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1 424 jeremybenn
// Stream buffer classes -*- C++ -*-
2
 
3
// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
4
// 2006, 2007, 2008, 2009, 2010 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
// .
25
 
26
/** @file 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 
40
#include 
41
#include 
42
#include 
43
#include 
44
#include 
45
 
46
_GLIBCXX_BEGIN_NAMESPACE(std)
47
 
48
  template
49
    streamsize
50
    __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>*,
51
                          basic_streambuf<_CharT, _Traits>*, bool&);
52
 
53
  /**
54
   *  @brief  The actual work of input and output (interface).
55
   *  @ingroup io
56
   *
57
   *  This is a base class.  Derived stream buffers each control a
58
   *  pair of character sequences:  one for input, and one for output.
59
   *
60
   *  Section [27.5.1] of the standard describes the requirements and
61
   *  behavior of stream buffer classes.  That section (three paragraphs)
62
   *  is reproduced here, for simplicity and accuracy.
63
   *
64
   *  -# Stream buffers can impose various constraints on the sequences
65
   *     they control.  Some constraints are:
66
   *     - The controlled input sequence can be not readable.
67
   *     - The controlled output sequence can be not writable.
68
   *     - The controlled sequences can be associated with the contents of
69
   *       other representations for character sequences, such as external
70
   *       files.
71
   *     - The controlled sequences can support operations @e directly to or
72
   *       from associated sequences.
73
   *     - The controlled sequences can impose limitations on how the
74
   *       program can read characters from a sequence, write characters to
75
   *       a sequence, put characters back into an input sequence, or alter
76
   *       the stream position.
77
   *     .
78
   *  -# Each sequence is characterized by three pointers which, if non-null,
79
   *     all point into the same @c charT array object.  The array object
80
   *     represents, at any moment, a (sub)sequence of characters from the
81
   *     sequence.  Operations performed on a sequence alter the values
82
   *     stored in these pointers, perform reads and writes directly to or
83
   *     from associated sequences, and alter the stream position and
84
   *     conversion state as needed to maintain this subsequence relationship.
85
   *     The three pointers are:
86
   *     - the beginning pointer, or lowest element address in the
87
   *       array (called @e xbeg here);
88
   *     - the next pointer, or next element address that is a
89
   *       current candidate for reading or writing (called @e xnext here);
90
   *     - the end pointer, or first element address beyond the
91
   *       end of the array (called @e xend here).
92
   *     .
93
   *  -# The following semantic constraints shall always apply for any set
94
   *     of three pointers for a sequence, using the pointer names given
95
   *     immediately above:
96
   *     - If @e xnext is not a null pointer, then @e xbeg and @e xend shall
97
   *       also be non-null pointers into the same @c charT array, as
98
   *       described above; otherwise, @e xbeg and @e xend shall also be null.
99
   *     - If @e xnext is not a null pointer and @e xnext < @e xend for an
100
   *       output sequence, then a write position is available.
101
   *       In this case, @e *xnext shall be assignable as the next element
102
   *       to write (to put, or to store a character value, into the sequence).
103
   *     - If @e xnext is not a null pointer and @e xbeg < @e xnext for an
104
   *       input sequence, then a putback position is available.
105
   *       In this case, @e xnext[-1] shall have a defined value and is the
106
   *       next (preceding) element to store a character that is put back
107
   *       into the input sequence.
108
   *     - If @e xnext is not a null pointer and @e xnext< @e xend for an
109
   *       input sequence, then a read position is available.
110
   *       In this case, @e *xnext shall have a defined value and is the
111
   *       next element to read (to get, or to obtain a character value,
112
   *       from the sequence).
113
  */
114
  template
115
    class basic_streambuf
116
    {
117
    public:
118
      //@{
119
      /**
120
       *  These are standard types.  They permit a standardized way of
121
       *  referring to names of (or names dependant on) the template
122
       *  parameters, which are specific to the implementation.
123
      */
124
      typedef _CharT                                    char_type;
125
      typedef _Traits                                   traits_type;
126
      typedef typename traits_type::int_type            int_type;
127
      typedef typename traits_type::pos_type            pos_type;
128
      typedef typename traits_type::off_type            off_type;
129
      //@}
130
 
131
      //@{
132
      /// This is a non-standard type.
133
      typedef basic_streambuf   __streambuf_type;
134
      //@}
135
 
136
      friend class basic_ios;
137
      friend class basic_istream;
138
      friend class basic_ostream;
139
      friend class istreambuf_iterator;
140
      friend class ostreambuf_iterator;
141
 
142
      friend streamsize
143
      __copy_streambufs_eof<>(__streambuf_type*, __streambuf_type*, bool&);
144
 
145
      template
146
        friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
147
                                               _CharT2*>::__type
148
        __copy_move_a2(istreambuf_iterator<_CharT2>,
149
                       istreambuf_iterator<_CharT2>, _CharT2*);
150
 
151
      template
152
        friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
153
                                  istreambuf_iterator<_CharT2> >::__type
154
        find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>,
155
             const _CharT2&);
156
 
157
      template
158
        friend basic_istream<_CharT2, _Traits2>&
159
        operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*);
160
 
161
      template
162
        friend basic_istream<_CharT2, _Traits2>&
163
        operator>>(basic_istream<_CharT2, _Traits2>&,
164
                   basic_string<_CharT2, _Traits2, _Alloc>&);
165
 
166
      template
167
        friend basic_istream<_CharT2, _Traits2>&
168
        getline(basic_istream<_CharT2, _Traits2>&,
169
                basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2);
170
 
171
    protected:
172
      //@{
173
      /**
174
       *  This is based on _IO_FILE, just reordered to be more consistent,
175
       *  and is intended to be the most minimal abstraction for an
176
       *  internal buffer.
177
       *  -  get == input == read
178
       *  -  put == output == write
179
      */
180
      char_type*                _M_in_beg;     // Start of get area.
181
      char_type*                _M_in_cur;     // Current read area.
182
      char_type*                _M_in_end;     // End of get area.
183
      char_type*                _M_out_beg;    // Start of put area.
184
      char_type*                _M_out_cur;    // Current put area.
185
      char_type*                _M_out_end;    // End of put area.
186
 
187
      /// Current locale setting.
188
      locale                    _M_buf_locale;
189
 
190
  public:
191
      /// Destructor deallocates no buffer space.
192
      virtual
193
      ~basic_streambuf()
194
      { }
195
 
196
      // [27.5.2.2.1] locales
197
      /**
198
       *  @brief  Entry point for imbue().
199
       *  @param  loc  The new locale.
200
       *  @return  The previous locale.
201
       *
202
       *  Calls the derived imbue(loc).
203
      */
204
      locale
205
      pubimbue(const locale &__loc)
206
      {
207
        locale __tmp(this->getloc());
208
        this->imbue(__loc);
209
        _M_buf_locale = __loc;
210
        return __tmp;
211
      }
212
 
213
      /**
214
       *  @brief  Locale access.
215
       *  @return  The current locale in effect.
216
       *
217
       *  If pubimbue(loc) has been called, then the most recent @c loc
218
       *  is returned.  Otherwise the global locale in effect at the time
219
       *  of construction is returned.
220
      */
221
      locale
222
      getloc() const
223
      { return _M_buf_locale; }
224
 
225
      // [27.5.2.2.2] buffer management and positioning
226
      //@{
227
      /**
228
       *  @brief  Entry points for derived buffer functions.
229
       *
230
       *  The public versions of @c pubfoo dispatch to the protected
231
       *  derived @c foo member functions, passing the arguments (if any)
232
       *  and returning the result unchanged.
233
      */
234
      __streambuf_type*
235
      pubsetbuf(char_type* __s, streamsize __n)
236
      { return this->setbuf(__s, __n); }
237
 
238
      pos_type
239
      pubseekoff(off_type __off, ios_base::seekdir __way,
240
                 ios_base::openmode __mode = ios_base::in | ios_base::out)
241
      { return this->seekoff(__off, __way, __mode); }
242
 
243
      pos_type
244
      pubseekpos(pos_type __sp,
245
                 ios_base::openmode __mode = ios_base::in | ios_base::out)
246
      { return this->seekpos(__sp, __mode); }
247
 
248
      int
249
      pubsync() { return this->sync(); }
250
      //@}
251
 
252
      // [27.5.2.2.3] get area
253
      /**
254
       *  @brief  Looking ahead into the stream.
255
       *  @return  The number of characters available.
256
       *
257
       *  If a read position is available, returns the number of characters
258
       *  available for reading before the buffer must be refilled.
259
       *  Otherwise returns the derived @c showmanyc().
260
      */
261
      streamsize
262
      in_avail()
263
      {
264
        const streamsize __ret = this->egptr() - this->gptr();
265
        return __ret ? __ret : this->showmanyc();
266
      }
267
 
268
      /**
269
       *  @brief  Getting the next character.
270
       *  @return  The next character, or eof.
271
       *
272
       *  Calls @c sbumpc(), and if that function returns
273
       *  @c traits::eof(), so does this function.  Otherwise, @c sgetc().
274
      */
275
      int_type
276
      snextc()
277
      {
278
        int_type __ret = traits_type::eof();
279
        if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(),
280
                                                       __ret), true))
281
          __ret = this->sgetc();
282
        return __ret;
283
      }
284
 
285
      /**
286
       *  @brief  Getting the next character.
287
       *  @return  The next character, or eof.
288
       *
289
       *  If the input read position is available, returns that character
290
       *  and increments the read pointer, otherwise calls and returns
291
       *  @c uflow().
292
      */
293
      int_type
294
      sbumpc()
295
      {
296
        int_type __ret;
297
        if (__builtin_expect(this->gptr() < this->egptr(), true))
298
          {
299
            __ret = traits_type::to_int_type(*this->gptr());
300
            this->gbump(1);
301
          }
302
        else
303
          __ret = this->uflow();
304
        return __ret;
305
      }
306
 
307
      /**
308
       *  @brief  Getting the next character.
309
       *  @return  The next character, or eof.
310
       *
311
       *  If the input read position is available, returns that character,
312
       *  otherwise calls and returns @c underflow().  Does not move the
313
       *  read position after fetching the character.
314
      */
315
      int_type
316
      sgetc()
317
      {
318
        int_type __ret;
319
        if (__builtin_expect(this->gptr() < this->egptr(), true))
320
          __ret = traits_type::to_int_type(*this->gptr());
321
        else
322
          __ret = this->underflow();
323
        return __ret;
324
      }
325
 
326
      /**
327
       *  @brief  Entry point for xsgetn.
328
       *  @param  s  A buffer area.
329
       *  @param  n  A count.
330
       *
331
       *  Returns xsgetn(s,n).  The effect is to fill @a s[0] through
332
       *  @a s[n-1] with characters from the input sequence, if possible.
333
      */
334
      streamsize
335
      sgetn(char_type* __s, streamsize __n)
336
      { return this->xsgetn(__s, __n); }
337
 
338
      // [27.5.2.2.4] putback
339
      /**
340
       *  @brief  Pushing characters back into the input stream.
341
       *  @param  c  The character to push back.
342
       *  @return  The previous character, if possible.
343
       *
344
       *  Similar to sungetc(), but @a c is pushed onto the stream
345
       *  instead of the previous character. If successful,
346
       *  the next character fetched from the input stream will be @a
347
       *  c.
348
      */
349
      int_type
350
      sputbackc(char_type __c)
351
      {
352
        int_type __ret;
353
        const bool __testpos = this->eback() < this->gptr();
354
        if (__builtin_expect(!__testpos ||
355
                             !traits_type::eq(__c, this->gptr()[-1]), false))
356
          __ret = this->pbackfail(traits_type::to_int_type(__c));
357
        else
358
          {
359
            this->gbump(-1);
360
            __ret = traits_type::to_int_type(*this->gptr());
361
          }
362
        return __ret;
363
      }
364
 
365
      /**
366
       *  @brief  Moving backwards in the input stream.
367
       *  @return  The previous character, if possible.
368
       *
369
       *  If a putback position is available, this function decrements
370
       *  the input pointer and returns that character.  Otherwise,
371
       *  calls and returns pbackfail().  The effect is to @a unget
372
       *  the last character @a gotten.
373
      */
374
      int_type
375
      sungetc()
376
      {
377
        int_type __ret;
378
        if (__builtin_expect(this->eback() < this->gptr(), true))
379
          {
380
            this->gbump(-1);
381
            __ret = traits_type::to_int_type(*this->gptr());
382
          }
383
        else
384
          __ret = this->pbackfail();
385
        return __ret;
386
      }
387
 
388
      // [27.5.2.2.5] put area
389
      /**
390
       *  @brief  Entry point for all single-character output functions.
391
       *  @param  c  A character to output.
392
       *  @return  @a c, if possible.
393
       *
394
       *  One of two public output functions.
395
       *
396
       *  If a write position is available for the output sequence (i.e.,
397
       *  the buffer is not full), stores @a c in that position, increments
398
       *  the position, and returns @c traits::to_int_type(c).  If a write
399
       *  position is not available, returns @c overflow(c).
400
      */
401
      int_type
402
      sputc(char_type __c)
403
      {
404
        int_type __ret;
405
        if (__builtin_expect(this->pptr() < this->epptr(), true))
406
          {
407
            *this->pptr() = __c;
408
            this->pbump(1);
409
            __ret = traits_type::to_int_type(__c);
410
          }
411
        else
412
          __ret = this->overflow(traits_type::to_int_type(__c));
413
        return __ret;
414
      }
415
 
416
      /**
417
       *  @brief  Entry point for all single-character output functions.
418
       *  @param  s  A buffer read area.
419
       *  @param  n  A count.
420
       *
421
       *  One of two public output functions.
422
       *
423
       *
424
       *  Returns xsputn(s,n).  The effect is to write @a s[0] through
425
       *  @a s[n-1] to the output sequence, if possible.
426
      */
427
      streamsize
428
      sputn(const char_type* __s, streamsize __n)
429
      { return this->xsputn(__s, __n); }
430
 
431
    protected:
432
      /**
433
       *  @brief  Base constructor.
434
       *
435
       *  Only called from derived constructors, and sets up all the
436
       *  buffer data to zero, including the pointers described in the
437
       *  basic_streambuf class description.  Note that, as a result,
438
       *  - the class starts with no read nor write positions available,
439
       *  - this is not an error
440
      */
441
      basic_streambuf()
442
      : _M_in_beg(0), _M_in_cur(0), _M_in_end(0),
443
      _M_out_beg(0), _M_out_cur(0), _M_out_end(0),
444
      _M_buf_locale(locale())
445
      { }
446
 
447
      // [27.5.2.3.1] get area access
448
      //@{
449
      /**
450
       *  @brief  Access to the get area.
451
       *
452
       *  These functions are only available to other protected functions,
453
       *  including derived classes.
454
       *
455
       *  - eback() returns the beginning pointer for the input sequence
456
       *  - gptr() returns the next pointer for the input sequence
457
       *  - egptr() returns the end pointer for the input sequence
458
      */
459
      char_type*
460
      eback() const { return _M_in_beg; }
461
 
462
      char_type*
463
      gptr()  const { return _M_in_cur;  }
464
 
465
      char_type*
466
      egptr() const { return _M_in_end; }
467
      //@}
468
 
469
      /**
470
       *  @brief  Moving the read position.
471
       *  @param  n  The delta by which to move.
472
       *
473
       *  This just advances the read position without returning any data.
474
      */
475
      void
476
      gbump(int __n) { _M_in_cur += __n; }
477
 
478
      /**
479
       *  @brief  Setting the three read area pointers.
480
       *  @param  gbeg  A pointer.
481
       *  @param  gnext  A pointer.
482
       *  @param  gend  A pointer.
483
       *  @post  @a gbeg == @c eback(), @a gnext == @c gptr(), and
484
       *         @a gend == @c egptr()
485
      */
486
      void
487
      setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
488
      {
489
        _M_in_beg = __gbeg;
490
        _M_in_cur = __gnext;
491
        _M_in_end = __gend;
492
      }
493
 
494
      // [27.5.2.3.2] put area access
495
      //@{
496
      /**
497
       *  @brief  Access to the put area.
498
       *
499
       *  These functions are only available to other protected functions,
500
       *  including derived classes.
501
       *
502
       *  - pbase() returns the beginning pointer for the output sequence
503
       *  - pptr() returns the next pointer for the output sequence
504
       *  - epptr() returns the end pointer for the output sequence
505
      */
506
      char_type*
507
      pbase() const { return _M_out_beg; }
508
 
509
      char_type*
510
      pptr() const { return _M_out_cur; }
511
 
512
      char_type*
513
      epptr() const { return _M_out_end; }
514
      //@}
515
 
516
      /**
517
       *  @brief  Moving the write position.
518
       *  @param  n  The delta by which to move.
519
       *
520
       *  This just advances the write position without returning any data.
521
      */
522
      void
523
      pbump(int __n) { _M_out_cur += __n; }
524
 
525
      /**
526
       *  @brief  Setting the three write area pointers.
527
       *  @param  pbeg  A pointer.
528
       *  @param  pend  A pointer.
529
       *  @post  @a pbeg == @c pbase(), @a pbeg == @c pptr(), and
530
       *         @a pend == @c epptr()
531
      */
532
      void
533
      setp(char_type* __pbeg, char_type* __pend)
534
      {
535
        _M_out_beg = _M_out_cur = __pbeg;
536
        _M_out_end = __pend;
537
      }
538
 
539
      // [27.5.2.4] virtual functions
540
      // [27.5.2.4.1] locales
541
      /**
542
       *  @brief  Changes translations.
543
       *  @param  loc  A new locale.
544
       *
545
       *  Translations done during I/O which depend on the current
546
       *  locale are changed by this call.  The standard adds,
547
       *  Between invocations of this function a class derived
548
       *  from streambuf can safely cache results of calls to locale
549
       *  functions and to members of facets so obtained.
550
       *
551
       *  @note  Base class version does nothing.
552
      */
553
      virtual void
554
      imbue(const locale&)
555
      { }
556
 
557
      // [27.5.2.4.2] buffer management and positioning
558
      /**
559
       *  @brief  Manipulates the buffer.
560
       *
561
       *  Each derived class provides its own appropriate behavior.  See
562
       *  the next-to-last paragraph of
563
       *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html
564
       *  for more on this function.
565
       *
566
       *  @note  Base class version does nothing, returns @c this.
567
      */
568
      virtual basic_streambuf*
569
      setbuf(char_type*, streamsize)
570
      { return this; }
571
 
572
      /**
573
       *  @brief  Alters the stream positions.
574
       *
575
       *  Each derived class provides its own appropriate behavior.
576
       *  @note  Base class version does nothing, returns a @c pos_type
577
       *         that represents an invalid stream position.
578
      */
579
      virtual pos_type
580
      seekoff(off_type, ios_base::seekdir,
581
              ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
582
      { return pos_type(off_type(-1)); }
583
 
584
      /**
585
       *  @brief  Alters the stream positions.
586
       *
587
       *  Each derived class provides its own appropriate behavior.
588
       *  @note  Base class version does nothing, returns a @c pos_type
589
       *         that represents an invalid stream position.
590
      */
591
      virtual pos_type
592
      seekpos(pos_type,
593
              ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
594
      { return pos_type(off_type(-1)); }
595
 
596
      /**
597
       *  @brief  Synchronizes the buffer arrays with the controlled sequences.
598
       *  @return  -1 on failure.
599
       *
600
       *  Each derived class provides its own appropriate behavior,
601
       *  including the definition of @a failure.
602
       *  @note  Base class version does nothing, returns zero.
603
      */
604
      virtual int
605
      sync() { return 0; }
606
 
607
      // [27.5.2.4.3] get area
608
      /**
609
       *  @brief  Investigating the data available.
610
       *  @return  An estimate of the number of characters available in the
611
       *           input sequence, or -1.
612
       *
613
       *  If it returns a positive value, then successive calls to
614
       *  @c underflow() will not return @c traits::eof() until at
615
       *  least that number of characters have been supplied.  If @c
616
       *  showmanyc() returns -1, then calls to @c underflow() or @c
617
       *  uflow() will fail. [27.5.2.4.3]/1
618
       *
619
       *  @note  Base class version does nothing, returns zero.
620
       *  @note  The standard adds that the intention is not only that the
621
       *         calls [to underflow or uflow] will not return @c eof() but
622
       *         that they will return immediately.
623
       *  @note  The standard adds that the morphemes of @c showmanyc are
624
       *         @b es-how-many-see, not @b show-manic.
625
      */
626
      virtual streamsize
627
      showmanyc() { return 0; }
628
 
629
      /**
630
       *  @brief  Multiple character extraction.
631
       *  @param  s  A buffer area.
632
       *  @param  n  Maximum number of characters to assign.
633
       *  @return  The number of characters assigned.
634
       *
635
       *  Fills @a s[0] through @a s[n-1] with characters from the input
636
       *  sequence, as if by @c sbumpc().  Stops when either @a n characters
637
       *  have been copied, or when @c traits::eof() would be copied.
638
       *
639
       *  It is expected that derived classes provide a more efficient
640
       *  implementation by overriding this definition.
641
      */
642
      virtual streamsize
643
      xsgetn(char_type* __s, streamsize __n);
644
 
645
      /**
646
       *  @brief  Fetches more data from the controlled sequence.
647
       *  @return  The first character from the pending sequence.
648
       *
649
       *  Informally, this function is called when the input buffer is
650
       *  exhausted (or does not exist, as buffering need not actually be
651
       *  done).  If a buffer exists, it is @a refilled.  In either case, the
652
       *  next available character is returned, or @c traits::eof() to
653
       *  indicate a null pending sequence.
654
       *
655
       *  For a formal definition of the pending sequence, see a good text
656
       *  such as Langer & Kreft, or [27.5.2.4.3]/7-14.
657
       *
658
       *  A functioning input streambuf can be created by overriding only
659
       *  this function (no buffer area will be used).  For an example, see
660
       *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25.html
661
       *
662
       *  @note  Base class version does nothing, returns eof().
663
      */
664
      virtual int_type
665
      underflow()
666
      { return traits_type::eof(); }
667
 
668
      /**
669
       *  @brief  Fetches more data from the controlled sequence.
670
       *  @return  The first character from the pending sequence.
671
       *
672
       *  Informally, this function does the same thing as @c underflow(),
673
       *  and in fact is required to call that function.  It also returns
674
       *  the new character, like @c underflow() does.  However, this
675
       *  function also moves the read position forward by one.
676
      */
677
      virtual int_type
678
      uflow()
679
      {
680
        int_type __ret = traits_type::eof();
681
        const bool __testeof = traits_type::eq_int_type(this->underflow(),
682
                                                        __ret);
683
        if (!__testeof)
684
          {
685
            __ret = traits_type::to_int_type(*this->gptr());
686
            this->gbump(1);
687
          }
688
        return __ret;
689
      }
690
 
691
      // [27.5.2.4.4] putback
692
      /**
693
       *  @brief  Tries to back up the input sequence.
694
       *  @param  c  The character to be inserted back into the sequence.
695
       *  @return  eof() on failure, some other value on success
696
       *  @post  The constraints of @c gptr(), @c eback(), and @c pptr()
697
       *         are the same as for @c underflow().
698
       *
699
       *  @note  Base class version does nothing, returns eof().
700
      */
701
      virtual int_type
702
      pbackfail(int_type /* __c */  = traits_type::eof())
703
      { return traits_type::eof(); }
704
 
705
      // Put area:
706
      /**
707
       *  @brief  Multiple character insertion.
708
       *  @param  s  A buffer area.
709
       *  @param  n  Maximum number of characters to write.
710
       *  @return  The number of characters written.
711
       *
712
       *  Writes @a s[0] through @a s[n-1] to the output sequence, as if
713
       *  by @c sputc().  Stops when either @a n characters have been
714
       *  copied, or when @c sputc() would return @c traits::eof().
715
       *
716
       *  It is expected that derived classes provide a more efficient
717
       *  implementation by overriding this definition.
718
      */
719
      virtual streamsize
720
      xsputn(const char_type* __s, streamsize __n);
721
 
722
      /**
723
       *  @brief  Consumes data from the buffer; writes to the
724
       *          controlled sequence.
725
       *  @param  c  An additional character to consume.
726
       *  @return  eof() to indicate failure, something else (usually
727
       *           @a c, or not_eof())
728
       *
729
       *  Informally, this function is called when the output buffer
730
       *  is full (or does not exist, as buffering need not actually
731
       *  be done).  If a buffer exists, it is @a consumed, with
732
       *  some effect on the controlled sequence.
733
       *  (Typically, the buffer is written out to the sequence
734
       *  verbatim.)  In either case, the character @a c is also
735
       *  written out, if @a c is not @c eof().
736
       *
737
       *  For a formal definition of this function, see a good text
738
       *  such as Langer & Kreft, or [27.5.2.4.5]/3-7.
739
       *
740
       *  A functioning output streambuf can be created by overriding only
741
       *  this function (no buffer area will be used).
742
       *
743
       *  @note  Base class version does nothing, returns eof().
744
      */
745
      virtual int_type
746
      overflow(int_type /* __c */ = traits_type::eof())
747
      { return traits_type::eof(); }
748
 
749
#if _GLIBCXX_DEPRECATED
750
    // Annex D.6
751
    public:
752
      /**
753
       *  @brief  Tosses a character.
754
       *
755
       *  Advances the read pointer, ignoring the character that would have
756
       *  been read.
757
       *
758
       *  See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html
759
       */
760
      void
761
      stossc()
762
      {
763
        if (this->gptr() < this->egptr())
764
          this->gbump(1);
765
        else
766
          this->uflow();
767
      }
768
#endif
769
 
770
    private:
771
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
772
      // Side effect of DR 50.
773
      basic_streambuf(const __streambuf_type& __sb)
774
      : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur),
775
      _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg),
776
      _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur),
777
      _M_buf_locale(__sb._M_buf_locale)
778
      { }
779
 
780
      __streambuf_type&
781
      operator=(const __streambuf_type&) { return *this; };
782
    };
783
 
784
  // Explicit specialization declarations, defined in src/streambuf.cc.
785
  template<>
786
    streamsize
787
    __copy_streambufs_eof(basic_streambuf* __sbin,
788
                          basic_streambuf* __sbout, bool& __ineof);
789
#ifdef _GLIBCXX_USE_WCHAR_T
790
  template<>
791
    streamsize
792
    __copy_streambufs_eof(basic_streambuf* __sbin,
793
                          basic_streambuf* __sbout, bool& __ineof);
794
#endif
795
 
796
_GLIBCXX_END_NAMESPACE
797
 
798
#ifndef _GLIBCXX_EXPORT_TEMPLATE
799
# include 
800
#endif
801
 
802
#endif /* _GLIBCXX_STREAMBUF */

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