00001 // Stream buffer classes -*- C++ -*- 00002 00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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, typename _Alloc> 00158 friend basic_istream<_CharT2, _Traits2>& 00159 getline(basic_istream<_CharT2, _Traits2>&, 00160 basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2); 00161 00162 protected: 00163 //@{ 00164 /** 00165 * @if maint 00166 * This is based on _IO_FILE, just reordered to be more consistent, 00167 * and is intended to be the most minimal abstraction for an 00168 * internal buffer. 00169 * - get == input == read 00170 * - put == output == write 00171 * @endif 00172 */ 00173 char_type* _M_in_beg; // Start of get area. 00174 char_type* _M_in_cur; // Current read area. 00175 char_type* _M_in_end; // End of get area. 00176 char_type* _M_out_beg; // Start of put area. 00177 char_type* _M_out_cur; // Current put area. 00178 char_type* _M_out_end; // End of put area. 00179 00180 /** 00181 * @if maint 00182 * Current locale setting. 00183 * @endif 00184 */ 00185 locale _M_buf_locale; 00186 00187 public: 00188 /// Destructor deallocates no buffer space. 00189 virtual 00190 ~basic_streambuf() 00191 { } 00192 00193 // [27.5.2.2.1] locales 00194 /** 00195 * @brief Entry point for imbue(). 00196 * @param loc The new locale. 00197 * @return The previous locale. 00198 * 00199 * Calls the derived imbue(loc). 00200 */ 00201 locale 00202 pubimbue(const locale &__loc) 00203 { 00204 locale __tmp(this->getloc()); 00205 this->imbue(__loc); 00206 _M_buf_locale = __loc; 00207 return __tmp; 00208 } 00209 00210 /** 00211 * @brief Locale access. 00212 * @return The current locale in effect. 00213 * 00214 * If pubimbue(loc) has been called, then the most recent @c loc 00215 * is returned. Otherwise the global locale in effect at the time 00216 * of construction is returned. 00217 */ 00218 locale 00219 getloc() const 00220 { return _M_buf_locale; } 00221 00222 // [27.5.2.2.2] buffer management and positioning 00223 //@{ 00224 /** 00225 * @brief Entry points for derived buffer functions. 00226 * 00227 * The public versions of @c pubfoo dispatch to the protected 00228 * derived @c foo member functions, passing the arguments (if any) 00229 * and returning the result unchanged. 00230 */ 00231 __streambuf_type* 00232 pubsetbuf(char_type* __s, streamsize __n) 00233 { return this->setbuf(__s, __n); } 00234 00235 pos_type 00236 pubseekoff(off_type __off, ios_base::seekdir __way, 00237 ios_base::openmode __mode = ios_base::in | ios_base::out) 00238 { return this->seekoff(__off, __way, __mode); } 00239 00240 pos_type 00241 pubseekpos(pos_type __sp, 00242 ios_base::openmode __mode = ios_base::in | ios_base::out) 00243 { return this->seekpos(__sp, __mode); } 00244 00245 int 00246 pubsync() { return this->sync(); } 00247 //@} 00248 00249 // [27.5.2.2.3] get area 00250 /** 00251 * @brief Looking ahead into the stream. 00252 * @return The number of characters available. 00253 * 00254 * If a read position is available, returns the number of characters 00255 * available for reading before the buffer must be refilled. 00256 * Otherwise returns the derived @c showmanyc(). 00257 */ 00258 streamsize 00259 in_avail() 00260 { 00261 const streamsize __ret = this->egptr() - this->gptr(); 00262 return __ret ? __ret : this->showmanyc(); 00263 } 00264 00265 /** 00266 * @brief Getting the next character. 00267 * @return The next character, or eof. 00268 * 00269 * Calls @c sbumpc(), and if that function returns 00270 * @c traits::eof(), so does this function. Otherwise, @c sgetc(). 00271 */ 00272 int_type 00273 snextc() 00274 { 00275 int_type __ret = traits_type::eof(); 00276 if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), 00277 __ret), true)) 00278 __ret = this->sgetc(); 00279 return __ret; 00280 } 00281 00282 /** 00283 * @brief Getting the next character. 00284 * @return The next character, or eof. 00285 * 00286 * If the input read position is available, returns that character 00287 * and increments the read pointer, otherwise calls and returns 00288 * @c uflow(). 00289 */ 00290 int_type 00291 sbumpc() 00292 { 00293 int_type __ret; 00294 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00295 { 00296 __ret = traits_type::to_int_type(*this->gptr()); 00297 this->gbump(1); 00298 } 00299 else 00300 __ret = this->uflow(); 00301 return __ret; 00302 } 00303 00304 /** 00305 * @brief Getting the next character. 00306 * @return The next character, or eof. 00307 * 00308 * If the input read position is available, returns that character, 00309 * otherwise calls and returns @c underflow(). Does not move the 00310 * read position after fetching the character. 00311 */ 00312 int_type 00313 sgetc() 00314 { 00315 int_type __ret; 00316 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00317 __ret = traits_type::to_int_type(*this->gptr()); 00318 else 00319 __ret = this->underflow(); 00320 return __ret; 00321 } 00322 00323 /** 00324 * @brief Entry point for xsgetn. 00325 * @param s A buffer area. 00326 * @param n A count. 00327 * 00328 * Returns xsgetn(s,n). The effect is to fill @a s[0] through 00329 * @a s[n-1] with characters from the input sequence, if possible. 00330 */ 00331 streamsize 00332 sgetn(char_type* __s, streamsize __n) 00333 { return this->xsgetn(__s, __n); } 00334 00335 // [27.5.2.2.4] putback 00336 /** 00337 * @brief Pushing characters back into the input stream. 00338 * @param c The character to push back. 00339 * @return The previous character, if possible. 00340 * 00341 * Similar to sungetc(), but @a c is pushed onto the stream instead 00342 * of "the previous character". If successful, the next character 00343 * fetched from the input stream will be @a c. 00344 */ 00345 int_type 00346 sputbackc(char_type __c) 00347 { 00348 int_type __ret; 00349 const bool __testpos = this->eback() < this->gptr(); 00350 if (__builtin_expect(!__testpos || 00351 !traits_type::eq(__c, this->gptr()[-1]), false)) 00352 __ret = this->pbackfail(traits_type::to_int_type(__c)); 00353 else 00354 { 00355 this->gbump(-1); 00356 __ret = traits_type::to_int_type(*this->gptr()); 00357 } 00358 return __ret; 00359 } 00360 00361 /** 00362 * @brief Moving backwards in the input stream. 00363 * @return The previous character, if possible. 00364 * 00365 * If a putback position is available, this function decrements the 00366 * input pointer and returns that character. Otherwise, calls and 00367 * returns pbackfail(). The effect is to "unget" the last character 00368 * "gotten". 00369 */ 00370 int_type 00371 sungetc() 00372 { 00373 int_type __ret; 00374 if (__builtin_expect(this->eback() < this->gptr(), true)) 00375 { 00376 this->gbump(-1); 00377 __ret = traits_type::to_int_type(*this->gptr()); 00378 } 00379 else 00380 __ret = this->pbackfail(); 00381 return __ret; 00382 } 00383 00384 // [27.5.2.2.5] put area 00385 /** 00386 * @brief Entry point for all single-character output functions. 00387 * @param c A character to output. 00388 * @return @a c, if possible. 00389 * 00390 * One of two public output functions. 00391 * 00392 * If a write position is available for the output sequence (i.e., 00393 * the buffer is not full), stores @a c in that position, increments 00394 * the position, and returns @c traits::to_int_type(c). If a write 00395 * position is not available, returns @c overflow(c). 00396 */ 00397 int_type 00398 sputc(char_type __c) 00399 { 00400 int_type __ret; 00401 if (__builtin_expect(this->pptr() < this->epptr(), true)) 00402 { 00403 *this->pptr() = __c; 00404 this->pbump(1); 00405 __ret = traits_type::to_int_type(__c); 00406 } 00407 else 00408 __ret = this->overflow(traits_type::to_int_type(__c)); 00409 return __ret; 00410 } 00411 00412 /** 00413 * @brief Entry point for all single-character output functions. 00414 * @param s A buffer read area. 00415 * @param n A count. 00416 * 00417 * One of two public output functions. 00418 * 00419 * 00420 * Returns xsputn(s,n). The effect is to write @a s[0] through 00421 * @a s[n-1] to the output sequence, if possible. 00422 */ 00423 streamsize 00424 sputn(const char_type* __s, streamsize __n) 00425 { return this->xsputn(__s, __n); } 00426 00427 protected: 00428 /** 00429 * @brief Base constructor. 00430 * 00431 * Only called from derived constructors, and sets up all the 00432 * buffer data to zero, including the pointers described in the 00433 * basic_streambuf class description. Note that, as a result, 00434 * - the class starts with no read nor write positions available, 00435 * - this is not an error 00436 */ 00437 basic_streambuf() 00438 : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 00439 _M_out_beg(0), _M_out_cur(0), _M_out_end(0), 00440 _M_buf_locale(locale()) 00441 { } 00442 00443 // [27.5.2.3.1] get area access 00444 //@{ 00445 /** 00446 * @brief Access to the get area. 00447 * 00448 * These functions are only available to other protected functions, 00449 * including derived classes. 00450 * 00451 * - eback() returns the beginning pointer for the input sequence 00452 * - gptr() returns the next pointer for the input sequence 00453 * - egptr() returns the end pointer for the input sequence 00454 */ 00455 char_type* 00456 eback() const { return _M_in_beg; } 00457 00458 char_type* 00459 gptr() const { return _M_in_cur; } 00460 00461 char_type* 00462 egptr() const { return _M_in_end; } 00463 //@} 00464 00465 /** 00466 * @brief Moving the read position. 00467 * @param n The delta by which to move. 00468 * 00469 * This just advances the read position without returning any data. 00470 */ 00471 void 00472 gbump(int __n) { _M_in_cur += __n; } 00473 00474 /** 00475 * @brief Setting the three read area pointers. 00476 * @param gbeg A pointer. 00477 * @param gnext A pointer. 00478 * @param gend A pointer. 00479 * @post @a gbeg == @c eback(), @a gnext == @c gptr(), and 00480 * @a gend == @c egptr() 00481 */ 00482 void 00483 setg(char_type* __gbeg, char_type* __gnext, char_type* __gend) 00484 { 00485 _M_in_beg = __gbeg; 00486 _M_in_cur = __gnext; 00487 _M_in_end = __gend; 00488 } 00489 00490 // [27.5.2.3.2] put area access 00491 //@{ 00492 /** 00493 * @brief Access to the put area. 00494 * 00495 * These functions are only available to other protected functions, 00496 * including derived classes. 00497 * 00498 * - pbase() returns the beginning pointer for the output sequence 00499 * - pptr() returns the next pointer for the output sequence 00500 * - epptr() returns the end pointer for the output sequence 00501 */ 00502 char_type* 00503 pbase() const { return _M_out_beg; } 00504 00505 char_type* 00506 pptr() const { return _M_out_cur; } 00507 00508 char_type* 00509 epptr() const { return _M_out_end; } 00510 //@} 00511 00512 /** 00513 * @brief Moving the write position. 00514 * @param n The delta by which to move. 00515 * 00516 * This just advances the write position without returning any data. 00517 */ 00518 void 00519 pbump(int __n) { _M_out_cur += __n; } 00520 00521 /** 00522 * @brief Setting the three write area pointers. 00523 * @param pbeg A pointer. 00524 * @param pend A pointer. 00525 * @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and 00526 * @a pend == @c epptr() 00527 */ 00528 void 00529 setp(char_type* __pbeg, char_type* __pend) 00530 { 00531 _M_out_beg = _M_out_cur = __pbeg; 00532 _M_out_end = __pend; 00533 } 00534 00535 // [27.5.2.4] virtual functions 00536 // [27.5.2.4.1] locales 00537 /** 00538 * @brief Changes translations. 00539 * @param loc A new locale. 00540 * 00541 * Translations done during I/O which depend on the current locale 00542 * are changed by this call. The standard adds, "Between invocations 00543 * of this function a class derived from streambuf can safely cache 00544 * results of calls to locale functions and to members of facets 00545 * so obtained." 00546 * 00547 * @note Base class version does nothing. 00548 */ 00549 virtual void 00550 imbue(const locale&) 00551 { } 00552 00553 // [27.5.2.4.2] buffer management and positioning 00554 /** 00555 * @brief Maniuplates the buffer. 00556 * 00557 * Each derived class provides its own appropriate behavior. See 00558 * the next-to-last paragraph of 00559 * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for 00560 * more on this function. 00561 * 00562 * @note Base class version does nothing, returns @c this. 00563 */ 00564 virtual basic_streambuf<char_type,_Traits>* 00565 setbuf(char_type*, streamsize) 00566 { return this; } 00567 00568 /** 00569 * @brief Alters the stream positions. 00570 * 00571 * Each derived class provides its own appropriate behavior. 00572 * @note Base class version does nothing, returns a @c pos_type 00573 * that represents an invalid stream position. 00574 */ 00575 virtual pos_type 00576 seekoff(off_type, ios_base::seekdir, 00577 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00578 { return pos_type(off_type(-1)); } 00579 00580 /** 00581 * @brief Alters the stream positions. 00582 * 00583 * Each derived class provides its own appropriate behavior. 00584 * @note Base class version does nothing, returns a @c pos_type 00585 * that represents an invalid stream position. 00586 */ 00587 virtual pos_type 00588 seekpos(pos_type, 00589 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00590 { return pos_type(off_type(-1)); } 00591 00592 /** 00593 * @brief Synchronizes the buffer arrays with the controlled sequences. 00594 * @return -1 on failure. 00595 * 00596 * Each derived class provides its own appropriate behavior, 00597 * including the definition of "failure". 00598 * @note Base class version does nothing, returns zero. 00599 */ 00600 virtual int 00601 sync() { return 0; } 00602 00603 // [27.5.2.4.3] get area 00604 /** 00605 * @brief Investigating the data available. 00606 * @return An estimate of the number of characters available in the 00607 * input sequence, or -1. 00608 * 00609 * "If it returns a positive value, then successive calls to 00610 * @c underflow() will not return @c traits::eof() until at least that 00611 * number of characters have been supplied. If @c showmanyc() 00612 * returns -1, then calls to @c underflow() or @c uflow() will fail." 00613 * [27.5.2.4.3]/1 00614 * 00615 * @note Base class version does nothing, returns zero. 00616 * @note The standard adds that "the intention is not only that the 00617 * calls [to underflow or uflow] will not return @c eof() but 00618 * that they will return "immediately". 00619 * @note The standard adds that "the morphemes of @c showmanyc are 00620 * "es-how-many-see", not "show-manic". 00621 */ 00622 virtual streamsize 00623 showmanyc() { return 0; } 00624 00625 /** 00626 * @brief Multiple character extraction. 00627 * @param s A buffer area. 00628 * @param n Maximum number of characters to assign. 00629 * @return The number of characters assigned. 00630 * 00631 * Fills @a s[0] through @a s[n-1] with characters from the input 00632 * sequence, as if by @c sbumpc(). Stops when either @a n characters 00633 * have been copied, or when @c traits::eof() would be copied. 00634 * 00635 * It is expected that derived classes provide a more efficient 00636 * implementation by overriding this definition. 00637 */ 00638 virtual streamsize 00639 xsgetn(char_type* __s, streamsize __n); 00640 00641 /** 00642 * @brief Fetches more data from the controlled sequence. 00643 * @return The first character from the <em>pending sequence</em>. 00644 * 00645 * Informally, this function is called when the input buffer is 00646 * exhausted (or does not exist, as buffering need not actually be 00647 * done). If a buffer exists, it is "refilled". In either case, the 00648 * next available character is returned, or @c traits::eof() to 00649 * indicate a null pending sequence. 00650 * 00651 * For a formal definiton of the pending sequence, see a good text 00652 * such as Langer & Kreft, or [27.5.2.4.3]/7-14. 00653 * 00654 * A functioning input streambuf can be created by overriding only 00655 * this function (no buffer area will be used). For an example, see 00656 * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#6 00657 * 00658 * @note Base class version does nothing, returns eof(). 00659 */ 00660 virtual int_type 00661 underflow() 00662 { return traits_type::eof(); } 00663 00664 /** 00665 * @brief Fetches more data from the controlled sequence. 00666 * @return The first character from the <em>pending sequence</em>. 00667 * 00668 * Informally, this function does the same thing as @c underflow(), 00669 * and in fact is required to call that function. It also returns 00670 * the new character, like @c underflow() does. However, this 00671 * function also moves the read position forward by one. 00672 */ 00673 virtual int_type 00674 uflow() 00675 { 00676 int_type __ret = traits_type::eof(); 00677 const bool __testeof = traits_type::eq_int_type(this->underflow(), 00678 __ret); 00679 if (!__testeof) 00680 { 00681 __ret = traits_type::to_int_type(*this->gptr()); 00682 this->gbump(1); 00683 } 00684 return __ret; 00685 } 00686 00687 // [27.5.2.4.4] putback 00688 /** 00689 * @brief Tries to back up the input sequence. 00690 * @param c The character to be inserted back into the sequence. 00691 * @return eof() on failure, "some other value" on success 00692 * @post The constraints of @c gptr(), @c eback(), and @c pptr() 00693 * are the same as for @c underflow(). 00694 * 00695 * @note Base class version does nothing, returns eof(). 00696 */ 00697 virtual int_type 00698 pbackfail(int_type /* __c */ = traits_type::eof()) 00699 { return traits_type::eof(); } 00700 00701 // Put area: 00702 /** 00703 * @brief Multiple character insertion. 00704 * @param s A buffer area. 00705 * @param n Maximum number of characters to write. 00706 * @return The number of characters written. 00707 * 00708 * Writes @a s[0] through @a s[n-1] to the output sequence, as if 00709 * by @c sputc(). Stops when either @a n characters have been 00710 * copied, or when @c sputc() would return @c traits::eof(). 00711 * 00712 * It is expected that derived classes provide a more efficient 00713 * implementation by overriding this definition. 00714 */ 00715 virtual streamsize 00716 xsputn(const char_type* __s, streamsize __n); 00717 00718 /** 00719 * @brief Consumes data from the buffer; writes to the 00720 * controlled sequence. 00721 * @param c An additional character to consume. 00722 * @return eof() to indicate failure, something else (usually 00723 * @a c, or not_eof()) 00724 * 00725 * Informally, this function is called when the output buffer is full 00726 * (or does not exist, as buffering need not actually be done). If a 00727 * buffer exists, it is "consumed", with "some effect" on the 00728 * controlled sequence. (Typically, the buffer is written out to the 00729 * sequence verbatim.) In either case, the character @a c is also 00730 * written out, if @a c is not @c eof(). 00731 * 00732 * For a formal definiton of this function, see a good text 00733 * such as Langer & Kreft, or [27.5.2.4.5]/3-7. 00734 * 00735 * A functioning output streambuf can be created by overriding only 00736 * this function (no buffer area will be used). 00737 * 00738 * @note Base class version does nothing, returns eof(). 00739 */ 00740 virtual int_type 00741 overflow(int_type /* __c */ = traits_type::eof()) 00742 { return traits_type::eof(); } 00743 00744 #ifdef _GLIBCXX_DEPRECATED 00745 // Annex D.6 00746 public: 00747 /** 00748 * @brief Tosses a character. 00749 * 00750 * Advances the read pointer, ignoring the character that would have 00751 * been read. 00752 * 00753 * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html 00754 * 00755 * @note This function has been deprecated by the standard. You 00756 * must define @c _GLIBCXX_DEPRECATED to make this visible; see 00757 * c++config.h. 00758 */ 00759 void 00760 stossc() 00761 { 00762 if (this->gptr() < this->egptr()) 00763 this->gbump(1); 00764 else 00765 this->uflow(); 00766 } 00767 #endif 00768 00769 private: 00770 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00771 // Side effect of DR 50. 00772 basic_streambuf(const __streambuf_type& __sb) 00773 : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur), 00774 _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg), 00775 _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur), 00776 _M_buf_locale(__sb._M_buf_locale) 00777 { } 00778 00779 __streambuf_type& 00780 operator=(const __streambuf_type&) { return *this; }; 00781 }; 00782 00783 // Explicit specialization declarations, defined in src/streambuf.cc. 00784 template<> 00785 streamsize 00786 __copy_streambufs(basic_streambuf<char>* __sbin, 00787 basic_streambuf<char>* __sbout); 00788 #ifdef _GLIBCXX_USE_WCHAR_T 00789 template<> 00790 streamsize 00791 __copy_streambufs(basic_streambuf<wchar_t>* __sbin, 00792 basic_streambuf<wchar_t>* __sbout); 00793 #endif 00794 } // namespace std 00795 00796 #ifndef _GLIBCXX_EXPORT_TEMPLATE 00797 # include <bits/streambuf.tcc> 00798 #endif 00799 00800 #endif /* _GLIBCXX_STREAMBUF */