1 : // Stream buffer classes -*- C++ -*-
2 :
3 : // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
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: 27.5 Stream buffers
33 : //
34 :
35 : /** @file streambuf
36 : * This is a Standard C++ Library header.
37 : */
38 :
39 : #ifndef _GLIBXX_STREAMBUF
40 : #define _GLIBXX_STREAMBUF 1
41 :
42 : #pragma GCC system_header
43 :
44 : #include <bits/c++config.h>
45 : #include <iosfwd>
46 : #include <bits/localefwd.h>
47 : #include <bits/ios_base.h>
48 :
49 : namespace std
50 : {
51 : /**
52 : * @if maint
53 : * Does stuff.
54 : * @endif
55 : */
56 : template<typename _CharT, typename _Traits>
57 : streamsize
58 : __copy_streambufs(basic_streambuf<_CharT, _Traits>* __sbin,
59 : basic_streambuf<_CharT, _Traits>* __sbout);
60 :
61 : /**
62 : * @brief The actual work of input and output (interface).
63 : *
64 : * This is a base class. Derived stream buffers each control a
65 : * pair of character sequences: one for input, and one for output.
66 : *
67 : * Section [27.5.1] of the standard describes the requirements and
68 : * behavior of stream buffer classes. That section (three paragraphs)
69 : * is reproduced here, for simplicity and accuracy.
70 : *
71 : * -# Stream buffers can impose various constraints on the sequences
72 : * they control. Some constraints are:
73 : * - The controlled input sequence can be not readable.
74 : * - The controlled output sequence can be not writable.
75 : * - The controlled sequences can be associated with the contents of
76 : * other representations for character sequences, such as external
77 : * files.
78 : * - The controlled sequences can support operations @e directly to or
79 : * from associated sequences.
80 : * - The controlled sequences can impose limitations on how the
81 : * program can read characters from a sequence, write characters to
82 : * a sequence, put characters back into an input sequence, or alter
83 : * the stream position.
84 : * .
85 : * -# Each sequence is characterized by three pointers which, if non-null,
86 : * all point into the same @c charT array object. The array object
87 : * represents, at any moment, a (sub)sequence of characters from the
88 : * sequence. Operations performed on a sequence alter the values
89 : * stored in these pointers, perform reads and writes directly to or
90 : * from associated sequences, and alter "the stream position" and
91 : * conversion state as needed to maintain this subsequence relationship.
92 : * The three pointers are:
93 : * - the <em>beginning pointer</em>, or lowest element address in the
94 : * array (called @e xbeg here);
95 : * - the <em>next pointer</em>, or next element address that is a
96 : * current candidate for reading or writing (called @e xnext here);
97 : * - the <em>end pointer</em>, or first element address beyond the
98 : * end of the array (called @e xend here).
99 : * .
100 : * -# The following semantic constraints shall always apply for any set
101 : * of three pointers for a sequence, using the pointer names given
102 : * immediately above:
103 : * - If @e xnext is not a null pointer, then @e xbeg and @e xend shall
104 : * also be non-null pointers into the same @c charT array, as
105 : * described above; otherwise, @e xbeg and @e xend shall also be null.
106 : * - If @e xnext is not a null pointer and @e xnext < @e xend for an
107 : * output sequence, then a <em>write position</em> is available.
108 : * In this case, @e *xnext shall be assignable as the next element
109 : * to write (to put, or to store a character value, into the sequence).
110 : * - If @e xnext is not a null pointer and @e xbeg < @e xnext for an
111 : * input sequence, then a <em>putback position</em> is available.
112 : * In this case, @e xnext[-1] shall have a defined value and is the
113 : * next (preceding) element to store a character that is put back
114 : * into the input sequence.
115 : * - If @e xnext is not a null pointer and @e xnext< @e xend for an
116 : * input sequence, then a <em>read position</em> is available.
117 : * In this case, @e *xnext shall have a defined value and is the
118 : * next element to read (to get, or to obtain a character value,
119 : * from the sequence).
120 : */
121 : template<typename _CharT, typename _Traits>
122 : class basic_streambuf
123 : {
124 : public:
125 : //@{
126 : /**
127 : * These are standard types. They permit a standardized way of
128 : * referring to names of (or names dependant on) the template
129 : * parameters, which are specific to the implementation.
130 : */
131 : typedef _CharT char_type;
132 : typedef _Traits traits_type;
133 : typedef typename traits_type::int_type int_type;
134 : typedef typename traits_type::pos_type pos_type;
135 : typedef typename traits_type::off_type off_type;
136 : //@}
137 :
138 : //@{
139 : /**
140 : * @if maint
141 : * This is a non-standard type.
142 : * @endif
143 : */
144 : typedef basic_streambuf<char_type, traits_type> __streambuf_type;
145 : //@}
146 :
147 : friend class basic_ios<char_type, traits_type>;
148 : friend class basic_istream<char_type, traits_type>;
149 : friend class basic_ostream<char_type, traits_type>;
150 : friend class istreambuf_iterator<char_type, traits_type>;
151 : friend class ostreambuf_iterator<char_type, traits_type>;
152 :
153 : friend streamsize
154 : __copy_streambufs<>(__streambuf_type* __sbin,
155 : __streambuf_type* __sbout);
156 :
157 : template<typename _CharT2, typename _Traits2>
158 : friend basic_istream<_CharT2, _Traits2>&
159 : operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*);
160 :
161 : template<typename _CharT2, typename _Traits2, typename _Alloc>
162 : friend basic_istream<_CharT2, _Traits2>&
163 : operator>>(basic_istream<_CharT2, _Traits2>&,
164 : basic_string<_CharT2, _Traits2, _Alloc>&);
165 :
166 : template<typename _CharT2, typename _Traits2, typename _Alloc>
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 : * @if maint
175 : * This is based on _IO_FILE, just reordered to be more consistent,
176 : * and is intended to be the most minimal abstraction for an
177 : * internal buffer.
178 : * - get == input == read
179 : * - put == output == write
180 : * @endif
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 : /**
190 : * @if maint
191 : * Current locale setting.
192 : * @endif
193 : */
194 : locale _M_buf_locale;
195 :
196 : public:
197 : /// Destructor deallocates no buffer space.
198 : virtual
199 0 : ~basic_streambuf()
200 0 : { }
201 :
202 : // [27.5.2.2.1] locales
203 : /**
204 : * @brief Entry point for imbue().
205 : * @param loc The new locale.
206 : * @return The previous locale.
207 : *
208 : * Calls the derived imbue(loc).
209 : */
210 : locale
211 : pubimbue(const locale &__loc)
212 : {
213 : locale __tmp(this->getloc());
214 : this->imbue(__loc);
215 : _M_buf_locale = __loc;
216 : return __tmp;
217 : }
218 :
219 : /**
220 : * @brief Locale access.
221 : * @return The current locale in effect.
222 : *
223 : * If pubimbue(loc) has been called, then the most recent @c loc
224 : * is returned. Otherwise the global locale in effect at the time
225 : * of construction is returned.
226 : */
227 : locale
228 : getloc() const
229 : { return _M_buf_locale; }
230 :
231 : // [27.5.2.2.2] buffer management and positioning
232 : //@{
233 : /**
234 : * @brief Entry points for derived buffer functions.
235 : *
236 : * The public versions of @c pubfoo dispatch to the protected
237 : * derived @c foo member functions, passing the arguments (if any)
238 : * and returning the result unchanged.
239 : */
240 : __streambuf_type*
241 0 : pubsetbuf(char_type* __s, streamsize __n)
242 0 : { return this->setbuf(__s, __n); }
243 :
244 : pos_type
245 : pubseekoff(off_type __off, ios_base::seekdir __way,
246 : ios_base::openmode __mode = ios_base::in | ios_base::out)
247 : { return this->seekoff(__off, __way, __mode); }
248 :
249 : pos_type
250 : pubseekpos(pos_type __sp,
251 : ios_base::openmode __mode = ios_base::in | ios_base::out)
252 : { return this->seekpos(__sp, __mode); }
253 :
254 : int
255 : pubsync() { return this->sync(); }
256 : //@}
257 :
258 : // [27.5.2.2.3] get area
259 : /**
260 : * @brief Looking ahead into the stream.
261 : * @return The number of characters available.
262 : *
263 : * If a read position is available, returns the number of characters
264 : * available for reading before the buffer must be refilled.
265 : * Otherwise returns the derived @c showmanyc().
266 : */
267 : streamsize
268 : in_avail()
269 : {
270 : const streamsize __ret = this->egptr() - this->gptr();
271 : return __ret ? __ret : this->showmanyc();
272 : }
273 :
274 : /**
275 : * @brief Getting the next character.
276 : * @return The next character, or eof.
277 : *
278 : * Calls @c sbumpc(), and if that function returns
279 : * @c traits::eof(), so does this function. Otherwise, @c sgetc().
280 : */
281 : int_type
282 : snextc()
283 : {
284 : int_type __ret = traits_type::eof();
285 : if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(),
286 : __ret), true))
287 : __ret = this->sgetc();
288 : return __ret;
289 : }
290 :
291 : /**
292 : * @brief Getting the next character.
293 : * @return The next character, or eof.
294 : *
295 : * If the input read position is available, returns that character
296 : * and increments the read pointer, otherwise calls and returns
297 : * @c uflow().
298 : */
299 : int_type
300 : sbumpc()
301 : {
302 : int_type __ret;
303 : if (__builtin_expect(this->gptr() < this->egptr(), true))
304 : {
305 : __ret = traits_type::to_int_type(*this->gptr());
306 : this->gbump(1);
307 : }
308 : else
309 : __ret = this->uflow();
310 : return __ret;
311 : }
312 :
313 : /**
314 : * @brief Getting the next character.
315 : * @return The next character, or eof.
316 : *
317 : * If the input read position is available, returns that character,
318 : * otherwise calls and returns @c underflow(). Does not move the
319 : * read position after fetching the character.
320 : */
321 : int_type
322 : sgetc()
323 : {
324 : int_type __ret;
325 : if (__builtin_expect(this->gptr() < this->egptr(), true))
326 : __ret = traits_type::to_int_type(*this->gptr());
327 : else
328 : __ret = this->underflow();
329 : return __ret;
330 : }
331 :
332 : /**
333 : * @brief Entry point for xsgetn.
334 : * @param s A buffer area.
335 : * @param n A count.
336 : *
337 : * Returns xsgetn(s,n). The effect is to fill @a s[0] through
338 : * @a s[n-1] with characters from the input sequence, if possible.
339 : */
340 : streamsize
341 : sgetn(char_type* __s, streamsize __n)
342 : { return this->xsgetn(__s, __n); }
343 :
344 : // [27.5.2.2.4] putback
345 : /**
346 : * @brief Pushing characters back into the input stream.
347 : * @param c The character to push back.
348 : * @return The previous character, if possible.
349 : *
350 : * Similar to sungetc(), but @a c is pushed onto the stream instead
351 : * of "the previous character". If successful, the next character
352 : * fetched from the input stream will be @a c.
353 : */
354 : int_type
355 : sputbackc(char_type __c)
356 : {
357 : int_type __ret;
358 : const bool __testpos = this->eback() < this->gptr();
359 : if (__builtin_expect(!__testpos ||
360 : !traits_type::eq(__c, this->gptr()[-1]), false))
361 : __ret = this->pbackfail(traits_type::to_int_type(__c));
362 : else
363 : {
364 : this->gbump(-1);
365 : __ret = traits_type::to_int_type(*this->gptr());
366 : }
367 : return __ret;
368 : }
369 :
370 : /**
371 : * @brief Moving backwards in the input stream.
372 : * @return The previous character, if possible.
373 : *
374 : * If a putback position is available, this function decrements the
375 : * input pointer and returns that character. Otherwise, calls and
376 : * returns pbackfail(). The effect is to "unget" the last character
377 : * "gotten".
378 : */
379 : int_type
380 : sungetc()
381 : {
382 : int_type __ret;
383 : if (__builtin_expect(this->eback() < this->gptr(), true))
384 : {
385 : this->gbump(-1);
386 : __ret = traits_type::to_int_type(*this->gptr());
387 : }
388 : else
389 : __ret = this->pbackfail();
390 : return __ret;
391 : }
392 :
393 : // [27.5.2.2.5] put area
394 : /**
395 : * @brief Entry point for all single-character output functions.
396 : * @param c A character to output.
397 : * @return @a c, if possible.
398 : *
399 : * One of two public output functions.
400 : *
401 : * If a write position is available for the output sequence (i.e.,
402 : * the buffer is not full), stores @a c in that position, increments
403 : * the position, and returns @c traits::to_int_type(c). If a write
404 : * position is not available, returns @c overflow(c).
405 : */
406 : int_type
407 : sputc(char_type __c)
408 : {
409 : int_type __ret;
410 : if (__builtin_expect(this->pptr() < this->epptr(), true))
411 : {
412 : *this->pptr() = __c;
413 : this->pbump(1);
414 : __ret = traits_type::to_int_type(__c);
415 : }
416 : else
417 : __ret = this->overflow(traits_type::to_int_type(__c));
418 : return __ret;
419 : }
420 :
421 : /**
422 : * @brief Entry point for all single-character output functions.
423 : * @param s A buffer read area.
424 : * @param n A count.
425 : *
426 : * One of two public output functions.
427 : *
428 : *
429 : * Returns xsputn(s,n). The effect is to write @a s[0] through
430 : * @a s[n-1] to the output sequence, if possible.
431 : */
432 : streamsize
433 : sputn(const char_type* __s, streamsize __n)
434 : { return this->xsputn(__s, __n); }
435 :
436 : protected:
437 : /**
438 : * @brief Base constructor.
439 : *
440 : * Only called from derived constructors, and sets up all the
441 : * buffer data to zero, including the pointers described in the
442 : * basic_streambuf class description. Note that, as a result,
443 : * - the class starts with no read nor write positions available,
444 : * - this is not an error
445 : */
446 0 : basic_streambuf()
447 : : _M_in_beg(0), _M_in_cur(0), _M_in_end(0),
448 : _M_out_beg(0), _M_out_cur(0), _M_out_end(0),
449 0 : _M_buf_locale(locale())
450 0 : { }
451 :
452 : // [27.5.2.3.1] get area access
453 : //@{
454 : /**
455 : * @brief Access to the get area.
456 : *
457 : * These functions are only available to other protected functions,
458 : * including derived classes.
459 : *
460 : * - eback() returns the beginning pointer for the input sequence
461 : * - gptr() returns the next pointer for the input sequence
462 : * - egptr() returns the end pointer for the input sequence
463 : */
464 : char_type*
465 : eback() const { return _M_in_beg; }
466 :
467 : char_type*
468 : gptr() const { return _M_in_cur; }
469 :
470 : char_type*
471 0 : egptr() const { return _M_in_end; }
472 : //@}
473 :
474 : /**
475 : * @brief Moving the read position.
476 : * @param n The delta by which to move.
477 : *
478 : * This just advances the read position without returning any data.
479 : */
480 : void
481 : gbump(int __n) { _M_in_cur += __n; }
482 :
483 : /**
484 : * @brief Setting the three read area pointers.
485 : * @param gbeg A pointer.
486 : * @param gnext A pointer.
487 : * @param gend A pointer.
488 : * @post @a gbeg == @c eback(), @a gnext == @c gptr(), and
489 : * @a gend == @c egptr()
490 : */
491 : void
492 : setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
493 : {
494 : _M_in_beg = __gbeg;
495 : _M_in_cur = __gnext;
496 : _M_in_end = __gend;
497 : }
498 :
499 : // [27.5.2.3.2] put area access
500 : //@{
501 : /**
502 : * @brief Access to the put area.
503 : *
504 : * These functions are only available to other protected functions,
505 : * including derived classes.
506 : *
507 : * - pbase() returns the beginning pointer for the output sequence
508 : * - pptr() returns the next pointer for the output sequence
509 : * - epptr() returns the end pointer for the output sequence
510 : */
511 : char_type*
512 0 : pbase() const { return _M_out_beg; }
513 :
514 : char_type*
515 0 : pptr() const { return _M_out_cur; }
516 :
517 : char_type*
518 : epptr() const { return _M_out_end; }
519 : //@}
520 :
521 : /**
522 : * @brief Moving the write position.
523 : * @param n The delta by which to move.
524 : *
525 : * This just advances the write position without returning any data.
526 : */
527 : void
528 : pbump(int __n) { _M_out_cur += __n; }
529 :
530 : /**
531 : * @brief Setting the three write area pointers.
532 : * @param pbeg A pointer.
533 : * @param pend A pointer.
534 : * @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and
535 : * @a pend == @c epptr()
536 : */
537 : void
538 : setp(char_type* __pbeg, char_type* __pend)
539 : {
540 : _M_out_beg = _M_out_cur = __pbeg;
541 : _M_out_end = __pend;
542 : }
543 :
544 : // [27.5.2.4] virtual functions
545 : // [27.5.2.4.1] locales
546 : /**
547 : * @brief Changes translations.
548 : * @param loc A new locale.
549 : *
550 : * Translations done during I/O which depend on the current locale
551 : * are changed by this call. The standard adds, "Between invocations
552 : * of this function a class derived from streambuf can safely cache
553 : * results of calls to locale functions and to members of facets
554 : * so obtained."
555 : *
556 : * @note Base class version does nothing.
557 : */
558 : virtual void
559 : imbue(const locale&)
560 : { }
561 :
562 : // [27.5.2.4.2] buffer management and positioning
563 : /**
564 : * @brief Maniuplates the buffer.
565 : *
566 : * Each derived class provides its own appropriate behavior. See
567 : * the next-to-last paragraph of
568 : * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for
569 : * more on this function.
570 : *
571 : * @note Base class version does nothing, returns @c this.
572 : */
573 : virtual basic_streambuf<char_type,_Traits>*
574 : setbuf(char_type*, streamsize)
575 : { return this; }
576 :
577 : /**
578 : * @brief Alters the stream positions.
579 : *
580 : * Each derived class provides its own appropriate behavior.
581 : * @note Base class version does nothing, returns a @c pos_type
582 : * that represents an invalid stream position.
583 : */
584 : virtual pos_type
585 : seekoff(off_type, ios_base::seekdir,
586 : ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
587 : { return pos_type(off_type(-1)); }
588 :
589 : /**
590 : * @brief Alters the stream positions.
591 : *
592 : * Each derived class provides its own appropriate behavior.
593 : * @note Base class version does nothing, returns a @c pos_type
594 : * that represents an invalid stream position.
595 : */
596 : virtual pos_type
597 : seekpos(pos_type,
598 : ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
599 : { return pos_type(off_type(-1)); }
600 :
601 : /**
602 : * @brief Synchronizes the buffer arrays with the controlled sequences.
603 : * @return -1 on failure.
604 : *
605 : * Each derived class provides its own appropriate behavior,
606 : * including the definition of "failure".
607 : * @note Base class version does nothing, returns zero.
608 : */
609 : virtual int
610 : sync() { return 0; }
611 :
612 : // [27.5.2.4.3] get area
613 : /**
614 : * @brief Investigating the data available.
615 : * @return An estimate of the number of characters available in the
616 : * input sequence, or -1.
617 : *
618 : * "If it returns a positive value, then successive calls to
619 : * @c underflow() will not return @c traits::eof() until at least that
620 : * number of characters have been supplied. If @c showmanyc()
621 : * returns -1, then calls to @c underflow() or @c uflow() will fail."
622 : * [27.5.2.4.3]/1
623 : *
624 : * @note Base class version does nothing, returns zero.
625 : * @note The standard adds that "the intention is not only that the
626 : * calls [to underflow or uflow] will not return @c eof() but
627 : * that they will return "immediately".
628 : * @note The standard adds that "the morphemes of @c showmanyc are
629 : * "es-how-many-see", not "show-manic".
630 : */
631 : virtual streamsize
632 : showmanyc() { return 0; }
633 :
634 : /**
635 : * @brief Multiple character extraction.
636 : * @param s A buffer area.
637 : * @param n Maximum number of characters to assign.
638 : * @return The number of characters assigned.
639 : *
640 : * Fills @a s[0] through @a s[n-1] with characters from the input
641 : * sequence, as if by @c sbumpc(). Stops when either @a n characters
642 : * have been copied, or when @c traits::eof() would be copied.
643 : *
644 : * It is expected that derived classes provide a more efficient
645 : * implementation by overriding this definition.
646 : */
647 : virtual streamsize
648 : xsgetn(char_type* __s, streamsize __n);
649 :
650 : /**
651 : * @brief Fetches more data from the controlled sequence.
652 : * @return The first character from the <em>pending sequence</em>.
653 : *
654 : * Informally, this function is called when the input buffer is
655 : * exhausted (or does not exist, as buffering need not actually be
656 : * done). If a buffer exists, it is "refilled". In either case, the
657 : * next available character is returned, or @c traits::eof() to
658 : * indicate a null pending sequence.
659 : *
660 : * For a formal definiton of the pending sequence, see a good text
661 : * such as Langer & Kreft, or [27.5.2.4.3]/7-14.
662 : *
663 : * A functioning input streambuf can be created by overriding only
664 : * this function (no buffer area will be used). For an example, see
665 : * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#6
666 : *
667 : * @note Base class version does nothing, returns eof().
668 : */
669 : virtual int_type
670 : underflow()
671 : { return traits_type::eof(); }
672 :
673 : /**
674 : * @brief Fetches more data from the controlled sequence.
675 : * @return The first character from the <em>pending sequence</em>.
676 : *
677 : * Informally, this function does the same thing as @c underflow(),
678 : * and in fact is required to call that function. It also returns
679 : * the new character, like @c underflow() does. However, this
680 : * function also moves the read position forward by one.
681 : */
682 : virtual int_type
683 : uflow()
684 : {
685 : int_type __ret = traits_type::eof();
686 : const bool __testeof = traits_type::eq_int_type(this->underflow(),
687 : __ret);
688 : if (!__testeof)
689 : {
690 : __ret = traits_type::to_int_type(*this->gptr());
691 : this->gbump(1);
692 : }
693 : return __ret;
694 : }
695 :
696 : // [27.5.2.4.4] putback
697 : /**
698 : * @brief Tries to back up the input sequence.
699 : * @param c The character to be inserted back into the sequence.
700 : * @return eof() on failure, "some other value" on success
701 : * @post The constraints of @c gptr(), @c eback(), and @c pptr()
702 : * are the same as for @c underflow().
703 : *
704 : * @note Base class version does nothing, returns eof().
705 : */
706 : virtual int_type
707 : pbackfail(int_type /* __c */ = traits_type::eof())
708 : { return traits_type::eof(); }
709 :
710 : // Put area:
711 : /**
712 : * @brief Multiple character insertion.
713 : * @param s A buffer area.
714 : * @param n Maximum number of characters to write.
715 : * @return The number of characters written.
716 : *
717 : * Writes @a s[0] through @a s[n-1] to the output sequence, as if
718 : * by @c sputc(). Stops when either @a n characters have been
719 : * copied, or when @c sputc() would return @c traits::eof().
720 : *
721 : * It is expected that derived classes provide a more efficient
722 : * implementation by overriding this definition.
723 : */
724 : virtual streamsize
725 : xsputn(const char_type* __s, streamsize __n);
726 :
727 : /**
728 : * @brief Consumes data from the buffer; writes to the
729 : * controlled sequence.
730 : * @param c An additional character to consume.
731 : * @return eof() to indicate failure, something else (usually
732 : * @a c, or not_eof())
733 : *
734 : * Informally, this function is called when the output buffer is full
735 : * (or does not exist, as buffering need not actually be done). If a
736 : * buffer exists, it is "consumed", with "some effect" on the
737 : * controlled sequence. (Typically, the buffer is written out to the
738 : * sequence verbatim.) In either case, the character @a c is also
739 : * written out, if @a c is not @c eof().
740 : *
741 : * For a formal definiton of this function, see a good text
742 : * such as Langer & Kreft, or [27.5.2.4.5]/3-7.
743 : *
744 : * A functioning output streambuf can be created by overriding only
745 : * this function (no buffer area will be used).
746 : *
747 : * @note Base class version does nothing, returns eof().
748 : */
749 : virtual int_type
750 : overflow(int_type /* __c */ = traits_type::eof())
751 : { return traits_type::eof(); }
752 :
753 : #ifdef _GLIBCXX_DEPRECATED
754 : // Annex D.6
755 : public:
756 : /**
757 : * @brief Tosses a character.
758 : *
759 : * Advances the read pointer, ignoring the character that would have
760 : * been read.
761 : *
762 : * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html
763 : *
764 : * @note This function has been deprecated by the standard. You
765 : * must define @c _GLIBCXX_DEPRECATED to make this visible; see
766 : * c++config.h.
767 : */
768 : void
769 : stossc()
770 : {
771 : if (this->gptr() < this->egptr())
772 : this->gbump(1);
773 : else
774 : this->uflow();
775 : }
776 : #endif
777 :
778 : private:
779 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
780 : // Side effect of DR 50.
781 : basic_streambuf(const __streambuf_type& __sb)
782 : : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur),
783 : _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg),
784 : _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur),
785 : _M_buf_locale(__sb._M_buf_locale)
786 : { }
787 :
788 : __streambuf_type&
789 : operator=(const __streambuf_type&) { return *this; };
790 : };
791 :
792 : // Explicit specialization declarations, defined in src/streambuf.cc.
793 : template<>
794 : streamsize
795 : __copy_streambufs(basic_streambuf<char>* __sbin,
796 : basic_streambuf<char>* __sbout);
797 : #ifdef _GLIBCXX_USE_WCHAR_T
798 : template<>
799 : streamsize
800 : __copy_streambufs(basic_streambuf<wchar_t>* __sbin,
801 : basic_streambuf<wchar_t>* __sbout);
802 : #endif
803 : } // namespace std
804 :
805 : #ifndef _GLIBCXX_EXPORT_TEMPLATE
806 : # include <bits/streambuf.tcc>
807 : #endif
808 :
809 : #endif /* _GLIBCXX_STREAMBUF */
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