1// Stream buffer classes -*- C++ -*- 2 3// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 4// 2006, 2007, 2008, 2009, 2010, 2011, 2013 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 include/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 46namespace std _GLIBCXX_VISIBILITY(default) 47{ 48_GLIBCXX_BEGIN_NAMESPACE_VERSION 49 50 template<typename _CharT, typename _Traits> 51 streamsize 52 __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>*, 53 basic_streambuf<_CharT, _Traits>*, bool&); 54 55 /** 56 * @brief The actual work of input and output (interface). 57 * @ingroup io 58 * 59 * This is a base class. Derived stream buffers each control a 60 * pair of character sequences: one for input, and one for output. 61 * 62 * Section [27.5.1] of the standard describes the requirements and 63 * behavior of stream buffer classes. That section (three paragraphs) 64 * is reproduced here, for simplicity and accuracy. 65 * 66 * -# Stream buffers can impose various constraints on the sequences 67 * they control. Some constraints are: 68 * - The controlled input sequence can be not readable. 69 * - The controlled output sequence can be not writable. 70 * - The controlled sequences can be associated with the contents of 71 * other representations for character sequences, such as external 72 * files. 73 * - The controlled sequences can support operations @e directly to or 74 * from associated sequences. 75 * - The controlled sequences can impose limitations on how the 76 * program can read characters from a sequence, write characters to 77 * a sequence, put characters back into an input sequence, or alter 78 * the stream position. 79 * . 80 * -# Each sequence is characterized by three pointers which, if non-null, 81 * all point into the same @c charT array object. The array object 82 * represents, at any moment, a (sub)sequence of characters from the 83 * sequence. Operations performed on a sequence alter the values 84 * stored in these pointers, perform reads and writes directly to or 85 * from associated sequences, and alter <em>the stream position</em> and 86 * conversion state as needed to maintain this subsequence relationship. 87 * The three pointers are: 88 * - the <em>beginning pointer</em>, or lowest element address in the 89 * array (called @e xbeg here); 90 * - the <em>next pointer</em>, or next element address that is a 91 * current candidate for reading or writing (called @e xnext here); 92 * - the <em>end pointer</em>, or first element address beyond the 93 * end of the array (called @e xend here). 94 * . 95 * -# The following semantic constraints shall always apply for any set 96 * of three pointers for a sequence, using the pointer names given 97 * immediately above: 98 * - If @e xnext is not a null pointer, then @e xbeg and @e xend shall 99 * also be non-null pointers into the same @c charT array, as 100 * described above; otherwise, @e xbeg and @e xend shall also be null. 101 * - If @e xnext is not a null pointer and @e xnext < @e xend for an 102 * output sequence, then a <em>write position</em> is available. 103 * In this case, @e *xnext shall be assignable as the next element 104 * to write (to put, or to store a character value, into the sequence). 105 * - If @e xnext is not a null pointer and @e xbeg < @e xnext for an 106 * input sequence, then a <em>putback position</em> is available. 107 * In this case, @e xnext[-1] shall have a defined value and is the 108 * next (preceding) element to store a character that is put back 109 * into the input sequence. 110 * - If @e xnext is not a null pointer and @e xnext< @e xend for an 111 * input sequence, then a <em>read position</em> is available. 112 * In this case, @e *xnext shall have a defined value and is the 113 * next element to read (to get, or to obtain a character value, 114 * from the sequence). 115 */ 116 template<typename _CharT, typename _Traits> 117 class basic_streambuf 118 { 119 public: 120 //@{ 121 /** 122 * These are standard types. They permit a standardized way of 123 * referring to names of (or names dependant on) the template 124 * parameters, which are specific to the implementation. 125 */ 126 typedef _CharT char_type; 127 typedef _Traits traits_type; 128 typedef typename traits_type::int_type int_type; 129 typedef typename traits_type::pos_type pos_type; 130 typedef typename traits_type::off_type off_type; 131 //@} 132 133 //@{ 134 /// This is a non-standard type. 135 typedef basic_streambuf<char_type, traits_type> __streambuf_type; 136 //@} 137 138 friend class basic_ios<char_type, traits_type>; 139 friend class basic_istream<char_type, traits_type>; 140 friend class basic_ostream<char_type, traits_type>; 141 friend class istreambuf_iterator<char_type, traits_type>; 142 friend class ostreambuf_iterator<char_type, traits_type>; 143 144 friend streamsize 145 __copy_streambufs_eof<>(__streambuf_type*, __streambuf_type*, bool&); 146 147 template<bool _IsMove, typename _CharT2> 148 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 149 _CharT2*>::__type 150 __copy_move_a2(istreambuf_iterator<_CharT2>, 151 istreambuf_iterator<_CharT2>, _CharT2*); 152 153 template<typename _CharT2> 154 friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 155 istreambuf_iterator<_CharT2> >::__type 156 find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>, 157 const _CharT2&); 158 159 template<typename _CharT2, typename _Traits2> 160 friend basic_istream<_CharT2, _Traits2>& 161 operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*); 162 163 template<typename _CharT2, typename _Traits2, typename _Alloc> 164 friend basic_istream<_CharT2, _Traits2>& 165 operator>>(basic_istream<_CharT2, _Traits2>&, 166 basic_string<_CharT2, _Traits2, _Alloc>&); 167 168 template<typename _CharT2, typename _Traits2, typename _Alloc> 169 friend basic_istream<_CharT2, _Traits2>& 170 getline(basic_istream<_CharT2, _Traits2>&, 171 basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2); 172 173 protected: 174 /* 175 * This is based on _IO_FILE, just reordered to be more consistent, 176 * and is intended to be the most minimal abstraction for an 177 * internal buffer. 178 * - get == input == read 179 * - put == output == write 180 */ 181 char_type* _M_in_beg; ///< Start of get area. 182 char_type* _M_in_cur; ///< Current read area. 183 char_type* _M_in_end; ///< End of get area. 184 char_type* _M_out_beg; ///< Start of put area. 185 char_type* _M_out_cur; ///< Current put area. 186 char_type* _M_out_end; ///< End of put area. 187 188 /// Current locale setting. 189 locale _M_buf_locale; 190 191 public: 192 /// Destructor deallocates no buffer space. 193 virtual 194 ~basic_streambuf() 195 { } 196 197 // [27.5.2.2.1] locales 198 /** 199 * @brief Entry point for imbue(). 200 * @param __loc The new locale. 201 * @return The previous locale. 202 * 203 * Calls the derived imbue(__loc). 204 */ 205 locale 206 pubimbue(const locale& __loc) 207 { 208 locale __tmp(this->getloc()); 209 this->imbue(__loc); 210 _M_buf_locale = __loc; 211 return __tmp; 212 } 213 214 /** 215 * @brief Locale access. 216 * @return The current locale in effect. 217 * 218 * If pubimbue(loc) has been called, then the most recent @c loc 219 * is returned. Otherwise the global locale in effect at the time 220 * of construction is returned. 221 */ 222 locale 223 getloc() const 224 { return _M_buf_locale; } 225 226 // [27.5.2.2.2] buffer management and positioning 227 //@{ 228 /** 229 * @brief Entry points for derived buffer functions. 230 * 231 * The public versions of @c pubfoo dispatch to the protected 232 * derived @c foo member functions, passing the arguments (if any) 233 * and returning the result unchanged. 234 */ 235 __streambuf_type* 236 pubsetbuf(char_type* __s, streamsize __n) 237 { return this->setbuf(__s, __n); } 238 239 /** 240 * @brief Alters the stream position. 241 * @param __off Offset. 242 * @param __way Value for ios_base::seekdir. 243 * @param __mode Value for ios_base::openmode. 244 * 245 * Calls virtual seekoff function. 246 */ 247 pos_type 248 pubseekoff(off_type __off, ios_base::seekdir __way, 249 ios_base::openmode __mode = ios_base::in | ios_base::out) 250 { return this->seekoff(__off, __way, __mode); } 251 252 /** 253 * @brief Alters the stream position. 254 * @param __sp Position 255 * @param __mode Value for ios_base::openmode. 256 * 257 * Calls virtual seekpos function. 258 */ 259 pos_type 260 pubseekpos(pos_type __sp, 261 ios_base::openmode __mode = ios_base::in | ios_base::out) 262 { return this->seekpos(__sp, __mode); } 263 264 /** 265 * @brief Calls virtual sync function. 266 */ 267 int 268 pubsync() { return this->sync(); } 269 //@} 270 271 // [27.5.2.2.3] get area 272 /** 273 * @brief Looking ahead into the stream. 274 * @return The number of characters available. 275 * 276 * If a read position is available, returns the number of characters 277 * available for reading before the buffer must be refilled. 278 * Otherwise returns the derived @c showmanyc(). 279 */ 280 streamsize 281 in_avail() 282 { 283 const streamsize __ret = this->egptr() - this->gptr(); 284 return __ret ? __ret : this->showmanyc(); 285 } 286 287 /** 288 * @brief Getting the next character. 289 * @return The next character, or eof. 290 * 291 * Calls @c sbumpc(), and if that function returns 292 * @c traits::eof(), so does this function. Otherwise, @c sgetc(). 293 */ 294 int_type 295 snextc() 296 { 297 int_type __ret = traits_type::eof(); 298 if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), 299 __ret), true)) 300 __ret = this->sgetc(); 301 return __ret; 302 } 303 304 /** 305 * @brief Getting the next character. 306 * @return The next character, or eof. 307 * 308 * If the input read position is available, returns that character 309 * and increments the read pointer, otherwise calls and returns 310 * @c uflow(). 311 */ 312 int_type 313 sbumpc() 314 { 315 int_type __ret; 316 if (__builtin_expect(this->gptr() < this->egptr(), true)) 317 { 318 __ret = traits_type::to_int_type(*this->gptr()); 319 this->gbump(1); 320 } 321 else 322 __ret = this->uflow(); 323 return __ret; 324 } 325 326 /** 327 * @brief Getting the next character. 328 * @return The next character, or eof. 329 * 330 * If the input read position is available, returns that character, 331 * otherwise calls and returns @c underflow(). Does not move the 332 * read position after fetching the character. 333 */ 334 int_type 335 sgetc() 336 { 337 int_type __ret; 338 if (__builtin_expect(this->gptr() < this->egptr(), true)) 339 __ret = traits_type::to_int_type(*this->gptr()); 340 else 341 __ret = this->underflow(); 342 return __ret; 343 } 344 345 /** 346 * @brief Entry point for xsgetn. 347 * @param __s A buffer area. 348 * @param __n A count. 349 * 350 * Returns xsgetn(__s,__n). The effect is to fill @a __s[0] through 351 * @a __s[__n-1] with characters from the input sequence, if possible. 352 */ 353 streamsize 354 sgetn(char_type* __s, streamsize __n) 355 { return this->xsgetn(__s, __n); } 356 357 // [27.5.2.2.4] putback 358 /** 359 * @brief Pushing characters back into the input stream. 360 * @param __c The character to push back. 361 * @return The previous character, if possible. 362 * 363 * Similar to sungetc(), but @a __c is pushed onto the stream 364 * instead of <em>the previous character.</em> If successful, 365 * the next character fetched from the input stream will be @a 366 * __c. 367 */ 368 int_type 369 sputbackc(char_type __c) 370 { 371 int_type __ret; 372 const bool __testpos = this->eback() < this->gptr(); 373 if (__builtin_expect(!__testpos || 374 !traits_type::eq(__c, this->gptr()[-1]), false)) 375 __ret = this->pbackfail(traits_type::to_int_type(__c)); 376 else 377 { 378 this->gbump(-1); 379 __ret = traits_type::to_int_type(*this->gptr()); 380 } 381 return __ret; 382 } 383 384 /** 385 * @brief Moving backwards in the input stream. 386 * @return The previous character, if possible. 387 * 388 * If a putback position is available, this function decrements 389 * the input pointer and returns that character. Otherwise, 390 * calls and returns pbackfail(). The effect is to @a unget 391 * the last character @a gotten. 392 */ 393 int_type 394 sungetc() 395 { 396 int_type __ret; 397 if (__builtin_expect(this->eback() < this->gptr(), true)) 398 { 399 this->gbump(-1); 400 __ret = traits_type::to_int_type(*this->gptr()); 401 } 402 else 403 __ret = this->pbackfail(); 404 return __ret; 405 } 406 407 // [27.5.2.2.5] put area 408 /** 409 * @brief Entry point for all single-character output functions. 410 * @param __c A character to output. 411 * @return @a __c, if possible. 412 * 413 * One of two public output functions. 414 * 415 * If a write position is available for the output sequence (i.e., 416 * the buffer is not full), stores @a __c in that position, increments 417 * the position, and returns @c traits::to_int_type(__c). If a write 418 * position is not available, returns @c overflow(__c). 419 */ 420 int_type 421 sputc(char_type __c) 422 { 423 int_type __ret; 424 if (__builtin_expect(this->pptr() < this->epptr(), true)) 425 { 426 *this->pptr() = __c; 427 this->pbump(1); 428 __ret = traits_type::to_int_type(__c); 429 } 430 else 431 __ret = this->overflow(traits_type::to_int_type(__c)); 432 return __ret; 433 } 434 435 /** 436 * @brief Entry point for all single-character output functions. 437 * @param __s A buffer read area. 438 * @param __n A count. 439 * 440 * One of two public output functions. 441 * 442 * 443 * Returns xsputn(__s,__n). The effect is to write @a __s[0] through 444 * @a __s[__n-1] to the output sequence, if possible. 445 */ 446 streamsize 447 sputn(const char_type* __s, streamsize __n) 448 { return this->xsputn(__s, __n); } 449 450 protected: 451 /** 452 * @brief Base constructor. 453 * 454 * Only called from derived constructors, and sets up all the 455 * buffer data to zero, including the pointers described in the 456 * basic_streambuf class description. Note that, as a result, 457 * - the class starts with no read nor write positions available, 458 * - this is not an error 459 */ 460 basic_streambuf() 461 : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 462 _M_out_beg(0), _M_out_cur(0), _M_out_end(0), 463 _M_buf_locale(locale()) 464 { } 465 466 // [27.5.2.3.1] get area access 467 //@{ 468 /** 469 * @brief Access to the get area. 470 * 471 * These functions are only available to other protected functions, 472 * including derived classes. 473 * 474 * - eback() returns the beginning pointer for the input sequence 475 * - gptr() returns the next pointer for the input sequence 476 * - egptr() returns the end pointer for the input sequence 477 */ 478 char_type* 479 eback() const { return _M_in_beg; } 480 481 char_type* 482 gptr() const { return _M_in_cur; } 483 484 char_type* 485 egptr() const { return _M_in_end; } 486 //@} 487 488 /** 489 * @brief Moving the read position. 490 * @param __n The delta by which to move. 491 * 492 * This just advances the read position without returning any data. 493 */ 494 void 495 gbump(int __n) { _M_in_cur += __n; } 496 497 /** 498 * @brief Setting the three read area pointers. 499 * @param __gbeg A pointer. 500 * @param __gnext A pointer. 501 * @param __gend A pointer. 502 * @post @a __gbeg == @c eback(), @a __gnext == @c gptr(), and 503 * @a __gend == @c egptr() 504 */ 505 void 506 setg(char_type* __gbeg, char_type* __gnext, char_type* __gend) 507 { 508 _M_in_beg = __gbeg; 509 _M_in_cur = __gnext; 510 _M_in_end = __gend; 511 } 512 513 // [27.5.2.3.2] put area access 514 //@{ 515 /** 516 * @brief Access to the put area. 517 * 518 * These functions are only available to other protected functions, 519 * including derived classes. 520 * 521 * - pbase() returns the beginning pointer for the output sequence 522 * - pptr() returns the next pointer for the output sequence 523 * - epptr() returns the end pointer for the output sequence 524 */ 525 char_type* 526 pbase() const { return _M_out_beg; } 527 528 char_type* 529 pptr() const { return _M_out_cur; } 530 531 char_type* 532 epptr() const { return _M_out_end; } 533 //@} 534 535 /** 536 * @brief Moving the write position. 537 * @param __n The delta by which to move. 538 * 539 * This just advances the write position without returning any data. 540 */ 541 void 542 pbump(int __n) { _M_out_cur += __n; } 543 544 /** 545 * @brief Setting the three write area pointers. 546 * @param __pbeg A pointer. 547 * @param __pend A pointer. 548 * @post @a __pbeg == @c pbase(), @a __pbeg == @c pptr(), and 549 * @a __pend == @c epptr() 550 */ 551 void 552 setp(char_type* __pbeg, char_type* __pend) 553 { 554 _M_out_beg = _M_out_cur = __pbeg; 555 _M_out_end = __pend; 556 } 557 558 // [27.5.2.4] virtual functions 559 // [27.5.2.4.1] locales 560 /** 561 * @brief Changes translations. 562 * @param __loc A new locale. 563 * 564 * Translations done during I/O which depend on the current 565 * locale are changed by this call. The standard adds, 566 * <em>Between invocations of this function a class derived 567 * from streambuf can safely cache results of calls to locale 568 * functions and to members of facets so obtained.</em> 569 * 570 * @note Base class version does nothing. 571 */ 572 virtual void 573 imbue(const locale& __loc) 574 { } 575 576 // [27.5.2.4.2] buffer management and positioning 577 /** 578 * @brief Manipulates the buffer. 579 * 580 * Each derived class provides its own appropriate behavior. See 581 * the next-to-last paragraph of 582 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html 583 * for more on this function. 584 * 585 * @note Base class version does nothing, returns @c this. 586 */ 587 virtual basic_streambuf<char_type,_Traits>* 588 setbuf(char_type*, streamsize) 589 { return this; } 590 591 /** 592 * @brief Alters the stream positions. 593 * 594 * Each derived class provides its own appropriate behavior. 595 * @note Base class version does nothing, returns a @c pos_type 596 * that represents an invalid stream position. 597 */ 598 virtual pos_type 599 seekoff(off_type, ios_base::seekdir, 600 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 601 { return pos_type(off_type(-1)); } 602 603 /** 604 * @brief Alters the stream positions. 605 * 606 * Each derived class provides its own appropriate behavior. 607 * @note Base class version does nothing, returns a @c pos_type 608 * that represents an invalid stream position. 609 */ 610 virtual pos_type 611 seekpos(pos_type, 612 ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) 613 { return pos_type(off_type(-1)); } 614 615 /** 616 * @brief Synchronizes the buffer arrays with the controlled sequences. 617 * @return -1 on failure. 618 * 619 * Each derived class provides its own appropriate behavior, 620 * including the definition of @a failure. 621 * @note Base class version does nothing, returns zero. 622 */ 623 virtual int 624 sync() { return 0; } 625 626 // [27.5.2.4.3] get area 627 /** 628 * @brief Investigating the data available. 629 * @return An estimate of the number of characters available in the 630 * input sequence, or -1. 631 * 632 * <em>If it returns a positive value, then successive calls to 633 * @c underflow() will not return @c traits::eof() until at 634 * least that number of characters have been supplied. If @c 635 * showmanyc() returns -1, then calls to @c underflow() or @c 636 * uflow() will fail.</em> [27.5.2.4.3]/1 637 * 638 * @note Base class version does nothing, returns zero. 639 * @note The standard adds that <em>the intention is not only that the 640 * calls [to underflow or uflow] will not return @c eof() but 641 * that they will return immediately.</em> 642 * @note The standard adds that <em>the morphemes of @c showmanyc are 643 * @b es-how-many-see, not @b show-manic.</em> 644 */ 645 virtual streamsize 646 showmanyc() { return 0; } 647 648 /** 649 * @brief Multiple character extraction. 650 * @param __s A buffer area. 651 * @param __n Maximum number of characters to assign. 652 * @return The number of characters assigned. 653 * 654 * Fills @a __s[0] through @a __s[__n-1] with characters from the input 655 * sequence, as if by @c sbumpc(). Stops when either @a __n characters 656 * have been copied, or when @c traits::eof() would be copied. 657 * 658 * It is expected that derived classes provide a more efficient 659 * implementation by overriding this definition. 660 */ 661 virtual streamsize 662 xsgetn(char_type* __s, streamsize __n); 663 664 /** 665 * @brief Fetches more data from the controlled sequence. 666 * @return The first character from the <em>pending sequence</em>. 667 * 668 * Informally, this function is called when the input buffer is 669 * exhausted (or does not exist, as buffering need not actually be 670 * done). If a buffer exists, it is @a refilled. In either case, the 671 * next available character is returned, or @c traits::eof() to 672 * indicate a null pending sequence. 673 * 674 * For a formal definition of the pending sequence, see a good text 675 * such as Langer & Kreft, or [27.5.2.4.3]/7-14. 676 * 677 * A functioning input streambuf can be created by overriding only 678 * this function (no buffer area will be used). For an example, see 679 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25.html 680 * 681 * @note Base class version does nothing, returns eof(). 682 */ 683 virtual int_type 684 underflow() 685 { return traits_type::eof(); } 686 687 /** 688 * @brief Fetches more data from the controlled sequence. 689 * @return The first character from the <em>pending sequence</em>. 690 * 691 * Informally, this function does the same thing as @c underflow(), 692 * and in fact is required to call that function. It also returns 693 * the new character, like @c underflow() does. However, this 694 * function also moves the read position forward by one. 695 */ 696 virtual int_type 697 uflow() 698 { 699 int_type __ret = traits_type::eof(); 700 const bool __testeof = traits_type::eq_int_type(this->underflow(), 701 __ret); 702 if (!__testeof) 703 { 704 __ret = traits_type::to_int_type(*this->gptr()); 705 this->gbump(1); 706 } 707 return __ret; 708 } 709 710 // [27.5.2.4.4] putback 711 /** 712 * @brief Tries to back up the input sequence. 713 * @param __c The character to be inserted back into the sequence. 714 * @return eof() on failure, <em>some other value</em> on success 715 * @post The constraints of @c gptr(), @c eback(), and @c pptr() 716 * are the same as for @c underflow(). 717 * 718 * @note Base class version does nothing, returns eof(). 719 */ 720 virtual int_type 721 pbackfail(int_type __c = traits_type::eof()) 722 { return traits_type::eof(); } 723 724 // Put area: 725 /** 726 * @brief Multiple character insertion. 727 * @param __s A buffer area. 728 * @param __n Maximum number of characters to write. 729 * @return The number of characters written. 730 * 731 * Writes @a __s[0] through @a __s[__n-1] to the output sequence, as if 732 * by @c sputc(). Stops when either @a n characters have been 733 * copied, or when @c sputc() would return @c traits::eof(). 734 * 735 * It is expected that derived classes provide a more efficient 736 * implementation by overriding this definition. 737 */ 738 virtual streamsize 739 xsputn(const char_type* __s, streamsize __n); 740 741 /** 742 * @brief Consumes data from the buffer; writes to the 743 * controlled sequence. 744 * @param __c An additional character to consume. 745 * @return eof() to indicate failure, something else (usually 746 * @a __c, or not_eof()) 747 * 748 * Informally, this function is called when the output buffer 749 * is full (or does not exist, as buffering need not actually 750 * be done). If a buffer exists, it is @a consumed, with 751 * <em>some effect</em> on the controlled sequence. 752 * (Typically, the buffer is written out to the sequence 753 * verbatim.) In either case, the character @a c is also 754 * written out, if @a __c is not @c eof(). 755 * 756 * For a formal definition of this function, see a good text 757 * such as Langer & Kreft, or [27.5.2.4.5]/3-7. 758 * 759 * A functioning output streambuf can be created by overriding only 760 * this function (no buffer area will be used). 761 * 762 * @note Base class version does nothing, returns eof(). 763 */ 764 virtual int_type 765 overflow(int_type __c = traits_type::eof()) 766 { return traits_type::eof(); } 767 768#if _GLIBCXX_USE_DEPRECATED 769 // Annex D.6 770 public: 771 /** 772 * @brief Tosses a character. 773 * 774 * Advances the read pointer, ignoring the character that would have 775 * been read. 776 * 777 * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html 778 */ 779 void 780 stossc() 781 { 782 if (this->gptr() < this->egptr()) 783 this->gbump(1); 784 else 785 this->uflow(); 786 } 787#endif 788 789 // Also used by specializations for char and wchar_t in src. 790 void 791 __safe_gbump(streamsize __n) { _M_in_cur += __n; } 792 793 void 794 __safe_pbump(streamsize __n) { _M_out_cur += __n; } 795 796 private: 797 // _GLIBCXX_RESOLVE_LIB_DEFECTS 798 // Side effect of DR 50. 799 basic_streambuf(const __streambuf_type& __sb) 800 : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur), 801 _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg), 802 _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur), 803 _M_buf_locale(__sb._M_buf_locale) 804 { } 805 806 __streambuf_type& 807 operator=(const __streambuf_type&) { return *this; }; 808 }; 809 810 // Explicit specialization declarations, defined in src/streambuf.cc. 811 template<> 812 streamsize 813 __copy_streambufs_eof(basic_streambuf<char>* __sbin, 814 basic_streambuf<char>* __sbout, bool& __ineof); 815#ifdef _GLIBCXX_USE_WCHAR_T 816 template<> 817 streamsize 818 __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin, 819 basic_streambuf<wchar_t>* __sbout, bool& __ineof); 820#endif 821 822_GLIBCXX_END_NAMESPACE_VERSION 823} // namespace 824 825#include <bits/streambuf.tcc> 826 827#endif /* _GLIBCXX_STREAMBUF */ 828