1// Stream buffer classes -*- C++ -*- 2 3// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 4// 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. 5// 6// This file is part of the GNU ISO C++ Library. This library is free 7// software; you can redistribute it and/or modify it under the 8// terms of the GNU General Public License as published by the 9// Free Software Foundation; either version 3, or (at your option) 10// any later version. 11 12// This library is distributed in the hope that it will be useful, 13// but WITHOUT ANY WARRANTY; without even the implied warranty of 14// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15// GNU General Public License for more details. 16 17// Under Section 7 of GPL version 3, you are granted additional 18// permissions described in the GCC Runtime Library Exception, version 19// 3.1, as published by the Free Software Foundation. 20 21// You should have received a copy of the GNU General Public License and 22// a copy of the GCC Runtime Library Exception along with this program; 23// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24// <http://www.gnu.org/licenses/>. 25 26/** @file streambuf 27 * This is a Standard C++ Library header. 28 */ 29 30// 31// ISO C++ 14882: 27.5 Stream buffers 32// 33 34#ifndef _GLIBXX_STREAMBUF 35#define _GLIBXX_STREAMBUF 1 36 37#pragma GCC system_header 38 39#include <bits/c++config.h> 40#include <iosfwd> 41#include <bits/localefwd.h> 42#include <bits/ios_base.h> 43#include <bits/cpp_type_traits.h> 44#include <ext/type_traits.h> 45 46_GLIBCXX_BEGIN_NAMESPACE(std) 47 48 template<typename _CharT, typename _Traits> 49 streamsize 50 __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>*, 51 basic_streambuf<_CharT, _Traits>*, bool&); 52 53 /** 54 * @brief The actual work of input and output (interface). 55 * @ingroup io 56 * 57 * This is a base class. Derived stream buffers each control a 58 * pair of character sequences: one for input, and one for output. 59 * 60 * Section [27.5.1] of the standard describes the requirements and 61 * behavior of stream buffer classes. That section (three paragraphs) 62 * is reproduced here, for simplicity and accuracy. 63 * 64 * -# Stream buffers can impose various constraints on the sequences 65 * they control. Some constraints are: 66 * - The controlled input sequence can be not readable. 67 * - The controlled output sequence can be not writable. 68 * - The controlled sequences can be associated with the contents of 69 * other representations for character sequences, such as external 70 * files. 71 * - The controlled sequences can support operations @e directly to or 72 * from associated sequences. 73 * - The controlled sequences can impose limitations on how the 74 * program can read characters from a sequence, write characters to 75 * a sequence, put characters back into an input sequence, or alter 76 * the stream position. 77 * . 78 * -# Each sequence is characterized by three pointers which, if non-null, 79 * all point into the same @c charT array object. The array object 80 * represents, at any moment, a (sub)sequence of characters from the 81 * sequence. Operations performed on a sequence alter the values 82 * stored in these pointers, perform reads and writes directly to or 83 * from associated sequences, and alter <em>the stream position</em> and 84 * conversion state as needed to maintain this subsequence relationship. 85 * The three pointers are: 86 * - the <em>beginning pointer</em>, or lowest element address in the 87 * array (called @e xbeg here); 88 * - the <em>next pointer</em>, or next element address that is a 89 * current candidate for reading or writing (called @e xnext here); 90 * - the <em>end pointer</em>, or first element address beyond the 91 * end of the array (called @e xend here). 92 * . 93 * -# The following semantic constraints shall always apply for any set 94 * of three pointers for a sequence, using the pointer names given 95 * immediately above: 96 * - If @e xnext is not a null pointer, then @e xbeg and @e xend shall 97 * also be non-null pointers into the same @c charT array, as 98 * described above; otherwise, @e xbeg and @e xend shall also be null. 99 * - If @e xnext is not a null pointer and @e xnext < @e xend for an 100 * output sequence, then a <em>write position</em> is available. 101 * In this case, @e *xnext shall be assignable as the next element 102 * to write (to put, or to store a character value, into the sequence). 103 * - If @e xnext is not a null pointer and @e xbeg < @e xnext for an 104 * input sequence, then a <em>putback position</em> is available. 105 * In this case, @e xnext[-1] shall have a defined value and is the 106 * next (preceding) element to store a character that is put back 107 * into the input sequence. 108 * - If @e xnext is not a null pointer and @e xnext< @e xend for an 109 * input sequence, then a <em>read position</em> is available. 110 * In this case, @e *xnext shall have a defined value and is the 111 * next element to read (to get, or to obtain a character value, 112 * from the sequence). 113 */ 114 template<typename _CharT, typename _Traits> 115 class basic_streambuf 116 { 117 public: 118 //@{ 119 /** 120 * These are standard types. They permit a standardized way of 121 * referring to names of (or names dependant on) the template 122 * parameters, which are specific to the implementation. 123 */ 124 typedef _CharT char_type; 125 typedef _Traits traits_type; 126 typedef typename traits_type::int_type int_type; 127 typedef typename traits_type::pos_type pos_type; 128 typedef typename traits_type::off_type off_type; 129 //@} 130 131 //@{ 132 /// This is a non-standard type. 133 typedef basic_streambuf<char_type, traits_type> __streambuf_type; 134 //@} 135 136 friend class basic_ios<char_type, traits_type>; 137 friend class basic_istream<char_type, traits_type>; 138 friend class basic_ostream<char_type, traits_type>; 139 friend class istreambuf_iterator<char_type, traits_type>; 140 friend class ostreambuf_iterator<char_type, traits_type>; 141 142 friend streamsize 143 __copy_streambufs_eof<>(__streambuf_type*, __streambuf_type*, bool&); 144 145 template<bool _IsMove, typename _CharT2> 146 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 147 _CharT2*>::__type 148 __copy_move_a2(istreambuf_iterator<_CharT2>, 149 istreambuf_iterator<_CharT2>, _CharT2*); 150 151 template<typename _CharT2> 152 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 153 istreambuf_iterator<_CharT2> >::__type 154 find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>, 155 const _CharT2&); 156 157 template<typename _CharT2, typename _Traits2> 158 friend basic_istream<_CharT2, _Traits2>& 159 operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*); 160 161 template<typename _CharT2, typename _Traits2, typename _Alloc> 162 friend basic_istream<_CharT2, _Traits2>& 163 operator>>(basic_istream<_CharT2, _Traits2>&, 164 basic_string<_CharT2, _Traits2, _Alloc>&); 165 166 template<typename _CharT2, typename _Traits2, typename _Alloc> 167 friend basic_istream<_CharT2, _Traits2>& 168 getline(basic_istream<_CharT2, _Traits2>&, 169 basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2); 170 171 protected: 172 //@{ 173 /** 174 * This is based on _IO_FILE, just reordered to be more consistent, 175 * and is intended to be the most minimal abstraction for an 176 * internal buffer. 177 * - get == input == read 178 * - put == output == write 179 */ 180 char_type* _M_in_beg; // Start of get area. 181 char_type* _M_in_cur; // Current read area. 182 char_type* _M_in_end; // End of get area. 183 char_type* _M_out_beg; // Start of put area. 184 char_type* _M_out_cur; // Current put area. 185 char_type* _M_out_end; // End of put area. 186 187 /// Current locale setting. 188 locale _M_buf_locale; 189 190 public: 191 /// Destructor deallocates no buffer space. 192 virtual 193 ~basic_streambuf() 194 { } 195 196 // [27.5.2.2.1] locales 197 /** 198 * @brief Entry point for imbue(). 199 * @param loc The new locale. 200 * @return The previous locale. 201 * 202 * Calls the derived imbue(loc). 203 */ 204 locale 205 pubimbue(const locale &__loc) 206 { 207 locale __tmp(this->getloc()); 208 this->imbue(__loc); 209 _M_buf_locale = __loc; 210 return __tmp; 211 } 212 213 /** 214 * @brief Locale access. 215 * @return The current locale in effect. 216 * 217 * If pubimbue(loc) has been called, then the most recent @c loc 218 * is returned. Otherwise the global locale in effect at the time 219 * of construction is returned. 220 */ 221 locale 222 getloc() const 223 { return _M_buf_locale; } 224 225 // [27.5.2.2.2] buffer management and positioning 226 //@{ 227 /** 228 * @brief Entry points for derived buffer functions. 229 * 230 * The public versions of @c pubfoo dispatch to the protected 231 * derived @c foo member functions, passing the arguments (if any) 232 * and returning the result unchanged. 233 */ 234 __streambuf_type* 235 pubsetbuf(char_type* __s, streamsize __n) 236 { return this->setbuf(__s, __n); } 237 238 pos_type 239 pubseekoff(off_type __off, ios_base::seekdir __way, 240 ios_base::openmode __mode = ios_base::in | ios_base::out) 241 { return this->seekoff(__off, __way, __mode); } 242 243 pos_type 244 pubseekpos(pos_type __sp, 245 ios_base::openmode __mode = ios_base::in | ios_base::out) 246 { return this->seekpos(__sp, __mode); } 247 248 int 249 pubsync() { return this->sync(); } 250 //@} 251 252 // [27.5.2.2.3] get area 253 /** 254 * @brief Looking ahead into the stream. 255 * @return The number of characters available. 256 * 257 * If a read position is available, returns the number of characters 258 * available for reading before the buffer must be refilled. 259 * Otherwise returns the derived @c showmanyc(). 260 */ 261 streamsize 262 in_avail() 263 { 264 const streamsize __ret = this->egptr() - this->gptr(); 265 return __ret ? __ret : this->showmanyc(); 266 } 267 268 /** 269 * @brief Getting the next character. 270 * @return The next character, or eof. 271 * 272 * Calls @c sbumpc(), and if that function returns 273 * @c traits::eof(), so does this function. Otherwise, @c sgetc(). 274 */ 275 int_type 276 snextc() 277 { 278 int_type __ret = traits_type::eof(); 279 if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), 280 __ret), true)) 281 __ret = this->sgetc(); 282 return __ret; 283 } 284 285 /** 286 * @brief Getting the next character. 287 * @return The next character, or eof. 288 * 289 * If the input read position is available, returns that character 290 * and increments the read pointer, otherwise calls and returns 291 * @c uflow(). 292 */ 293 int_type 294 sbumpc() 295 { 296 int_type __ret; 297 if (__builtin_expect(this->gptr() < this->egptr(), true)) 298 { 299 __ret = traits_type::to_int_type(*this->gptr()); 300 this->gbump(1); 301 } 302 else 303 __ret = this->uflow(); 304 return __ret; 305 } 306 307 /** 308 * @brief Getting the next character. 309 * @return The next character, or eof. 310 * 311 * If the input read position is available, returns that character, 312 * otherwise calls and returns @c underflow(). Does not move the 313 * read position after fetching the character. 314 */ 315 int_type 316 sgetc() 317 { 318 int_type __ret; 319 if (__builtin_expect(this->gptr() < this->egptr(), true)) 320 __ret = traits_type::to_int_type(*this->gptr()); 321 else 322 __ret = this->underflow(); 323 return __ret; 324 } 325 326 /** 327 * @brief Entry point for xsgetn. 328 * @param s A buffer area. 329 * @param n A count. 330 * 331 * Returns xsgetn(s,n). The effect is to fill @a s[0] through 332 * @a s[n-1] with characters from the input sequence, if possible. 333 */ 334 streamsize 335 sgetn(char_type* __s, streamsize __n) 336 { return this->xsgetn(__s, __n); } 337 338 // [27.5.2.2.4] putback 339 /** 340 * @brief Pushing characters back into the input stream. 341 * @param c The character to push back. 342 * @return The previous character, if possible. 343 * 344 * Similar to sungetc(), but @a c is pushed onto the stream 345 * instead of <em>the previous character.</em> If successful, 346 * the next character fetched from the input stream will be @a 347 * c. 348 */ 349 int_type 350 sputbackc(char_type __c) 351 { 352 int_type __ret; 353 const bool __testpos = this->eback() < this->gptr(); 354 if (__builtin_expect(!__testpos || 355 !traits_type::eq(__c, this->gptr()[-1]), false)) 356 __ret = this->pbackfail(traits_type::to_int_type(__c)); 357 else 358 { 359 this->gbump(-1); 360 __ret = traits_type::to_int_type(*this->gptr()); 361 } 362 return __ret; 363 } 364 365 /** 366 * @brief Moving backwards in the input stream. 367 * @return The previous character, if possible. 368 * 369 * If a putback position is available, this function decrements 370 * the input pointer and returns that character. Otherwise, 371 * calls and returns pbackfail(). The effect is to @a unget 372 * the last character @a gotten. 373 */ 374 int_type 375 sungetc() 376 { 377 int_type __ret; 378 if (__builtin_expect(this->eback() < this->gptr(), true)) 379 { 380 this->gbump(-1); 381 __ret = traits_type::to_int_type(*this->gptr()); 382 } 383 else 384 __ret = this->pbackfail(); 385 return __ret; 386 } 387 388 // [27.5.2.2.5] put area 389 /** 390 * @brief Entry point for all single-character output functions. 391 * @param c A character to output. 392 * @return @a c, if possible. 393 * 394 * One of two public output functions. 395 * 396 * If a write position is available for the output sequence (i.e., 397 * the buffer is not full), stores @a c in that position, increments 398 * the position, and returns @c traits::to_int_type(c). If a write 399 * position is not available, returns @c overflow(c). 400 */ 401 int_type 402 sputc(char_type __c) 403 { 404 int_type __ret; 405 if (__builtin_expect(this->pptr() < this->epptr(), true)) 406 { 407 *this->pptr() = __c; 408 this->pbump(1); 409 __ret = traits_type::to_int_type(__c); 410 } 411 else 412 __ret = this->overflow(traits_type::to_int_type(__c)); 413 return __ret; 414 } 415 416 /** 417 * @brief Entry point for all single-character output functions. 418 * @param s A buffer read area. 419 * @param n A count. 420 * 421 * One of two public output functions. 422 * 423 * 424 * Returns xsputn(s,n). The effect is to write @a s[0] through 425 * @a s[n-1] to the output sequence, if possible. 426 */ 427 streamsize 428 sputn(const char_type* __s, streamsize __n) 429 { return this->xsputn(__s, __n); } 430 431 protected: 432 /** 433 * @brief Base constructor. 434 * 435 * Only called from derived constructors, and sets up all the 436 * buffer data to zero, including the pointers described in the 437 * basic_streambuf class description. Note that, as a result, 438 * - the class starts with no read nor write positions available, 439 * - this is not an error 440 */ 441 basic_streambuf() 442 : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 443 _M_out_beg(0), _M_out_cur(0), _M_out_end(0), 444 _M_buf_locale(locale()) 445 { } 446 447 // [27.5.2.3.1] get area access 448 //@{ 449 /** 450 * @brief Access to the get area. 451 * 452 * These functions are only available to other protected functions, 453 * including derived classes. 454 * 455 * - eback() returns the beginning pointer for the input sequence 456 * - gptr() returns the next pointer for the input sequence 457 * - egptr() returns the end pointer for the input sequence 458 */ 459 char_type* 460 eback() const { return _M_in_beg; } 461 462 char_type* 463 gptr() const { return _M_in_cur; } 464 465 char_type* 466 egptr() const { return _M_in_end; } 467 //@} 468 469 /** 470 * @brief Moving the read position. 471 * @param n The delta by which to move. 472 * 473 * This just advances the read position without returning any data. 474 */ 475 void 476 gbump(int __n) { _M_in_cur += __n; } 477 478 /** 479 * @brief Setting the three read area pointers. 480 * @param gbeg A pointer. 481 * @param gnext A pointer. 482 * @param gend A pointer. 483 * @post @a gbeg == @c eback(), @a gnext == @c gptr(), and 484 * @a gend == @c egptr() 485 */ 486 void 487 setg(char_type* __gbeg, char_type* __gnext, char_type* __gend) 488 { 489 _M_in_beg = __gbeg; 490 _M_in_cur = __gnext; 491 _M_in_end = __gend; 492 } 493 494 // [27.5.2.3.2] put area access 495 //@{ 496 /** 497 * @brief Access to the put area. 498 * 499 * These functions are only available to other protected functions, 500 * including derived classes. 501 * 502 * - pbase() returns the beginning pointer for the output sequence 503 * - pptr() returns the next pointer for the output sequence 504 * - epptr() returns the end pointer for the output sequence 505 */ 506 char_type* 507 pbase() const { return _M_out_beg; } 508 509 char_type* 510 pptr() const { return _M_out_cur; } 511 512 char_type* 513 epptr() const { return _M_out_end; } 514 //@} 515 516 /** 517 * @brief Moving the write position. 518 * @param n The delta by which to move. 519 * 520 * This just advances the write position without returning any data. 521 */ 522 void 523 pbump(int __n) { _M_out_cur += __n; } 524 525 /** 526 * @brief Setting the three write area pointers. 527 * @param pbeg A pointer. 528 * @param pend A pointer. 529 * @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and 530 * @a pend == @c epptr() 531 */ 532 void 533 setp(char_type* __pbeg, char_type* __pend) 534 { 535 _M_out_beg = _M_out_cur = __pbeg; 536 _M_out_end = __pend; 537 } 538 539 // [27.5.2.4] virtual functions 540 // [27.5.2.4.1] locales 541 /** 542 * @brief Changes translations. 543 * @param loc A new locale. 544 * 545 * Translations done during I/O which depend on the current 546 * locale are changed by this call. The standard adds, 547 * <em>Between invocations of this function a class derived 548 * from streambuf can safely cache results of calls to locale 549 * functions and to members of facets so obtained.</em> 550 * 551 * @note Base class version does nothing. 552 */ 553 virtual void 554 imbue(const locale&) 555 { } 556 557 // [27.5.2.4.2] buffer management and positioning 558 /** 559 * @brief Manipulates the buffer. 560 * 561 * Each derived class provides its own appropriate behavior. See 562 * the next-to-last paragraph of 563 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html 564 * for more on this function. 565 * 566 * @note Base class version does nothing, returns @c this. 567 */ 568 virtual basic_streambuf<char_type,_Traits>* 569 setbuf(char_type*, streamsize) 570 { return this; } 571 572 /** 573 * @brief Alters the stream positions. 574 * 575 * Each derived class provides its own appropriate behavior. 576 * @note Base class version does nothing, returns a @c pos_type 577 * that represents an invalid stream position. 578 */ 579 virtual pos_type 580 seekoff(off_type, ios_base::seekdir, 581 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 582 { return pos_type(off_type(-1)); } 583 584 /** 585 * @brief Alters the stream positions. 586 * 587 * Each derived class provides its own appropriate behavior. 588 * @note Base class version does nothing, returns a @c pos_type 589 * that represents an invalid stream position. 590 */ 591 virtual pos_type 592 seekpos(pos_type, 593 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 594 { return pos_type(off_type(-1)); } 595 596 /** 597 * @brief Synchronizes the buffer arrays with the controlled sequences. 598 * @return -1 on failure. 599 * 600 * Each derived class provides its own appropriate behavior, 601 * including the definition of @a failure. 602 * @note Base class version does nothing, returns zero. 603 */ 604 virtual int 605 sync() { return 0; } 606 607 // [27.5.2.4.3] get area 608 /** 609 * @brief Investigating the data available. 610 * @return An estimate of the number of characters available in the 611 * input sequence, or -1. 612 * 613 * <em>If it returns a positive value, then successive calls to 614 * @c underflow() will not return @c traits::eof() until at 615 * least that number of characters have been supplied. If @c 616 * showmanyc() returns -1, then calls to @c underflow() or @c 617 * uflow() will fail.</em> [27.5.2.4.3]/1 618 * 619 * @note Base class version does nothing, returns zero. 620 * @note The standard adds that <em>the intention is not only that the 621 * calls [to underflow or uflow] will not return @c eof() but 622 * that they will return immediately.</em> 623 * @note The standard adds that <em>the morphemes of @c showmanyc are 624 * @b es-how-many-see, not @b show-manic.</em> 625 */ 626 virtual streamsize 627 showmanyc() { return 0; } 628 629 /** 630 * @brief Multiple character extraction. 631 * @param s A buffer area. 632 * @param n Maximum number of characters to assign. 633 * @return The number of characters assigned. 634 * 635 * Fills @a s[0] through @a s[n-1] with characters from the input 636 * sequence, as if by @c sbumpc(). Stops when either @a n characters 637 * have been copied, or when @c traits::eof() would be copied. 638 * 639 * It is expected that derived classes provide a more efficient 640 * implementation by overriding this definition. 641 */ 642 virtual streamsize 643 xsgetn(char_type* __s, streamsize __n); 644 645 /** 646 * @brief Fetches more data from the controlled sequence. 647 * @return The first character from the <em>pending sequence</em>. 648 * 649 * Informally, this function is called when the input buffer is 650 * exhausted (or does not exist, as buffering need not actually be 651 * done). If a buffer exists, it is @a refilled. In either case, the 652 * next available character is returned, or @c traits::eof() to 653 * indicate a null pending sequence. 654 * 655 * For a formal definition of the pending sequence, see a good text 656 * such as Langer & Kreft, or [27.5.2.4.3]/7-14. 657 * 658 * A functioning input streambuf can be created by overriding only 659 * this function (no buffer area will be used). For an example, see 660 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25.html 661 * 662 * @note Base class version does nothing, returns eof(). 663 */ 664 virtual int_type 665 underflow() 666 { return traits_type::eof(); } 667 668 /** 669 * @brief Fetches more data from the controlled sequence. 670 * @return The first character from the <em>pending sequence</em>. 671 * 672 * Informally, this function does the same thing as @c underflow(), 673 * and in fact is required to call that function. It also returns 674 * the new character, like @c underflow() does. However, this 675 * function also moves the read position forward by one. 676 */ 677 virtual int_type 678 uflow() 679 { 680 int_type __ret = traits_type::eof(); 681 const bool __testeof = traits_type::eq_int_type(this->underflow(), 682 __ret); 683 if (!__testeof) 684 { 685 __ret = traits_type::to_int_type(*this->gptr()); 686 this->gbump(1); 687 } 688 return __ret; 689 } 690 691 // [27.5.2.4.4] putback 692 /** 693 * @brief Tries to back up the input sequence. 694 * @param c The character to be inserted back into the sequence. 695 * @return eof() on failure, <em>some other value</em> on success 696 * @post The constraints of @c gptr(), @c eback(), and @c pptr() 697 * are the same as for @c underflow(). 698 * 699 * @note Base class version does nothing, returns eof(). 700 */ 701 virtual int_type 702 pbackfail(int_type /* __c */ = traits_type::eof()) 703 { return traits_type::eof(); } 704 705 // Put area: 706 /** 707 * @brief Multiple character insertion. 708 * @param s A buffer area. 709 * @param n Maximum number of characters to write. 710 * @return The number of characters written. 711 * 712 * Writes @a s[0] through @a s[n-1] to the output sequence, as if 713 * by @c sputc(). Stops when either @a n characters have been 714 * copied, or when @c sputc() would return @c traits::eof(). 715 * 716 * It is expected that derived classes provide a more efficient 717 * implementation by overriding this definition. 718 */ 719 virtual streamsize 720 xsputn(const char_type* __s, streamsize __n); 721 722 /** 723 * @brief Consumes data from the buffer; writes to the 724 * controlled sequence. 725 * @param c An additional character to consume. 726 * @return eof() to indicate failure, something else (usually 727 * @a c, or not_eof()) 728 * 729 * Informally, this function is called when the output buffer 730 * is full (or does not exist, as buffering need not actually 731 * be done). If a buffer exists, it is @a consumed, with 732 * <em>some effect</em> on the controlled sequence. 733 * (Typically, the buffer is written out to the sequence 734 * verbatim.) In either case, the character @a c is also 735 * written out, if @a c is not @c eof(). 736 * 737 * For a formal definition of this function, see a good text 738 * such as Langer & Kreft, or [27.5.2.4.5]/3-7. 739 * 740 * A functioning output streambuf can be created by overriding only 741 * this function (no buffer area will be used). 742 * 743 * @note Base class version does nothing, returns eof(). 744 */ 745 virtual int_type 746 overflow(int_type /* __c */ = traits_type::eof()) 747 { return traits_type::eof(); } 748 749#if _GLIBCXX_DEPRECATED 750 // Annex D.6 751 public: 752 /** 753 * @brief Tosses a character. 754 * 755 * Advances the read pointer, ignoring the character that would have 756 * been read. 757 * 758 * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html 759 */ 760 void 761 stossc() 762 { 763 if (this->gptr() < this->egptr()) 764 this->gbump(1); 765 else 766 this->uflow(); 767 } 768#endif 769 770 private: 771 // _GLIBCXX_RESOLVE_LIB_DEFECTS 772 // Side effect of DR 50. 773 basic_streambuf(const __streambuf_type& __sb) 774 : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur), 775 _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg), 776 _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur), 777 _M_buf_locale(__sb._M_buf_locale) 778 { } 779 780 __streambuf_type& 781 operator=(const __streambuf_type&) { return *this; }; 782 }; 783 784 // Explicit specialization declarations, defined in src/streambuf.cc. 785 template<> 786 streamsize 787 __copy_streambufs_eof(basic_streambuf<char>* __sbin, 788 basic_streambuf<char>* __sbout, bool& __ineof); 789#ifdef _GLIBCXX_USE_WCHAR_T 790 template<> 791 streamsize 792 __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin, 793 basic_streambuf<wchar_t>* __sbout, bool& __ineof); 794#endif 795 796_GLIBCXX_END_NAMESPACE 797 798#ifndef _GLIBCXX_EXPORT_TEMPLATE 799# include <bits/streambuf.tcc> 800#endif 801 802#endif /* _GLIBCXX_STREAMBUF */ 803