00001 // Stream buffer classes -*- C++ -*- 00002 00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 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 /** @file streambuf 00032 * This is a Standard C++ Library header. 00033 */ 00034 00035 // 00036 // ISO C++ 14882: 27.5 Stream buffers 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 #include <bits/cpp_type_traits.h> 00049 #include <ext/type_traits.h> 00050 00051 _GLIBCXX_BEGIN_NAMESPACE(std) 00052 00053 /** 00054 * @if maint 00055 * Does stuff. 00056 * @endif 00057 */ 00058 template<typename _CharT, typename _Traits> 00059 streamsize 00060 __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>*, 00061 basic_streambuf<_CharT, _Traits>*, bool&); 00062 00063 /** 00064 * @brief The actual work of input and output (interface). 00065 * 00066 * This is a base class. Derived stream buffers each control a 00067 * pair of character sequences: one for input, and one for output. 00068 * 00069 * Section [27.5.1] of the standard describes the requirements and 00070 * behavior of stream buffer classes. That section (three paragraphs) 00071 * is reproduced here, for simplicity and accuracy. 00072 * 00073 * -# Stream buffers can impose various constraints on the sequences 00074 * they control. Some constraints are: 00075 * - The controlled input sequence can be not readable. 00076 * - The controlled output sequence can be not writable. 00077 * - The controlled sequences can be associated with the contents of 00078 * other representations for character sequences, such as external 00079 * files. 00080 * - The controlled sequences can support operations @e directly to or 00081 * from associated sequences. 00082 * - The controlled sequences can impose limitations on how the 00083 * program can read characters from a sequence, write characters to 00084 * a sequence, put characters back into an input sequence, or alter 00085 * the stream position. 00086 * . 00087 * -# Each sequence is characterized by three pointers which, if non-null, 00088 * all point into the same @c charT array object. The array object 00089 * represents, at any moment, a (sub)sequence of characters from the 00090 * sequence. Operations performed on a sequence alter the values 00091 * stored in these pointers, perform reads and writes directly to or 00092 * from associated sequences, and alter "the stream position" and 00093 * conversion state as needed to maintain this subsequence relationship. 00094 * The three pointers are: 00095 * - the <em>beginning pointer</em>, or lowest element address in the 00096 * array (called @e xbeg here); 00097 * - the <em>next pointer</em>, or next element address that is a 00098 * current candidate for reading or writing (called @e xnext here); 00099 * - the <em>end pointer</em>, or first element address beyond the 00100 * end of the array (called @e xend here). 00101 * . 00102 * -# The following semantic constraints shall always apply for any set 00103 * of three pointers for a sequence, using the pointer names given 00104 * immediately above: 00105 * - If @e xnext is not a null pointer, then @e xbeg and @e xend shall 00106 * also be non-null pointers into the same @c charT array, as 00107 * described above; otherwise, @e xbeg and @e xend shall also be null. 00108 * - If @e xnext is not a null pointer and @e xnext < @e xend for an 00109 * output sequence, then a <em>write position</em> is available. 00110 * In this case, @e *xnext shall be assignable as the next element 00111 * to write (to put, or to store a character value, into the sequence). 00112 * - If @e xnext is not a null pointer and @e xbeg < @e xnext for an 00113 * input sequence, then a <em>putback position</em> is available. 00114 * In this case, @e xnext[-1] shall have a defined value and is the 00115 * next (preceding) element to store a character that is put back 00116 * into the input sequence. 00117 * - If @e xnext is not a null pointer and @e xnext< @e xend for an 00118 * input sequence, then a <em>read position</em> is available. 00119 * In this case, @e *xnext shall have a defined value and is the 00120 * next element to read (to get, or to obtain a character value, 00121 * from the sequence). 00122 */ 00123 template<typename _CharT, typename _Traits> 00124 class basic_streambuf 00125 { 00126 public: 00127 //@{ 00128 /** 00129 * These are standard types. They permit a standardized way of 00130 * referring to names of (or names dependant on) the template 00131 * parameters, which are specific to the implementation. 00132 */ 00133 typedef _CharT char_type; 00134 typedef _Traits traits_type; 00135 typedef typename traits_type::int_type int_type; 00136 typedef typename traits_type::pos_type pos_type; 00137 typedef typename traits_type::off_type off_type; 00138 //@} 00139 00140 //@{ 00141 /** 00142 * @if maint 00143 * This is a non-standard type. 00144 * @endif 00145 */ 00146 typedef basic_streambuf<char_type, traits_type> __streambuf_type; 00147 //@} 00148 00149 friend class basic_ios<char_type, traits_type>; 00150 friend class basic_istream<char_type, traits_type>; 00151 friend class basic_ostream<char_type, traits_type>; 00152 friend class istreambuf_iterator<char_type, traits_type>; 00153 friend class ostreambuf_iterator<char_type, traits_type>; 00154 00155 friend streamsize 00156 __copy_streambufs_eof<>(__streambuf_type*, __streambuf_type*, bool&); 00157 00158 template<typename _CharT2> 00159 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 00160 _CharT2*>::__type 00161 __copy_aux(istreambuf_iterator<_CharT2>, 00162 istreambuf_iterator<_CharT2>, _CharT2*); 00163 00164 template<typename _CharT2> 00165 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 00166 istreambuf_iterator<_CharT2> >::__type 00167 find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>, 00168 const _CharT2&); 00169 00170 template<typename _CharT2, typename _Traits2> 00171 friend basic_istream<_CharT2, _Traits2>& 00172 operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*); 00173 00174 template<typename _CharT2, typename _Traits2, typename _Alloc> 00175 friend basic_istream<_CharT2, _Traits2>& 00176 operator>>(basic_istream<_CharT2, _Traits2>&, 00177 basic_string<_CharT2, _Traits2, _Alloc>&); 00178 00179 template<typename _CharT2, typename _Traits2, typename _Alloc> 00180 friend basic_istream<_CharT2, _Traits2>& 00181 getline(basic_istream<_CharT2, _Traits2>&, 00182 basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2); 00183 00184 protected: 00185 //@{ 00186 /** 00187 * @if maint 00188 * This is based on _IO_FILE, just reordered to be more consistent, 00189 * and is intended to be the most minimal abstraction for an 00190 * internal buffer. 00191 * - get == input == read 00192 * - put == output == write 00193 * @endif 00194 */ 00195 char_type* _M_in_beg; // Start of get area. 00196 char_type* _M_in_cur; // Current read area. 00197 char_type* _M_in_end; // End of get area. 00198 char_type* _M_out_beg; // Start of put area. 00199 char_type* _M_out_cur; // Current put area. 00200 char_type* _M_out_end; // End of put area. 00201 00202 /** 00203 * @if maint 00204 * Current locale setting. 00205 * @endif 00206 */ 00207 locale _M_buf_locale; 00208 00209 public: 00210 /// Destructor deallocates no buffer space. 00211 virtual 00212 ~basic_streambuf() 00213 { } 00214 00215 // [27.5.2.2.1] locales 00216 /** 00217 * @brief Entry point for imbue(). 00218 * @param loc The new locale. 00219 * @return The previous locale. 00220 * 00221 * Calls the derived imbue(loc). 00222 */ 00223 locale 00224 pubimbue(const locale &__loc) 00225 { 00226 locale __tmp(this->getloc()); 00227 this->imbue(__loc); 00228 _M_buf_locale = __loc; 00229 return __tmp; 00230 } 00231 00232 /** 00233 * @brief Locale access. 00234 * @return The current locale in effect. 00235 * 00236 * If pubimbue(loc) has been called, then the most recent @c loc 00237 * is returned. Otherwise the global locale in effect at the time 00238 * of construction is returned. 00239 */ 00240 locale 00241 getloc() const 00242 { return _M_buf_locale; } 00243 00244 // [27.5.2.2.2] buffer management and positioning 00245 //@{ 00246 /** 00247 * @brief Entry points for derived buffer functions. 00248 * 00249 * The public versions of @c pubfoo dispatch to the protected 00250 * derived @c foo member functions, passing the arguments (if any) 00251 * and returning the result unchanged. 00252 */ 00253 __streambuf_type* 00254 pubsetbuf(char_type* __s, streamsize __n) 00255 { return this->setbuf(__s, __n); } 00256 00257 pos_type 00258 pubseekoff(off_type __off, ios_base::seekdir __way, 00259 ios_base::openmode __mode = ios_base::in | ios_base::out) 00260 { return this->seekoff(__off, __way, __mode); } 00261 00262 pos_type 00263 pubseekpos(pos_type __sp, 00264 ios_base::openmode __mode = ios_base::in | ios_base::out) 00265 { return this->seekpos(__sp, __mode); } 00266 00267 int 00268 pubsync() { return this->sync(); } 00269 //@} 00270 00271 // [27.5.2.2.3] get area 00272 /** 00273 * @brief Looking ahead into the stream. 00274 * @return The number of characters available. 00275 * 00276 * If a read position is available, returns the number of characters 00277 * available for reading before the buffer must be refilled. 00278 * Otherwise returns the derived @c showmanyc(). 00279 */ 00280 streamsize 00281 in_avail() 00282 { 00283 const streamsize __ret = this->egptr() - this->gptr(); 00284 return __ret ? __ret : this->showmanyc(); 00285 } 00286 00287 /** 00288 * @brief Getting the next character. 00289 * @return The next character, or eof. 00290 * 00291 * Calls @c sbumpc(), and if that function returns 00292 * @c traits::eof(), so does this function. Otherwise, @c sgetc(). 00293 */ 00294 int_type 00295 snextc() 00296 { 00297 int_type __ret = traits_type::eof(); 00298 if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), 00299 __ret), true)) 00300 __ret = this->sgetc(); 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 * and increments the read pointer, otherwise calls and returns 00310 * @c uflow(). 00311 */ 00312 int_type 00313 sbumpc() 00314 { 00315 int_type __ret; 00316 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00317 { 00318 __ret = traits_type::to_int_type(*this->gptr()); 00319 this->gbump(1); 00320 } 00321 else 00322 __ret = this->uflow(); 00323 return __ret; 00324 } 00325 00326 /** 00327 * @brief Getting the next character. 00328 * @return The next character, or eof. 00329 * 00330 * If the input read position is available, returns that character, 00331 * otherwise calls and returns @c underflow(). Does not move the 00332 * read position after fetching the character. 00333 */ 00334 int_type 00335 sgetc() 00336 { 00337 int_type __ret; 00338 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00339 __ret = traits_type::to_int_type(*this->gptr()); 00340 else 00341 __ret = this->underflow(); 00342 return __ret; 00343 } 00344 00345 /** 00346 * @brief Entry point for xsgetn. 00347 * @param s A buffer area. 00348 * @param n A count. 00349 * 00350 * Returns xsgetn(s,n). The effect is to fill @a s[0] through 00351 * @a s[n-1] with characters from the input sequence, if possible. 00352 */ 00353 streamsize 00354 sgetn(char_type* __s, streamsize __n) 00355 { return this->xsgetn(__s, __n); } 00356 00357 // [27.5.2.2.4] putback 00358 /** 00359 * @brief Pushing characters back into the input stream. 00360 * @param c The character to push back. 00361 * @return The previous character, if possible. 00362 * 00363 * Similar to sungetc(), but @a c is pushed onto the stream instead 00364 * of "the previous character". If successful, the next character 00365 * fetched from the input stream will be @a c. 00366 */ 00367 int_type 00368 sputbackc(char_type __c) 00369 { 00370 int_type __ret; 00371 const bool __testpos = this->eback() < this->gptr(); 00372 if (__builtin_expect(!__testpos || 00373 !traits_type::eq(__c, this->gptr()[-1]), false)) 00374 __ret = this->pbackfail(traits_type::to_int_type(__c)); 00375 else 00376 { 00377 this->gbump(-1); 00378 __ret = traits_type::to_int_type(*this->gptr()); 00379 } 00380 return __ret; 00381 } 00382 00383 /** 00384 * @brief Moving backwards in the input stream. 00385 * @return The previous character, if possible. 00386 * 00387 * If a putback position is available, this function decrements the 00388 * input pointer and returns that character. Otherwise, calls and 00389 * returns pbackfail(). The effect is to "unget" the last character 00390 * "gotten". 00391 */ 00392 int_type 00393 sungetc() 00394 { 00395 int_type __ret; 00396 if (__builtin_expect(this->eback() < this->gptr(), true)) 00397 { 00398 this->gbump(-1); 00399 __ret = traits_type::to_int_type(*this->gptr()); 00400 } 00401 else 00402 __ret = this->pbackfail(); 00403 return __ret; 00404 } 00405 00406 // [27.5.2.2.5] put area 00407 /** 00408 * @brief Entry point for all single-character output functions. 00409 * @param c A character to output. 00410 * @return @a c, if possible. 00411 * 00412 * One of two public output functions. 00413 * 00414 * If a write position is available for the output sequence (i.e., 00415 * the buffer is not full), stores @a c in that position, increments 00416 * the position, and returns @c traits::to_int_type(c). If a write 00417 * position is not available, returns @c overflow(c). 00418 */ 00419 int_type 00420 sputc(char_type __c) 00421 { 00422 int_type __ret; 00423 if (__builtin_expect(this->pptr() < this->epptr(), true)) 00424 { 00425 *this->pptr() = __c; 00426 this->pbump(1); 00427 __ret = traits_type::to_int_type(__c); 00428 } 00429 else 00430 __ret = this->overflow(traits_type::to_int_type(__c)); 00431 return __ret; 00432 } 00433 00434 /** 00435 * @brief Entry point for all single-character output functions. 00436 * @param s A buffer read area. 00437 * @param n A count. 00438 * 00439 * One of two public output functions. 00440 * 00441 * 00442 * Returns xsputn(s,n). The effect is to write @a s[0] through 00443 * @a s[n-1] to the output sequence, if possible. 00444 */ 00445 streamsize 00446 sputn(const char_type* __s, streamsize __n) 00447 { return this->xsputn(__s, __n); } 00448 00449 protected: 00450 /** 00451 * @brief Base constructor. 00452 * 00453 * Only called from derived constructors, and sets up all the 00454 * buffer data to zero, including the pointers described in the 00455 * basic_streambuf class description. Note that, as a result, 00456 * - the class starts with no read nor write positions available, 00457 * - this is not an error 00458 */ 00459 basic_streambuf() 00460 : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 00461 _M_out_beg(0), _M_out_cur(0), _M_out_end(0), 00462 _M_buf_locale(locale()) 00463 { } 00464 00465 // [27.5.2.3.1] get area access 00466 //@{ 00467 /** 00468 * @brief Access to the get area. 00469 * 00470 * These functions are only available to other protected functions, 00471 * including derived classes. 00472 * 00473 * - eback() returns the beginning pointer for the input sequence 00474 * - gptr() returns the next pointer for the input sequence 00475 * - egptr() returns the end pointer for the input sequence 00476 */ 00477 char_type* 00478 eback() const { return _M_in_beg; } 00479 00480 char_type* 00481 gptr() const { return _M_in_cur; } 00482 00483 char_type* 00484 egptr() const { return _M_in_end; } 00485 //@} 00486 00487 /** 00488 * @brief Moving the read position. 00489 * @param n The delta by which to move. 00490 * 00491 * This just advances the read position without returning any data. 00492 */ 00493 void 00494 gbump(int __n) { _M_in_cur += __n; } 00495 00496 /** 00497 * @brief Setting the three read area pointers. 00498 * @param gbeg A pointer. 00499 * @param gnext A pointer. 00500 * @param gend A pointer. 00501 * @post @a gbeg == @c eback(), @a gnext == @c gptr(), and 00502 * @a gend == @c egptr() 00503 */ 00504 void 00505 setg(char_type* __gbeg, char_type* __gnext, char_type* __gend) 00506 { 00507 _M_in_beg = __gbeg; 00508 _M_in_cur = __gnext; 00509 _M_in_end = __gend; 00510 } 00511 00512 // [27.5.2.3.2] put area access 00513 //@{ 00514 /** 00515 * @brief Access to the put area. 00516 * 00517 * These functions are only available to other protected functions, 00518 * including derived classes. 00519 * 00520 * - pbase() returns the beginning pointer for the output sequence 00521 * - pptr() returns the next pointer for the output sequence 00522 * - epptr() returns the end pointer for the output sequence 00523 */ 00524 char_type* 00525 pbase() const { return _M_out_beg; } 00526 00527 char_type* 00528 pptr() const { return _M_out_cur; } 00529 00530 char_type* 00531 epptr() const { return _M_out_end; } 00532 //@} 00533 00534 /** 00535 * @brief Moving the write position. 00536 * @param n The delta by which to move. 00537 * 00538 * This just advances the write position without returning any data. 00539 */ 00540 void 00541 pbump(int __n) { _M_out_cur += __n; } 00542 00543 /** 00544 * @brief Setting the three write area pointers. 00545 * @param pbeg A pointer. 00546 * @param pend A pointer. 00547 * @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and 00548 * @a pend == @c epptr() 00549 */ 00550 void 00551 setp(char_type* __pbeg, char_type* __pend) 00552 { 00553 _M_out_beg = _M_out_cur = __pbeg; 00554 _M_out_end = __pend; 00555 } 00556 00557 // [27.5.2.4] virtual functions 00558 // [27.5.2.4.1] locales 00559 /** 00560 * @brief Changes translations. 00561 * @param loc A new locale. 00562 * 00563 * Translations done during I/O which depend on the current locale 00564 * are changed by this call. The standard adds, "Between invocations 00565 * of this function a class derived from streambuf can safely cache 00566 * results of calls to locale functions and to members of facets 00567 * so obtained." 00568 * 00569 * @note Base class version does nothing. 00570 */ 00571 virtual void 00572 imbue(const locale&) 00573 { } 00574 00575 // [27.5.2.4.2] buffer management and positioning 00576 /** 00577 * @brief Maniuplates the buffer. 00578 * 00579 * Each derived class provides its own appropriate behavior. See 00580 * the next-to-last paragraph of 00581 * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for 00582 * more on this function. 00583 * 00584 * @note Base class version does nothing, returns @c this. 00585 */ 00586 virtual basic_streambuf<char_type,_Traits>* 00587 setbuf(char_type*, streamsize) 00588 { return this; } 00589 00590 /** 00591 * @brief Alters the stream positions. 00592 * 00593 * Each derived class provides its own appropriate behavior. 00594 * @note Base class version does nothing, returns a @c pos_type 00595 * that represents an invalid stream position. 00596 */ 00597 virtual pos_type 00598 seekoff(off_type, ios_base::seekdir, 00599 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00600 { return pos_type(off_type(-1)); } 00601 00602 /** 00603 * @brief Alters the stream positions. 00604 * 00605 * Each derived class provides its own appropriate behavior. 00606 * @note Base class version does nothing, returns a @c pos_type 00607 * that represents an invalid stream position. 00608 */ 00609 virtual pos_type 00610 seekpos(pos_type, 00611 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00612 { return pos_type(off_type(-1)); } 00613 00614 /** 00615 * @brief Synchronizes the buffer arrays with the controlled sequences. 00616 * @return -1 on failure. 00617 * 00618 * Each derived class provides its own appropriate behavior, 00619 * including the definition of "failure". 00620 * @note Base class version does nothing, returns zero. 00621 */ 00622 virtual int 00623 sync() { return 0; } 00624 00625 // [27.5.2.4.3] get area 00626 /** 00627 * @brief Investigating the data available. 00628 * @return An estimate of the number of characters available in the 00629 * input sequence, or -1. 00630 * 00631 * "If it returns a positive value, then successive calls to 00632 * @c underflow() will not return @c traits::eof() until at least that 00633 * number of characters have been supplied. If @c showmanyc() 00634 * returns -1, then calls to @c underflow() or @c uflow() will fail." 00635 * [27.5.2.4.3]/1 00636 * 00637 * @note Base class version does nothing, returns zero. 00638 * @note The standard adds that "the intention is not only that the 00639 * calls [to underflow or uflow] will not return @c eof() but 00640 * that they will return "immediately". 00641 * @note The standard adds that "the morphemes of @c showmanyc are 00642 * "es-how-many-see", not "show-manic". 00643 */ 00644 virtual streamsize 00645 showmanyc() { return 0; } 00646 00647 /** 00648 * @brief Multiple character extraction. 00649 * @param s A buffer area. 00650 * @param n Maximum number of characters to assign. 00651 * @return The number of characters assigned. 00652 * 00653 * Fills @a s[0] through @a s[n-1] with characters from the input 00654 * sequence, as if by @c sbumpc(). Stops when either @a n characters 00655 * have been copied, or when @c traits::eof() would be copied. 00656 * 00657 * It is expected that derived classes provide a more efficient 00658 * implementation by overriding this definition. 00659 */ 00660 virtual streamsize 00661 xsgetn(char_type* __s, streamsize __n); 00662 00663 /** 00664 * @brief Fetches more data from the controlled sequence. 00665 * @return The first character from the <em>pending sequence</em>. 00666 * 00667 * Informally, this function is called when the input buffer is 00668 * exhausted (or does not exist, as buffering need not actually be 00669 * done). If a buffer exists, it is "refilled". In either case, the 00670 * next available character is returned, or @c traits::eof() to 00671 * indicate a null pending sequence. 00672 * 00673 * For a formal definiton of the pending sequence, see a good text 00674 * such as Langer & Kreft, or [27.5.2.4.3]/7-14. 00675 * 00676 * A functioning input streambuf can be created by overriding only 00677 * this function (no buffer area will be used). For an example, see 00678 * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#6 00679 * 00680 * @note Base class version does nothing, returns eof(). 00681 */ 00682 virtual int_type 00683 underflow() 00684 { return traits_type::eof(); } 00685 00686 /** 00687 * @brief Fetches more data from the controlled sequence. 00688 * @return The first character from the <em>pending sequence</em>. 00689 * 00690 * Informally, this function does the same thing as @c underflow(), 00691 * and in fact is required to call that function. It also returns 00692 * the new character, like @c underflow() does. However, this 00693 * function also moves the read position forward by one. 00694 */ 00695 virtual int_type 00696 uflow() 00697 { 00698 int_type __ret = traits_type::eof(); 00699 const bool __testeof = traits_type::eq_int_type(this->underflow(), 00700 __ret); 00701 if (!__testeof) 00702 { 00703 __ret = traits_type::to_int_type(*this->gptr()); 00704 this->gbump(1); 00705 } 00706 return __ret; 00707 } 00708 00709 // [27.5.2.4.4] putback 00710 /** 00711 * @brief Tries to back up the input sequence. 00712 * @param c The character to be inserted back into the sequence. 00713 * @return eof() on failure, "some other value" on success 00714 * @post The constraints of @c gptr(), @c eback(), and @c pptr() 00715 * are the same as for @c underflow(). 00716 * 00717 * @note Base class version does nothing, returns eof(). 00718 */ 00719 virtual int_type 00720 pbackfail(int_type /* __c */ = traits_type::eof()) 00721 { return traits_type::eof(); } 00722 00723 // Put area: 00724 /** 00725 * @brief Multiple character insertion. 00726 * @param s A buffer area. 00727 * @param n Maximum number of characters to write. 00728 * @return The number of characters written. 00729 * 00730 * Writes @a s[0] through @a s[n-1] to the output sequence, as if 00731 * by @c sputc(). Stops when either @a n characters have been 00732 * copied, or when @c sputc() would return @c traits::eof(). 00733 * 00734 * It is expected that derived classes provide a more efficient 00735 * implementation by overriding this definition. 00736 */ 00737 virtual streamsize 00738 xsputn(const char_type* __s, streamsize __n); 00739 00740 /** 00741 * @brief Consumes data from the buffer; writes to the 00742 * controlled sequence. 00743 * @param c An additional character to consume. 00744 * @return eof() to indicate failure, something else (usually 00745 * @a c, or not_eof()) 00746 * 00747 * Informally, this function is called when the output buffer is full 00748 * (or does not exist, as buffering need not actually be done). If a 00749 * buffer exists, it is "consumed", with "some effect" on the 00750 * controlled sequence. (Typically, the buffer is written out to the 00751 * sequence verbatim.) In either case, the character @a c is also 00752 * written out, if @a c is not @c eof(). 00753 * 00754 * For a formal definiton of this function, see a good text 00755 * such as Langer & Kreft, or [27.5.2.4.5]/3-7. 00756 * 00757 * A functioning output streambuf can be created by overriding only 00758 * this function (no buffer area will be used). 00759 * 00760 * @note Base class version does nothing, returns eof(). 00761 */ 00762 virtual int_type 00763 overflow(int_type /* __c */ = traits_type::eof()) 00764 { return traits_type::eof(); } 00765 00766 #ifdef _GLIBCXX_DEPRECATED 00767 // Annex D.6 00768 public: 00769 /** 00770 * @brief Tosses a character. 00771 * 00772 * Advances the read pointer, ignoring the character that would have 00773 * been read. 00774 * 00775 * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html 00776 * 00777 * @note This function has been deprecated by the standard. You 00778 * must define @c _GLIBCXX_DEPRECATED to make this visible; see 00779 * c++config.h. 00780 */ 00781 void 00782 stossc() 00783 { 00784 if (this->gptr() < this->egptr()) 00785 this->gbump(1); 00786 else 00787 this->uflow(); 00788 } 00789 #endif 00790 00791 private: 00792 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00793 // Side effect of DR 50. 00794 basic_streambuf(const __streambuf_type& __sb) 00795 : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur), 00796 _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg), 00797 _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur), 00798 _M_buf_locale(__sb._M_buf_locale) 00799 { } 00800 00801 __streambuf_type& 00802 operator=(const __streambuf_type&) { return *this; }; 00803 }; 00804 00805 // Explicit specialization declarations, defined in src/streambuf.cc. 00806 template<> 00807 streamsize 00808 __copy_streambufs_eof(basic_streambuf<char>* __sbin, 00809 basic_streambuf<char>* __sbout, bool& __ineof); 00810 #ifdef _GLIBCXX_USE_WCHAR_T 00811 template<> 00812 streamsize 00813 __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin, 00814 basic_streambuf<wchar_t>* __sbout, bool& __ineof); 00815 #endif 00816 00817 _GLIBCXX_END_NAMESPACE 00818 00819 #ifndef _GLIBCXX_EXPORT_TEMPLATE 00820 # include <bits/streambuf.tcc> 00821 #endif 00822 00823 #endif /* _GLIBCXX_STREAMBUF */