00001 // Stream buffer classes -*- C++ -*- 00002 00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 00004 // Free Software Foundation, Inc. 00005 // 00006 // This file is part of the GNU ISO C++ Library. This library is free 00007 // software; you can redistribute it and/or modify it under the 00008 // terms of the GNU General Public License as published by the 00009 // Free Software Foundation; either version 2, or (at your option) 00010 // any later version. 00011 00012 // This library is distributed in the hope that it will be useful, 00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 // GNU General Public License for more details. 00016 00017 // You should have received a copy of the GNU General Public License along 00018 // with this library; see the file COPYING. If not, write to the Free 00019 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 00020 // USA. 00021 00022 // As a special exception, you may use this file as part of a free software 00023 // library without restriction. Specifically, if other files instantiate 00024 // templates or use macros or inline functions from this file, or you compile 00025 // this file and link it with other files to produce an executable, this 00026 // file does not by itself cause the resulting executable to be covered by 00027 // the GNU General Public License. This exception does not however 00028 // invalidate any other reasons why the executable file might be covered by 00029 // the GNU General Public License. 00030 00031 // 00032 // ISO C++ 14882: 27.5 Stream buffers 00033 // 00034 00035 /** @file streambuf 00036 * This is a Standard C++ Library header. 00037 */ 00038 00039 #ifndef _GLIBXX_STREAMBUF 00040 #define _GLIBXX_STREAMBUF 1 00041 00042 #pragma GCC system_header 00043 00044 #include <bits/c++config.h> 00045 #include <iosfwd> 00046 #include <bits/localefwd.h> 00047 #include <bits/ios_base.h> 00048 00049 namespace std 00050 { 00051 /** 00052 * @if maint 00053 * Does stuff. 00054 * @endif 00055 */ 00056 template<typename _CharT, typename _Traits> 00057 streamsize 00058 __copy_streambufs(basic_streambuf<_CharT, _Traits>* __sbin, 00059 basic_streambuf<_CharT, _Traits>* __sbout); 00060 00061 /** 00062 * @brief The actual work of input and output (interface). 00063 * 00064 * This is a base class. Derived stream buffers each control a 00065 * pair of character sequences: one for input, and one for output. 00066 * 00067 * Section [27.5.1] of the standard describes the requirements and 00068 * behavior of stream buffer classes. That section (three paragraphs) 00069 * is reproduced here, for simplicity and accuracy. 00070 * 00071 * -# Stream buffers can impose various constraints on the sequences 00072 * they control. Some constraints are: 00073 * - The controlled input sequence can be not readable. 00074 * - The controlled output sequence can be not writable. 00075 * - The controlled sequences can be associated with the contents of 00076 * other representations for character sequences, such as external 00077 * files. 00078 * - The controlled sequences can support operations @e directly to or 00079 * from associated sequences. 00080 * - The controlled sequences can impose limitations on how the 00081 * program can read characters from a sequence, write characters to 00082 * a sequence, put characters back into an input sequence, or alter 00083 * the stream position. 00084 * . 00085 * -# Each sequence is characterized by three pointers which, if non-null, 00086 * all point into the same @c charT array object. The array object 00087 * represents, at any moment, a (sub)sequence of characters from the 00088 * sequence. Operations performed on a sequence alter the values 00089 * stored in these pointers, perform reads and writes directly to or 00090 * from associated sequences, and alter "the stream position" and 00091 * conversion state as needed to maintain this subsequence relationship. 00092 * The three pointers are: 00093 * - the <em>beginning pointer</em>, or lowest element address in the 00094 * array (called @e xbeg here); 00095 * - the <em>next pointer</em>, or next element address that is a 00096 * current candidate for reading or writing (called @e xnext here); 00097 * - the <em>end pointer</em>, or first element address beyond the 00098 * end of the array (called @e xend here). 00099 * . 00100 * -# The following semantic constraints shall always apply for any set 00101 * of three pointers for a sequence, using the pointer names given 00102 * immediately above: 00103 * - If @e xnext is not a null pointer, then @e xbeg and @e xend shall 00104 * also be non-null pointers into the same @c charT array, as 00105 * described above; otherwise, @e xbeg and @e xend shall also be null. 00106 * - If @e xnext is not a null pointer and @e xnext < @e xend for an 00107 * output sequence, then a <em>write position</em> is available. 00108 * In this case, @e *xnext shall be assignable as the next element 00109 * to write (to put, or to store a character value, into the sequence). 00110 * - If @e xnext is not a null pointer and @e xbeg < @e xnext for an 00111 * input sequence, then a <em>putback position</em> is available. 00112 * In this case, @e xnext[-1] shall have a defined value and is the 00113 * next (preceding) element to store a character that is put back 00114 * into the input sequence. 00115 * - If @e xnext is not a null pointer and @e xnext< @e xend for an 00116 * input sequence, then a <em>read position</em> is available. 00117 * In this case, @e *xnext shall have a defined value and is the 00118 * next element to read (to get, or to obtain a character value, 00119 * from the sequence). 00120 */ 00121 template<typename _CharT, typename _Traits> 00122 class basic_streambuf 00123 { 00124 public: 00125 //@{ 00126 /** 00127 * These are standard types. They permit a standardized way of 00128 * referring to names of (or names dependant on) the template 00129 * parameters, which are specific to the implementation. 00130 */ 00131 typedef _CharT char_type; 00132 typedef _Traits traits_type; 00133 typedef typename traits_type::int_type int_type; 00134 typedef typename traits_type::pos_type pos_type; 00135 typedef typename traits_type::off_type off_type; 00136 //@} 00137 00138 //@{ 00139 /** 00140 * @if maint 00141 * This is a non-standard type. 00142 * @endif 00143 */ 00144 typedef basic_streambuf<char_type, traits_type> __streambuf_type; 00145 //@} 00146 00147 friend class basic_ios<char_type, traits_type>; 00148 friend class basic_istream<char_type, traits_type>; 00149 friend class basic_ostream<char_type, traits_type>; 00150 friend class istreambuf_iterator<char_type, traits_type>; 00151 friend class ostreambuf_iterator<char_type, traits_type>; 00152 00153 friend streamsize 00154 __copy_streambufs<>(__streambuf_type* __sbin, 00155 __streambuf_type* __sbout); 00156 00157 template<typename _CharT2, typename _Traits2> 00158 friend basic_istream<_CharT2, _Traits2>& 00159 operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*); 00160 00161 template<typename _CharT2, typename _Traits2, typename _Alloc> 00162 friend basic_istream<_CharT2, _Traits2>& 00163 operator>>(basic_istream<_CharT2, _Traits2>&, 00164 basic_string<_CharT2, _Traits2, _Alloc>&); 00165 00166 template<typename _CharT2, typename _Traits2, typename _Alloc> 00167 friend basic_istream<_CharT2, _Traits2>& 00168 getline(basic_istream<_CharT2, _Traits2>&, 00169 basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2); 00170 00171 protected: 00172 //@{ 00173 /** 00174 * @if maint 00175 * This is based on _IO_FILE, just reordered to be more consistent, 00176 * and is intended to be the most minimal abstraction for an 00177 * internal buffer. 00178 * - get == input == read 00179 * - put == output == write 00180 * @endif 00181 */ 00182 char_type* _M_in_beg; // Start of get area. 00183 char_type* _M_in_cur; // Current read area. 00184 char_type* _M_in_end; // End of get area. 00185 char_type* _M_out_beg; // Start of put area. 00186 char_type* _M_out_cur; // Current put area. 00187 char_type* _M_out_end; // End of put area. 00188 00189 /** 00190 * @if maint 00191 * Current locale setting. 00192 * @endif 00193 */ 00194 locale _M_buf_locale; 00195 00196 public: 00197 /// Destructor deallocates no buffer space. 00198 virtual 00199 ~basic_streambuf() 00200 { } 00201 00202 // [27.5.2.2.1] locales 00203 /** 00204 * @brief Entry point for imbue(). 00205 * @param loc The new locale. 00206 * @return The previous locale. 00207 * 00208 * Calls the derived imbue(loc). 00209 */ 00210 locale 00211 pubimbue(const locale &__loc) 00212 { 00213 locale __tmp(this->getloc()); 00214 this->imbue(__loc); 00215 _M_buf_locale = __loc; 00216 return __tmp; 00217 } 00218 00219 /** 00220 * @brief Locale access. 00221 * @return The current locale in effect. 00222 * 00223 * If pubimbue(loc) has been called, then the most recent @c loc 00224 * is returned. Otherwise the global locale in effect at the time 00225 * of construction is returned. 00226 */ 00227 locale 00228 getloc() const 00229 { return _M_buf_locale; } 00230 00231 // [27.5.2.2.2] buffer management and positioning 00232 //@{ 00233 /** 00234 * @brief Entry points for derived buffer functions. 00235 * 00236 * The public versions of @c pubfoo dispatch to the protected 00237 * derived @c foo member functions, passing the arguments (if any) 00238 * and returning the result unchanged. 00239 */ 00240 __streambuf_type* 00241 pubsetbuf(char_type* __s, streamsize __n) 00242 { return this->setbuf(__s, __n); } 00243 00244 pos_type 00245 pubseekoff(off_type __off, ios_base::seekdir __way, 00246 ios_base::openmode __mode = ios_base::in | ios_base::out) 00247 { return this->seekoff(__off, __way, __mode); } 00248 00249 pos_type 00250 pubseekpos(pos_type __sp, 00251 ios_base::openmode __mode = ios_base::in | ios_base::out) 00252 { return this->seekpos(__sp, __mode); } 00253 00254 int 00255 pubsync() { return this->sync(); } 00256 //@} 00257 00258 // [27.5.2.2.3] get area 00259 /** 00260 * @brief Looking ahead into the stream. 00261 * @return The number of characters available. 00262 * 00263 * If a read position is available, returns the number of characters 00264 * available for reading before the buffer must be refilled. 00265 * Otherwise returns the derived @c showmanyc(). 00266 */ 00267 streamsize 00268 in_avail() 00269 { 00270 const streamsize __ret = this->egptr() - this->gptr(); 00271 return __ret ? __ret : this->showmanyc(); 00272 } 00273 00274 /** 00275 * @brief Getting the next character. 00276 * @return The next character, or eof. 00277 * 00278 * Calls @c sbumpc(), and if that function returns 00279 * @c traits::eof(), so does this function. Otherwise, @c sgetc(). 00280 */ 00281 int_type 00282 snextc() 00283 { 00284 int_type __ret = traits_type::eof(); 00285 if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), 00286 __ret), true)) 00287 __ret = this->sgetc(); 00288 return __ret; 00289 } 00290 00291 /** 00292 * @brief Getting the next character. 00293 * @return The next character, or eof. 00294 * 00295 * If the input read position is available, returns that character 00296 * and increments the read pointer, otherwise calls and returns 00297 * @c uflow(). 00298 */ 00299 int_type 00300 sbumpc() 00301 { 00302 int_type __ret; 00303 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00304 { 00305 __ret = traits_type::to_int_type(*this->gptr()); 00306 this->gbump(1); 00307 } 00308 else 00309 __ret = this->uflow(); 00310 return __ret; 00311 } 00312 00313 /** 00314 * @brief Getting the next character. 00315 * @return The next character, or eof. 00316 * 00317 * If the input read position is available, returns that character, 00318 * otherwise calls and returns @c underflow(). Does not move the 00319 * read position after fetching the character. 00320 */ 00321 int_type 00322 sgetc() 00323 { 00324 int_type __ret; 00325 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00326 __ret = traits_type::to_int_type(*this->gptr()); 00327 else 00328 __ret = this->underflow(); 00329 return __ret; 00330 } 00331 00332 /** 00333 * @brief Entry point for xsgetn. 00334 * @param s A buffer area. 00335 * @param n A count. 00336 * 00337 * Returns xsgetn(s,n). The effect is to fill @a s[0] through 00338 * @a s[n-1] with characters from the input sequence, if possible. 00339 */ 00340 streamsize 00341 sgetn(char_type* __s, streamsize __n) 00342 { return this->xsgetn(__s, __n); } 00343 00344 // [27.5.2.2.4] putback 00345 /** 00346 * @brief Pushing characters back into the input stream. 00347 * @param c The character to push back. 00348 * @return The previous character, if possible. 00349 * 00350 * Similar to sungetc(), but @a c is pushed onto the stream instead 00351 * of "the previous character". If successful, the next character 00352 * fetched from the input stream will be @a c. 00353 */ 00354 int_type 00355 sputbackc(char_type __c) 00356 { 00357 int_type __ret; 00358 const bool __testpos = this->eback() < this->gptr(); 00359 if (__builtin_expect(!__testpos || 00360 !traits_type::eq(__c, this->gptr()[-1]), false)) 00361 __ret = this->pbackfail(traits_type::to_int_type(__c)); 00362 else 00363 { 00364 this->gbump(-1); 00365 __ret = traits_type::to_int_type(*this->gptr()); 00366 } 00367 return __ret; 00368 } 00369 00370 /** 00371 * @brief Moving backwards in the input stream. 00372 * @return The previous character, if possible. 00373 * 00374 * If a putback position is available, this function decrements the 00375 * input pointer and returns that character. Otherwise, calls and 00376 * returns pbackfail(). The effect is to "unget" the last character 00377 * "gotten". 00378 */ 00379 int_type 00380 sungetc() 00381 { 00382 int_type __ret; 00383 if (__builtin_expect(this->eback() < this->gptr(), true)) 00384 { 00385 this->gbump(-1); 00386 __ret = traits_type::to_int_type(*this->gptr()); 00387 } 00388 else 00389 __ret = this->pbackfail(); 00390 return __ret; 00391 } 00392 00393 // [27.5.2.2.5] put area 00394 /** 00395 * @brief Entry point for all single-character output functions. 00396 * @param c A character to output. 00397 * @return @a c, if possible. 00398 * 00399 * One of two public output functions. 00400 * 00401 * If a write position is available for the output sequence (i.e., 00402 * the buffer is not full), stores @a c in that position, increments 00403 * the position, and returns @c traits::to_int_type(c). If a write 00404 * position is not available, returns @c overflow(c). 00405 */ 00406 int_type 00407 sputc(char_type __c) 00408 { 00409 int_type __ret; 00410 if (__builtin_expect(this->pptr() < this->epptr(), true)) 00411 { 00412 *this->pptr() = __c; 00413 this->pbump(1); 00414 __ret = traits_type::to_int_type(__c); 00415 } 00416 else 00417 __ret = this->overflow(traits_type::to_int_type(__c)); 00418 return __ret; 00419 } 00420 00421 /** 00422 * @brief Entry point for all single-character output functions. 00423 * @param s A buffer read area. 00424 * @param n A count. 00425 * 00426 * One of two public output functions. 00427 * 00428 * 00429 * Returns xsputn(s,n). The effect is to write @a s[0] through 00430 * @a s[n-1] to the output sequence, if possible. 00431 */ 00432 streamsize 00433 sputn(const char_type* __s, streamsize __n) 00434 { return this->xsputn(__s, __n); } 00435 00436 protected: 00437 /** 00438 * @brief Base constructor. 00439 * 00440 * Only called from derived constructors, and sets up all the 00441 * buffer data to zero, including the pointers described in the 00442 * basic_streambuf class description. Note that, as a result, 00443 * - the class starts with no read nor write positions available, 00444 * - this is not an error 00445 */ 00446 basic_streambuf() 00447 : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 00448 _M_out_beg(0), _M_out_cur(0), _M_out_end(0), 00449 _M_buf_locale(locale()) 00450 { } 00451 00452 // [27.5.2.3.1] get area access 00453 //@{ 00454 /** 00455 * @brief Access to the get area. 00456 * 00457 * These functions are only available to other protected functions, 00458 * including derived classes. 00459 * 00460 * - eback() returns the beginning pointer for the input sequence 00461 * - gptr() returns the next pointer for the input sequence 00462 * - egptr() returns the end pointer for the input sequence 00463 */ 00464 char_type* 00465 eback() const { return _M_in_beg; } 00466 00467 char_type* 00468 gptr() const { return _M_in_cur; } 00469 00470 char_type* 00471 egptr() const { return _M_in_end; } 00472 //@} 00473 00474 /** 00475 * @brief Moving the read position. 00476 * @param n The delta by which to move. 00477 * 00478 * This just advances the read position without returning any data. 00479 */ 00480 void 00481 gbump(int __n) { _M_in_cur += __n; } 00482 00483 /** 00484 * @brief Setting the three read area pointers. 00485 * @param gbeg A pointer. 00486 * @param gnext A pointer. 00487 * @param gend A pointer. 00488 * @post @a gbeg == @c eback(), @a gnext == @c gptr(), and 00489 * @a gend == @c egptr() 00490 */ 00491 void 00492 setg(char_type* __gbeg, char_type* __gnext, char_type* __gend) 00493 { 00494 _M_in_beg = __gbeg; 00495 _M_in_cur = __gnext; 00496 _M_in_end = __gend; 00497 } 00498 00499 // [27.5.2.3.2] put area access 00500 //@{ 00501 /** 00502 * @brief Access to the put area. 00503 * 00504 * These functions are only available to other protected functions, 00505 * including derived classes. 00506 * 00507 * - pbase() returns the beginning pointer for the output sequence 00508 * - pptr() returns the next pointer for the output sequence 00509 * - epptr() returns the end pointer for the output sequence 00510 */ 00511 char_type* 00512 pbase() const { return _M_out_beg; } 00513 00514 char_type* 00515 pptr() const { return _M_out_cur; } 00516 00517 char_type* 00518 epptr() const { return _M_out_end; } 00519 //@} 00520 00521 /** 00522 * @brief Moving the write position. 00523 * @param n The delta by which to move. 00524 * 00525 * This just advances the write position without returning any data. 00526 */ 00527 void 00528 pbump(int __n) { _M_out_cur += __n; } 00529 00530 /** 00531 * @brief Setting the three write area pointers. 00532 * @param pbeg A pointer. 00533 * @param pend A pointer. 00534 * @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and 00535 * @a pend == @c epptr() 00536 */ 00537 void 00538 setp(char_type* __pbeg, char_type* __pend) 00539 { 00540 _M_out_beg = _M_out_cur = __pbeg; 00541 _M_out_end = __pend; 00542 } 00543 00544 // [27.5.2.4] virtual functions 00545 // [27.5.2.4.1] locales 00546 /** 00547 * @brief Changes translations. 00548 * @param loc A new locale. 00549 * 00550 * Translations done during I/O which depend on the current locale 00551 * are changed by this call. The standard adds, "Between invocations 00552 * of this function a class derived from streambuf can safely cache 00553 * results of calls to locale functions and to members of facets 00554 * so obtained." 00555 * 00556 * @note Base class version does nothing. 00557 */ 00558 virtual void 00559 imbue(const locale&) 00560 { } 00561 00562 // [27.5.2.4.2] buffer management and positioning 00563 /** 00564 * @brief Maniuplates the buffer. 00565 * 00566 * Each derived class provides its own appropriate behavior. See 00567 * the next-to-last paragraph of 00568 * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for 00569 * more on this function. 00570 * 00571 * @note Base class version does nothing, returns @c this. 00572 */ 00573 virtual basic_streambuf<char_type,_Traits>* 00574 setbuf(char_type*, streamsize) 00575 { return this; } 00576 00577 /** 00578 * @brief Alters the stream positions. 00579 * 00580 * Each derived class provides its own appropriate behavior. 00581 * @note Base class version does nothing, returns a @c pos_type 00582 * that represents an invalid stream position. 00583 */ 00584 virtual pos_type 00585 seekoff(off_type, ios_base::seekdir, 00586 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00587 { return pos_type(off_type(-1)); } 00588 00589 /** 00590 * @brief Alters the stream positions. 00591 * 00592 * Each derived class provides its own appropriate behavior. 00593 * @note Base class version does nothing, returns a @c pos_type 00594 * that represents an invalid stream position. 00595 */ 00596 virtual pos_type 00597 seekpos(pos_type, 00598 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00599 { return pos_type(off_type(-1)); } 00600 00601 /** 00602 * @brief Synchronizes the buffer arrays with the controlled sequences. 00603 * @return -1 on failure. 00604 * 00605 * Each derived class provides its own appropriate behavior, 00606 * including the definition of "failure". 00607 * @note Base class version does nothing, returns zero. 00608 */ 00609 virtual int 00610 sync() { return 0; } 00611 00612 // [27.5.2.4.3] get area 00613 /** 00614 * @brief Investigating the data available. 00615 * @return An estimate of the number of characters available in the 00616 * input sequence, or -1. 00617 * 00618 * "If it returns a positive value, then successive calls to 00619 * @c underflow() will not return @c traits::eof() until at least that 00620 * number of characters have been supplied. If @c showmanyc() 00621 * returns -1, then calls to @c underflow() or @c uflow() will fail." 00622 * [27.5.2.4.3]/1 00623 * 00624 * @note Base class version does nothing, returns zero. 00625 * @note The standard adds that "the intention is not only that the 00626 * calls [to underflow or uflow] will not return @c eof() but 00627 * that they will return "immediately". 00628 * @note The standard adds that "the morphemes of @c showmanyc are 00629 * "es-how-many-see", not "show-manic". 00630 */ 00631 virtual streamsize 00632 showmanyc() { return 0; } 00633 00634 /** 00635 * @brief Multiple character extraction. 00636 * @param s A buffer area. 00637 * @param n Maximum number of characters to assign. 00638 * @return The number of characters assigned. 00639 * 00640 * Fills @a s[0] through @a s[n-1] with characters from the input 00641 * sequence, as if by @c sbumpc(). Stops when either @a n characters 00642 * have been copied, or when @c traits::eof() would be copied. 00643 * 00644 * It is expected that derived classes provide a more efficient 00645 * implementation by overriding this definition. 00646 */ 00647 virtual streamsize 00648 xsgetn(char_type* __s, streamsize __n); 00649 00650 /** 00651 * @brief Fetches more data from the controlled sequence. 00652 * @return The first character from the <em>pending sequence</em>. 00653 * 00654 * Informally, this function is called when the input buffer is 00655 * exhausted (or does not exist, as buffering need not actually be 00656 * done). If a buffer exists, it is "refilled". In either case, the 00657 * next available character is returned, or @c traits::eof() to 00658 * indicate a null pending sequence. 00659 * 00660 * For a formal definiton of the pending sequence, see a good text 00661 * such as Langer & Kreft, or [27.5.2.4.3]/7-14. 00662 * 00663 * A functioning input streambuf can be created by overriding only 00664 * this function (no buffer area will be used). For an example, see 00665 * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#6 00666 * 00667 * @note Base class version does nothing, returns eof(). 00668 */ 00669 virtual int_type 00670 underflow() 00671 { return traits_type::eof(); } 00672 00673 /** 00674 * @brief Fetches more data from the controlled sequence. 00675 * @return The first character from the <em>pending sequence</em>. 00676 * 00677 * Informally, this function does the same thing as @c underflow(), 00678 * and in fact is required to call that function. It also returns 00679 * the new character, like @c underflow() does. However, this 00680 * function also moves the read position forward by one. 00681 */ 00682 virtual int_type 00683 uflow() 00684 { 00685 int_type __ret = traits_type::eof(); 00686 const bool __testeof = traits_type::eq_int_type(this->underflow(), 00687 __ret); 00688 if (!__testeof) 00689 { 00690 __ret = traits_type::to_int_type(*this->gptr()); 00691 this->gbump(1); 00692 } 00693 return __ret; 00694 } 00695 00696 // [27.5.2.4.4] putback 00697 /** 00698 * @brief Tries to back up the input sequence. 00699 * @param c The character to be inserted back into the sequence. 00700 * @return eof() on failure, "some other value" on success 00701 * @post The constraints of @c gptr(), @c eback(), and @c pptr() 00702 * are the same as for @c underflow(). 00703 * 00704 * @note Base class version does nothing, returns eof(). 00705 */ 00706 virtual int_type 00707 pbackfail(int_type /* __c */ = traits_type::eof()) 00708 { return traits_type::eof(); } 00709 00710 // Put area: 00711 /** 00712 * @brief Multiple character insertion. 00713 * @param s A buffer area. 00714 * @param n Maximum number of characters to write. 00715 * @return The number of characters written. 00716 * 00717 * Writes @a s[0] through @a s[n-1] to the output sequence, as if 00718 * by @c sputc(). Stops when either @a n characters have been 00719 * copied, or when @c sputc() would return @c traits::eof(). 00720 * 00721 * It is expected that derived classes provide a more efficient 00722 * implementation by overriding this definition. 00723 */ 00724 virtual streamsize 00725 xsputn(const char_type* __s, streamsize __n); 00726 00727 /** 00728 * @brief Consumes data from the buffer; writes to the 00729 * controlled sequence. 00730 * @param c An additional character to consume. 00731 * @return eof() to indicate failure, something else (usually 00732 * @a c, or not_eof()) 00733 * 00734 * Informally, this function is called when the output buffer is full 00735 * (or does not exist, as buffering need not actually be done). If a 00736 * buffer exists, it is "consumed", with "some effect" on the 00737 * controlled sequence. (Typically, the buffer is written out to the 00738 * sequence verbatim.) In either case, the character @a c is also 00739 * written out, if @a c is not @c eof(). 00740 * 00741 * For a formal definiton of this function, see a good text 00742 * such as Langer & Kreft, or [27.5.2.4.5]/3-7. 00743 * 00744 * A functioning output streambuf can be created by overriding only 00745 * this function (no buffer area will be used). 00746 * 00747 * @note Base class version does nothing, returns eof(). 00748 */ 00749 virtual int_type 00750 overflow(int_type /* __c */ = traits_type::eof()) 00751 { return traits_type::eof(); } 00752 00753 #ifdef _GLIBCXX_DEPRECATED 00754 // Annex D.6 00755 public: 00756 /** 00757 * @brief Tosses a character. 00758 * 00759 * Advances the read pointer, ignoring the character that would have 00760 * been read. 00761 * 00762 * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html 00763 * 00764 * @note This function has been deprecated by the standard. You 00765 * must define @c _GLIBCXX_DEPRECATED to make this visible; see 00766 * c++config.h. 00767 */ 00768 void 00769 stossc() 00770 { 00771 if (this->gptr() < this->egptr()) 00772 this->gbump(1); 00773 else 00774 this->uflow(); 00775 } 00776 #endif 00777 00778 private: 00779 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00780 // Side effect of DR 50. 00781 basic_streambuf(const __streambuf_type& __sb) 00782 : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur), 00783 _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg), 00784 _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur), 00785 _M_buf_locale(__sb._M_buf_locale) 00786 { } 00787 00788 __streambuf_type& 00789 operator=(const __streambuf_type&) { return *this; }; 00790 }; 00791 00792 // Explicit specialization declarations, defined in src/streambuf.cc. 00793 template<> 00794 streamsize 00795 __copy_streambufs(basic_streambuf<char>* __sbin, 00796 basic_streambuf<char>* __sbout); 00797 #ifdef _GLIBCXX_USE_WCHAR_T 00798 template<> 00799 streamsize 00800 __copy_streambufs(basic_streambuf<wchar_t>* __sbin, 00801 basic_streambuf<wchar_t>* __sbout); 00802 #endif 00803 } // namespace std 00804 00805 #ifndef _GLIBCXX_EXPORT_TEMPLATE 00806 # include <bits/streambuf.tcc> 00807 #endif 00808 00809 #endif /* _GLIBCXX_STREAMBUF */