1 : // Stream buffer classes -*- C++ -*-
2 :
3 : // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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, typename _Alloc>
158 : friend basic_istream<_CharT2, _Traits2>&
159 : getline(basic_istream<_CharT2, _Traits2>&,
160 : basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2);
161 :
162 : protected:
163 : //@{
164 : /**
165 : * @if maint
166 : * This is based on _IO_FILE, just reordered to be more consistent,
167 : * and is intended to be the most minimal abstraction for an
168 : * internal buffer.
169 : * - get == input == read
170 : * - put == output == write
171 : * @endif
172 : */
173 : char_type* _M_in_beg; // Start of get area.
174 : char_type* _M_in_cur; // Current read area.
175 : char_type* _M_in_end; // End of get area.
176 : char_type* _M_out_beg; // Start of put area.
177 : char_type* _M_out_cur; // Current put area.
178 : char_type* _M_out_end; // End of put area.
179 :
180 : /**
181 : * @if maint
182 : * Current locale setting.
183 : * @endif
184 : */
185 : locale _M_buf_locale;
186 :
187 : public:
188 : /// Destructor deallocates no buffer space.
189 : virtual
190 : ~basic_streambuf()
191 37 : { }
192 :
193 : // [27.5.2.2.1] locales
194 : /**
195 : * @brief Entry point for imbue().
196 : * @param loc The new locale.
197 : * @return The previous locale.
198 : *
199 : * Calls the derived imbue(loc).
200 : */
201 : locale
202 : pubimbue(const locale &__loc)
203 : {
204 : locale __tmp(this->getloc());
205 : this->imbue(__loc);
206 : _M_buf_locale = __loc;
207 : return __tmp;
208 : }
209 :
210 : /**
211 : * @brief Locale access.
212 : * @return The current locale in effect.
213 : *
214 : * If pubimbue(loc) has been called, then the most recent @c loc
215 : * is returned. Otherwise the global locale in effect at the time
216 : * of construction is returned.
217 : */
218 : locale
219 : getloc() const
220 : { return _M_buf_locale; }
221 :
222 : // [27.5.2.2.2] buffer management and positioning
223 : //@{
224 : /**
225 : * @brief Entry points for derived buffer functions.
226 : *
227 : * The public versions of @c pubfoo dispatch to the protected
228 : * derived @c foo member functions, passing the arguments (if any)
229 : * and returning the result unchanged.
230 : */
231 : __streambuf_type*
232 : pubsetbuf(char_type* __s, streamsize __n)
233 : { return this->setbuf(__s, __n); }
234 :
235 : pos_type
236 : pubseekoff(off_type __off, ios_base::seekdir __way,
237 : ios_base::openmode __mode = ios_base::in | ios_base::out)
238 : { return this->seekoff(__off, __way, __mode); }
239 :
240 : pos_type
241 : pubseekpos(pos_type __sp,
242 : ios_base::openmode __mode = ios_base::in | ios_base::out)
243 : { return this->seekpos(__sp, __mode); }
244 :
245 : int
246 : pubsync() { return this->sync(); }
247 : //@}
248 :
249 : // [27.5.2.2.3] get area
250 : /**
251 : * @brief Looking ahead into the stream.
252 : * @return The number of characters available.
253 : *
254 : * If a read position is available, returns the number of characters
255 : * available for reading before the buffer must be refilled.
256 : * Otherwise returns the derived @c showmanyc().
257 : */
258 : streamsize
259 : in_avail()
260 : {
261 : const streamsize __ret = this->egptr() - this->gptr();
262 : return __ret ? __ret : this->showmanyc();
263 : }
264 :
265 : /**
266 : * @brief Getting the next character.
267 : * @return The next character, or eof.
268 : *
269 : * Calls @c sbumpc(), and if that function returns
270 : * @c traits::eof(), so does this function. Otherwise, @c sgetc().
271 : */
272 : int_type
273 : snextc()
274 : {
275 : int_type __ret = traits_type::eof();
276 : if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(),
277 : __ret), true))
278 : __ret = this->sgetc();
279 : return __ret;
280 : }
281 :
282 : /**
283 : * @brief Getting the next character.
284 : * @return The next character, or eof.
285 : *
286 : * If the input read position is available, returns that character
287 : * and increments the read pointer, otherwise calls and returns
288 : * @c uflow().
289 : */
290 : int_type
291 : sbumpc()
292 : {
293 : int_type __ret;
294 : if (__builtin_expect(this->gptr() < this->egptr(), true))
295 : {
296 : __ret = traits_type::to_int_type(*this->gptr());
297 : this->gbump(1);
298 : }
299 : else
300 : __ret = this->uflow();
301 : return __ret;
302 : }
303 :
304 : /**
305 : * @brief Getting the next character.
306 : * @return The next character, or eof.
307 : *
308 : * If the input read position is available, returns that character,
309 : * otherwise calls and returns @c underflow(). Does not move the
310 : * read position after fetching the character.
311 : */
312 : int_type
313 : sgetc()
314 : {
315 : int_type __ret;
316 : if (__builtin_expect(this->gptr() < this->egptr(), true))
317 : __ret = traits_type::to_int_type(*this->gptr());
318 : else
319 : __ret = this->underflow();
320 : return __ret;
321 : }
322 :
323 : /**
324 : * @brief Entry point for xsgetn.
325 : * @param s A buffer area.
326 : * @param n A count.
327 : *
328 : * Returns xsgetn(s,n). The effect is to fill @a s[0] through
329 : * @a s[n-1] with characters from the input sequence, if possible.
330 : */
331 : streamsize
332 : sgetn(char_type* __s, streamsize __n)
333 : { return this->xsgetn(__s, __n); }
334 :
335 : // [27.5.2.2.4] putback
336 : /**
337 : * @brief Pushing characters back into the input stream.
338 : * @param c The character to push back.
339 : * @return The previous character, if possible.
340 : *
341 : * Similar to sungetc(), but @a c is pushed onto the stream instead
342 : * of "the previous character". If successful, the next character
343 : * fetched from the input stream will be @a c.
344 : */
345 : int_type
346 : sputbackc(char_type __c)
347 : {
348 : int_type __ret;
349 : const bool __testpos = this->eback() < this->gptr();
350 : if (__builtin_expect(!__testpos ||
351 : !traits_type::eq(__c, this->gptr()[-1]), false))
352 : __ret = this->pbackfail(traits_type::to_int_type(__c));
353 : else
354 : {
355 : this->gbump(-1);
356 : __ret = traits_type::to_int_type(*this->gptr());
357 : }
358 : return __ret;
359 : }
360 :
361 : /**
362 : * @brief Moving backwards in the input stream.
363 : * @return The previous character, if possible.
364 : *
365 : * If a putback position is available, this function decrements the
366 : * input pointer and returns that character. Otherwise, calls and
367 : * returns pbackfail(). The effect is to "unget" the last character
368 : * "gotten".
369 : */
370 : int_type
371 : sungetc()
372 : {
373 : int_type __ret;
374 : if (__builtin_expect(this->eback() < this->gptr(), true))
375 : {
376 : this->gbump(-1);
377 : __ret = traits_type::to_int_type(*this->gptr());
378 : }
379 : else
380 : __ret = this->pbackfail();
381 : return __ret;
382 : }
383 :
384 : // [27.5.2.2.5] put area
385 : /**
386 : * @brief Entry point for all single-character output functions.
387 : * @param c A character to output.
388 : * @return @a c, if possible.
389 : *
390 : * One of two public output functions.
391 : *
392 : * If a write position is available for the output sequence (i.e.,
393 : * the buffer is not full), stores @a c in that position, increments
394 : * the position, and returns @c traits::to_int_type(c). If a write
395 : * position is not available, returns @c overflow(c).
396 : */
397 : int_type
398 : sputc(char_type __c)
399 : {
400 : int_type __ret;
401 : if (__builtin_expect(this->pptr() < this->epptr(), true))
402 : {
403 : *this->pptr() = __c;
404 : this->pbump(1);
405 : __ret = traits_type::to_int_type(__c);
406 : }
407 : else
408 : __ret = this->overflow(traits_type::to_int_type(__c));
409 : return __ret;
410 : }
411 :
412 : /**
413 : * @brief Entry point for all single-character output functions.
414 : * @param s A buffer read area.
415 : * @param n A count.
416 : *
417 : * One of two public output functions.
418 : *
419 : *
420 : * Returns xsputn(s,n). The effect is to write @a s[0] through
421 : * @a s[n-1] to the output sequence, if possible.
422 : */
423 : streamsize
424 : sputn(const char_type* __s, streamsize __n)
425 : { return this->xsputn(__s, __n); }
426 :
427 : protected:
428 : /**
429 : * @brief Base constructor.
430 : *
431 : * Only called from derived constructors, and sets up all the
432 : * buffer data to zero, including the pointers described in the
433 : * basic_streambuf class description. Note that, as a result,
434 : * - the class starts with no read nor write positions available,
435 : * - this is not an error
436 : */
437 : basic_streambuf()
438 : : _M_in_beg(0), _M_in_cur(0), _M_in_end(0),
439 : _M_out_beg(0), _M_out_cur(0), _M_out_end(0),
440 : _M_buf_locale(locale())
441 : { }
442 :
443 : // [27.5.2.3.1] get area access
444 : //@{
445 : /**
446 : * @brief Access to the get area.
447 : *
448 : * These functions are only available to other protected functions,
449 : * including derived classes.
450 : *
451 : * - eback() returns the beginning pointer for the input sequence
452 : * - gptr() returns the next pointer for the input sequence
453 : * - egptr() returns the end pointer for the input sequence
454 : */
455 : char_type*
456 : eback() const { return _M_in_beg; }
457 :
458 : char_type*
459 : gptr() const { return _M_in_cur; }
460 :
461 : char_type*
462 : egptr() const { return _M_in_end; }
463 : //@}
464 :
465 : /**
466 : * @brief Moving the read position.
467 : * @param n The delta by which to move.
468 : *
469 : * This just advances the read position without returning any data.
470 : */
471 : void
472 : gbump(int __n) { _M_in_cur += __n; }
473 :
474 : /**
475 : * @brief Setting the three read area pointers.
476 : * @param gbeg A pointer.
477 : * @param gnext A pointer.
478 : * @param gend A pointer.
479 : * @post @a gbeg == @c eback(), @a gnext == @c gptr(), and
480 : * @a gend == @c egptr()
481 : */
482 : void
483 : setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
484 : {
485 : _M_in_beg = __gbeg;
486 : _M_in_cur = __gnext;
487 : _M_in_end = __gend;
488 : }
489 :
490 : // [27.5.2.3.2] put area access
491 : //@{
492 : /**
493 : * @brief Access to the put area.
494 : *
495 : * These functions are only available to other protected functions,
496 : * including derived classes.
497 : *
498 : * - pbase() returns the beginning pointer for the output sequence
499 : * - pptr() returns the next pointer for the output sequence
500 : * - epptr() returns the end pointer for the output sequence
501 : */
502 : char_type*
503 : pbase() const { return _M_out_beg; }
504 :
505 : char_type*
506 : pptr() const { return _M_out_cur; }
507 :
508 : char_type*
509 : epptr() const { return _M_out_end; }
510 : //@}
511 :
512 : /**
513 : * @brief Moving the write position.
514 : * @param n The delta by which to move.
515 : *
516 : * This just advances the write position without returning any data.
517 : */
518 : void
519 : pbump(int __n) { _M_out_cur += __n; }
520 :
521 : /**
522 : * @brief Setting the three write area pointers.
523 : * @param pbeg A pointer.
524 : * @param pend A pointer.
525 : * @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and
526 : * @a pend == @c epptr()
527 : */
528 : void
529 : setp(char_type* __pbeg, char_type* __pend)
530 : {
531 : _M_out_beg = _M_out_cur = __pbeg;
532 : _M_out_end = __pend;
533 : }
534 :
535 : // [27.5.2.4] virtual functions
536 : // [27.5.2.4.1] locales
537 : /**
538 : * @brief Changes translations.
539 : * @param loc A new locale.
540 : *
541 : * Translations done during I/O which depend on the current locale
542 : * are changed by this call. The standard adds, "Between invocations
543 : * of this function a class derived from streambuf can safely cache
544 : * results of calls to locale functions and to members of facets
545 : * so obtained."
546 : *
547 : * @note Base class version does nothing.
548 : */
549 : virtual void
550 : imbue(const locale&)
551 : { }
552 :
553 : // [27.5.2.4.2] buffer management and positioning
554 : /**
555 : * @brief Maniuplates the buffer.
556 : *
557 : * Each derived class provides its own appropriate behavior. See
558 : * the next-to-last paragraph of
559 : * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for
560 : * more on this function.
561 : *
562 : * @note Base class version does nothing, returns @c this.
563 : */
564 : virtual basic_streambuf<char_type,_Traits>*
565 : setbuf(char_type*, streamsize)
566 : { return this; }
567 :
568 : /**
569 : * @brief Alters the stream positions.
570 : *
571 : * Each derived class provides its own appropriate behavior.
572 : * @note Base class version does nothing, returns a @c pos_type
573 : * that represents an invalid stream position.
574 : */
575 : virtual pos_type
576 : seekoff(off_type, ios_base::seekdir,
577 : ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
578 : { return pos_type(off_type(-1)); }
579 :
580 : /**
581 : * @brief Alters the stream positions.
582 : *
583 : * Each derived class provides its own appropriate behavior.
584 : * @note Base class version does nothing, returns a @c pos_type
585 : * that represents an invalid stream position.
586 : */
587 : virtual pos_type
588 : seekpos(pos_type,
589 : ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
590 : { return pos_type(off_type(-1)); }
591 :
592 : /**
593 : * @brief Synchronizes the buffer arrays with the controlled sequences.
594 : * @return -1 on failure.
595 : *
596 : * Each derived class provides its own appropriate behavior,
597 : * including the definition of "failure".
598 : * @note Base class version does nothing, returns zero.
599 : */
600 : virtual int
601 : sync() { return 0; }
602 :
603 : // [27.5.2.4.3] get area
604 : /**
605 : * @brief Investigating the data available.
606 : * @return An estimate of the number of characters available in the
607 : * input sequence, or -1.
608 : *
609 : * "If it returns a positive value, then successive calls to
610 : * @c underflow() will not return @c traits::eof() until at least that
611 : * number of characters have been supplied. If @c showmanyc()
612 : * returns -1, then calls to @c underflow() or @c uflow() will fail."
613 : * [27.5.2.4.3]/1
614 : *
615 : * @note Base class version does nothing, returns zero.
616 : * @note The standard adds that "the intention is not only that the
617 : * calls [to underflow or uflow] will not return @c eof() but
618 : * that they will return "immediately".
619 : * @note The standard adds that "the morphemes of @c showmanyc are
620 : * "es-how-many-see", not "show-manic".
621 : */
622 : virtual streamsize
623 : showmanyc() { return 0; }
624 :
625 : /**
626 : * @brief Multiple character extraction.
627 : * @param s A buffer area.
628 : * @param n Maximum number of characters to assign.
629 : * @return The number of characters assigned.
630 : *
631 : * Fills @a s[0] through @a s[n-1] with characters from the input
632 : * sequence, as if by @c sbumpc(). Stops when either @a n characters
633 : * have been copied, or when @c traits::eof() would be copied.
634 : *
635 : * It is expected that derived classes provide a more efficient
636 : * implementation by overriding this definition.
637 : */
638 : virtual streamsize
639 : xsgetn(char_type* __s, streamsize __n);
640 :
641 : /**
642 : * @brief Fetches more data from the controlled sequence.
643 : * @return The first character from the <em>pending sequence</em>.
644 : *
645 : * Informally, this function is called when the input buffer is
646 : * exhausted (or does not exist, as buffering need not actually be
647 : * done). If a buffer exists, it is "refilled". In either case, the
648 : * next available character is returned, or @c traits::eof() to
649 : * indicate a null pending sequence.
650 : *
651 : * For a formal definiton of the pending sequence, see a good text
652 : * such as Langer & Kreft, or [27.5.2.4.3]/7-14.
653 : *
654 : * A functioning input streambuf can be created by overriding only
655 : * this function (no buffer area will be used). For an example, see
656 : * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#6
657 : *
658 : * @note Base class version does nothing, returns eof().
659 : */
660 : virtual int_type
661 : underflow()
662 : { return traits_type::eof(); }
663 :
664 : /**
665 : * @brief Fetches more data from the controlled sequence.
666 : * @return The first character from the <em>pending sequence</em>.
667 : *
668 : * Informally, this function does the same thing as @c underflow(),
669 : * and in fact is required to call that function. It also returns
670 : * the new character, like @c underflow() does. However, this
671 : * function also moves the read position forward by one.
672 : */
673 : virtual int_type
674 : uflow()
675 : {
676 : int_type __ret = traits_type::eof();
677 : const bool __testeof = traits_type::eq_int_type(this->underflow(),
678 : __ret);
679 : if (!__testeof)
680 : {
681 : __ret = traits_type::to_int_type(*this->gptr());
682 : this->gbump(1);
683 : }
684 : return __ret;
685 : }
686 :
687 : // [27.5.2.4.4] putback
688 : /**
689 : * @brief Tries to back up the input sequence.
690 : * @param c The character to be inserted back into the sequence.
691 : * @return eof() on failure, "some other value" on success
692 : * @post The constraints of @c gptr(), @c eback(), and @c pptr()
693 : * are the same as for @c underflow().
694 : *
695 : * @note Base class version does nothing, returns eof().
696 : */
697 : virtual int_type
698 : pbackfail(int_type /* __c */ = traits_type::eof())
699 : { return traits_type::eof(); }
700 :
701 : // Put area:
702 : /**
703 : * @brief Multiple character insertion.
704 : * @param s A buffer area.
705 : * @param n Maximum number of characters to write.
706 : * @return The number of characters written.
707 : *
708 : * Writes @a s[0] through @a s[n-1] to the output sequence, as if
709 : * by @c sputc(). Stops when either @a n characters have been
710 : * copied, or when @c sputc() would return @c traits::eof().
711 : *
712 : * It is expected that derived classes provide a more efficient
713 : * implementation by overriding this definition.
714 : */
715 : virtual streamsize
716 : xsputn(const char_type* __s, streamsize __n);
717 :
718 : /**
719 : * @brief Consumes data from the buffer; writes to the
720 : * controlled sequence.
721 : * @param c An additional character to consume.
722 : * @return eof() to indicate failure, something else (usually
723 : * @a c, or not_eof())
724 : *
725 : * Informally, this function is called when the output buffer is full
726 : * (or does not exist, as buffering need not actually be done). If a
727 : * buffer exists, it is "consumed", with "some effect" on the
728 : * controlled sequence. (Typically, the buffer is written out to the
729 : * sequence verbatim.) In either case, the character @a c is also
730 : * written out, if @a c is not @c eof().
731 : *
732 : * For a formal definiton of this function, see a good text
733 : * such as Langer & Kreft, or [27.5.2.4.5]/3-7.
734 : *
735 : * A functioning output streambuf can be created by overriding only
736 : * this function (no buffer area will be used).
737 : *
738 : * @note Base class version does nothing, returns eof().
739 : */
740 : virtual int_type
741 : overflow(int_type /* __c */ = traits_type::eof())
742 : { return traits_type::eof(); }
743 :
744 : #ifdef _GLIBCXX_DEPRECATED
745 : // Annex D.6
746 : public:
747 : /**
748 : * @brief Tosses a character.
749 : *
750 : * Advances the read pointer, ignoring the character that would have
751 : * been read.
752 : *
753 : * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html
754 : *
755 : * @note This function has been deprecated by the standard. You
756 : * must define @c _GLIBCXX_DEPRECATED to make this visible; see
757 : * c++config.h.
758 : */
759 : void
760 : stossc()
761 : {
762 : if (this->gptr() < this->egptr())
763 : this->gbump(1);
764 : else
765 : this->uflow();
766 : }
767 : #endif
768 :
769 : private:
770 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
771 : // Side effect of DR 50.
772 : basic_streambuf(const __streambuf_type& __sb)
773 : : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur),
774 : _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg),
775 : _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur),
776 : _M_buf_locale(__sb._M_buf_locale)
777 : { }
778 :
779 : __streambuf_type&
780 : operator=(const __streambuf_type&) { return *this; };
781 : };
782 :
783 : // Explicit specialization declarations, defined in src/streambuf.cc.
784 : template<>
785 : streamsize
786 : __copy_streambufs(basic_streambuf<char>* __sbin,
787 : basic_streambuf<char>* __sbout);
788 : #ifdef _GLIBCXX_USE_WCHAR_T
789 : template<>
790 : streamsize
791 : __copy_streambufs(basic_streambuf<wchar_t>* __sbin,
792 : basic_streambuf<wchar_t>* __sbout);
793 : #endif
794 : } // namespace std
795 :
796 : #ifndef _GLIBCXX_EXPORT_TEMPLATE
797 : # include <bits/streambuf.tcc>
798 : #endif
799 :
800 : #endif /* _GLIBCXX_STREAMBUF */
|
