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>
51 : streamsize
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>
117 : class basic_streambuf
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.
135 : typedef basic_streambuf<char_type, traits_type> __streambuf_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>;
141 : friend class istreambuf_iterator<char_type, traits_type>;
142 : friend class ostreambuf_iterator<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,
155 : istreambuf_iterator<_CharT2> >::__type
156 : find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>,
157 : const _CharT2&);
158 :
159 : template<typename _CharT2, typename _Traits2>
160 : friend basic_istream<_CharT2, _Traits2>&
161 : operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*);
162 :
163 : template<typename _CharT2, typename _Traits2, typename _Alloc>
164 : friend basic_istream<_CharT2, _Traits2>&
165 : operator>>(basic_istream<_CharT2, _Traits2>&,
166 : basic_string<_CharT2, _Traits2, _Alloc>&);
167 :
168 : template<typename _CharT2, typename _Traits2, typename _Alloc>
169 : friend basic_istream<_CharT2, _Traits2>&
170 : getline(basic_istream<_CharT2, _Traits2>&,
171 : basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2);
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.
190 : locale _M_buf_locale;
191 :
192 : public:
193 : /// Destructor deallocates no buffer space.
194 : virtual
195 0 : ~basic_streambuf()
196 0 : { }
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 : */
236 : __streambuf_type*
237 : pubsetbuf(char_type* __s, streamsize __n)
238 : { return this->setbuf(__s, __n); }
239 :
240 : pos_type
241 : pubseekoff(off_type __off, ios_base::seekdir __way,
242 : ios_base::openmode __mode = ios_base::in | ios_base::out)
243 : { return this->seekoff(__off, __way, __mode); }
244 :
245 : pos_type
246 : pubseekpos(pos_type __sp,
247 : ios_base::openmode __mode = ios_base::in | ios_base::out)
248 : { return this->seekpos(__sp, __mode); }
249 :
250 : int
251 : pubsync() { return this->sync(); }
252 : //@}
253 :
254 : // [27.5.2.2.3] get area
255 : /**
256 : * @brief Looking ahead into the stream.
257 : * @return The number of characters available.
258 : *
259 : * If a read position is available, returns the number of characters
260 : * available for reading before the buffer must be refilled.
261 : * Otherwise returns the derived @c showmanyc().
262 : */
263 : streamsize
264 : in_avail()
265 : {
266 : const streamsize __ret = this->egptr() - this->gptr();
267 : return __ret ? __ret : this->showmanyc();
268 : }
269 :
270 : /**
271 : * @brief Getting the next character.
272 : * @return The next character, or eof.
273 : *
274 : * Calls @c sbumpc(), and if that function returns
275 : * @c traits::eof(), so does this function. Otherwise, @c sgetc().
276 : */
277 : int_type
278 : snextc()
279 : {
280 : int_type __ret = traits_type::eof();
281 : if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(),
282 : __ret), true))
283 : __ret = this->sgetc();
284 : return __ret;
285 : }
286 :
287 : /**
288 : * @brief Getting the next character.
289 : * @return The next character, or eof.
290 : *
291 : * If the input read position is available, returns that character
292 : * and increments the read pointer, otherwise calls and returns
293 : * @c uflow().
294 : */
295 : int_type
296 : sbumpc()
297 : {
298 : int_type __ret;
299 : if (__builtin_expect(this->gptr() < this->egptr(), true))
300 : {
301 : __ret = traits_type::to_int_type(*this->gptr());
302 : this->gbump(1);
303 : }
304 : else
305 : __ret = this->uflow();
306 : return __ret;
307 : }
308 :
309 : /**
310 : * @brief Getting the next character.
311 : * @return The next character, or eof.
312 : *
313 : * If the input read position is available, returns that character,
314 : * otherwise calls and returns @c underflow(). Does not move the
315 : * read position after fetching the character.
316 : */
317 : int_type
318 : sgetc()
319 : {
320 : int_type __ret;
321 : if (__builtin_expect(this->gptr() < this->egptr(), true))
322 : __ret = traits_type::to_int_type(*this->gptr());
323 : else
324 : __ret = this->underflow();
325 : return __ret;
326 : }
327 :
328 : /**
329 : * @brief Entry point for xsgetn.
330 : * @param s A buffer area.
331 : * @param n A count.
332 : *
333 : * Returns xsgetn(s,n). The effect is to fill @a s[0] through
334 : * @a s[n-1] with characters from the input sequence, if possible.
335 : */
336 : streamsize
337 : sgetn(char_type* __s, streamsize __n)
338 : { return this->xsgetn(__s, __n); }
339 :
340 : // [27.5.2.2.4] putback
341 : /**
342 : * @brief Pushing characters back into the input stream.
343 : * @param c The character to push back.
344 : * @return The previous character, if possible.
345 : *
346 : * Similar to sungetc(), but @a c is pushed onto the stream
347 : * instead of <em>the previous character.</em> If successful,
348 : * the next character fetched from the input stream will be @a
349 : * c.
350 : */
351 : int_type
352 : sputbackc(char_type __c)
353 : {
354 : int_type __ret;
355 : const bool __testpos = this->eback() < this->gptr();
356 : if (__builtin_expect(!__testpos ||
357 : !traits_type::eq(__c, this->gptr()[-1]), false))
358 : __ret = this->pbackfail(traits_type::to_int_type(__c));
359 : else
360 : {
361 : this->gbump(-1);
362 : __ret = traits_type::to_int_type(*this->gptr());
363 : }
364 : return __ret;
365 : }
366 :
367 : /**
368 : * @brief Moving backwards in the input stream.
369 : * @return The previous character, if possible.
370 : *
371 : * If a putback position is available, this function decrements
372 : * the input pointer and returns that character. Otherwise,
373 : * calls and returns pbackfail(). The effect is to @a unget
374 : * the last character @a gotten.
375 : */
376 : int_type
377 : sungetc()
378 : {
379 : int_type __ret;
380 : if (__builtin_expect(this->eback() < this->gptr(), true))
381 : {
382 : this->gbump(-1);
383 : __ret = traits_type::to_int_type(*this->gptr());
384 : }
385 : else
386 : __ret = this->pbackfail();
387 : return __ret;
388 : }
389 :
390 : // [27.5.2.2.5] put area
391 : /**
392 : * @brief Entry point for all single-character output functions.
393 : * @param c A character to output.
394 : * @return @a c, if possible.
395 : *
396 : * One of two public output functions.
397 : *
398 : * If a write position is available for the output sequence (i.e.,
399 : * the buffer is not full), stores @a c in that position, increments
400 : * the position, and returns @c traits::to_int_type(c). If a write
401 : * position is not available, returns @c overflow(c).
402 : */
403 : int_type
404 : sputc(char_type __c)
405 : {
406 : int_type __ret;
407 : if (__builtin_expect(this->pptr() < this->epptr(), true))
408 : {
409 : *this->pptr() = __c;
410 : this->pbump(1);
411 : __ret = traits_type::to_int_type(__c);
412 : }
413 : else
414 : __ret = this->overflow(traits_type::to_int_type(__c));
415 : return __ret;
416 : }
417 :
418 : /**
419 : * @brief Entry point for all single-character output functions.
420 : * @param s A buffer read area.
421 : * @param n A count.
422 : *
423 : * One of two public output functions.
424 : *
425 : *
426 : * Returns xsputn(s,n). The effect is to write @a s[0] through
427 : * @a s[n-1] to the output sequence, if possible.
428 : */
429 : streamsize
430 : sputn(const char_type* __s, streamsize __n)
431 : { return this->xsputn(__s, __n); }
432 :
433 : protected:
434 : /**
435 : * @brief Base constructor.
436 : *
437 : * Only called from derived constructors, and sets up all the
438 : * buffer data to zero, including the pointers described in the
439 : * basic_streambuf class description. Note that, as a result,
440 : * - the class starts with no read nor write positions available,
441 : * - this is not an error
442 : */
443 0 : basic_streambuf()
444 : : _M_in_beg(0), _M_in_cur(0), _M_in_end(0),
445 : _M_out_beg(0), _M_out_cur(0), _M_out_end(0),
446 0 : _M_buf_locale(locale())
447 0 : { }
448 :
449 : // [27.5.2.3.1] get area access
450 : //@{
451 : /**
452 : * @brief Access to the get area.
453 : *
454 : * These functions are only available to other protected functions,
455 : * including derived classes.
456 : *
457 : * - eback() returns the beginning pointer for the input sequence
458 : * - gptr() returns the next pointer for the input sequence
459 : * - egptr() returns the end pointer for the input sequence
460 : */
461 : char_type*
462 : eback() const { return _M_in_beg; }
463 :
464 : char_type*
465 : gptr() const { return _M_in_cur; }
466 :
467 : char_type*
468 0 : egptr() const { return _M_in_end; }
469 : //@}
470 :
471 : /**
472 : * @brief Moving the read position.
473 : * @param n The delta by which to move.
474 : *
475 : * This just advances the read position without returning any data.
476 : */
477 : void
478 : gbump(int __n) { _M_in_cur += __n; }
479 :
480 : /**
481 : * @brief Setting the three read area pointers.
482 : * @param gbeg A pointer.
483 : * @param gnext A pointer.
484 : * @param gend A pointer.
485 : * @post @a gbeg == @c eback(), @a gnext == @c gptr(), and
486 : * @a gend == @c egptr()
487 : */
488 : void
489 : setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
490 : {
491 : _M_in_beg = __gbeg;
492 : _M_in_cur = __gnext;
493 : _M_in_end = __gend;
494 : }
495 :
496 : // [27.5.2.3.2] put area access
497 : //@{
498 : /**
499 : * @brief Access to the put area.
500 : *
501 : * These functions are only available to other protected functions,
502 : * including derived classes.
503 : *
504 : * - pbase() returns the beginning pointer for the output sequence
505 : * - pptr() returns the next pointer for the output sequence
506 : * - epptr() returns the end pointer for the output sequence
507 : */
508 : char_type*
509 0 : pbase() const { return _M_out_beg; }
510 :
511 : char_type*
512 0 : pptr() const { return _M_out_cur; }
513 :
514 : char_type*
515 : epptr() const { return _M_out_end; }
516 : //@}
517 :
518 : /**
519 : * @brief Moving the write position.
520 : * @param n The delta by which to move.
521 : *
522 : * This just advances the write position without returning any data.
523 : */
524 : void
525 : pbump(int __n) { _M_out_cur += __n; }
526 :
527 : /**
528 : * @brief Setting the three write area pointers.
529 : * @param pbeg A pointer.
530 : * @param pend A pointer.
531 : * @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and
532 : * @a pend == @c epptr()
533 : */
534 : void
535 : setp(char_type* __pbeg, char_type* __pend)
536 : {
537 : _M_out_beg = _M_out_cur = __pbeg;
538 : _M_out_end = __pend;
539 : }
540 :
541 : // [27.5.2.4] virtual functions
542 : // [27.5.2.4.1] locales
543 : /**
544 : * @brief Changes translations.
545 : * @param loc A new locale.
546 : *
547 : * Translations done during I/O which depend on the current
548 : * locale are changed by this call. The standard adds,
549 : * <em>Between invocations of this function a class derived
550 : * from streambuf can safely cache results of calls to locale
551 : * functions and to members of facets so obtained.</em>
552 : *
553 : * @note Base class version does nothing.
554 : */
555 : virtual void
556 : imbue(const locale&)
557 : { }
558 :
559 : // [27.5.2.4.2] buffer management and positioning
560 : /**
561 : * @brief Manipulates the buffer.
562 : *
563 : * Each derived class provides its own appropriate behavior. See
564 : * the next-to-last paragraph of
565 : * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html
566 : * for more on this function.
567 : *
568 : * @note Base class version does nothing, returns @c this.
569 : */
570 : virtual basic_streambuf<char_type,_Traits>*
571 : setbuf(char_type*, streamsize)
572 : { return this; }
573 :
574 : /**
575 : * @brief Alters the stream positions.
576 : *
577 : * Each derived class provides its own appropriate behavior.
578 : * @note Base class version does nothing, returns a @c pos_type
579 : * that represents an invalid stream position.
580 : */
581 : virtual pos_type
582 : seekoff(off_type, ios_base::seekdir,
583 : ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
584 : { return pos_type(off_type(-1)); }
585 :
586 : /**
587 : * @brief Alters the stream positions.
588 : *
589 : * Each derived class provides its own appropriate behavior.
590 : * @note Base class version does nothing, returns a @c pos_type
591 : * that represents an invalid stream position.
592 : */
593 : virtual pos_type
594 : seekpos(pos_type,
595 : ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
596 : { return pos_type(off_type(-1)); }
597 :
598 : /**
599 : * @brief Synchronizes the buffer arrays with the controlled sequences.
600 : * @return -1 on failure.
601 : *
602 : * Each derived class provides its own appropriate behavior,
603 : * including the definition of @a failure.
604 : * @note Base class version does nothing, returns zero.
605 : */
606 : virtual int
607 : sync() { return 0; }
608 :
609 : // [27.5.2.4.3] get area
610 : /**
611 : * @brief Investigating the data available.
612 : * @return An estimate of the number of characters available in the
613 : * input sequence, or -1.
614 : *
615 : * <em>If it returns a positive value, then successive calls to
616 : * @c underflow() will not return @c traits::eof() until at
617 : * least that number of characters have been supplied. If @c
618 : * showmanyc() returns -1, then calls to @c underflow() or @c
619 : * uflow() will fail.</em> [27.5.2.4.3]/1
620 : *
621 : * @note Base class version does nothing, returns zero.
622 : * @note The standard adds that <em>the intention is not only that the
623 : * calls [to underflow or uflow] will not return @c eof() but
624 : * that they will return immediately.</em>
625 : * @note The standard adds that <em>the morphemes of @c showmanyc are
626 : * @b es-how-many-see, not @b show-manic.</em>
627 : */
628 : virtual streamsize
629 : showmanyc() { return 0; }
630 :
631 : /**
632 : * @brief Multiple character extraction.
633 : * @param s A buffer area.
634 : * @param n Maximum number of characters to assign.
635 : * @return The number of characters assigned.
636 : *
637 : * Fills @a s[0] through @a s[n-1] with characters from the input
638 : * sequence, as if by @c sbumpc(). Stops when either @a n characters
639 : * have been copied, or when @c traits::eof() would be copied.
640 : *
641 : * It is expected that derived classes provide a more efficient
642 : * implementation by overriding this definition.
643 : */
644 : virtual streamsize
645 : xsgetn(char_type* __s, streamsize __n);
646 :
647 : /**
648 : * @brief Fetches more data from the controlled sequence.
649 : * @return The first character from the <em>pending sequence</em>.
650 : *
651 : * Informally, this function is called when the input buffer is
652 : * exhausted (or does not exist, as buffering need not actually be
653 : * done). If a buffer exists, it is @a refilled. In either case, the
654 : * next available character is returned, or @c traits::eof() to
655 : * indicate a null pending sequence.
656 : *
657 : * For a formal definition of the pending sequence, see a good text
658 : * such as Langer & Kreft, or [27.5.2.4.3]/7-14.
659 : *
660 : * A functioning input streambuf can be created by overriding only
661 : * this function (no buffer area will be used). For an example, see
662 : * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25.html
663 : *
664 : * @note Base class version does nothing, returns eof().
665 : */
666 : virtual int_type
667 : underflow()
668 : { return traits_type::eof(); }
669 :
670 : /**
671 : * @brief Fetches more data from the controlled sequence.
672 : * @return The first character from the <em>pending sequence</em>.
673 : *
674 : * Informally, this function does the same thing as @c underflow(),
675 : * and in fact is required to call that function. It also returns
676 : * the new character, like @c underflow() does. However, this
677 : * function also moves the read position forward by one.
678 : */
679 : virtual int_type
680 : uflow()
681 : {
682 : int_type __ret = traits_type::eof();
683 : const bool __testeof = traits_type::eq_int_type(this->underflow(),
684 : __ret);
685 : if (!__testeof)
686 : {
687 : __ret = traits_type::to_int_type(*this->gptr());
688 : this->gbump(1);
689 : }
690 : return __ret;
691 : }
692 :
693 : // [27.5.2.4.4] putback
694 : /**
695 : * @brief Tries to back up the input sequence.
696 : * @param c The character to be inserted back into the sequence.
697 : * @return eof() on failure, <em>some other value</em> on success
698 : * @post The constraints of @c gptr(), @c eback(), and @c pptr()
699 : * are the same as for @c underflow().
700 : *
701 : * @note Base class version does nothing, returns eof().
702 : */
703 : virtual int_type
704 : pbackfail(int_type /* __c */ = traits_type::eof())
705 : { return traits_type::eof(); }
706 :
707 : // Put area:
708 : /**
709 : * @brief Multiple character insertion.
710 : * @param s A buffer area.
711 : * @param n Maximum number of characters to write.
712 : * @return The number of characters written.
713 : *
714 : * Writes @a s[0] through @a s[n-1] to the output sequence, as if
715 : * by @c sputc(). Stops when either @a n characters have been
716 : * copied, or when @c sputc() would return @c traits::eof().
717 : *
718 : * It is expected that derived classes provide a more efficient
719 : * implementation by overriding this definition.
720 : */
721 : virtual streamsize
722 : xsputn(const char_type* __s, streamsize __n);
723 :
724 : /**
725 : * @brief Consumes data from the buffer; writes to the
726 : * controlled sequence.
727 : * @param c An additional character to consume.
728 : * @return eof() to indicate failure, something else (usually
729 : * @a c, or not_eof())
730 : *
731 : * Informally, this function is called when the output buffer
732 : * is full (or does not exist, as buffering need not actually
733 : * be done). If a buffer exists, it is @a consumed, with
734 : * <em>some effect</em> on the controlled sequence.
735 : * (Typically, the buffer is written out to the sequence
736 : * verbatim.) In either case, the character @a c is also
737 : * written out, if @a c is not @c eof().
738 : *
739 : * For a formal definition of this function, see a good text
740 : * such as Langer & Kreft, or [27.5.2.4.5]/3-7.
741 : *
742 : * A functioning output streambuf can be created by overriding only
743 : * this function (no buffer area will be used).
744 : *
745 : * @note Base class version does nothing, returns eof().
746 : */
747 : virtual int_type
748 : overflow(int_type /* __c */ = traits_type::eof())
749 : { return traits_type::eof(); }
750 :
751 : #if _GLIBCXX_USE_DEPRECATED
752 : // Annex D.6
753 : public:
754 : /**
755 : * @brief Tosses a character.
756 : *
757 : * Advances the read pointer, ignoring the character that would have
758 : * been read.
759 : *
760 : * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html
761 : */
762 : void
763 : stossc()
764 : {
765 : if (this->gptr() < this->egptr())
766 : this->gbump(1);
767 : else
768 : this->uflow();
769 : }
770 : #endif
771 :
772 : // Also used by specializations for char and wchar_t in src.
773 : void
774 : __safe_gbump(streamsize __n) { _M_in_cur += __n; }
775 :
776 : void
777 : __safe_pbump(streamsize __n) { _M_out_cur += __n; }
778 :
779 : private:
780 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
781 : // Side effect of DR 50.
782 : basic_streambuf(const __streambuf_type& __sb)
783 : : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur),
784 : _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg),
785 : _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur),
786 : _M_buf_locale(__sb._M_buf_locale)
787 : { }
788 :
789 : __streambuf_type&
790 : operator=(const __streambuf_type&) { return *this; };
791 : };
792 :
793 : // Explicit specialization declarations, defined in src/streambuf.cc.
794 : template<>
795 : streamsize
796 : __copy_streambufs_eof(basic_streambuf<char>* __sbin,
797 : basic_streambuf<char>* __sbout, bool& __ineof);
798 : #ifdef _GLIBCXX_USE_WCHAR_T
799 : template<>
800 : streamsize
801 : __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin,
802 : basic_streambuf<wchar_t>* __sbout, bool& __ineof);
803 : #endif
804 :
805 : _GLIBCXX_END_NAMESPACE_VERSION
806 : } // namespace
807 :
808 : #include <bits/streambuf.tcc>
809 :
810 : #endif /* _GLIBCXX_STREAMBUF */
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