libstdc++
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00001 // Stream buffer classes -*- C++ -*- 00002 00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 00004 // 2006, 2007, 2008, 2009, 2010, 2011, 2013 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 include/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 namespace std _GLIBCXX_VISIBILITY(default) 00047 { 00048 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00049 00050 template<typename _CharT, typename _Traits> 00051 streamsize 00052 __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>*, 00053 basic_streambuf<_CharT, _Traits>*, bool&); 00054 00055 /** 00056 * @brief The actual work of input and output (interface). 00057 * @ingroup io 00058 * 00059 * This is a base class. Derived stream buffers each control a 00060 * pair of character sequences: one for input, and one for output. 00061 * 00062 * Section [27.5.1] of the standard describes the requirements and 00063 * behavior of stream buffer classes. That section (three paragraphs) 00064 * is reproduced here, for simplicity and accuracy. 00065 * 00066 * -# Stream buffers can impose various constraints on the sequences 00067 * they control. Some constraints are: 00068 * - The controlled input sequence can be not readable. 00069 * - The controlled output sequence can be not writable. 00070 * - The controlled sequences can be associated with the contents of 00071 * other representations for character sequences, such as external 00072 * files. 00073 * - The controlled sequences can support operations @e directly to or 00074 * from associated sequences. 00075 * - The controlled sequences can impose limitations on how the 00076 * program can read characters from a sequence, write characters to 00077 * a sequence, put characters back into an input sequence, or alter 00078 * the stream position. 00079 * . 00080 * -# Each sequence is characterized by three pointers which, if non-null, 00081 * all point into the same @c charT array object. The array object 00082 * represents, at any moment, a (sub)sequence of characters from the 00083 * sequence. Operations performed on a sequence alter the values 00084 * stored in these pointers, perform reads and writes directly to or 00085 * from associated sequences, and alter <em>the stream position</em> and 00086 * conversion state as needed to maintain this subsequence relationship. 00087 * The three pointers are: 00088 * - the <em>beginning pointer</em>, or lowest element address in the 00089 * array (called @e xbeg here); 00090 * - the <em>next pointer</em>, or next element address that is a 00091 * current candidate for reading or writing (called @e xnext here); 00092 * - the <em>end pointer</em>, or first element address beyond the 00093 * end of the array (called @e xend here). 00094 * . 00095 * -# The following semantic constraints shall always apply for any set 00096 * of three pointers for a sequence, using the pointer names given 00097 * immediately above: 00098 * - If @e xnext is not a null pointer, then @e xbeg and @e xend shall 00099 * also be non-null pointers into the same @c charT array, as 00100 * described above; otherwise, @e xbeg and @e xend shall also be null. 00101 * - If @e xnext is not a null pointer and @e xnext < @e xend for an 00102 * output sequence, then a <em>write position</em> is available. 00103 * In this case, @e *xnext shall be assignable as the next element 00104 * to write (to put, or to store a character value, into the sequence). 00105 * - If @e xnext is not a null pointer and @e xbeg < @e xnext for an 00106 * input sequence, then a <em>putback position</em> is available. 00107 * In this case, @e xnext[-1] shall have a defined value and is the 00108 * next (preceding) element to store a character that is put back 00109 * into the input sequence. 00110 * - If @e xnext is not a null pointer and @e xnext< @e xend for an 00111 * input sequence, then a <em>read position</em> is available. 00112 * In this case, @e *xnext shall have a defined value and is the 00113 * next element to read (to get, or to obtain a character value, 00114 * from the sequence). 00115 */ 00116 template<typename _CharT, typename _Traits> 00117 class basic_streambuf 00118 { 00119 public: 00120 //@{ 00121 /** 00122 * These are standard types. They permit a standardized way of 00123 * referring to names of (or names dependant on) the template 00124 * parameters, which are specific to the implementation. 00125 */ 00126 typedef _CharT char_type; 00127 typedef _Traits traits_type; 00128 typedef typename traits_type::int_type int_type; 00129 typedef typename traits_type::pos_type pos_type; 00130 typedef typename traits_type::off_type off_type; 00131 //@} 00132 00133 //@{ 00134 /// This is a non-standard type. 00135 typedef basic_streambuf<char_type, traits_type> __streambuf_type; 00136 //@} 00137 00138 friend class basic_ios<char_type, traits_type>; 00139 friend class basic_istream<char_type, traits_type>; 00140 friend class basic_ostream<char_type, traits_type>; 00141 friend class istreambuf_iterator<char_type, traits_type>; 00142 friend class ostreambuf_iterator<char_type, traits_type>; 00143 00144 friend streamsize 00145 __copy_streambufs_eof<>(__streambuf_type*, __streambuf_type*, bool&); 00146 00147 template<bool _IsMove, typename _CharT2> 00148 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 00149 _CharT2*>::__type 00150 __copy_move_a2(istreambuf_iterator<_CharT2>, 00151 istreambuf_iterator<_CharT2>, _CharT2*); 00152 00153 template<typename _CharT2> 00154 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 00155 istreambuf_iterator<_CharT2> >::__type 00156 find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>, 00157 const _CharT2&); 00158 00159 template<typename _CharT2, typename _Traits2> 00160 friend basic_istream<_CharT2, _Traits2>& 00161 operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*); 00162 00163 template<typename _CharT2, typename _Traits2, typename _Alloc> 00164 friend basic_istream<_CharT2, _Traits2>& 00165 operator>>(basic_istream<_CharT2, _Traits2>&, 00166 basic_string<_CharT2, _Traits2, _Alloc>&); 00167 00168 template<typename _CharT2, typename _Traits2, typename _Alloc> 00169 friend basic_istream<_CharT2, _Traits2>& 00170 getline(basic_istream<_CharT2, _Traits2>&, 00171 basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2); 00172 00173 protected: 00174 /* 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 */ 00181 char_type* _M_in_beg; //< Start of get area. 00182 char_type* _M_in_cur; //< Current read area. 00183 char_type* _M_in_end; //< End of get area. 00184 char_type* _M_out_beg; //< Start of put area. 00185 char_type* _M_out_cur; //< Current put area. 00186 char_type* _M_out_end; //< End of put area. 00187 00188 /// Current locale setting. 00189 locale _M_buf_locale; 00190 00191 public: 00192 /// Destructor deallocates no buffer space. 00193 virtual 00194 ~basic_streambuf() 00195 { } 00196 00197 // [27.5.2.2.1] locales 00198 /** 00199 * @brief Entry point for imbue(). 00200 * @param loc The new locale. 00201 * @return The previous locale. 00202 * 00203 * Calls the derived imbue(loc). 00204 */ 00205 locale 00206 pubimbue(const locale &__loc) 00207 { 00208 locale __tmp(this->getloc()); 00209 this->imbue(__loc); 00210 _M_buf_locale = __loc; 00211 return __tmp; 00212 } 00213 00214 /** 00215 * @brief Locale access. 00216 * @return The current locale in effect. 00217 * 00218 * If pubimbue(loc) has been called, then the most recent @c loc 00219 * is returned. Otherwise the global locale in effect at the time 00220 * of construction is returned. 00221 */ 00222 locale 00223 getloc() const 00224 { return _M_buf_locale; } 00225 00226 // [27.5.2.2.2] buffer management and positioning 00227 //@{ 00228 /** 00229 * @brief Entry points for derived buffer functions. 00230 * 00231 * The public versions of @c pubfoo dispatch to the protected 00232 * derived @c foo member functions, passing the arguments (if any) 00233 * and returning the result unchanged. 00234 */ 00235 __streambuf_type* 00236 pubsetbuf(char_type* __s, streamsize __n) 00237 { return this->setbuf(__s, __n); } 00238 00239 pos_type 00240 pubseekoff(off_type __off, ios_base::seekdir __way, 00241 ios_base::openmode __mode = ios_base::in | ios_base::out) 00242 { return this->seekoff(__off, __way, __mode); } 00243 00244 pos_type 00245 pubseekpos(pos_type __sp, 00246 ios_base::openmode __mode = ios_base::in | ios_base::out) 00247 { return this->seekpos(__sp, __mode); } 00248 00249 int 00250 pubsync() { return this->sync(); } 00251 //@} 00252 00253 // [27.5.2.2.3] get area 00254 /** 00255 * @brief Looking ahead into the stream. 00256 * @return The number of characters available. 00257 * 00258 * If a read position is available, returns the number of characters 00259 * available for reading before the buffer must be refilled. 00260 * Otherwise returns the derived @c showmanyc(). 00261 */ 00262 streamsize 00263 in_avail() 00264 { 00265 const streamsize __ret = this->egptr() - this->gptr(); 00266 return __ret ? __ret : this->showmanyc(); 00267 } 00268 00269 /** 00270 * @brief Getting the next character. 00271 * @return The next character, or eof. 00272 * 00273 * Calls @c sbumpc(), and if that function returns 00274 * @c traits::eof(), so does this function. Otherwise, @c sgetc(). 00275 */ 00276 int_type 00277 snextc() 00278 { 00279 int_type __ret = traits_type::eof(); 00280 if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), 00281 __ret), true)) 00282 __ret = this->sgetc(); 00283 return __ret; 00284 } 00285 00286 /** 00287 * @brief Getting the next character. 00288 * @return The next character, or eof. 00289 * 00290 * If the input read position is available, returns that character 00291 * and increments the read pointer, otherwise calls and returns 00292 * @c uflow(). 00293 */ 00294 int_type 00295 sbumpc() 00296 { 00297 int_type __ret; 00298 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00299 { 00300 __ret = traits_type::to_int_type(*this->gptr()); 00301 this->gbump(1); 00302 } 00303 else 00304 __ret = this->uflow(); 00305 return __ret; 00306 } 00307 00308 /** 00309 * @brief Getting the next character. 00310 * @return The next character, or eof. 00311 * 00312 * If the input read position is available, returns that character, 00313 * otherwise calls and returns @c underflow(). Does not move the 00314 * read position after fetching the character. 00315 */ 00316 int_type 00317 sgetc() 00318 { 00319 int_type __ret; 00320 if (__builtin_expect(this->gptr() < this->egptr(), true)) 00321 __ret = traits_type::to_int_type(*this->gptr()); 00322 else 00323 __ret = this->underflow(); 00324 return __ret; 00325 } 00326 00327 /** 00328 * @brief Entry point for xsgetn. 00329 * @param s A buffer area. 00330 * @param n A count. 00331 * 00332 * Returns xsgetn(s,n). The effect is to fill @a s[0] through 00333 * @a s[n-1] with characters from the input sequence, if possible. 00334 */ 00335 streamsize 00336 sgetn(char_type* __s, streamsize __n) 00337 { return this->xsgetn(__s, __n); } 00338 00339 // [27.5.2.2.4] putback 00340 /** 00341 * @brief Pushing characters back into the input stream. 00342 * @param c The character to push back. 00343 * @return The previous character, if possible. 00344 * 00345 * Similar to sungetc(), but @a c is pushed onto the stream 00346 * instead of <em>the previous character.</em> If successful, 00347 * the next character fetched from the input stream will be @a 00348 * c. 00349 */ 00350 int_type 00351 sputbackc(char_type __c) 00352 { 00353 int_type __ret; 00354 const bool __testpos = this->eback() < this->gptr(); 00355 if (__builtin_expect(!__testpos || 00356 !traits_type::eq(__c, this->gptr()[-1]), false)) 00357 __ret = this->pbackfail(traits_type::to_int_type(__c)); 00358 else 00359 { 00360 this->gbump(-1); 00361 __ret = traits_type::to_int_type(*this->gptr()); 00362 } 00363 return __ret; 00364 } 00365 00366 /** 00367 * @brief Moving backwards in the input stream. 00368 * @return The previous character, if possible. 00369 * 00370 * If a putback position is available, this function decrements 00371 * the input pointer and returns that character. Otherwise, 00372 * calls and returns pbackfail(). The effect is to @a unget 00373 * the last character @a gotten. 00374 */ 00375 int_type 00376 sungetc() 00377 { 00378 int_type __ret; 00379 if (__builtin_expect(this->eback() < this->gptr(), true)) 00380 { 00381 this->gbump(-1); 00382 __ret = traits_type::to_int_type(*this->gptr()); 00383 } 00384 else 00385 __ret = this->pbackfail(); 00386 return __ret; 00387 } 00388 00389 // [27.5.2.2.5] put area 00390 /** 00391 * @brief Entry point for all single-character output functions. 00392 * @param c A character to output. 00393 * @return @a c, if possible. 00394 * 00395 * One of two public output functions. 00396 * 00397 * If a write position is available for the output sequence (i.e., 00398 * the buffer is not full), stores @a c in that position, increments 00399 * the position, and returns @c traits::to_int_type(c). If a write 00400 * position is not available, returns @c overflow(c). 00401 */ 00402 int_type 00403 sputc(char_type __c) 00404 { 00405 int_type __ret; 00406 if (__builtin_expect(this->pptr() < this->epptr(), true)) 00407 { 00408 *this->pptr() = __c; 00409 this->pbump(1); 00410 __ret = traits_type::to_int_type(__c); 00411 } 00412 else 00413 __ret = this->overflow(traits_type::to_int_type(__c)); 00414 return __ret; 00415 } 00416 00417 /** 00418 * @brief Entry point for all single-character output functions. 00419 * @param s A buffer read area. 00420 * @param n A count. 00421 * 00422 * One of two public output functions. 00423 * 00424 * 00425 * Returns xsputn(s,n). The effect is to write @a s[0] through 00426 * @a s[n-1] to the output sequence, if possible. 00427 */ 00428 streamsize 00429 sputn(const char_type* __s, streamsize __n) 00430 { return this->xsputn(__s, __n); } 00431 00432 protected: 00433 /** 00434 * @brief Base constructor. 00435 * 00436 * Only called from derived constructors, and sets up all the 00437 * buffer data to zero, including the pointers described in the 00438 * basic_streambuf class description. Note that, as a result, 00439 * - the class starts with no read nor write positions available, 00440 * - this is not an error 00441 */ 00442 basic_streambuf() 00443 : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 00444 _M_out_beg(0), _M_out_cur(0), _M_out_end(0), 00445 _M_buf_locale(locale()) 00446 { } 00447 00448 // [27.5.2.3.1] get area access 00449 //@{ 00450 /** 00451 * @brief Access to the get area. 00452 * 00453 * These functions are only available to other protected functions, 00454 * including derived classes. 00455 * 00456 * - eback() returns the beginning pointer for the input sequence 00457 * - gptr() returns the next pointer for the input sequence 00458 * - egptr() returns the end pointer for the input sequence 00459 */ 00460 char_type* 00461 eback() const { return _M_in_beg; } 00462 00463 char_type* 00464 gptr() const { return _M_in_cur; } 00465 00466 char_type* 00467 egptr() const { return _M_in_end; } 00468 //@} 00469 00470 /** 00471 * @brief Moving the read position. 00472 * @param n The delta by which to move. 00473 * 00474 * This just advances the read position without returning any data. 00475 */ 00476 void 00477 gbump(int __n) { _M_in_cur += __n; } 00478 00479 /** 00480 * @brief Setting the three read area pointers. 00481 * @param gbeg A pointer. 00482 * @param gnext A pointer. 00483 * @param gend A pointer. 00484 * @post @a gbeg == @c eback(), @a gnext == @c gptr(), and 00485 * @a gend == @c egptr() 00486 */ 00487 void 00488 setg(char_type* __gbeg, char_type* __gnext, char_type* __gend) 00489 { 00490 _M_in_beg = __gbeg; 00491 _M_in_cur = __gnext; 00492 _M_in_end = __gend; 00493 } 00494 00495 // [27.5.2.3.2] put area access 00496 //@{ 00497 /** 00498 * @brief Access to the put area. 00499 * 00500 * These functions are only available to other protected functions, 00501 * including derived classes. 00502 * 00503 * - pbase() returns the beginning pointer for the output sequence 00504 * - pptr() returns the next pointer for the output sequence 00505 * - epptr() returns the end pointer for the output sequence 00506 */ 00507 char_type* 00508 pbase() const { return _M_out_beg; } 00509 00510 char_type* 00511 pptr() const { return _M_out_cur; } 00512 00513 char_type* 00514 epptr() const { return _M_out_end; } 00515 //@} 00516 00517 /** 00518 * @brief Moving the write position. 00519 * @param n The delta by which to move. 00520 * 00521 * This just advances the write position without returning any data. 00522 */ 00523 void 00524 pbump(int __n) { _M_out_cur += __n; } 00525 00526 /** 00527 * @brief Setting the three write area pointers. 00528 * @param pbeg A pointer. 00529 * @param pend A pointer. 00530 * @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and 00531 * @a pend == @c epptr() 00532 */ 00533 void 00534 setp(char_type* __pbeg, char_type* __pend) 00535 { 00536 _M_out_beg = _M_out_cur = __pbeg; 00537 _M_out_end = __pend; 00538 } 00539 00540 // [27.5.2.4] virtual functions 00541 // [27.5.2.4.1] locales 00542 /** 00543 * @brief Changes translations. 00544 * @param loc A new locale. 00545 * 00546 * Translations done during I/O which depend on the current 00547 * locale are changed by this call. The standard adds, 00548 * <em>Between invocations of this function a class derived 00549 * from streambuf can safely cache results of calls to locale 00550 * functions and to members of facets so obtained.</em> 00551 * 00552 * @note Base class version does nothing. 00553 */ 00554 virtual void 00555 imbue(const locale&) 00556 { } 00557 00558 // [27.5.2.4.2] buffer management and positioning 00559 /** 00560 * @brief Manipulates the buffer. 00561 * 00562 * Each derived class provides its own appropriate behavior. See 00563 * the next-to-last paragraph of 00564 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html 00565 * for more on this function. 00566 * 00567 * @note Base class version does nothing, returns @c this. 00568 */ 00569 virtual basic_streambuf<char_type,_Traits>* 00570 setbuf(char_type*, streamsize) 00571 { return this; } 00572 00573 /** 00574 * @brief Alters the stream positions. 00575 * 00576 * Each derived class provides its own appropriate behavior. 00577 * @note Base class version does nothing, returns a @c pos_type 00578 * that represents an invalid stream position. 00579 */ 00580 virtual pos_type 00581 seekoff(off_type, ios_base::seekdir, 00582 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00583 { return pos_type(off_type(-1)); } 00584 00585 /** 00586 * @brief Alters the stream positions. 00587 * 00588 * Each derived class provides its own appropriate behavior. 00589 * @note Base class version does nothing, returns a @c pos_type 00590 * that represents an invalid stream position. 00591 */ 00592 virtual pos_type 00593 seekpos(pos_type, 00594 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 00595 { return pos_type(off_type(-1)); } 00596 00597 /** 00598 * @brief Synchronizes the buffer arrays with the controlled sequences. 00599 * @return -1 on failure. 00600 * 00601 * Each derived class provides its own appropriate behavior, 00602 * including the definition of @a failure. 00603 * @note Base class version does nothing, returns zero. 00604 */ 00605 virtual int 00606 sync() { return 0; } 00607 00608 // [27.5.2.4.3] get area 00609 /** 00610 * @brief Investigating the data available. 00611 * @return An estimate of the number of characters available in the 00612 * input sequence, or -1. 00613 * 00614 * <em>If it returns a positive value, then successive calls to 00615 * @c underflow() will not return @c traits::eof() until at 00616 * least that number of characters have been supplied. If @c 00617 * showmanyc() returns -1, then calls to @c underflow() or @c 00618 * uflow() will fail.</em> [27.5.2.4.3]/1 00619 * 00620 * @note Base class version does nothing, returns zero. 00621 * @note The standard adds that <em>the intention is not only that the 00622 * calls [to underflow or uflow] will not return @c eof() but 00623 * that they will return immediately.</em> 00624 * @note The standard adds that <em>the morphemes of @c showmanyc are 00625 * @b es-how-many-see, not @b show-manic.</em> 00626 */ 00627 virtual streamsize 00628 showmanyc() { return 0; } 00629 00630 /** 00631 * @brief Multiple character extraction. 00632 * @param s A buffer area. 00633 * @param n Maximum number of characters to assign. 00634 * @return The number of characters assigned. 00635 * 00636 * Fills @a s[0] through @a s[n-1] with characters from the input 00637 * sequence, as if by @c sbumpc(). Stops when either @a n characters 00638 * have been copied, or when @c traits::eof() would be copied. 00639 * 00640 * It is expected that derived classes provide a more efficient 00641 * implementation by overriding this definition. 00642 */ 00643 virtual streamsize 00644 xsgetn(char_type* __s, streamsize __n); 00645 00646 /** 00647 * @brief Fetches more data from the controlled sequence. 00648 * @return The first character from the <em>pending sequence</em>. 00649 * 00650 * Informally, this function is called when the input buffer is 00651 * exhausted (or does not exist, as buffering need not actually be 00652 * done). If a buffer exists, it is @a refilled. In either case, the 00653 * next available character is returned, or @c traits::eof() to 00654 * indicate a null pending sequence. 00655 * 00656 * For a formal definition of the pending sequence, see a good text 00657 * such as Langer & Kreft, or [27.5.2.4.3]/7-14. 00658 * 00659 * A functioning input streambuf can be created by overriding only 00660 * this function (no buffer area will be used). For an example, see 00661 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25.html 00662 * 00663 * @note Base class version does nothing, returns eof(). 00664 */ 00665 virtual int_type 00666 underflow() 00667 { return traits_type::eof(); } 00668 00669 /** 00670 * @brief Fetches more data from the controlled sequence. 00671 * @return The first character from the <em>pending sequence</em>. 00672 * 00673 * Informally, this function does the same thing as @c underflow(), 00674 * and in fact is required to call that function. It also returns 00675 * the new character, like @c underflow() does. However, this 00676 * function also moves the read position forward by one. 00677 */ 00678 virtual int_type 00679 uflow() 00680 { 00681 int_type __ret = traits_type::eof(); 00682 const bool __testeof = traits_type::eq_int_type(this->underflow(), 00683 __ret); 00684 if (!__testeof) 00685 { 00686 __ret = traits_type::to_int_type(*this->gptr()); 00687 this->gbump(1); 00688 } 00689 return __ret; 00690 } 00691 00692 // [27.5.2.4.4] putback 00693 /** 00694 * @brief Tries to back up the input sequence. 00695 * @param c The character to be inserted back into the sequence. 00696 * @return eof() on failure, <em>some other value</em> on success 00697 * @post The constraints of @c gptr(), @c eback(), and @c pptr() 00698 * are the same as for @c underflow(). 00699 * 00700 * @note Base class version does nothing, returns eof(). 00701 */ 00702 virtual int_type 00703 pbackfail(int_type /* __c */ = traits_type::eof()) 00704 { return traits_type::eof(); } 00705 00706 // Put area: 00707 /** 00708 * @brief Multiple character insertion. 00709 * @param s A buffer area. 00710 * @param n Maximum number of characters to write. 00711 * @return The number of characters written. 00712 * 00713 * Writes @a s[0] through @a s[n-1] to the output sequence, as if 00714 * by @c sputc(). Stops when either @a n characters have been 00715 * copied, or when @c sputc() would return @c traits::eof(). 00716 * 00717 * It is expected that derived classes provide a more efficient 00718 * implementation by overriding this definition. 00719 */ 00720 virtual streamsize 00721 xsputn(const char_type* __s, streamsize __n); 00722 00723 /** 00724 * @brief Consumes data from the buffer; writes to the 00725 * controlled sequence. 00726 * @param c An additional character to consume. 00727 * @return eof() to indicate failure, something else (usually 00728 * @a c, or not_eof()) 00729 * 00730 * Informally, this function is called when the output buffer 00731 * is full (or does not exist, as buffering need not actually 00732 * be done). If a buffer exists, it is @a consumed, with 00733 * <em>some effect</em> on the controlled sequence. 00734 * (Typically, the buffer is written out to the sequence 00735 * verbatim.) In either case, the character @a c is also 00736 * written out, if @a c is not @c eof(). 00737 * 00738 * For a formal definition of this function, see a good text 00739 * such as Langer & Kreft, or [27.5.2.4.5]/3-7. 00740 * 00741 * A functioning output streambuf can be created by overriding only 00742 * this function (no buffer area will be used). 00743 * 00744 * @note Base class version does nothing, returns eof(). 00745 */ 00746 virtual int_type 00747 overflow(int_type /* __c */ = traits_type::eof()) 00748 { return traits_type::eof(); } 00749 00750 #if _GLIBCXX_USE_DEPRECATED 00751 // Annex D.6 00752 public: 00753 /** 00754 * @brief Tosses a character. 00755 * 00756 * Advances the read pointer, ignoring the character that would have 00757 * been read. 00758 * 00759 * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html 00760 */ 00761 void 00762 stossc() 00763 { 00764 if (this->gptr() < this->egptr()) 00765 this->gbump(1); 00766 else 00767 this->uflow(); 00768 } 00769 #endif 00770 00771 // Also used by specializations for char and wchar_t in src. 00772 void 00773 __safe_gbump(streamsize __n) { _M_in_cur += __n; } 00774 00775 void 00776 __safe_pbump(streamsize __n) { _M_out_cur += __n; } 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_eof(basic_streambuf<char>* __sbin, 00796 basic_streambuf<char>* __sbout, bool& __ineof); 00797 #ifdef _GLIBCXX_USE_WCHAR_T 00798 template<> 00799 streamsize 00800 __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin, 00801 basic_streambuf<wchar_t>* __sbout, bool& __ineof); 00802 #endif 00803 00804 _GLIBCXX_END_NAMESPACE_VERSION 00805 } // namespace 00806 00807 #include <bits/streambuf.tcc> 00808 00809 #endif /* _GLIBCXX_STREAMBUF */