00001 // Stream buffer classes -*- C++ -*- 00002 00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 00004 // 2006, 2007, 2008, 2009, 2010 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 3, 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 // Under Section 7 of GPL version 3, you are granted additional 00018 // permissions described in the GCC Runtime Library Exception, version 00019 // 3.1, as published by the Free Software Foundation. 00020 00021 // You should have received a copy of the GNU General Public License and 00022 // a copy of the GCC Runtime Library Exception along with this program; 00023 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00024 // <http://www.gnu.org/licenses/>. 00025 00026 /** @file streambuf 00027 * This is a Standard C++ Library header. 00028 */ 00029 00030 // 00031 // ISO C++ 14882: 27.5 Stream buffers 00032 // 00033 00034 #ifndef _GLIBXX_STREAMBUF 00035 #define _GLIBXX_STREAMBUF 1 00036 00037 #pragma GCC system_header 00038 00039 #include <bits/c++config.h> 00040 #include <iosfwd> 00041 #include <bits/localefwd.h> 00042 #include <bits/ios_base.h> 00043 #include <bits/cpp_type_traits.h> 00044 #include <ext/type_traits.h> 00045 00046 _GLIBCXX_BEGIN_NAMESPACE(std) 00047 00048 template<typename _CharT, typename _Traits> 00049 streamsize 00050 __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>*, 00051 basic_streambuf<_CharT, _Traits>*, bool&); 00052 00053 /** 00054 * @brief The actual work of input and output (interface). 00055 * @ingroup io 00056 * 00057 * This is a base class. Derived stream buffers each control a 00058 * pair of character sequences: one for input, and one for output. 00059 * 00060 * Section [27.5.1] of the standard describes the requirements and 00061 * behavior of stream buffer classes. That section (three paragraphs) 00062 * is reproduced here, for simplicity and accuracy. 00063 * 00064 * -# Stream buffers can impose various constraints on the sequences 00065 * they control. Some constraints are: 00066 * - The controlled input sequence can be not readable. 00067 * - The controlled output sequence can be not writable. 00068 * - The controlled sequences can be associated with the contents of 00069 * other representations for character sequences, such as external 00070 * files. 00071 * - The controlled sequences can support operations @e directly to or 00072 * from associated sequences. 00073 * - The controlled sequences can impose limitations on how the 00074 * program can read characters from a sequence, write characters to 00075 * a sequence, put characters back into an input sequence, or alter 00076 * the stream position. 00077 * . 00078 * -# Each sequence is characterized by three pointers which, if non-null, 00079 * all point into the same @c charT array object. The array object 00080 * represents, at any moment, a (sub)sequence of characters from the 00081 * sequence. Operations performed on a sequence alter the values 00082 * stored in these pointers, perform reads and writes directly to or 00083 * from associated sequences, and alter <em>the stream position</em> and 00084 * conversion state as needed to maintain this subsequence relationship. 00085 * The three pointers are: 00086 * - the <em>beginning pointer</em>, or lowest element address in the 00087 * array (called @e xbeg here); 00088 * - the <em>next pointer</em>, or next element address that is a 00089 * current candidate for reading or writing (called @e xnext here); 00090 * - the <em>end pointer</em>, or first element address beyond the 00091 * end of the array (called @e xend here). 00092 * . 00093 * -# The following semantic constraints shall always apply for any set 00094 * of three pointers for a sequence, using the pointer names given 00095 * immediately above: 00096 * - If @e xnext is not a null pointer, then @e xbeg and @e xend shall 00097 * also be non-null pointers into the same @c charT array, as 00098 * described above; otherwise, @e xbeg and @e xend shall also be null. 00099 * - If @e xnext is not a null pointer and @e xnext < @e xend for an 00100 * output sequence, then a <em>write position</em> is available. 00101 * In this case, @e *xnext shall be assignable as the next element 00102 * to write (to put, or to store a character value, into the sequence). 00103 * - If @e xnext is not a null pointer and @e xbeg < @e xnext for an 00104 * input sequence, then a <em>putback position</em> is available. 00105 * In this case, @e xnext[-1] shall have a defined value and is the 00106 * next (preceding) element to store a character that is put back 00107 * into the input sequence. 00108 * - If @e xnext is not a null pointer and @e xnext< @e xend for an 00109 * input sequence, then a <em>read position</em> is available. 00110 * In this case, @e *xnext shall have a defined value and is the 00111 * next element to read (to get, or to obtain a character value, 00112 * from the sequence). 00113 */ 00114 template<typename _CharT, typename _Traits> 00115 class basic_streambuf 00116 { 00117 public: 00118 //@{ 00119 /** 00120 * These are standard types. They permit a standardized way of 00121 * referring to names of (or names dependant on) the template 00122 * parameters, which are specific to the implementation. 00123 */ 00124 typedef _CharT char_type; 00125 typedef _Traits traits_type; 00126 typedef typename traits_type::int_type int_type; 00127 typedef typename traits_type::pos_type pos_type; 00128 typedef typename traits_type::off_type off_type; 00129 //@} 00130 00131 //@{ 00132 /// This is a non-standard type. 00133 typedef basic_streambuf<char_type, traits_type> __streambuf_type; 00134 //@} 00135 00136 friend class basic_ios<char_type, traits_type>; 00137 friend class basic_istream<char_type, traits_type>; 00138 friend class basic_ostream<char_type, traits_type>; 00139 friend class istreambuf_iterator<char_type, traits_type>; 00140 friend class ostreambuf_iterator<char_type, traits_type>; 00141 00142 friend streamsize 00143 __copy_streambufs_eof<>(__streambuf_type*, __streambuf_type*, bool&); 00144 00145 template<bool _IsMove, typename _CharT2> 00146 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 00147 _CharT2*>::__type 00148 __copy_move_a2(istreambuf_iterator<_CharT2>, 00149 istreambuf_iterator<_CharT2>, _CharT2*); 00150 00151 template<typename _CharT2> 00152 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 00153 istreambuf_iterator<_CharT2> >::__type 00154 find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>, 00155 const _CharT2&); 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 * This is based on _IO_FILE, just reordered to be more consistent, 00175 * and is intended to be the most minimal abstraction for an 00176 * internal buffer. 00177 * - get == input == read 00178 * - put == output == write 00179 */ 00180 char_type* _M_in_beg; // Start of get area. 00181 char_type* _M_in_cur; // Current read area. 00182 char_type* _M_in_end; // End of get area. 00183 char_type* _M_out_beg; // Start of put area. 00184 char_type* _M_out_cur; // Current put area. 00185 char_type* _M_out_end; // End of put area. 00186 00187 /// Current locale setting. 00188 locale _M_buf_locale; 00189 00190 public: 00191 /// Destructor deallocates no buffer space. 00192 virtual 00193 ~basic_streambuf() 00194 { } 00195 00196 // [27.5.2.2.1] locales 00197 /** 00198 * @brief Entry point for imbue(). 00199 * @param loc The new locale. 00200 * @return The previous locale. 00201 * 00202 * Calls the derived imbue(loc). 00203 */ 00204 locale 00205 pubimbue(const locale &__loc) 00206 { 00207 locale __tmp(this->getloc()); 00208 this->imbue(__loc); 00209 _M_buf_locale = __loc; 00210 return __tmp; 00211 } 00212 00213 /** 00214 * @brief Locale access. 00215 * @return The current locale in effect. 00216 * 00217 * If pubimbue(loc) has been called, then the most recent @c loc 00218 * is returned. Otherwise the global locale in effect at the time 00219 * of construction is returned. 00220 */ 00221 locale 00222 getloc() const 00223 { return _M_buf_locale; } 00224 00225 // [27.5.2.2.2] buffer management and positioning 00226 //@{ 00227 /** 00228 * @brief Entry points for derived buffer functions. 00229 * 00230 * The public versions of @c pubfoo dispatch to the protected 00231 * derived @c foo member functions, passing the arguments (if any) 00232 * and returning the result unchanged. 00233 */ 00234 __streambuf_type* 00235 pubsetbuf(char_type* __s, streamsize __n) 00236 { return this->setbuf(__s, __n); } 00237 00238 pos_type 00239 pubseekoff(off_type __off, ios_base::seekdir __way, 00240 ios_base::openmode __mode = ios_base::in | ios_base::out) 00241 { return this->seekoff(__off, __way, __mode); } 00242 00243 pos_type 00244 pubseekpos(pos_type __sp, 00245 ios_base::openmode __mode = ios_base::in | ios_base::out) 00246 { return this->seekpos(__sp, __mode); } 00247 00248 int 00249 pubsync() { return this->sync(); } 00250 //@} 00251 00252 // [27.5.2.2.3] get area 00253 /** 00254 * @brief Looking ahead into the stream. 00255 * @return The number of characters available. 00256 * 00257 * If a read position is available, returns the number of characters 00258 * available for reading before the buffer must be refilled. 00259 * Otherwise returns the derived @c showmanyc(). 00260 */ 00261 streamsize 00262 in_avail() 00263 { 00264 const streamsize __ret = this->egptr() - this->gptr(); 00265 return __ret ? __ret : this->showmanyc(); 00266 } 00267 00268 /** 00269 * @brief Getting the next character. 00270 * @return The next character, or eof. 00271 * 00272 * Calls @c sbumpc(), and if that function returns 00273 * @c traits::eof(), so does this function. Otherwise, @c sgetc(). 00274 */ 00275 int_type 00276 snextc() 00277 { 00278 int_type __ret = traits_type::eof(); 00279 if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), 00280 __ret), true)) 00281 __ret = this->sgetc(); 00282 return __ret; 00283 } 00284 00285 /** 00286 * @brief Getting the next character. 00287 * @return The next character, or eof. 00288 * 00289 * If the input read position is available, returns that character 00290 * and increments the read pointer, otherwise calls and returns 00291 * @c uflow(). 00292 */ 00293 int_type 00294 sbumpc() 00295 { 00296 int_type __ret; 00297 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00298 { 00299 __ret = traits_type::to_int_type(*this->gptr()); 00300 this->gbump(1); 00301 } 00302 else 00303 __ret = this->uflow(); 00304 return __ret; 00305 } 00306 00307 /** 00308 * @brief Getting the next character. 00309 * @return The next character, or eof. 00310 * 00311 * If the input read position is available, returns that character, 00312 * otherwise calls and returns @c underflow(). Does not move the 00313 * read position after fetching the character. 00314 */ 00315 int_type 00316 sgetc() 00317 { 00318 int_type __ret; 00319 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00320 __ret = traits_type::to_int_type(*this->gptr()); 00321 else 00322 __ret = this->underflow(); 00323 return __ret; 00324 } 00325 00326 /** 00327 * @brief Entry point for xsgetn. 00328 * @param s A buffer area. 00329 * @param n A count. 00330 * 00331 * Returns xsgetn(s,n). The effect is to fill @a s[0] through 00332 * @a s[n-1] with characters from the input sequence, if possible. 00333 */ 00334 streamsize 00335 sgetn(char_type* __s, streamsize __n) 00336 { return this->xsgetn(__s, __n); } 00337 00338 // [27.5.2.2.4] putback 00339 /** 00340 * @brief Pushing characters back into the input stream. 00341 * @param c The character to push back. 00342 * @return The previous character, if possible. 00343 * 00344 * Similar to sungetc(), but @a c is pushed onto the stream 00345 * instead of <em>the previous character.</em> If successful, 00346 * the next character fetched from the input stream will be @a 00347 * c. 00348 */ 00349 int_type 00350 sputbackc(char_type __c) 00351 { 00352 int_type __ret; 00353 const bool __testpos = this->eback() < this->gptr(); 00354 if (__builtin_expect(!__testpos || 00355 !traits_type::eq(__c, this->gptr()[-1]), false)) 00356 __ret = this->pbackfail(traits_type::to_int_type(__c)); 00357 else 00358 { 00359 this->gbump(-1); 00360 __ret = traits_type::to_int_type(*this->gptr()); 00361 } 00362 return __ret; 00363 } 00364 00365 /** 00366 * @brief Moving backwards in the input stream. 00367 * @return The previous character, if possible. 00368 * 00369 * If a putback position is available, this function decrements 00370 * the input pointer and returns that character. Otherwise, 00371 * calls and returns pbackfail(). The effect is to @a unget 00372 * the last character @a gotten. 00373 */ 00374 int_type 00375 sungetc() 00376 { 00377 int_type __ret; 00378 if (__builtin_expect(this->eback() < this->gptr(), true)) 00379 { 00380 this->gbump(-1); 00381 __ret = traits_type::to_int_type(*this->gptr()); 00382 } 00383 else 00384 __ret = this->pbackfail(); 00385 return __ret; 00386 } 00387 00388 // [27.5.2.2.5] put area 00389 /** 00390 * @brief Entry point for all single-character output functions. 00391 * @param c A character to output. 00392 * @return @a c, if possible. 00393 * 00394 * One of two public output functions. 00395 * 00396 * If a write position is available for the output sequence (i.e., 00397 * the buffer is not full), stores @a c in that position, increments 00398 * the position, and returns @c traits::to_int_type(c). If a write 00399 * position is not available, returns @c overflow(c). 00400 */ 00401 int_type 00402 sputc(char_type __c) 00403 { 00404 int_type __ret; 00405 if (__builtin_expect(this->pptr() < this->epptr(), true)) 00406 { 00407 *this->pptr() = __c; 00408 this->pbump(1); 00409 __ret = traits_type::to_int_type(__c); 00410 } 00411 else 00412 __ret = this->overflow(traits_type::to_int_type(__c)); 00413 return __ret; 00414 } 00415 00416 /** 00417 * @brief Entry point for all single-character output functions. 00418 * @param s A buffer read area. 00419 * @param n A count. 00420 * 00421 * One of two public output functions. 00422 * 00423 * 00424 * Returns xsputn(s,n). The effect is to write @a s[0] through 00425 * @a s[n-1] to the output sequence, if possible. 00426 */ 00427 streamsize 00428 sputn(const char_type* __s, streamsize __n) 00429 { return this->xsputn(__s, __n); } 00430 00431 protected: 00432 /** 00433 * @brief Base constructor. 00434 * 00435 * Only called from derived constructors, and sets up all the 00436 * buffer data to zero, including the pointers described in the 00437 * basic_streambuf class description. Note that, as a result, 00438 * - the class starts with no read nor write positions available, 00439 * - this is not an error 00440 */ 00441 basic_streambuf() 00442 : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 00443 _M_out_beg(0), _M_out_cur(0), _M_out_end(0), 00444 _M_buf_locale(locale()) 00445 { } 00446 00447 // [27.5.2.3.1] get area access 00448 //@{ 00449 /** 00450 * @brief Access to the get area. 00451 * 00452 * These functions are only available to other protected functions, 00453 * including derived classes. 00454 * 00455 * - eback() returns the beginning pointer for the input sequence 00456 * - gptr() returns the next pointer for the input sequence 00457 * - egptr() returns the end pointer for the input sequence 00458 */ 00459 char_type* 00460 eback() const { return _M_in_beg; } 00461 00462 char_type* 00463 gptr() const { return _M_in_cur; } 00464 00465 char_type* 00466 egptr() const { return _M_in_end; } 00467 //@} 00468 00469 /** 00470 * @brief Moving the read position. 00471 * @param n The delta by which to move. 00472 * 00473 * This just advances the read position without returning any data. 00474 */ 00475 void 00476 gbump(int __n) { _M_in_cur += __n; } 00477 00478 /** 00479 * @brief Setting the three read area pointers. 00480 * @param gbeg A pointer. 00481 * @param gnext A pointer. 00482 * @param gend A pointer. 00483 * @post @a gbeg == @c eback(), @a gnext == @c gptr(), and 00484 * @a gend == @c egptr() 00485 */ 00486 void 00487 setg(char_type* __gbeg, char_type* __gnext, char_type* __gend) 00488 { 00489 _M_in_beg = __gbeg; 00490 _M_in_cur = __gnext; 00491 _M_in_end = __gend; 00492 } 00493 00494 // [27.5.2.3.2] put area access 00495 //@{ 00496 /** 00497 * @brief Access to the put area. 00498 * 00499 * These functions are only available to other protected functions, 00500 * including derived classes. 00501 * 00502 * - pbase() returns the beginning pointer for the output sequence 00503 * - pptr() returns the next pointer for the output sequence 00504 * - epptr() returns the end pointer for the output sequence 00505 */ 00506 char_type* 00507 pbase() const { return _M_out_beg; } 00508 00509 char_type* 00510 pptr() const { return _M_out_cur; } 00511 00512 char_type* 00513 epptr() const { return _M_out_end; } 00514 //@} 00515 00516 /** 00517 * @brief Moving the write position. 00518 * @param n The delta by which to move. 00519 * 00520 * This just advances the write position without returning any data. 00521 */ 00522 void 00523 pbump(int __n) { _M_out_cur += __n; } 00524 00525 /** 00526 * @brief Setting the three write area pointers. 00527 * @param pbeg A pointer. 00528 * @param pend A pointer. 00529 * @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and 00530 * @a pend == @c epptr() 00531 */ 00532 void 00533 setp(char_type* __pbeg, char_type* __pend) 00534 { 00535 _M_out_beg = _M_out_cur = __pbeg; 00536 _M_out_end = __pend; 00537 } 00538 00539 // [27.5.2.4] virtual functions 00540 // [27.5.2.4.1] locales 00541 /** 00542 * @brief Changes translations. 00543 * @param loc A new locale. 00544 * 00545 * Translations done during I/O which depend on the current 00546 * locale are changed by this call. The standard adds, 00547 * <em>Between invocations of this function a class derived 00548 * from streambuf can safely cache results of calls to locale 00549 * functions and to members of facets so obtained.</em> 00550 * 00551 * @note Base class version does nothing. 00552 */ 00553 virtual void 00554 imbue(const locale&) 00555 { } 00556 00557 // [27.5.2.4.2] buffer management and positioning 00558 /** 00559 * @brief Manipulates the buffer. 00560 * 00561 * Each derived class provides its own appropriate behavior. See 00562 * the next-to-last paragraph of 00563 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html 00564 * for more on this function. 00565 * 00566 * @note Base class version does nothing, returns @c this. 00567 */ 00568 virtual basic_streambuf<char_type,_Traits>* 00569 setbuf(char_type*, streamsize) 00570 { return this; } 00571 00572 /** 00573 * @brief Alters the stream positions. 00574 * 00575 * Each derived class provides its own appropriate behavior. 00576 * @note Base class version does nothing, returns a @c pos_type 00577 * that represents an invalid stream position. 00578 */ 00579 virtual pos_type 00580 seekoff(off_type, ios_base::seekdir, 00581 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00582 { return pos_type(off_type(-1)); } 00583 00584 /** 00585 * @brief Alters the stream positions. 00586 * 00587 * Each derived class provides its own appropriate behavior. 00588 * @note Base class version does nothing, returns a @c pos_type 00589 * that represents an invalid stream position. 00590 */ 00591 virtual pos_type 00592 seekpos(pos_type, 00593 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00594 { return pos_type(off_type(-1)); } 00595 00596 /** 00597 * @brief Synchronizes the buffer arrays with the controlled sequences. 00598 * @return -1 on failure. 00599 * 00600 * Each derived class provides its own appropriate behavior, 00601 * including the definition of @a failure. 00602 * @note Base class version does nothing, returns zero. 00603 */ 00604 virtual int 00605 sync() { return 0; } 00606 00607 // [27.5.2.4.3] get area 00608 /** 00609 * @brief Investigating the data available. 00610 * @return An estimate of the number of characters available in the 00611 * input sequence, or -1. 00612 * 00613 * <em>If it returns a positive value, then successive calls to 00614 * @c underflow() will not return @c traits::eof() until at 00615 * least that number of characters have been supplied. If @c 00616 * showmanyc() returns -1, then calls to @c underflow() or @c 00617 * uflow() will fail.</em> [27.5.2.4.3]/1 00618 * 00619 * @note Base class version does nothing, returns zero. 00620 * @note The standard adds that <em>the intention is not only that the 00621 * calls [to underflow or uflow] will not return @c eof() but 00622 * that they will return immediately.</em> 00623 * @note The standard adds that <em>the morphemes of @c showmanyc are 00624 * @b es-how-many-see, not @b show-manic.</em> 00625 */ 00626 virtual streamsize 00627 showmanyc() { return 0; } 00628 00629 /** 00630 * @brief Multiple character extraction. 00631 * @param s A buffer area. 00632 * @param n Maximum number of characters to assign. 00633 * @return The number of characters assigned. 00634 * 00635 * Fills @a s[0] through @a s[n-1] with characters from the input 00636 * sequence, as if by @c sbumpc(). Stops when either @a n characters 00637 * have been copied, or when @c traits::eof() would be copied. 00638 * 00639 * It is expected that derived classes provide a more efficient 00640 * implementation by overriding this definition. 00641 */ 00642 virtual streamsize 00643 xsgetn(char_type* __s, streamsize __n); 00644 00645 /** 00646 * @brief Fetches more data from the controlled sequence. 00647 * @return The first character from the <em>pending sequence</em>. 00648 * 00649 * Informally, this function is called when the input buffer is 00650 * exhausted (or does not exist, as buffering need not actually be 00651 * done). If a buffer exists, it is @a refilled. In either case, the 00652 * next available character is returned, or @c traits::eof() to 00653 * indicate a null pending sequence. 00654 * 00655 * For a formal definition of the pending sequence, see a good text 00656 * such as Langer & Kreft, or [27.5.2.4.3]/7-14. 00657 * 00658 * A functioning input streambuf can be created by overriding only 00659 * this function (no buffer area will be used). For an example, see 00660 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25.html 00661 * 00662 * @note Base class version does nothing, returns eof(). 00663 */ 00664 virtual int_type 00665 underflow() 00666 { return traits_type::eof(); } 00667 00668 /** 00669 * @brief Fetches more data from the controlled sequence. 00670 * @return The first character from the <em>pending sequence</em>. 00671 * 00672 * Informally, this function does the same thing as @c underflow(), 00673 * and in fact is required to call that function. It also returns 00674 * the new character, like @c underflow() does. However, this 00675 * function also moves the read position forward by one. 00676 */ 00677 virtual int_type 00678 uflow() 00679 { 00680 int_type __ret = traits_type::eof(); 00681 const bool __testeof = traits_type::eq_int_type(this->underflow(), 00682 __ret); 00683 if (!__testeof) 00684 { 00685 __ret = traits_type::to_int_type(*this->gptr()); 00686 this->gbump(1); 00687 } 00688 return __ret; 00689 } 00690 00691 // [27.5.2.4.4] putback 00692 /** 00693 * @brief Tries to back up the input sequence. 00694 * @param c The character to be inserted back into the sequence. 00695 * @return eof() on failure, <em>some other value</em> on success 00696 * @post The constraints of @c gptr(), @c eback(), and @c pptr() 00697 * are the same as for @c underflow(). 00698 * 00699 * @note Base class version does nothing, returns eof(). 00700 */ 00701 virtual int_type 00702 pbackfail(int_type /* __c */ = traits_type::eof()) 00703 { return traits_type::eof(); } 00704 00705 // Put area: 00706 /** 00707 * @brief Multiple character insertion. 00708 * @param s A buffer area. 00709 * @param n Maximum number of characters to write. 00710 * @return The number of characters written. 00711 * 00712 * Writes @a s[0] through @a s[n-1] to the output sequence, as if 00713 * by @c sputc(). Stops when either @a n characters have been 00714 * copied, or when @c sputc() would return @c traits::eof(). 00715 * 00716 * It is expected that derived classes provide a more efficient 00717 * implementation by overriding this definition. 00718 */ 00719 virtual streamsize 00720 xsputn(const char_type* __s, streamsize __n); 00721 00722 /** 00723 * @brief Consumes data from the buffer; writes to the 00724 * controlled sequence. 00725 * @param c An additional character to consume. 00726 * @return eof() to indicate failure, something else (usually 00727 * @a c, or not_eof()) 00728 * 00729 * Informally, this function is called when the output buffer 00730 * is full (or does not exist, as buffering need not actually 00731 * be done). If a buffer exists, it is @a consumed, with 00732 * <em>some effect</em> on the controlled sequence. 00733 * (Typically, the buffer is written out to the sequence 00734 * verbatim.) In either case, the character @a c is also 00735 * written out, if @a c is not @c eof(). 00736 * 00737 * For a formal definition of this function, see a good text 00738 * such as Langer & Kreft, or [27.5.2.4.5]/3-7. 00739 * 00740 * A functioning output streambuf can be created by overriding only 00741 * this function (no buffer area will be used). 00742 * 00743 * @note Base class version does nothing, returns eof(). 00744 */ 00745 virtual int_type 00746 overflow(int_type /* __c */ = traits_type::eof()) 00747 { return traits_type::eof(); } 00748 00749 #if _GLIBCXX_DEPRECATED 00750 // Annex D.6 00751 public: 00752 /** 00753 * @brief Tosses a character. 00754 * 00755 * Advances the read pointer, ignoring the character that would have 00756 * been read. 00757 * 00758 * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html 00759 */ 00760 void 00761 stossc() 00762 { 00763 if (this->gptr() < this->egptr()) 00764 this->gbump(1); 00765 else 00766 this->uflow(); 00767 } 00768 #endif 00769 00770 private: 00771 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00772 // Side effect of DR 50. 00773 basic_streambuf(const __streambuf_type& __sb) 00774 : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur), 00775 _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg), 00776 _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur), 00777 _M_buf_locale(__sb._M_buf_locale) 00778 { } 00779 00780 __streambuf_type& 00781 operator=(const __streambuf_type&) { return *this; }; 00782 }; 00783 00784 // Explicit specialization declarations, defined in src/streambuf.cc. 00785 template<> 00786 streamsize 00787 __copy_streambufs_eof(basic_streambuf<char>* __sbin, 00788 basic_streambuf<char>* __sbout, bool& __ineof); 00789 #ifdef _GLIBCXX_USE_WCHAR_T 00790 template<> 00791 streamsize 00792 __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin, 00793 basic_streambuf<wchar_t>* __sbout, bool& __ineof); 00794 #endif 00795 00796 _GLIBCXX_END_NAMESPACE 00797 00798 #ifndef _GLIBCXX_EXPORT_TEMPLATE 00799 # include <bits/streambuf.tcc> 00800 #endif 00801 00802 #endif /* _GLIBCXX_STREAMBUF */