1 // Input streams -*- C++ -*- 2 3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 4 // 2006, 2007, 2008, 2009 5 // Free Software Foundation, Inc. 6 // 7 // This file is part of the GNU ISO C++ Library. This library is free 8 // software; you can redistribute it and/or modify it under the 9 // terms of the GNU General Public License as published by the 10 // Free Software Foundation; either version 3, or (at your option) 11 // any later version. 12 13 // This library is distributed in the hope that it will be useful, 14 // but WITHOUT ANY WARRANTY; without even the implied warranty of 15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 // GNU General Public License for more details. 17 18 // Under Section 7 of GPL version 3, you are granted additional 19 // permissions described in the GCC Runtime Library Exception, version 20 // 3.1, as published by the Free Software Foundation. 21 22 // You should have received a copy of the GNU General Public License and 23 // a copy of the GCC Runtime Library Exception along with this program; 24 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 25 // <http://www.gnu.org/licenses/>. 26 27 // 28 // ISO C++ 14882: 27.6.1 Input streams 29 // 30 31 /** @file istream 32 * This is a Standard C++ Library header. 33 */ 34 35 #ifndef _GLIBCXX_ISTREAM 36 #define _GLIBCXX_ISTREAM 1 37 38 #pragma GCC system_header 39 40 #include <ios> 41 #include <ostream> 42 43 _GLIBCXX_BEGIN_NAMESPACE(std) 44 45 // [27.6.1.1] Template class basic_istream 46 /** 47 * @brief Controlling input. 48 * @ingroup io 49 * 50 * This is the base class for all input streams. It provides text 51 * formatting of all builtin types, and communicates with any class 52 * derived from basic_streambuf to do the actual input. 53 */ 54 template<typename _CharT, typename _Traits> 55 class basic_istream : virtual public basic_ios<_CharT, _Traits> 56 { 57 public: 58 // Types (inherited from basic_ios (27.4.4)): 59 typedef _CharT char_type; 60 typedef typename _Traits::int_type int_type; 61 typedef typename _Traits::pos_type pos_type; 62 typedef typename _Traits::off_type off_type; 63 typedef _Traits traits_type; 64 65 // Non-standard Types: 66 typedef basic_streambuf<_CharT, _Traits> __streambuf_type; 67 typedef basic_ios<_CharT, _Traits> __ios_type; 68 typedef basic_istream<_CharT, _Traits> __istream_type; 69 typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> > 70 __num_get_type; 71 typedef ctype<_CharT> __ctype_type; 72 73 protected: 74 // Data Members: 75 /** 76 * The number of characters extracted in the previous unformatted 77 * function; see gcount(). 78 */ 79 streamsize _M_gcount; 80 81 public: 82 // [27.6.1.1.1] constructor/destructor 83 /** 84 * @brief Base constructor. 85 * 86 * This ctor is almost never called by the user directly, rather from 87 * derived classes' initialization lists, which pass a pointer to 88 * their own stream buffer. 89 */ 90 explicit 91 basic_istream(__streambuf_type* __sb) 92 : _M_gcount(streamsize(0)) 93 { this->init(__sb); } 94 95 /** 96 * @brief Base destructor. 97 * 98 * This does very little apart from providing a virtual base dtor. 99 */ 100 virtual 101 ~basic_istream() 102 { _M_gcount = streamsize(0); } 103 104 // [27.6.1.1.2] prefix/suffix 105 class sentry; 106 friend class sentry; 107 108 // [27.6.1.2] formatted input 109 // [27.6.1.2.3] basic_istream::operator>> 110 //@{ 111 /** 112 * @brief Interface for manipulators. 113 * 114 * Manipulators such as @c std::ws and @c std::dec use these 115 * functions in constructs like "std::cin >> std::ws". For more 116 * information, see the iomanip header. 117 */ 118 __istream_type& 119 operator>>(__istream_type& (*__pf)(__istream_type&)) 120 { return __pf(*this); } 121 122 __istream_type& 123 operator>>(__ios_type& (*__pf)(__ios_type&)) 124 { 125 __pf(*this); 126 return *this; 127 } 128 129 __istream_type& 130 operator>>(ios_base& (*__pf)(ios_base&)) 131 { 132 __pf(*this); 133 return *this; 134 } 135 //@} 136 137 // [27.6.1.2.2] arithmetic extractors 138 /** 139 * @name Arithmetic Extractors 140 * 141 * All the @c operator>> functions (aka <em>formatted input 142 * functions</em>) have some common behavior. Each starts by 143 * constructing a temporary object of type std::basic_istream::sentry 144 * with the second argument (noskipws) set to false. This has several 145 * effects, concluding with the setting of a status flag; see the 146 * sentry documentation for more. 147 * 148 * If the sentry status is good, the function tries to extract 149 * whatever data is appropriate for the type of the argument. 150 * 151 * If an exception is thrown during extraction, ios_base::badbit 152 * will be turned on in the stream's error state without causing an 153 * ios_base::failure to be thrown. The original exception will then 154 * be rethrown. 155 */ 156 //@{ 157 /** 158 * @brief Basic arithmetic extractors 159 * @param A variable of builtin type. 160 * @return @c *this if successful 161 * 162 * These functions use the stream's current locale (specifically, the 163 * @c num_get facet) to parse the input data. 164 */ 165 __istream_type& 166 operator>>(bool& __n) 167 { return _M_extract(__n); } 168 169 __istream_type& 170 operator>>(short& __n); 171 172 __istream_type& 173 operator>>(unsigned short& __n) 174 { return _M_extract(__n); } 175 176 __istream_type& 177 operator>>(int& __n); 178 179 __istream_type& 180 operator>>(unsigned int& __n) 181 { return _M_extract(__n); } 182 183 __istream_type& 184 operator>>(long& __n) 185 { return _M_extract(__n); } 186 187 __istream_type& 188 operator>>(unsigned long& __n) 189 { return _M_extract(__n); } 190 191 #ifdef _GLIBCXX_USE_LONG_LONG 192 __istream_type& 193 operator>>(long long& __n) 194 { return _M_extract(__n); } 195 196 __istream_type& 197 operator>>(unsigned long long& __n) 198 { return _M_extract(__n); } 199 #endif 200 201 __istream_type& 202 operator>>(float& __f) 203 { return _M_extract(__f); } 204 205 __istream_type& 206 operator>>(double& __f) 207 { return _M_extract(__f); } 208 209 __istream_type& 210 operator>>(long double& __f) 211 { return _M_extract(__f); } 212 213 __istream_type& 214 operator>>(void*& __p) 215 { return _M_extract(__p); } 216 217 /** 218 * @brief Extracting into another streambuf. 219 * @param sb A pointer to a streambuf 220 * 221 * This function behaves like one of the basic arithmetic extractors, 222 * in that it also constructs a sentry object and has the same error 223 * handling behavior. 224 * 225 * If @a sb is NULL, the stream will set failbit in its error state. 226 * 227 * Characters are extracted from this stream and inserted into the 228 * @a sb streambuf until one of the following occurs: 229 * 230 * - the input stream reaches end-of-file, 231 * - insertion into the output buffer fails (in this case, the 232 * character that would have been inserted is not extracted), or 233 * - an exception occurs (and in this case is caught) 234 * 235 * If the function inserts no characters, failbit is set. 236 */ 237 __istream_type& 238 operator>>(__streambuf_type* __sb); 239 //@} 240 241 // [27.6.1.3] unformatted input 242 /** 243 * @brief Character counting 244 * @return The number of characters extracted by the previous 245 * unformatted input function dispatched for this stream. 246 */ 247 streamsize 248 gcount() const 249 { return _M_gcount; } 250 251 /** 252 * @name Unformatted Input Functions 253 * 254 * All the unformatted input functions have some common behavior. 255 * Each starts by constructing a temporary object of type 256 * std::basic_istream::sentry with the second argument (noskipws) 257 * set to true. This has several effects, concluding with the 258 * setting of a status flag; see the sentry documentation for more. 259 * 260 * If the sentry status is good, the function tries to extract 261 * whatever data is appropriate for the type of the argument. 262 * 263 * The number of characters extracted is stored for later retrieval 264 * by gcount(). 265 * 266 * If an exception is thrown during extraction, ios_base::badbit 267 * will be turned on in the stream's error state without causing an 268 * ios_base::failure to be thrown. The original exception will then 269 * be rethrown. 270 */ 271 //@{ 272 /** 273 * @brief Simple extraction. 274 * @return A character, or eof(). 275 * 276 * Tries to extract a character. If none are available, sets failbit 277 * and returns traits::eof(). 278 */ 279 int_type 280 get(); 281 282 /** 283 * @brief Simple extraction. 284 * @param c The character in which to store data. 285 * @return *this 286 * 287 * Tries to extract a character and store it in @a c. If none are 288 * available, sets failbit and returns traits::eof(). 289 * 290 * @note This function is not overloaded on signed char and 291 * unsigned char. 292 */ 293 __istream_type& 294 get(char_type& __c); 295 296 /** 297 * @brief Simple multiple-character extraction. 298 * @param s Pointer to an array. 299 * @param n Maximum number of characters to store in @a s. 300 * @param delim A "stop" character. 301 * @return *this 302 * 303 * Characters are extracted and stored into @a s until one of the 304 * following happens: 305 * 306 * - @c n-1 characters are stored 307 * - the input sequence reaches EOF 308 * - the next character equals @a delim, in which case the character 309 * is not extracted 310 * 311 * If no characters are stored, failbit is set in the stream's error 312 * state. 313 * 314 * In any case, a null character is stored into the next location in 315 * the array. 316 * 317 * @note This function is not overloaded on signed char and 318 * unsigned char. 319 */ 320 __istream_type& 321 get(char_type* __s, streamsize __n, char_type __delim); 322 323 /** 324 * @brief Simple multiple-character extraction. 325 * @param s Pointer to an array. 326 * @param n Maximum number of characters to store in @a s. 327 * @return *this 328 * 329 * Returns @c get(s,n,widen('\n')). 330 */ 331 __istream_type& 332 get(char_type* __s, streamsize __n) 333 { return this->get(__s, __n, this->widen('\n')); } 334 335 /** 336 * @brief Extraction into another streambuf. 337 * @param sb A streambuf in which to store data. 338 * @param delim A "stop" character. 339 * @return *this 340 * 341 * Characters are extracted and inserted into @a sb until one of the 342 * following happens: 343 * 344 * - the input sequence reaches EOF 345 * - insertion into the output buffer fails (in this case, the 346 * character that would have been inserted is not extracted) 347 * - the next character equals @a delim (in this case, the character 348 * is not extracted) 349 * - an exception occurs (and in this case is caught) 350 * 351 * If no characters are stored, failbit is set in the stream's error 352 * state. 353 */ 354 __istream_type& 355 get(__streambuf_type& __sb, char_type __delim); 356 357 /** 358 * @brief Extraction into another streambuf. 359 * @param sb A streambuf in which to store data. 360 * @return *this 361 * 362 * Returns @c get(sb,widen('\n')). 363 */ 364 __istream_type& 365 get(__streambuf_type& __sb) 366 { return this->get(__sb, this->widen('\n')); } 367 368 /** 369 * @brief String extraction. 370 * @param s A character array in which to store the data. 371 * @param n Maximum number of characters to extract. 372 * @param delim A "stop" character. 373 * @return *this 374 * 375 * Extracts and stores characters into @a s until one of the 376 * following happens. Note that these criteria are required to be 377 * tested in the order listed here, to allow an input line to exactly 378 * fill the @a s array without setting failbit. 379 * 380 * -# the input sequence reaches end-of-file, in which case eofbit 381 * is set in the stream error state 382 * -# the next character equals @c delim, in which case the character 383 * is extracted (and therefore counted in @c gcount()) but not stored 384 * -# @c n-1 characters are stored, in which case failbit is set 385 * in the stream error state 386 * 387 * If no characters are extracted, failbit is set. (An empty line of 388 * input should therefore not cause failbit to be set.) 389 * 390 * In any case, a null character is stored in the next location in 391 * the array. 392 */ 393 __istream_type& 394 getline(char_type* __s, streamsize __n, char_type __delim); 395 396 /** 397 * @brief String extraction. 398 * @param s A character array in which to store the data. 399 * @param n Maximum number of characters to extract. 400 * @return *this 401 * 402 * Returns @c getline(s,n,widen('\n')). 403 */ 404 __istream_type& 405 getline(char_type* __s, streamsize __n) 406 { return this->getline(__s, __n, this->widen('\n')); } 407 408 /** 409 * @brief Discarding characters 410 * @param n Number of characters to discard. 411 * @param delim A "stop" character. 412 * @return *this 413 * 414 * Extracts characters and throws them away until one of the 415 * following happens: 416 * - if @a n @c != @c std::numeric_limits<int>::max(), @a n 417 * characters are extracted 418 * - the input sequence reaches end-of-file 419 * - the next character equals @a delim (in this case, the character 420 * is extracted); note that this condition will never occur if 421 * @a delim equals @c traits::eof(). 422 * 423 * NB: Provide three overloads, instead of the single function 424 * (with defaults) mandated by the Standard: this leads to a 425 * better performing implementation, while still conforming to 426 * the Standard. 427 */ 428 __istream_type& 429 ignore(); 430 431 __istream_type& 432 ignore(streamsize __n); 433 434 __istream_type& 435 ignore(streamsize __n, int_type __delim); 436 437 /** 438 * @brief Looking ahead in the stream 439 * @return The next character, or eof(). 440 * 441 * If, after constructing the sentry object, @c good() is false, 442 * returns @c traits::eof(). Otherwise reads but does not extract 443 * the next input character. 444 */ 445 int_type 446 peek(); 447 448 /** 449 * @brief Extraction without delimiters. 450 * @param s A character array. 451 * @param n Maximum number of characters to store. 452 * @return *this 453 * 454 * If the stream state is @c good(), extracts characters and stores 455 * them into @a s until one of the following happens: 456 * - @a n characters are stored 457 * - the input sequence reaches end-of-file, in which case the error 458 * state is set to @c failbit|eofbit. 459 * 460 * @note This function is not overloaded on signed char and 461 * unsigned char. 462 */ 463 __istream_type& 464 read(char_type* __s, streamsize __n); 465 466 /** 467 * @brief Extraction until the buffer is exhausted, but no more. 468 * @param s A character array. 469 * @param n Maximum number of characters to store. 470 * @return The number of characters extracted. 471 * 472 * Extracts characters and stores them into @a s depending on the 473 * number of characters remaining in the streambuf's buffer, 474 * @c rdbuf()->in_avail(), called @c A here: 475 * - if @c A @c == @c -1, sets eofbit and extracts no characters 476 * - if @c A @c == @c 0, extracts no characters 477 * - if @c A @c > @c 0, extracts @c min(A,n) 478 * 479 * The goal is to empty the current buffer, and to not request any 480 * more from the external input sequence controlled by the streambuf. 481 */ 482 streamsize 483 readsome(char_type* __s, streamsize __n); 484 485 /** 486 * @brief Unextracting a single character. 487 * @param c The character to push back into the input stream. 488 * @return *this 489 * 490 * If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c). 491 * 492 * If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in 493 * the error state. 494 * 495 * @note Since no characters are extracted, the next call to 496 * @c gcount() will return 0, as required by DR 60. 497 */ 498 __istream_type& 499 putback(char_type __c); 500 501 /** 502 * @brief Unextracting the previous character. 503 * @return *this 504 * 505 * If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c). 506 * 507 * If @c rdbuf() is null or if @c sungetc() fails, sets badbit in 508 * the error state. 509 * 510 * @note Since no characters are extracted, the next call to 511 * @c gcount() will return 0, as required by DR 60. 512 */ 513 __istream_type& 514 unget(); 515 516 /** 517 * @brief Synchronizing the stream buffer. 518 * @return 0 on success, -1 on failure 519 * 520 * If @c rdbuf() is a null pointer, returns -1. 521 * 522 * Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1, 523 * sets badbit and returns -1. 524 * 525 * Otherwise, returns 0. 526 * 527 * @note This function does not count the number of characters 528 * extracted, if any, and therefore does not affect the next 529 * call to @c gcount(). 530 */ 531 int 532 sync(); 533 534 /** 535 * @brief Getting the current read position. 536 * @return A file position object. 537 * 538 * If @c fail() is not false, returns @c pos_type(-1) to indicate 539 * failure. Otherwise returns @c rdbuf()->pubseekoff(0,cur,in). 540 * 541 * @note This function does not count the number of characters 542 * extracted, if any, and therefore does not affect the next 543 * call to @c gcount(). 544 */ 545 pos_type 546 tellg(); 547 548 /** 549 * @brief Changing the current read position. 550 * @param pos A file position object. 551 * @return *this 552 * 553 * If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos). If 554 * that function fails, sets failbit. 555 * 556 * @note This function does not count the number of characters 557 * extracted, if any, and therefore does not affect the next 558 * call to @c gcount(). 559 */ 560 __istream_type& 561 seekg(pos_type); 562 563 /** 564 * @brief Changing the current read position. 565 * @param off A file offset object. 566 * @param dir The direction in which to seek. 567 * @return *this 568 * 569 * If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir). 570 * If that function fails, sets failbit. 571 * 572 * @note This function does not count the number of characters 573 * extracted, if any, and therefore does not affect the next 574 * call to @c gcount(). 575 */ 576 __istream_type& 577 seekg(off_type, ios_base::seekdir); 578 //@} 579 580 protected: 581 basic_istream() 582 : _M_gcount(streamsize(0)) 583 { this->init(0); } 584 585 template<typename _ValueT> 586 __istream_type& 587 _M_extract(_ValueT& __v); 588 }; 589 590 // Explicit specialization declarations, defined in src/istream.cc. 591 template<> 592 basic_istream<char>& 593 basic_istream<char>:: 594 getline(char_type* __s, streamsize __n, char_type __delim); 595 596 template<> 597 basic_istream<char>& 598 basic_istream<char>:: 599 ignore(streamsize __n); 600 601 template<> 602 basic_istream<char>& 603 basic_istream<char>:: 604 ignore(streamsize __n, int_type __delim); 605 606 #ifdef _GLIBCXX_USE_WCHAR_T 607 template<> 608 basic_istream<wchar_t>& 609 basic_istream<wchar_t>:: 610 getline(char_type* __s, streamsize __n, char_type __delim); 611 612 template<> 613 basic_istream<wchar_t>& 614 basic_istream<wchar_t>:: 615 ignore(streamsize __n); 616 617 template<> 618 basic_istream<wchar_t>& 619 basic_istream<wchar_t>:: 620 ignore(streamsize __n, int_type __delim); 621 #endif 622 623 /** 624 * @brief Performs setup work for input streams. 625 * 626 * Objects of this class are created before all of the standard 627 * extractors are run. It is responsible for "exception-safe prefix and 628 * suffix operations," although only prefix actions are currently required 629 * by the standard. 630 */ 631 template<typename _CharT, typename _Traits> 632 class basic_istream<_CharT, _Traits>::sentry 633 { 634 public: 635 /// Easy access to dependant types. 636 typedef _Traits traits_type; 637 typedef basic_streambuf<_CharT, _Traits> __streambuf_type; 638 typedef basic_istream<_CharT, _Traits> __istream_type; 639 typedef typename __istream_type::__ctype_type __ctype_type; 640 typedef typename _Traits::int_type __int_type; 641 642 /** 643 * @brief The constructor performs all the work. 644 * @param is The input stream to guard. 645 * @param noskipws Whether to consume whitespace or not. 646 * 647 * If the stream state is good (@a is.good() is true), then the 648 * following actions are performed, otherwise the sentry state is 649 * false ("not okay") and failbit is set in the stream state. 650 * 651 * The sentry's preparatory actions are: 652 * 653 * -# if the stream is tied to an output stream, @c is.tie()->flush() 654 * is called to synchronize the output sequence 655 * -# if @a noskipws is false, and @c ios_base::skipws is set in 656 * @c is.flags(), the sentry extracts and discards whitespace 657 * characters from the stream. The currently imbued locale is 658 * used to determine whether each character is whitespace. 659 * 660 * If the stream state is still good, then the sentry state becomes 661 * true ("okay"). 662 */ 663 explicit 664 sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false); 665 666 /** 667 * @brief Quick status checking. 668 * @return The sentry state. 669 * 670 * For ease of use, sentries may be converted to booleans. The 671 * return value is that of the sentry state (true == okay). 672 */ 673 operator bool() const 674 { return _M_ok; } 675 676 private: 677 bool _M_ok; 678 }; 679 680 // [27.6.1.2.3] character extraction templates 681 //@{ 682 /** 683 * @brief Character extractors 684 * @param in An input stream. 685 * @param c A character reference. 686 * @return in 687 * 688 * Behaves like one of the formatted arithmetic extractors described in 689 * std::basic_istream. After constructing a sentry object with good 690 * status, this function extracts a character (if one is available) and 691 * stores it in @a c. Otherwise, sets failbit in the input stream. 692 */ 693 template<typename _CharT, typename _Traits> 694 basic_istream<_CharT, _Traits>& 695 operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c); 696 697 template<class _Traits> 698 inline basic_istream<char, _Traits>& 699 operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c) 700 { return (__in >> reinterpret_cast<char&>(__c)); } 701 702 template<class _Traits> 703 inline basic_istream<char, _Traits>& 704 operator>>(basic_istream<char, _Traits>& __in, signed char& __c) 705 { return (__in >> reinterpret_cast<char&>(__c)); } 706 //@} 707 708 //@{ 709 /** 710 * @brief Character string extractors 711 * @param in An input stream. 712 * @param s A pointer to a character array. 713 * @return in 714 * 715 * Behaves like one of the formatted arithmetic extractors described in 716 * std::basic_istream. After constructing a sentry object with good 717 * status, this function extracts up to @c n characters and stores them 718 * into the array starting at @a s. @c n is defined as: 719 * 720 * - if @c width() is greater than zero, @c n is width() 721 * - otherwise @c n is "the number of elements of the largest array of 722 * @c char_type that can store a terminating @c eos." [27.6.1.2.3]/6 723 * 724 * Characters are extracted and stored until one of the following happens: 725 * - @c n-1 characters are stored 726 * - EOF is reached 727 * - the next character is whitespace according to the current locale 728 * - the next character is a null byte (i.e., @c charT() ) 729 * 730 * @c width(0) is then called for the input stream. 731 * 732 * If no characters are extracted, sets failbit. 733 */ 734 template<typename _CharT, typename _Traits> 735 basic_istream<_CharT, _Traits>& 736 operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s); 737 738 // Explicit specialization declaration, defined in src/istream.cc. 739 template<> 740 basic_istream<char>& 741 operator>>(basic_istream<char>& __in, char* __s); 742 743 template<class _Traits> 744 inline basic_istream<char, _Traits>& 745 operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s) 746 { return (__in >> reinterpret_cast<char*>(__s)); } 747 748 template<class _Traits> 749 inline basic_istream<char, _Traits>& 750 operator>>(basic_istream<char, _Traits>& __in, signed char* __s) 751 { return (__in >> reinterpret_cast<char*>(__s)); } 752 //@} 753 754 // 27.6.1.5 Template class basic_iostream 755 /** 756 * @brief Merging istream and ostream capabilities. 757 * @ingroup io 758 * 759 * This class multiply inherits from the input and output stream classes 760 * simply to provide a single interface. 761 */ 762 template<typename _CharT, typename _Traits> 763 class basic_iostream 764 : public basic_istream<_CharT, _Traits>, 765 public basic_ostream<_CharT, _Traits> 766 { 767 public: 768 // _GLIBCXX_RESOLVE_LIB_DEFECTS 769 // 271. basic_iostream missing typedefs 770 // Types (inherited): 771 typedef _CharT char_type; 772 typedef typename _Traits::int_type int_type; 773 typedef typename _Traits::pos_type pos_type; 774 typedef typename _Traits::off_type off_type; 775 typedef _Traits traits_type; 776 777 // Non-standard Types: 778 typedef basic_istream<_CharT, _Traits> __istream_type; 779 typedef basic_ostream<_CharT, _Traits> __ostream_type; 780 781 /** 782 * @brief Constructor does nothing. 783 * 784 * Both of the parent classes are initialized with the same 785 * streambuf pointer passed to this constructor. 786 */ 787 explicit 788 basic_iostream(basic_streambuf<_CharT, _Traits>* __sb) 789 : __istream_type(__sb), __ostream_type(__sb) { } 790 791 /** 792 * @brief Destructor does nothing. 793 */ 794 virtual 795 ~basic_iostream() { } 796 797 protected: 798 basic_iostream() 799 : __istream_type(), __ostream_type() { } 800 }; 801 802 // [27.6.1.4] standard basic_istream manipulators 803 /** 804 * @brief Quick and easy way to eat whitespace 805 * 806 * This manipulator extracts whitespace characters, stopping when the 807 * next character is non-whitespace, or when the input sequence is empty. 808 * If the sequence is empty, @c eofbit is set in the stream, but not 809 * @c failbit. 810 * 811 * The current locale is used to distinguish whitespace characters. 812 * 813 * Example: 814 * @code 815 * MyClass mc; 816 * 817 * std::cin >> std::ws >> mc; 818 * @endcode 819 * will skip leading whitespace before calling operator>> on cin and your 820 * object. Note that the same effect can be achieved by creating a 821 * std::basic_istream::sentry inside your definition of operator>>. 822 */ 823 template<typename _CharT, typename _Traits> 824 basic_istream<_CharT, _Traits>& 825 ws(basic_istream<_CharT, _Traits>& __is); 826 827 _GLIBCXX_END_NAMESPACE 828 829 #ifndef _GLIBCXX_EXPORT_TEMPLATE 830 # include <bits/istream.tcc> 831 #endif 832 833 #endif /* _GLIBCXX_ISTREAM */ 834
