1// Input streams -*- C++ -*- 2 3// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 4// 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 2, 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// You should have received a copy of the GNU General Public License along 18// with this library; see the file COPYING. If not, write to the Free 19// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 20// USA. 21 22// As a special exception, you may use this file as part of a free software 23// library without restriction. Specifically, if other files instantiate 24// templates or use macros or inline functions from this file, or you compile 25// this file and link it with other files to produce an executable, this 26// file does not by itself cause the resulting executable to be covered by 27// the GNU General Public License. This exception does not however 28// invalidate any other reasons why the executable file might be covered by 29// the GNU General Public License. 30 31// 32// ISO C++ 14882: 27.6.1 Input streams 33// 34 35/** @file istream 36 * This is a Standard C++ Library header. 37 */ 38 39#ifndef _GLIBCXX_ISTREAM 40#define _GLIBCXX_ISTREAM 1 41 42#pragma GCC system_header 43 44#include <ios> 45#include <limits> // For numeric_limits 46 47_GLIBCXX_BEGIN_NAMESPACE(std) 48 49 // [27.6.1.1] Template class basic_istream 50 /** 51 * @brief Controlling input. 52 * 53 * This is the base class for all input streams. It provides text 54 * formatting of all builtin types, and communicates with any class 55 * derived from basic_streambuf to do the actual input. 56 */ 57 template<typename _CharT, typename _Traits> 58 class basic_istream : virtual public basic_ios<_CharT, _Traits> 59 { 60 public: 61 // Types (inherited from basic_ios (27.4.4)): 62 typedef _CharT char_type; 63 typedef typename _Traits::int_type int_type; 64 typedef typename _Traits::pos_type pos_type; 65 typedef typename _Traits::off_type off_type; 66 typedef _Traits traits_type; 67 68 // Non-standard Types: 69 typedef basic_streambuf<_CharT, _Traits> __streambuf_type; 70 typedef basic_ios<_CharT, _Traits> __ios_type; 71 typedef basic_istream<_CharT, _Traits> __istream_type; 72 typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> > 73 __num_get_type; 74 typedef ctype<_CharT> __ctype_type; 75 76 template<typename _CharT2, typename _Traits2> 77 friend basic_istream<_CharT2, _Traits2>& 78 operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2&); 79 80 template<typename _CharT2, typename _Traits2> 81 friend basic_istream<_CharT2, _Traits2>& 82 operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*); 83 84 protected: 85 // Data Members: 86 /** 87 * @if maint 88 * The number of characters extracted in the previous unformatted 89 * function; see gcount(). 90 * @endif 91 */ 92 streamsize _M_gcount; 93 94 public: 95 // [27.6.1.1.1] constructor/destructor 96 /** 97 * @brief Base constructor. 98 * 99 * This ctor is almost never called by the user directly, rather from 100 * derived classes' initialization lists, which pass a pointer to 101 * their own stream buffer. 102 */ 103 explicit 104 basic_istream(__streambuf_type* __sb): _M_gcount(streamsize(0)) 105 { this->init(__sb); } 106 107 /** 108 * @brief Base destructor. 109 * 110 * This does very little apart from providing a virtual base dtor. 111 */ 112 virtual 113 ~basic_istream() 114 { _M_gcount = streamsize(0); } 115 116 // [27.6.1.1.2] prefix/suffix 117 class sentry; 118 friend class sentry; 119 120 // [27.6.1.2] formatted input 121 // [27.6.1.2.3] basic_istream::operator>> 122 //@{ 123 /** 124 * @brief Interface for manipulators. 125 * 126 * Manuipulators such as @c std::ws and @c std::dec use these 127 * functions in constructs like "std::cin >> std::ws". For more 128 * information, see the iomanip header. 129 */ 130 __istream_type& 131 operator>>(__istream_type& (*__pf)(__istream_type&)) 132 { return __pf(*this); } 133 134 __istream_type& 135 operator>>(__ios_type& (*__pf)(__ios_type&)) 136 { 137 __pf(*this); 138 return *this; 139 } 140 141 __istream_type& 142 operator>>(ios_base& (*__pf)(ios_base&)) 143 { 144 __pf(*this); 145 return *this; 146 } 147 //@} 148 149 // [27.6.1.2.2] arithmetic extractors 150 /** 151 * @name Arithmetic Extractors 152 * 153 * All the @c operator>> functions (aka <em>formatted input 154 * functions</em>) have some common behavior. Each starts by 155 * constructing a temporary object of type std::basic_istream::sentry 156 * with the second argument (noskipws) set to false. This has several 157 * effects, concluding with the setting of a status flag; see the 158 * sentry documentation for more. 159 * 160 * If the sentry status is good, the function tries to extract 161 * whatever data is appropriate for the type of the argument. 162 * 163 * If an exception is thrown during extraction, ios_base::badbit 164 * will be turned on in the stream's error state without causing an 165 * ios_base::failure to be thrown. The original exception will then 166 * be rethrown. 167 */ 168 //@{ 169 /** 170 * @brief Basic arithmetic extractors 171 * @param A variable of builtin type. 172 * @return @c *this if successful 173 * 174 * These functions use the stream's current locale (specifically, the 175 * @c num_get facet) to parse the input data. 176 */ 177 __istream_type& 178 operator>>(bool& __n) 179 { return _M_extract(__n); } 180 181 __istream_type& 182 operator>>(short& __n); 183 184 __istream_type& 185 operator>>(unsigned short& __n) 186 { return _M_extract(__n); } 187 188 __istream_type& 189 operator>>(int& __n); 190 191 __istream_type& 192 operator>>(unsigned int& __n) 193 { return _M_extract(__n); } 194 195 __istream_type& 196 operator>>(long& __n) 197 { return _M_extract(__n); } 198 199 __istream_type& 200 operator>>(unsigned long& __n) 201 { return _M_extract(__n); } 202 203#ifdef _GLIBCXX_USE_LONG_LONG 204 __istream_type& 205 operator>>(long long& __n) 206 { return _M_extract(__n); } 207 208 __istream_type& 209 operator>>(unsigned long long& __n) 210 { return _M_extract(__n); } 211#endif 212 213 __istream_type& 214 operator>>(float& __f) 215 { return _M_extract(__f); } 216 217 __istream_type& 218 operator>>(double& __f) 219 { return _M_extract(__f); } 220 221 __istream_type& 222 operator>>(long double& __f) 223 { return _M_extract(__f); } 224 225 __istream_type& 226 operator>>(void*& __p) 227 { return _M_extract(__p); } 228 229 /** 230 * @brief Extracting into another streambuf. 231 * @param sb A pointer to a streambuf 232 * 233 * This function behaves like one of the basic arithmetic extractors, 234 * in that it also constructs a sentry object and has the same error 235 * handling behavior. 236 * 237 * If @a sb is NULL, the stream will set failbit in its error state. 238 * 239 * Characters are extracted from this stream and inserted into the 240 * @a sb streambuf until one of the following occurs: 241 * 242 * - the input stream reaches end-of-file, 243 * - insertion into the output buffer fails (in this case, the 244 * character that would have been inserted is not extracted), or 245 * - an exception occurs (and in this case is caught) 246 * 247 * If the function inserts no characters, failbit is set. 248 */ 249 __istream_type& 250 operator>>(__streambuf_type* __sb); 251 //@} 252 253 // [27.6.1.3] unformatted input 254 /** 255 * @brief Character counting 256 * @return The number of characters extracted by the previous 257 * unformatted input function dispatched for this stream. 258 */ 259 streamsize 260 gcount() const 261 { return _M_gcount; } 262 263 /** 264 * @name Unformatted Input Functions 265 * 266 * All the unformatted input functions have some common behavior. 267 * Each starts by constructing a temporary object of type 268 * std::basic_istream::sentry with the second argument (noskipws) 269 * set to true. This has several effects, concluding with the 270 * setting of a status flag; see the sentry documentation for more. 271 * 272 * If the sentry status is good, the function tries to extract 273 * whatever data is appropriate for the type of the argument. 274 * 275 * The number of characters extracted is stored for later retrieval 276 * by gcount(). 277 * 278 * If an exception is thrown during extraction, ios_base::badbit 279 * will be turned on in the stream's error state without causing an 280 * ios_base::failure to be thrown. The original exception will then 281 * be rethrown. 282 */ 283 //@{ 284 /** 285 * @brief Simple extraction. 286 * @return A character, or eof(). 287 * 288 * Tries to extract a character. If none are available, sets failbit 289 * and returns traits::eof(). 290 */ 291 int_type 292 get(); 293 294 /** 295 * @brief Simple extraction. 296 * @param c The character in which to store data. 297 * @return *this 298 * 299 * Tries to extract a character and store it in @a c. If none are 300 * available, sets failbit and returns traits::eof(). 301 * 302 * @note This function is not overloaded on signed char and 303 * unsigned char. 304 */ 305 __istream_type& 306 get(char_type& __c); 307 308 /** 309 * @brief Simple multiple-character extraction. 310 * @param s Pointer to an array. 311 * @param n Maximum number of characters to store in @a s. 312 * @param delim A "stop" character. 313 * @return *this 314 * 315 * Characters are extracted and stored into @a s until one of the 316 * following happens: 317 * 318 * - @c n-1 characters are stored 319 * - the input sequence reaches EOF 320 * - the next character equals @a delim, in which case the character 321 * is not extracted 322 * 323 * If no characters are stored, failbit is set in the stream's error 324 * state. 325 * 326 * In any case, a null character is stored into the next location in 327 * the array. 328 * 329 * @note This function is not overloaded on signed char and 330 * unsigned char. 331 */ 332 __istream_type& 333 get(char_type* __s, streamsize __n, char_type __delim); 334 335 /** 336 * @brief Simple multiple-character extraction. 337 * @param s Pointer to an array. 338 * @param n Maximum number of characters to store in @a s. 339 * @return *this 340 * 341 * Returns @c get(s,n,widen('\n')). 342 */ 343 __istream_type& 344 get(char_type* __s, streamsize __n) 345 { return this->get(__s, __n, this->widen('\n')); } 346 347 /** 348 * @brief Extraction into another streambuf. 349 * @param sb A streambuf in which to store data. 350 * @param delim A "stop" character. 351 * @return *this 352 * 353 * Characters are extracted and inserted into @a sb until one of the 354 * following happens: 355 * 356 * - the input sequence reaches EOF 357 * - insertion into the output buffer fails (in this case, the 358 * character that would have been inserted is not extracted) 359 * - the next character equals @a delim (in this case, the character 360 * is not extracted) 361 * - an exception occurs (and in this case is caught) 362 * 363 * If no characters are stored, failbit is set in the stream's error 364 * state. 365 */ 366 __istream_type& 367 get(__streambuf_type& __sb, char_type __delim); 368 369 /** 370 * @brief Extraction into another streambuf. 371 * @param sb A streambuf in which to store data. 372 * @return *this 373 * 374 * Returns @c get(sb,widen('\n')). 375 */ 376 __istream_type& 377 get(__streambuf_type& __sb) 378 { return this->get(__sb, this->widen('\n')); } 379 380 /** 381 * @brief String extraction. 382 * @param s A character array in which to store the data. 383 * @param n Maximum number of characters to extract. 384 * @param delim A "stop" character. 385 * @return *this 386 * 387 * Extracts and stores characters into @a s until one of the 388 * following happens. Note that these criteria are required to be 389 * tested in the order listed here, to allow an input line to exactly 390 * fill the @a s array without setting failbit. 391 * 392 * -# the input sequence reaches end-of-file, in which case eofbit 393 * is set in the stream error state 394 * -# the next character equals @c delim, in which case the character 395 * is extracted (and therefore counted in @c gcount()) but not stored 396 * -# @c n-1 characters are stored, in which case failbit is set 397 * in the stream error state 398 * 399 * If no characters are extracted, failbit is set. (An empty line of 400 * input should therefore not cause failbit to be set.) 401 * 402 * In any case, a null character is stored in the next location in 403 * the array. 404 */ 405 __istream_type& 406 getline(char_type* __s, streamsize __n, char_type __delim); 407 408 /** 409 * @brief String extraction. 410 * @param s A character array in which to store the data. 411 * @param n Maximum number of characters to extract. 412 * @return *this 413 * 414 * Returns @c getline(s,n,widen('\n')). 415 */ 416 __istream_type& 417 getline(char_type* __s, streamsize __n) 418 { return this->getline(__s, __n, this->widen('\n')); } 419 420 /** 421 * @brief Discarding characters 422 * @param n Number of characters to discard. 423 * @param delim A "stop" character. 424 * @return *this 425 * 426 * Extracts characters and throws them away until one of the 427 * following happens: 428 * - if @a n @c != @c std::numeric_limits<int>::max(), @a n 429 * characters are extracted 430 * - the input sequence reaches end-of-file 431 * - the next character equals @a delim (in this case, the character 432 * is extracted); note that this condition will never occur if 433 * @a delim equals @c traits::eof(). 434 * 435 * NB: Provide three overloads, instead of the single function 436 * (with defaults) mandated by the Standard: this leads to a 437 * better performing implementation, while still conforming to 438 * the Standard. 439 */ 440 __istream_type& 441 ignore(); 442 443 __istream_type& 444 ignore(streamsize __n); 445 446 __istream_type& 447 ignore(streamsize __n, int_type __delim); 448 449 /** 450 * @brief Looking ahead in the stream 451 * @return The next character, or eof(). 452 * 453 * If, after constructing the sentry object, @c good() is false, 454 * returns @c traits::eof(). Otherwise reads but does not extract 455 * the next input character. 456 */ 457 int_type 458 peek(); 459 460 /** 461 * @brief Extraction without delimiters. 462 * @param s A character array. 463 * @param n Maximum number of characters to store. 464 * @return *this 465 * 466 * If the stream state is @c good(), extracts characters and stores 467 * them into @a s until one of the following happens: 468 * - @a n characters are stored 469 * - the input sequence reaches end-of-file, in which case the error 470 * state is set to @c failbit|eofbit. 471 * 472 * @note This function is not overloaded on signed char and 473 * unsigned char. 474 */ 475 __istream_type& 476 read(char_type* __s, streamsize __n); 477 478 /** 479 * @brief Extraction until the buffer is exhausted, but no more. 480 * @param s A character array. 481 * @param n Maximum number of characters to store. 482 * @return The number of characters extracted. 483 * 484 * Extracts characters and stores them into @a s depending on the 485 * number of characters remaining in the streambuf's buffer, 486 * @c rdbuf()->in_avail(), called @c A here: 487 * - if @c A @c == @c -1, sets eofbit and extracts no characters 488 * - if @c A @c == @c 0, extracts no characters 489 * - if @c A @c > @c 0, extracts @c min(A,n) 490 * 491 * The goal is to empty the current buffer, and to not request any 492 * more from the external input sequence controlled by the streambuf. 493 */ 494 streamsize 495 readsome(char_type* __s, streamsize __n); 496 497 /** 498 * @brief Unextracting a single character. 499 * @param c The character to push back into the input stream. 500 * @return *this 501 * 502 * If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c). 503 * 504 * If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in 505 * the error state. 506 * 507 * @note Since no characters are extracted, the next call to 508 * @c gcount() will return 0, as required by DR 60. 509 */ 510 __istream_type& 511 putback(char_type __c); 512 513 /** 514 * @brief Unextracting the previous character. 515 * @return *this 516 * 517 * If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c). 518 * 519 * If @c rdbuf() is null or if @c sungetc() fails, sets badbit in 520 * the error state. 521 * 522 * @note Since no characters are extracted, the next call to 523 * @c gcount() will return 0, as required by DR 60. 524 */ 525 __istream_type& 526 unget(); 527 528 /** 529 * @brief Synchronizing the stream buffer. 530 * @return 0 on success, -1 on failure 531 * 532 * If @c rdbuf() is a null pointer, returns -1. 533 * 534 * Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1, 535 * sets badbit and returns -1. 536 * 537 * Otherwise, returns 0. 538 * 539 * @note This function does not count the number of characters 540 * extracted, if any, and therefore does not affect the next 541 * call to @c gcount(). 542 */ 543 int 544 sync(); 545 546 /** 547 * @brief Getting the current read position. 548 * @return A file position object. 549 * 550 * If @c fail() is not false, returns @c pos_type(-1) to indicate 551 * failure. Otherwise returns @c rdbuf()->pubseekoff(0,cur,in). 552 * 553 * @note This function does not count the number of characters 554 * extracted, if any, and therefore does not affect the next 555 * call to @c gcount(). 556 */ 557 pos_type 558 tellg(); 559 560 /** 561 * @brief Changing the current read position. 562 * @param pos A file position object. 563 * @return *this 564 * 565 * If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos). If 566 * that function fails, sets failbit. 567 * 568 * @note This function does not count the number of characters 569 * extracted, if any, and therefore does not affect the next 570 * call to @c gcount(). 571 */ 572 __istream_type& 573 seekg(pos_type); 574 575 /** 576 * @brief Changing the current read position. 577 * @param off A file offset object. 578 * @param dir The direction in which to seek. 579 * @return *this 580 * 581 * If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir). 582 * If that function fails, sets failbit. 583 * 584 * @note This function does not count the number of characters 585 * extracted, if any, and therefore does not affect the next 586 * call to @c gcount(). 587 */ 588 __istream_type& 589 seekg(off_type, ios_base::seekdir); 590 //@} 591 592 protected: 593 explicit 594 basic_istream(): _M_gcount(streamsize(0)) { } 595 596 template<typename _ValueT> 597 __istream_type& 598 _M_extract(_ValueT& __v); 599 }; 600 601 // Explicit specialization declarations, defined in src/istream.cc. 602 template<> 603 basic_istream<char>& 604 basic_istream<char>:: 605 getline(char_type* __s, streamsize __n, char_type __delim); 606 607 template<> 608 basic_istream<char>& 609 basic_istream<char>:: 610 ignore(streamsize __n); 611 612 template<> 613 basic_istream<char>& 614 basic_istream<char>:: 615 ignore(streamsize __n, int_type __delim); 616 617#ifdef _GLIBCXX_USE_WCHAR_T 618 template<> 619 basic_istream<wchar_t>& 620 basic_istream<wchar_t>:: 621 getline(char_type* __s, streamsize __n, char_type __delim); 622 623 template<> 624 basic_istream<wchar_t>& 625 basic_istream<wchar_t>:: 626 ignore(streamsize __n); 627 628 template<> 629 basic_istream<wchar_t>& 630 basic_istream<wchar_t>:: 631 ignore(streamsize __n, int_type __delim); 632#endif 633 634 /** 635 * @brief Performs setup work for input streams. 636 * 637 * Objects of this class are created before all of the standard 638 * extractors are run. It is responsible for "exception-safe prefix and 639 * suffix operations," although only prefix actions are currently required 640 * by the standard. Additional actions may be added by the 641 * implementation, and we list them in 642 * http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#5 643 * under [27.6] notes. 644 */ 645 template<typename _CharT, typename _Traits> 646 class basic_istream<_CharT, _Traits>::sentry 647 { 648 public: 649 /// Easy access to dependant types. 650 typedef _Traits traits_type; 651 typedef basic_streambuf<_CharT, _Traits> __streambuf_type; 652 typedef basic_istream<_CharT, _Traits> __istream_type; 653 typedef typename __istream_type::__ctype_type __ctype_type; 654 typedef typename _Traits::int_type __int_type; 655 656 /** 657 * @brief The constructor performs all the work. 658 * @param is The input stream to guard. 659 * @param noskipws Whether to consume whitespace or not. 660 * 661 * If the stream state is good (@a is.good() is true), then the 662 * following actions are performed, otherwise the sentry state is 663 * false ("not okay") and failbit is set in the stream state. 664 * 665 * The sentry's preparatory actions are: 666 * 667 * -# if the stream is tied to an output stream, @c is.tie()->flush() 668 * is called to synchronize the output sequence 669 * -# if @a noskipws is false, and @c ios_base::skipws is set in 670 * @c is.flags(), the sentry extracts and discards whitespace 671 * characters from the stream. The currently imbued locale is 672 * used to determine whether each character is whitespace. 673 * 674 * If the stream state is still good, then the sentry state becomes 675 * true ("okay"). 676 */ 677 explicit 678 sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false); 679 680 /** 681 * @brief Quick status checking. 682 * @return The sentry state. 683 * 684 * For ease of use, sentries may be converted to booleans. The 685 * return value is that of the sentry state (true == okay). 686 */ 687 operator bool() const 688 { return _M_ok; } 689 690 private: 691 bool _M_ok; 692 }; 693 694 // [27.6.1.2.3] character extraction templates 695 //@{ 696 /** 697 * @brief Character extractors 698 * @param in An input stream. 699 * @param c A character reference. 700 * @return in 701 * 702 * Behaves like one of the formatted arithmetic extractors described in 703 * std::basic_istream. After constructing a sentry object with good 704 * status, this function extracts a character (if one is available) and 705 * stores it in @a c. Otherwise, sets failbit in the input stream. 706 */ 707 template<typename _CharT, typename _Traits> 708 basic_istream<_CharT, _Traits>& 709 operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c); 710 711 template<class _Traits> 712 inline basic_istream<char, _Traits>& 713 operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c) 714 { return (__in >> reinterpret_cast<char&>(__c)); } 715 716 template<class _Traits> 717 inline basic_istream<char, _Traits>& 718 operator>>(basic_istream<char, _Traits>& __in, signed char& __c) 719 { return (__in >> reinterpret_cast<char&>(__c)); } 720 //@} 721 722 //@{ 723 /** 724 * @brief Character string extractors 725 * @param in An input stream. 726 * @param s A pointer to a character array. 727 * @return in 728 * 729 * Behaves like one of the formatted arithmetic extractors described in 730 * std::basic_istream. After constructing a sentry object with good 731 * status, this function extracts up to @c n characters and stores them 732 * into the array starting at @a s. @c n is defined as: 733 * 734 * - if @c width() is greater than zero, @c n is width() 735 * - otherwise @c n is "the number of elements of the largest array of 736 * @c char_type that can store a terminating @c eos." [27.6.1.2.3]/6 737 * 738 * Characters are extracted and stored until one of the following happens: 739 * - @c n-1 characters are stored 740 * - EOF is reached 741 * - the next character is whitespace according to the current locale 742 * - the next character is a null byte (i.e., @c charT() ) 743 * 744 * @c width(0) is then called for the input stream. 745 * 746 * If no characters are extracted, sets failbit. 747 */ 748 template<typename _CharT, typename _Traits> 749 basic_istream<_CharT, _Traits>& 750 operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s); 751 752 // Explicit specialization declaration, defined in src/istream.cc. 753 template<> 754 basic_istream<char>& 755 operator>>(basic_istream<char>& __in, char* __s); 756 757 template<class _Traits> 758 inline basic_istream<char, _Traits>& 759 operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s) 760 { return (__in >> reinterpret_cast<char*>(__s)); } 761 762 template<class _Traits> 763 inline basic_istream<char, _Traits>& 764 operator>>(basic_istream<char, _Traits>& __in, signed char* __s) 765 { return (__in >> reinterpret_cast<char*>(__s)); } 766 //@} 767 768 // 27.6.1.5 Template class basic_iostream 769 /** 770 * @brief Merging istream and ostream capabilities. 771 * 772 * This class multiply inherits from the input and output stream classes 773 * simply to provide a single interface. 774 */ 775 template<typename _CharT, typename _Traits> 776 class basic_iostream 777 : public basic_istream<_CharT, _Traits>, 778 public basic_ostream<_CharT, _Traits> 779 { 780 public: 781 // _GLIBCXX_RESOLVE_LIB_DEFECTS 782 // 271. basic_iostream missing typedefs 783 // Types (inherited): 784 typedef _CharT char_type; 785 typedef typename _Traits::int_type int_type; 786 typedef typename _Traits::pos_type pos_type; 787 typedef typename _Traits::off_type off_type; 788 typedef _Traits traits_type; 789 790 // Non-standard Types: 791 typedef basic_istream<_CharT, _Traits> __istream_type; 792 typedef basic_ostream<_CharT, _Traits> __ostream_type; 793 794 /** 795 * @brief Constructor does nothing. 796 * 797 * Both of the parent classes are initialized with the same 798 * streambuf pointer passed to this constructor. 799 */ 800 explicit 801 basic_iostream(basic_streambuf<_CharT, _Traits>* __sb) 802 : __istream_type(), __ostream_type() 803 { this->init(__sb); } 804 805 /** 806 * @brief Destructor does nothing. 807 */ 808 virtual 809 ~basic_iostream() { } 810 811 protected: 812 explicit 813 basic_iostream() : __istream_type(), __ostream_type() 814 { } 815 }; 816 817 // [27.6.1.4] standard basic_istream manipulators 818 /** 819 * @brief Quick and easy way to eat whitespace 820 * 821 * This manipulator extracts whitespace characters, stopping when the 822 * next character is non-whitespace, or when the input sequence is empty. 823 * If the sequence is empty, @c eofbit is set in the stream, but not 824 * @c failbit. 825 * 826 * The current locale is used to distinguish whitespace characters. 827 * 828 * Example: 829 * @code 830 * MyClass mc; 831 * 832 * std::cin >> std::ws >> mc; 833 * @endcode 834 * will skip leading whitespace before calling operator>> on cin and your 835 * object. Note that the same effect can be achieved by creating a 836 * std::basic_istream::sentry inside your definition of operator>>. 837 */ 838 template<typename _CharT, typename _Traits> 839 basic_istream<_CharT, _Traits>& 840 ws(basic_istream<_CharT, _Traits>& __is); 841 842_GLIBCXX_END_NAMESPACE 843 844#ifndef _GLIBCXX_EXPORT_TEMPLATE 845# include <bits/istream.tcc> 846#endif 847 848#endif /* _GLIBCXX_ISTREAM */ 849