, 2011 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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
18 // permissions described in the GCC Runtime Library Exception, version
19 // 3.1, as published by the Free Software Foundation.
20 
21 // You should have received a copy of the GNU General Public License and
22 // a copy of the GCC Runtime Library Exception along with this program;
23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 // <http://www.gnu.org/licenses/>.
25 
26 /** @file include/streambuf
27  * This is a Standard C++ Library header.
28  */
29 
30 //
31 // ISO C++ 14882: 27.5 Stream buffers
32 //
33 
34 #ifndef _GLIBXX_STREAMBUF
35 #define _GLIBXX_STREAMBUF 1
36 
37 #pragma GCC system_header
38 
39 #include <bits/c++config.h>
40 #include <iosfwd>
41 #include <bits/localefwd.h>
42 #include <bits/ios_base.h>
43 #include <bits/cpp_type_traits.h>
44 #include <ext/type_traits.h>
45 
46 namespace std _GLIBCXX_VISIBILITY(default)
47 {
48 _GLIBCXX_BEGIN_NAMESPACE_VERSION
49 
50  template<typename _CharT, typename _Traits>
52  __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>*,
53  basic_streambuf<_CharT, _Traits>*, bool&);
54 
55  /**
56  * @brief The actual work of input and output (interface).
57  * @ingroup io
58  *
59  * This is a base class. Derived stream buffers each control a
60  * pair of character sequences: one for input, and one for output.
61  *
62  * Section [27.5.1] of the standard describes the requirements and
63  * behavior of stream buffer classes. That section (three paragraphs)
64  * is reproduced here, for simplicity and accuracy.
65  *
66  * -# Stream buffers can impose various constraints on the sequences
67  * they control. Some constraints are:
68  * - The controlled input sequence can be not readable.
69  * - The controlled output sequence can be not writable.
70  * - The controlled sequences can be associated with the contents of
71  * other representations for character sequences, such as external
72  * files.
73  * - The controlled sequences can support operations @e directly to or
74  * from associated sequences.
75  * - The controlled sequences can impose limitations on how the
76  * program can read characters from a sequence, write characters to
77  * a sequence, put characters back into an input sequence, or alter
78  * the stream position.
79  * .
80  * -# Each sequence is characterized by three pointers which, if non-null,
81  * all point into the same @c charT array object. The array object
82  * represents, at any moment, a (sub)sequence of characters from the
83  * sequence. Operations performed on a sequence alter the values
84  * stored in these pointers, perform reads and writes directly to or
85  * from associated sequences, and alter <em>the stream position</em> and
86  * conversion state as needed to maintain this subsequence relationship.
87  * The three pointers are:
88  * - the <em>beginning pointer</em>, or lowest element address in the
89  * array (called @e xbeg here);
90  * - the <em>next pointer</em>, or next element address that is a
91  * current candidate for reading or writing (called @e xnext here);
92  * - the <em>end pointer</em>, or first element address beyond the
93  * end of the array (called @e xend here).
94  * .
95  * -# The following semantic constraints shall always apply for any set
96  * of three pointers for a sequence, using the pointer names given
97  * immediately above:
98  * - If @e xnext is not a null pointer, then @e xbeg and @e xend shall
99  * also be non-null pointers into the same @c charT array, as
100  * described above; otherwise, @e xbeg and @e xend shall also be null.
101  * - If @e xnext is not a null pointer and @e xnext < @e xend for an
102  * output sequence, then a <em>write position</em> is available.
103  * In this case, @e *xnext shall be assignable as the next element
104  * to write (to put, or to store a character value, into the sequence).
105  * - If @e xnext is not a null pointer and @e xbeg < @e xnext for an
106  * input sequence, then a <em>putback position</em> is available.
107  * In this case, @e xnext[-1] shall have a defined value and is the
108  * next (preceding) element to store a character that is put back
109  * into the input sequence.
110  * - If @e xnext is not a null pointer and @e xnext< @e xend for an
111  * input sequence, then a <em>read position</em> is available.
112  * In this case, @e *xnext shall have a defined value and is the
113  * next element to read (to get, or to obtain a character value,
114  * from the sequence).
115  */
116  template<typename _CharT, typename _Traits>
118  {
119  public:
120  //@{
121  /**
122  * These are standard types. They permit a standardized way of
123  * referring to names of (or names dependant on) the template
124  * parameters, which are specific to the implementation.
125  */
126  typedef _CharT char_type;
127  typedef _Traits traits_type;
128  typedef typename traits_type::int_type int_type;
129  typedef typename traits_type::pos_type pos_type;
130  typedef typename traits_type::off_type off_type;
131  //@}
132 
133  //@{
134  /// This is a non-standard type.
136  //@}
137 
138  friend class basic_ios<char_type, traits_type>;
139  friend class basic_istream<char_type, traits_type>;
140  friend class basic_ostream<char_type, traits_type>;
143 
144  friend streamsize
145  __copy_streambufs_eof<>(__streambuf_type*, __streambuf_type*, bool&);
146 
147  template<bool _IsMove, typename _CharT2>
148  friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
149  _CharT2*>::__type
150  __copy_move_a2(istreambuf_iterator<_CharT2>,
151  istreambuf_iterator<_CharT2>, _CharT2*);
152 
153  template<typename _CharT2>
154  friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
157  const _CharT2&);
158 
159  template<typename _CharT2, typename _Traits2>
162 
163  template<typename _CharT2, typename _Traits2, typename _Alloc>
167 
168  template<typename _CharT2, typename _Traits2, typename _Alloc>
172 
173  protected:
174  //@{
175  /**
176  * This is based on _IO_FILE, just reordered to be more consistent,
177  * and is intended to be the most minimal abstraction for an
178  * internal buffer.
179  * - get == input == read
180  * - put == output == write
181  */
182  char_type* _M_in_beg; // Start of get area.
183  char_type* _M_in_cur; // Current read area.
184  char_type* _M_in_end; // End of get area.
185  char_type* _M_out_beg; // Start of put area.
186  char_type* _M_out_cur; // Current put area.
187  char_type* _M_out_end; // End of put area.
188 
189  /// Current locale setting.
191 
192  public:
193  /// Destructor deallocates no buffer space.
194  virtual
196  { }
197 
198  // [27.5.2.2.1] locales
199  /**
200  * @brief Entry point for imbue().
201  * @param __loc The new locale.
202  * @return The previous locale.
203  *
204  * Calls the derived imbue(__loc).
205  */
206  locale
207  pubimbue(const locale& __loc)
208  {
209  locale __tmp(this->getloc());
210  this->imbue(__loc);
211  _M_buf_locale = __loc;
212  return __tmp;
213  }
214 
215  /**
216  * @brief Locale access.
217  * @return The current locale in effect.
218  *
219  * If pubimbue(loc) has been called, then the most recent @c loc
220  * is returned. Otherwise the global locale in effect at the time
221  * of construction is returned.
222  */
223  locale
224  getloc() const
225  { return _M_buf_locale; }
226 
227  // [27.5.2.2.2] buffer management and positioning
228  //@{
229  /**
230  * @brief Entry points for derived buffer functions.
231  *
232  * The public versions of @c pubfoo dispatch to the protected
233  * derived @c foo member functions, passing the arguments (if any)
234  * and returning the result unchanged.
235  */
238  { return this->setbuf(__s, __n); }
239 
240  /**
241  * @brief Alters the stream position.
242  * @param __off Offset.
243  * @param __way Value for ios_base::seekdir.
244  * @param __mode Value for ios_base::openmode.
245  *
246  * Calls virtual seekoff function.
247  */
248  pos_type
249  pubseekoff(off_type __off, ios_base::seekdir __way,
250  ios_base::openmode __mode = ios_base::in | ios_base::out)
251  { return this->seekoff(__off, __way, __mode); }
252 
253  /**
254  * @brief Alters the stream position.
255  * @param __sp Position
256  * @param __mode Value for ios_base::openmode.
257  *
258  * Calls virtual seekpos function.
259  */
260  pos_type
262  ios_base::openmode __mode = ios_base::in | ios_base::out)
263  { return this->seekpos(__sp, __mode); }
264 
265  /**
266  * @brief Calls virtual sync function.
267  */
268  int
269  pubsync() { return this->sync(); }
270  //@}
271 
272  // [27.5.2.2.3] get area
273  /**
274  * @brief Looking ahead into the stream.
275  * @return The number of characters available.
276  *
277  * If a read position is available, returns the number of characters
278  * available for reading before the buffer must be refilled.
279  * Otherwise returns the derived @c showmanyc().
280  */
281  streamsize
283  {
284  const streamsize __ret = this->egptr() - this->gptr();
285  return __ret ? __ret : this->showmanyc();
286  }
287 
288  /**
289  * @brief Getting the next character.
290  * @return The next character, or eof.
291  *
292  * Calls @c sbumpc(), and if that function returns
293  * @c traits::eof(), so does this function. Otherwise, @c sgetc().
294  */
295  int_type
297  {
298  int_type __ret = traits_type::eof();
299  if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(),
300  __ret), true))
301  __ret = this->sgetc();
302  return __ret;
303  }
304 
305  /**
306  * @brief Getting the next character.
307  * @return The next character, or eof.
308  *
309  * If the input read position is available, returns that character
310  * and increments the read pointer, otherwise calls and returns
311  * @c uflow().
312  */
313  int_type
315  {
316  int_type __ret;
317  if (__builtin_expect(this->gptr() < this->egptr(), true))
318  {
319  __ret = traits_type::to_int_type(*this->gptr());
320  this->gbump(1);
321  }
322  else
323  __ret = this->uflow();
324  return __ret;
325  }
326 
327  /**
328  * @brief Getting the next character.
329  * @return The next character, or eof.
330  *
331  * If the input read position is available, returns that character,
332  * otherwise calls and returns @c underflow(). Does not move the
333  * read position after fetching the character.
334  */
335  int_type
337  {
338  int_type __ret;
339  if (__builtin_expect(this->gptr() < this->egptr(), true))
340  __ret = traits_type::to_int_type(*this->gptr());
341  else
342  __ret = this->underflow();
343  return __ret;
344  }
345 
346  /**
347  * @brief Entry point for xsgetn.
348  * @param __s A buffer area.
349  * @param __n A count.
350  *
351  * Returns xsgetn(__s,__n). The effect is to fill @a __s[0] through
352  * @a __s[__n-1] with characters from the input sequence, if possible.
353  */
354  streamsize
356  { return this->xsgetn(__s, __n); }
357 
358  // [27.5.2.2.4] putback
359  /**
360  * @brief Pushing characters back into the input stream.
361  * @param __c The character to push back.
362  * @return The previous character, if possible.
363  *
364  * Similar to sungetc(), but @a __c is pushed onto the stream
365  * instead of <em>the previous character.</em> If successful,
366  * the next character fetched from the input stream will be @a
367  * __c.
368  */
369  int_type
371  {
372  int_type __ret;
373  const bool __testpos = this->eback() < this->gptr();
374  if (__builtin_expect(!__testpos ||
375  !traits_type::eq(__c, this->gptr()[-1]), false))
376  __ret = this->pbackfail(traits_type::to_int_type(__c));
377  else
378  {
379  this->gbump(-1);
380  __ret = traits_type::to_int_type(*this->gptr());
381  }
382  return __ret;
383  }
384 
385  /**
386  * @brief Moving backwards in the input stream.
387  * @return The previous character, if possible.
388  *
389  * If a putback position is available, this function decrements
390  * the input pointer and returns that character. Otherwise,
391  * calls and returns pbackfail(). The effect is to @a unget
392  * the last character @a gotten.
393  */
394  int_type
396  {
397  int_type __ret;
398  if (__builtin_expect(this->eback() < this->gptr(), true))
399  {
400  this->gbump(-1);
401  __ret = traits_type::to_int_type(*this->gptr());
402  }
403  else
404  __ret = this->pbackfail();
405  return __ret;
406  }
407 
408  // [27.5.2.2.5] put area
409  /**
410  * @brief Entry point for all single-character output functions.
411  * @param __c A character to output.
412  * @return @a __c, if possible.
413  *
414  * One of two public output functions.
415  *
416  * If a write position is available for the output sequence (i.e.,
417  * the buffer is not full), stores @a __c in that position, increments
418  * the position, and returns @c traits::to_int_type(__c). If a write
419  * position is not available, returns @c overflow(__c).
420  */
421  int_type
423  {
424  int_type __ret;
425  if (__builtin_expect(this->pptr() < this->epptr(), true))
426  {
427  *this->pptr() = __c;
428  this->pbump(1);
429  __ret = traits_type::to_int_type(__c);
430  }
431  else
432  __ret = this->overflow(traits_type::to_int_type(__c));
433  return __ret;
434  }
435 
436  /**
437  * @brief Entry point for all single-character output functions.
438  * @param __s A buffer read area.
439  * @param __n A count.
440  *
441  * One of two public output functions.
442  *
443  *
444  * Returns xsputn(__s,__n). The effect is to write @a __s[0] through
445  * @a __s[__n-1] to the output sequence, if possible.
446  */
447  streamsize
448  sputn(const char_type* __s, streamsize __n)
449  { return this->xsputn(__s, __n); }
450 
451  protected:
452  /**
453  * @brief Base constructor.
454  *
455  * Only called from derived constructors, and sets up all the
456  * buffer data to zero, including the pointers described in the
457  * basic_streambuf class description. Note that, as a result,
458  * - the class starts with no read nor write positions available,
459  * - this is not an error
460  */
462  : _M_in_beg(0), _M_in_cur(0), _M_in_end(0),
463  _M_out_beg(0), _M_out_cur(0), _M_out_end(0),
465  { }
466 
467  // [27.5.2.3.1] get area access
468  //@{
469  /**
470  * @brief Access to the get area.
471  *
472  * These functions are only available to other protected functions,
473  * including derived classes.
474  *
475  * - eback() returns the beginning pointer for the input sequence
476  * - gptr() returns the next pointer for the input sequence
477  * - egptr() returns the end pointer for the input sequence
478  */
479  char_type*
480  eback() const { return _M_in_beg; }
481 
482  char_type*
483  gptr() const { return _M_in_cur; }
484 
485  char_type*
486  egptr() const { return _M_in_end; }
487  //@}
488 
489  /**
490  * @brief Moving the read position.
491  * @param __n The delta by which to move.
492  *
493  * This just advances the read position without returning any data.
494  */
495  void
496  gbump(int __n) { _M_in_cur += __n; }
497 
498  /**
499  * @brief Setting the three read area pointers.
500  * @param __gbeg A pointer.
501  * @param __gnext A pointer.
502  * @param __gend A pointer.
503  * @post @a __gbeg == @c eback(), @a __gnext == @c gptr(), and
504  * @a __gend == @c egptr()
505  */
506  void
507  setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
508  {
509  _M_in_beg = __gbeg;
510  _M_in_cur = __gnext;
511  _M_in_end = __gend;
512  }
513 
514  // [27.5.2.3.2] put area access
515  //@{
516  /**
517  * @brief Access to the put area.
518  *
519  * These functions are only available to other protected functions,
520  * including derived classes.
521  *
522  * - pbase() returns the beginning pointer for the output sequence
523  * - pptr() returns the next pointer for the output sequence
524  * - epptr() returns the end pointer for the output sequence
525  */
526  char_type*
527  pbase() const { return _M_out_beg; }
528 
529  char_type*
530  pptr() const { return _M_out_cur; }
531 
532  char_type*
533  epptr() const { return _M_out_end; }
534  //@}
535 
536  /**
537  * @brief Moving the write position.
538  * @param __n The delta by which to move.
539  *
540  * This just advances the write position without returning any data.
541  */
542  void
543  pbump(int __n) { _M_out_cur += __n; }
544 
545  /**
546  * @brief Setting the three write area pointers.
547  * @param __pbeg A pointer.
548  * @param __pend A pointer.
549  * @post @a __pbeg == @c pbase(), @a __pbeg == @c pptr(), and
550  * @a __pend == @c epptr()
551  */
552  void
553  setp(char_type* __pbeg, char_type* __pend)
554  {
555  _M_out_beg = _M_out_cur = __pbeg;
556  _M_out_end = __pend;
557  }
558 
559  // [27.5.2.4] virtual functions
560  // [27.5.2.4.1] locales
561  /**
562  * @brief Changes translations.
563  * @param __loc A new locale.
564  *
565  * Translations done during I/O which depend on the current
566  * locale are changed by this call. The standard adds,
567  * <em>Between invocations of this function a class derived
568  * from streambuf can safely cache results of calls to locale
569  * functions and to members of facets so obtained.</em>
570  *
571  * @note Base class version does nothing.
572  */
573  virtual void
574  imbue(const locale& __loc)
575  { }
576 
577  // [27.5.2.4.2] buffer management and positioning
578  /**
579  * @brief Manipulates the buffer.
580  *
581  * Each derived class provides its own appropriate behavior. See
582  * the next-to-last paragraph of
583  * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html
584  * for more on this function.
585  *
586  * @note Base class version does nothing, returns @c this.
587  */
590  { return this; }
591 
592  /**
593  * @brief Alters the stream positions.
594  *
595  * Each derived class provides its own appropriate behavior.
596  * @note Base class version does nothing, returns a @c pos_type
597  * that represents an invalid stream position.
598  */
599  virtual pos_type
600  seekoff(off_type, ios_base::seekdir,
601  ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
602  { return pos_type(off_type(-1)); }
603 
604  /**
605  * @brief Alters the stream positions.
606  *
607  * Each derived class provides its own appropriate behavior.
608  * @note Base class version does nothing, returns a @c pos_type
609  * that represents an invalid stream position.
610  */
611  virtual pos_type
613  ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
614  { return pos_type(off_type(-1)); }
615 
616  /**
617  * @brief Synchronizes the buffer arrays with the controlled sequences.
618  * @return -1 on failure.
619  *
620  * Each derived class provides its own appropriate behavior,
621  * including the definition of @a failure.
622  * @note Base class version does nothing, returns zero.
623  */
624  virtual int
625  sync() { return 0; }
626 
627  // [27.5.2.4.3] get area
628  /**
629  * @brief Investigating the data available.
630  * @return An estimate of the number of characters available in the
631  * input sequence, or -1.
632  *
633  * <em>If it returns a positive value, then successive calls to
634  * @c underflow() will not return @c traits::eof() until at
635  * least that number of characters have been supplied. If @c
636  * showmanyc() returns -1, then calls to @c underflow() or @c
637  * uflow() will fail.</em> [27.5.2.4.3]/1
638  *
639  * @note Base class version does nothing, returns zero.
640  * @note The standard adds that <em>the intention is not only that the
641  * calls [to underflow or uflow] will not return @c eof() but
642  * that they will return immediately.</em>
643  * @note The standard adds that <em>the morphemes of @c showmanyc are
644  * @b es-how-many-see, not @b show-manic.</em>
645  */
646  virtual streamsize
647  showmanyc() { return 0; }
648 
649  /**
650  * @brief Multiple character extraction.
651  * @param __s A buffer area.
652  * @param __n Maximum number of characters to assign.
653  * @return The number of characters assigned.
654  *
655  * Fills @a __s[0] through @a __s[__n-1] with characters from the input
656  * sequence, as if by @c sbumpc(). Stops when either @a __n characters
657  * have been copied, or when @c traits::eof() would be copied.
658  *
659  * It is expected that derived classes provide a more efficient
660  * implementation by overriding this definition.
661  */
662  virtual streamsize
663  xsgetn(char_type* __s, streamsize __n);
664 
665  /**
666  * @brief Fetches more data from the controlled sequence.
667  * @return The first character from the <em>pending sequence</em>.
668  *
669  * Informally, this function is called when the input buffer is
670  * exhausted (or does not exist, as buffering need not actually be
671  * done). If a buffer exists, it is @a refilled. In either case, the
672  * next available character is returned, or @c traits::eof() to
673  * indicate a null pending sequence.
674  *
675  * For a formal definition of the pending sequence, see a good text
676  * such as Langer & Kreft, or [27.5.2.4.3]/7-14.
677  *
678  * A functioning input streambuf can be created by overriding only
679  * this function (no buffer area will be used). For an example, see
680  * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25.html
681  *
682  * @note Base class version does nothing, returns eof().
683  */
684  virtual int_type
686  { return traits_type::eof(); }
687 
688  /**
689  * @brief Fetches more data from the controlled sequence.
690  * @return The first character from the <em>pending sequence</em>.
691  *
692  * Informally, this function does the same thing as @c underflow(),
693  * and in fact is required to call that function. It also returns
694  * the new character, like @c underflow() does. However, this
695  * function also moves the read position forward by one.
696  */
697  virtual int_type
698  uflow()
699  {
700  int_type __ret = traits_type::eof();
701  const bool __testeof = traits_type::eq_int_type(this->underflow(),
702  __ret);
703  if (!__testeof)
704  {
705  __ret = traits_type::to_int_type(*this->gptr());
706  this->gbump(1);
707  }
708  return __ret;
709  }
710 
711  // [27.5.2.4.4] putback
712  /**
713  * @brief Tries to back up the input sequence.
714  * @param __c The character to be inserted back into the sequence.
715  * @return eof() on failure, <em>some other value</em> on success
716  * @post The constraints of @c gptr(), @c eback(), and @c pptr()
717  * are the same as for @c underflow().
718  *
719  * @note Base class version does nothing, returns eof().
720  */
721  virtual int_type
722  pbackfail(int_type __c = traits_type::eof())
723  { return traits_type::eof(); }
724 
725  // Put area:
726  /**
727  * @brief Multiple character insertion.
728  * @param __s A buffer area.
729  * @param __n Maximum number of characters to write.
730  * @return The number of characters written.
731  *
732  * Writes @a __s[0] through @a __s[__n-1] to the output sequence, as if
733  * by @c sputc(). Stops when either @a n characters have been
734  * copied, or when @c sputc() would return @c traits::eof().
735  *
736  * It is expected that derived classes provide a more efficient
737  * implementation by overriding this definition.
738  */
739  virtual streamsize
740  xsputn(const char_type* __s, streamsize __n);
741 
742  /**
743  * @brief Consumes data from the buffer; writes to the
744  * controlled sequence.
745  * @param __c An additional character to consume.
746  * @return eof() to indicate failure, something else (usually
747  * @a __c, or not_eof())
748  *
749  * Informally, this function is called when the output buffer
750  * is full (or does not exist, as buffering need not actually
751  * be done). If a buffer exists, it is @a consumed, with
752  * <em>some effect</em> on the controlled sequence.
753  * (Typically, the buffer is written out to the sequence
754  * verbatim.) In either case, the character @a c is also
755  * written out, if @a __c is not @c eof().
756  *
757  * For a formal definition of this function, see a good text
758  * such as Langer & Kreft, or [27.5.2.4.5]/3-7.
759  *
760  * A functioning output streambuf can be created by overriding only
761  * this function (no buffer area will be used).
762  *
763  * @note Base class version does nothing, returns eof().
764  */
765  virtual int_type
766  overflow(int_type __c = traits_type::eof())
767  { return traits_type::eof(); }
768 
769 #if _GLIBCXX_USE_DEPRECATED
770  // Annex D.6
771  public:
772  /**
773  * @brief Tosses a character.
774  *
775  * Advances the read pointer, ignoring the character that would have
776  * been read.
777  *
778  * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html
779  */
780  void
781  stossc()
782  {
783  if (this->gptr() < this->egptr())
784  this->gbump(1);
785  else
786  this->uflow();
787  }
788 #endif
789 
790  // Also used by specializations for char and wchar_t in src.
791  void
792  __safe_gbump(streamsize __n) { _M_in_cur += __n; }
793 
794  void
795  __safe_pbump(streamsize __n) { _M_out_cur += __n; }
796 
797  private:
798  // _GLIBCXX_RESOLVE_LIB_DEFECTS
799  // Side effect of DR 50.
800  basic_streambuf(const __streambuf_type& __sb)
801  : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur),
805  { }
806 
808  operator=(const __streambuf_type&) { return *this; };
809  };
810 
811  // Explicit specialization declarations, defined in src/streambuf.cc.
812  template<>
813  streamsize
814  __copy_streambufs_eof(basic_streambuf<char>* __sbin,
815  basic_streambuf<char>* __sbout, bool& __ineof);
816 #ifdef _GLIBCXX_USE_WCHAR_T
817  template<>
818  streamsize
819  __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin,
820  basic_streambuf<wchar_t>* __sbout, bool& __ineof);
821 #endif
822 
823 _GLIBCXX_END_NAMESPACE_VERSION
824 } // namespace
825 
826 #include <bits/streambuf.tcc>
827 
828 #endif /* _GLIBCXX_STREAMBUF */