1 : // 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 : // <http://www.gnu.org/licenses/>.
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 <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 : _GLIBCXX_BEGIN_NAMESPACE(std)
47 :
48 : template<typename _CharT, typename _Traits>
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 <em>the stream position</em> and
84 : * conversion state as needed to maintain this subsequence relationship.
85 : * The three pointers are:
86 : * - the <em>beginning pointer</em>, or lowest element address in the
87 : * array (called @e xbeg here);
88 : * - the <em>next pointer</em>, or next element address that is a
89 : * current candidate for reading or writing (called @e xnext here);
90 : * - the <em>end pointer</em>, 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 <em>write position</em> 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 <em>putback position</em> 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 <em>read position</em> 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<typename _CharT, typename _Traits>
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<char_type, traits_type> __streambuf_type;
134 : //@}
135 :
136 : friend class basic_ios<char_type, traits_type>;
137 : friend class basic_istream<char_type, traits_type>;
138 : friend class basic_ostream<char_type, traits_type>;
139 : friend class istreambuf_iterator<char_type, traits_type>;
140 : friend class ostreambuf_iterator<char_type, traits_type>;
141 :
142 : friend streamsize
143 : __copy_streambufs_eof<>(__streambuf_type*, __streambuf_type*, bool&);
144 :
145 : template<bool _IsMove, typename _CharT2>
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<typename _CharT2>
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<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 : * 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 0 : ~basic_streambuf()
194 0 : { }
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 0 : 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 <em>the previous character.</em> 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 0 : sputc(char_type __c)
403 : {
404 : int_type __ret;
405 0 : if (__builtin_expect(this->pptr() < this->epptr(), true))
406 : {
407 0 : *this->pptr() = __c;
408 0 : this->pbump(1);
409 0 : __ret = traits_type::to_int_type(__c);
410 : }
411 : else
412 0 : __ret = this->overflow(traits_type::to_int_type(__c));
413 0 : 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 0 : sputn(const char_type* __s, streamsize __n)
429 0 : { 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 0 : 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 0 : _M_buf_locale(locale())
445 0 : { }
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 0 : eback() const { return _M_in_beg; }
461 :
462 : char_type*
463 0 : gptr() const { return _M_in_cur; }
464 :
465 : char_type*
466 0 : 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 0 : 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 0 : setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
488 : {
489 0 : _M_in_beg = __gbeg;
490 0 : _M_in_cur = __gnext;
491 0 : _M_in_end = __gend;
492 0 : }
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 0 : pbase() const { return _M_out_beg; }
508 :
509 : char_type*
510 0 : pptr() const { return _M_out_cur; }
511 :
512 : char_type*
513 0 : 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 0 : 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 0 : setp(char_type* __pbeg, char_type* __pend)
534 : {
535 0 : _M_out_beg = _M_out_cur = __pbeg;
536 0 : _M_out_end = __pend;
537 0 : }
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 : * <em>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.</em>
550 : *
551 : * @note Base class version does nothing.
552 : */
553 : virtual void
554 0 : imbue(const locale&)
555 0 : { }
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<char_type,_Traits>*
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 0 : 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 : * <em>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.</em> [27.5.2.4.3]/1
618 : *
619 : * @note Base class version does nothing, returns zero.
620 : * @note The standard adds that <em>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.</em>
623 : * @note The standard adds that <em>the morphemes of @c showmanyc are
624 : * @b es-how-many-see, not @b show-manic.</em>
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 <em>pending sequence</em>.
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 <em>pending sequence</em>.
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 0 : uflow()
679 : {
680 0 : int_type __ret = traits_type::eof();
681 : const bool __testeof = traits_type::eq_int_type(this->underflow(),
682 0 : __ret);
683 0 : if (!__testeof)
684 : {
685 0 : __ret = traits_type::to_int_type(*this->gptr());
686 0 : this->gbump(1);
687 : }
688 0 : 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, <em>some other value</em> 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 : * <em>some effect</em> 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<char>* __sbin,
788 : basic_streambuf<char>* __sbout, bool& __ineof);
789 : #ifdef _GLIBCXX_USE_WCHAR_T
790 : template<>
791 : streamsize
792 : __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin,
793 : basic_streambuf<wchar_t>* __sbout, bool& __ineof);
794 : #endif
795 :
796 : _GLIBCXX_END_NAMESPACE
797 :
798 : #ifndef _GLIBCXX_EXPORT_TEMPLATE
799 : # include <bits/streambuf.tcc>
800 : #endif
801 :
802 : #endif /* _GLIBCXX_STREAMBUF */
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