libstdc++-v3/include/std/std_istream.h

   1 // Input streams -*- C++ -*-
   2
   3 // Copyright (C) 1997, 1998, 1999, 2001, 2002, 2003
   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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  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.  You should @c #include this header
  37  *  in your programs, rather than any of the "st[dl]_*.h" implementation files.
  38  */
  39
  40 #ifndef _ISTREAM
  41 #define _ISTREAM 1
  42
  43 #pragma GCC system_header
  44
  45 #include <ios>
  46 #include <limits> // For numeric_limits
  47
  48 namespace std
  49 {
  50   // [27.6.1.1] Template class basic_istream
  51   /**
  52    *  @brief  Controlling input.
  53    *
  54    *  This is the base class for all input streams.  It provides text
  55    *  formatting of all builtin types, and communicates with any class
  56    *  derived from basic_streambuf to do the actual input.
  57   */
  58   template<typename _CharT, typename _Traits>
  59     class basic_istream : virtual public basic_ios<_CharT, _Traits>
  60     {
  61     public:
  62       // Types (inherited from basic_ios (27.4.4)):
  63       typedef _CharT                                    char_type;
  64       typedef typename _Traits::int_type                int_type;
  65       typedef typename _Traits::pos_type                pos_type;
  66       typedef typename _Traits::off_type                off_type;
  67       typedef _Traits                                   traits_type;
  68
  69       // Non-standard Types:
  70       typedef basic_streambuf<_CharT, _Traits>          __streambuf_type;
  71       typedef basic_ios<_CharT, _Traits>                __ios_type;
  72       typedef basic_istream<_CharT, _Traits>            __istream_type;
  73       typedef istreambuf_iterator<_CharT, _Traits>      __istreambuf_iter;
  74       typedef num_get<_CharT, __istreambuf_iter>        __numget_type;
  75       typedef ctype<_CharT>                             __ctype_type;
  76
  77       template<typename _CharT2, typename _Traits2>
  78         friend basic_istream<_CharT2, _Traits2>&
  79         operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2&);
  80
  81       template<typename _CharT2, typename _Traits2>
  82         friend basic_istream<_CharT2, _Traits2>&
  83         operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*);
  84
  85     protected:
  86       // Data Members:
  87       /**
  88        *  @if maint
  89        *  The number of characters extracted in the previous unformatted
  90        *  function; see gcount().
  91        *  @endif
  92       */
  93       streamsize                _M_gcount;
  94
  95     public:
  96       // [27.6.1.1.1] constructor/destructor
  97       /**
  98        *  @brief  Base constructor.
  99        *
 100        *  This ctor is almost never called by the user directly, rather from
 101        *  derived classes' initialization lists, which pass a pointer to
 102        *  their own stream buffer.
 103       */
 104       explicit
 105       basic_istream(__streambuf_type* __sb): _M_gcount(streamsize(0))
 106       { this->init(__sb); }
 107
 108       /**
 109        *  @brief  Base destructor.
 110        *
 111        *  This does very little apart from providing a virtual base dtor.
 112       */
 113       virtual
 114       ~basic_istream()
 115       { _M_gcount = streamsize(0); }
 116
 117       // [27.6.1.1.2] prefix/suffix
 118       class sentry;
 119       friend class sentry;
 120
 121       // [27.6.1.2] formatted input
 122       // [27.6.1.2.3] basic_istream::operator>>
 123       //@{
 124       /**
 125        *  @brief  Interface for manipulators.
 126        *
 127        *  Manuipulators such as @c std::ws and @c std::dec use these
 128        *  functions in constructs like "std::cin >> std::ws".  For more
 129        *  information, see the iomanip header.
 130       */
 131       __istream_type&
 132       operator>>(__istream_type& (*__pf)(__istream_type&));
 133
 134       __istream_type&
 135       operator>>(__ios_type& (*__pf)(__ios_type&));
 136
 137       __istream_type&
 138       operator>>(ios_base& (*__pf)(ios_base&));
 139       //@}
 140
 141       // [27.6.1.2.2] arithmetic extractors
 142       /**
 143        *  @name Arithmetic Extractors
 144        *
 145        *  All the @c operator>> functions (aka <em>formatted input
 146        *  functions</em>) have some common behavior.  Each starts by
 147        *  constructing a temporary object of type std::basic_istream::sentry
 148        *  with the second argument (noskipws) set to false.  This has several
 149        *  effects, concluding with the setting of a status flag; see the
 150        *  sentry documentation for more.
 151        *
 152        *  If the sentry status is good, the function tries to extract
 153        *  whatever data is appropriate for the type of the argument.
 154        *
 155        *  If an exception is thrown during extraction, ios_base::badbit
 156        *  will be turned on in the stream's error state without causing an
 157        *  ios_base::failure to be thrown.  The original exception will then
 158        *  be rethrown.
 159       */
 160       //@{
 161       /**
 162        *  @brief  Basic arithmetic extractors
 163        *  @param  A variable of builtin type.
 164        *  @return  @c *this if successful
 165        *
 166        *  These functions use the stream's current locale (specifically, the
 167        *  @c num_get facet) to parse the input data.
 168       */
 169       __istream_type&
 170       operator>>(bool& __n);
 171
 172       __istream_type&
 173       operator>>(short& __n);
 174
 175       __istream_type&
 176       operator>>(unsigned short& __n);
 177
 178       __istream_type&
 179       operator>>(int& __n);
 180
 181       __istream_type&
 182       operator>>(unsigned int& __n);
 183
 184       __istream_type&
 185       operator>>(long& __n);
 186
 187       __istream_type&
 188       operator>>(unsigned long& __n);
 189
 190 #ifdef _GLIBCXX_USE_LONG_LONG
 191       __istream_type&
 192       operator>>(long long& __n);
 193
 194       __istream_type&
 195       operator>>(unsigned long long& __n);
 196 #endif
 197
 198       __istream_type&
 199       operator>>(float& __f);
 200
 201       __istream_type&
 202       operator>>(double& __f);
 203
 204       __istream_type&
 205       operator>>(long double& __f);
 206
 207       __istream_type&
 208       operator>>(void*& __p);
 209
 210       /**
 211        *  @brief  Extracting into another streambuf.
 212        *  @param  sb  A pointer to a streambuf
 213        *
 214        *  This function behaves like one of the basic arithmetic extractors,
 215        *  in that it also constructs a sentry object and has the same error
 216        *  handling behavior.
 217        *
 218        *  If @a sb is NULL, the stream will set failbit in its error state.
 219        *
 220        *  Characters are extracted from this stream and inserted into the
 221        *  @a sb streambuf until one of the following occurs:
 222        *
 223        *  - the input stream reaches end-of-file,
 224        *  - insertion into the output buffer fails (in this case, the
 225        *    character that would have been inserted is not extracted), or
 226        *  - an exception occurs (and in this case is caught)
 227        *
 228        *  If the function inserts no characters, failbit is set.
 229       */
 230       __istream_type&
 231       operator>>(__streambuf_type* __sb);
 232       //@}
 233
 234       // [27.6.1.3] unformatted input
 235       /**
 236        *  @brief  Character counting
 237        *  @return  The number of characters extracted by the previous
 238        *           unformatted input function dispatched for this stream.
 239       */
 240       inline streamsize
 241       gcount() const
 242       { return _M_gcount; }
 243
 244       /**
 245        *  @name Unformatted Input Functions
 246        *
 247        *  All the unformatted input functions have some common behavior.
 248        *  Each starts by constructing a temporary object of type
 249        *  std::basic_istream::sentry with the second argument (noskipws)
 250        *  set to true.  This has several effects, concluding with the
 251        *  setting of a status flag; see the sentry documentation for more.
 252        *
 253        *  If the sentry status is good, the function tries to extract
 254        *  whatever data is appropriate for the type of the argument.
 255        *
 256        *  The number of characters extracted is stored for later retrieval
 257        *  by gcount().
 258        *
 259        *  If an exception is thrown during extraction, ios_base::badbit
 260        *  will be turned on in the stream's error state without causing an
 261        *  ios_base::failure to be thrown.  The original exception will then
 262        *  be rethrown.
 263       */
 264       //@{
 265       /**
 266        *  @brief  Simple extraction.
 267        *  @return  A character, or eof().
 268        *
 269        *  Tries to extract a character.  If none are available, sets failbit
 270        *  and returns traits::eof().
 271       */
 272       int_type
 273       get();
 274
 275       /**
 276        *  @brief  Simple extraction.
 277        *  @param  c  The character in which to store data.
 278        *  @return  *this
 279        *
 280        *  Tries to extract a character and store it in @a c.  If none are
 281        *  available, sets failbit and returns traits::eof().
 282        *
 283        *  @note  This function is not overloaded on signed char and
 284        *         unsigned char.
 285       */
 286       __istream_type&
 287       get(char_type& __c);
 288
 289       /**
 290        *  @brief  Simple multiple-character extraction.
 291        *  @param  s  Pointer to an array.
 292        *  @param  n  Maximum number of characters to store in @a s.
 293        *  @param  delim  A "stop" character.
 294        *  @return  *this
 295        *
 296        *  Characters are extracted and stored into @a s until one of the
 297        *  following happens:
 298        *
 299        *  - @c n-1 characters are stored
 300        *  - the input sequence reaches EOF
 301        *  - the next character equals @a delim, in which case the character
 302        *    is not extracted
 303        *
 304        * If no characters are stored, failbit is set in the stream's error
 305        * state.
 306        *
 307        * In any case, a null character is stored into the next location in
 308        * the array.
 309        *
 310        *  @note  This function is not overloaded on signed char and
 311        *         unsigned char.
 312       */
 313       __istream_type&
 314       get(char_type* __s, streamsize __n, char_type __delim);
 315
 316       /**
 317        *  @brief  Simple multiple-character extraction.
 318        *  @param  s  Pointer to an array.
 319        *  @param  n  Maximum number of characters to store in @a s.
 320        *  @return  *this
 321        *
 322        *  Returns @c get(s,n,widen('\n')).
 323       */
 324       inline __istream_type&
 325       get(char_type* __s, streamsize __n)
 326       { return this->get(__s, __n, this->widen('\n')); }
 327
 328       /**
 329        *  @brief  Extraction into another streambuf.
 330        *  @param  sb  A streambuf in which to store data.
 331        *  @param  delim  A "stop" character.
 332        *  @return  *this
 333        *
 334        *  Characters are extracted and inserted into @a sb until one of the
 335        *  following happens:
 336        *
 337        *  - the input sequence reaches EOF
 338        *  - insertion into the output buffer fails (in this case, the
 339        *    character that would have been inserted is not extracted)
 340        *  - the next character equals @a delim (in this case, the character
 341        *    is not extracted)
 342        *  - an exception occurs (and in this case is caught)
 343        *
 344        * If no characters are stored, failbit is set in the stream's error
 345        * state.
 346       */
 347       __istream_type&
 348       get(__streambuf_type& __sb, char_type __delim);
 349
 350       /**
 351        *  @brief  Extraction into another streambuf.
 352        *  @param  sb  A streambuf in which to store data.
 353        *  @return  *this
 354        *
 355        *  Returns @c get(sb,widen('\n')).
 356       */
 357       inline __istream_type&
 358       get(__streambuf_type& __sb)
 359       { return this->get(__sb, this->widen('\n')); }
 360
 361       /**
 362        *  @brief  String extraction.
 363        *  @param  s  A character array in which to store the data.
 364        *  @param  n  Maximum number of characters to extract.
 365        *  @param  delim  A "stop" character.
 366        *  @return  *this
 367        *
 368        *  Extracts and stores characters into @a s until one of the
 369        *  following happens.  Note that these criteria are required to be
 370        *  tested in the order listed here, to allow an input line to exactly
 371        *  fill the @a s array without setting failbit.
 372        *
 373        *  -# the input sequence reaches end-of-file, in which case eofbit
 374        *     is set in the stream error state
 375        *  -# the next character equals @c delim, in which case the character
 376        *     is extracted (and therefore counted in @c gcount()) but not stored
 377        *  -# @c n-1 characters are stored, in which case failbit is set
 378        *     in the stream error state
 379        *
 380        *  If no characters are extracted, failbit is set.  (An empty line of
 381        *  input should therefore not cause failbit to be set.)
 382        *
 383        *  In any case, a null character is stored in the next location in
 384        *  the array.
 385       */
 386       __istream_type&
 387       getline(char_type* __s, streamsize __n, char_type __delim);
 388
 389       /**
 390        *  @brief  String extraction.
 391        *  @param  s  A character array in which to store the data.
 392        *  @param  n  Maximum number of characters to extract.
 393        *  @return  *this
 394        *
 395        *  Returns @c getline(s,n,widen('\n')).
 396       */
 397       inline __istream_type&
 398       getline(char_type* __s, streamsize __n)
 399       { return this->getline(__s, __n, this->widen('\n')); }
 400
 401       /**
 402        *  @brief  Discarding characters
 403        *  @param  n  Number of characters to discard.
 404        *  @param  delim  A "stop" character.
 405        *  @return  *this
 406        *
 407        *  Extracts characters and throws them away until one of the
 408        *  following happens:
 409        *  - if @a n @c != @c std::numeric_limits<int>::max(), @a n
 410        *    characters are extracted
 411        *  - the input sequence reaches end-of-file
 412        *  - the next character equals @a delim (in this case, the character
 413        *    is extracted); note that this condition will never occur if
 414        *    @a delim equals @c traits::eof().
 415       */
 416       __istream_type&
 417       ignore(streamsize __n = 1, int_type __delim = traits_type::eof());
 418
 419       /**
 420        *  @brief  Looking ahead in the stream
 421        *  @return  The next character, or eof().
 422        *
 423        *  If, after constructing the sentry object, @c good() is false,
 424        *  returns @c traits::eof().  Otherwise reads but does not extract
 425        *  the next input character.
 426       */
 427       int_type
 428       peek();
 429
 430       /**
 431        *  @brief  Extraction without delimiters.
 432        *  @param  s  A character array.
 433        *  @param  n  Maximum number of characters to store.
 434        *  @return  *this
 435        *
 436        *  If the stream state is @c good(), extracts characters and stores
 437        *  them into @a s until one of the following happens:
 438        *  - @a n characters are stored
 439        *  - the input sequence reaches end-of-file, in which case the error
 440        *    state is set to @c failbit|eofbit.
 441        *
 442        *  @note  This function is not overloaded on signed char and
 443        *         unsigned char.
 444       */
 445       __istream_type&
 446       read(char_type* __s, streamsize __n);
 447
 448       /**
 449        *  @brief  Extraction until the buffer is exhausted, but no more.
 450        *  @param  s  A character array.
 451        *  @param  n  Maximum number of characters to store.
 452        *  @return  The number of characters extracted.
 453        *
 454        *  Extracts characters and stores them into @a s depending on the
 455        *  number of characters remaining in the streambuf's buffer,
 456        *  @c rdbuf()->in_avail(), called @c A here:
 457        *  - if @c A @c == @c -1, sets eofbit and extracts no characters
 458        *  - if @c A @c == @c 0, extracts no characters
 459        *  - if @c A @c > @c 0, extracts @c min(A,n)
 460        *
 461        *  The goal is to empty the current buffer, and to not request any
 462        *  more from the external input sequence controlled by the streambuf.
 463       */
 464       streamsize
 465       readsome(char_type* __s, streamsize __n);
 466
 467       /**
 468        *  @brief  Unextracting a single character.
 469        *  @param  c  The character to push back into the input stream.
 470        *  @return  *this
 471        *
 472        *  If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c).
 473        *
 474        *  If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in
 475        *  the error state.
 476        *
 477        *  @note  Since no characters are extracted, the next call to
 478        *         @c gcount() will return 0, as required by DR 60.
 479       */
 480       __istream_type&
 481       putback(char_type __c);
 482
 483       /**
 484        *  @brief  Unextracting the previous character.
 485        *  @return  *this
 486        *
 487        *  If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c).
 488        *
 489        *  If @c rdbuf() is null or if @c sungetc() fails, sets badbit in
 490        *  the error state.
 491        *
 492        *  @note  Since no characters are extracted, the next call to
 493        *         @c gcount() will return 0, as required by DR 60.
 494       */
 495       __istream_type&
 496       unget();
 497
 498       /**
 499        *  @brief  Synchronizing the stream buffer.
 500        *  @return  0 on success, -1 on failure
 501        *
 502        *  If @c rdbuf() is a null pointer, returns -1.
 503        *
 504        *  Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
 505        *  sets badbit and returns -1.
 506        *
 507        *  Otherwise, returns 0.
 508        *
 509        *  @note  This function does not count the number of characters
 510        *         extracted, if any, and therefore does not affect the next
 511        *         call to @c gcount().
 512       */
 513       int
 514       sync();
 515
 516       /**
 517        *  @brief  Getting the current read position.
 518        *  @return  A file position object.
 519        *
 520        *  If @c fail() is not false, returns @c pos_type(-1) to indicate
 521        *  failure.  Otherwise returns @c rdbuf()->pubseekoff(0,cur,in).
 522        *
 523        *  @note  This function does not count the number of characters
 524        *         extracted, if any, and therefore does not affect the next
 525        *         call to @c gcount().
 526       */
 527       pos_type
 528       tellg();
 529
 530       /**
 531        *  @brief  Changing the current read position.
 532        *  @param  pos  A file position object.
 533        *  @return  *this
 534        *
 535        *  If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos).  If
 536        *  that function fails, sets failbit.
 537        *
 538        *  @note  This function does not count the number of characters
 539        *         extracted, if any, and therefore does not affect the next
 540        *         call to @c gcount().
 541       */
 542       __istream_type&
 543       seekg(pos_type);
 544
 545       /**
 546        *  @brief  Changing the current read position.
 547        *  @param  off  A file offset object.
 548        *  @param  dir  The direction in which to seek.
 549        *  @return  *this
 550        *
 551        *  If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir).
 552        *  If that function fails, sets failbit.
 553        *
 554        *  @note  This function does not count the number of characters
 555        *         extracted, if any, and therefore does not affect the next
 556        *         call to @c gcount().
 557       */
 558       __istream_type&
 559       seekg(off_type, ios_base::seekdir);
 560       //@}
 561
 562     protected:
 563       explicit
 564       basic_istream(): _M_gcount(streamsize(0)) { }
 565     };
 566
 567   /**
 568    *  @brief  Performs setup work for input streams.
 569    *
 570    *  Objects of this class are created before all of the standard
 571    *  extractors are run.  It is responsible for "exception-safe prefix and
 572    *  suffix operations," although only prefix actions are currently required
 573    *  by the standard.  Additional actions may be added by the
 574    *  implementation, and we list them in
 575    *  http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#5
 576    *  under [27.6] notes.
 577   */
 578   template<typename _CharT, typename _Traits>
 579     class basic_istream<_CharT, _Traits>::sentry
 580     {
 581     public:
 582       /// Easy access to dependant types.
 583       typedef _Traits                                   traits_type;
 584       typedef basic_streambuf<_CharT, _Traits>          __streambuf_type;
 585       typedef basic_istream<_CharT, _Traits>            __istream_type;
 586       typedef typename __istream_type::__ctype_type     __ctype_type;
 587       typedef typename _Traits::int_type                __int_type;
 588
 589       /**
 590        *  @brief  The constructor performs all the work.
 591        *  @param  is  The input stream to guard.
 592        *  @param  noskipws  Whether to consume whitespace or not.
 593        *
 594        *  If the stream state is good (@a is.good() is true), then the
 595        *  following actions are performed, otherwise the sentry state is
 596        *  false ("not okay") and failbit is set in the stream state.
 597        *
 598        *  The sentry's preparatory actions are:
 599        *
 600        *  -# if the stream is tied to an output stream, @c is.tie()->flush()
 601        *     is called to synchronize the output sequence
 602        *  -# if @a noskipws is false, and @c ios_base::skipws is set in
 603        *     @c is.flags(), the sentry extracts and discards whitespace
 604        *     characters from the stream.  The currently imbued locale is
 605        *     used to determine whether each character is whitespace.
 606        *
 607        *  If the stream state is still good, then the sentry state becomes
 608        *  true ("okay").
 609       */
 610       explicit
 611       sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false);
 612
 613       /**
 614        *  @brief  Quick status checking.
 615        *  @return  The sentry state.
 616        *
 617        *  For ease of use, sentries may be converted to booleans.  The
 618        *  return value is that of the sentry state (true == okay).
 619       */
 620       operator bool() const { return _M_ok; }
 621
 622     private:
 623       bool _M_ok;
 624     };
 625
 626   // [27.6.1.2.3] character extraction templates
 627   //@{
 628   /**
 629    *  @brief  Character extractors
 630    *  @param  in  An input stream.
 631    *  @param  c  A character reference.
 632    *  @return  in
 633    *
 634    *  Behaves like one of the formatted arithmetic extractors described in
 635    *  std::basic_istream.  After constructing a sentry object with good
 636    *  status, this function extracts a character (if one is available) and
 637    *  stores it in @a c.  Otherwise, sets failbit in the input stream.
 638   */
 639   template<typename _CharT, typename _Traits>
 640     basic_istream<_CharT, _Traits>&
 641     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c);
 642
 643   template<class _Traits>
 644     basic_istream<char, _Traits>&
 645     operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
 646     { return (__in >> reinterpret_cast<char&>(__c)); }
 647
 648   template<class _Traits>
 649     basic_istream<char, _Traits>&
 650     operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
 651     { return (__in >> reinterpret_cast<char&>(__c)); }
 652   //@}
 653
 654   //@{
 655   /**
 656    *  @brief  Character string extractors
 657    *  @param  in  An input stream.
 658    *  @param  s  A pointer to a character array.
 659    *  @return  in
 660    *
 661    *  Behaves like one of the formatted arithmetic extractors described in
 662    *  std::basic_istream.  After constructing a sentry object with good
 663    *  status, this function extracts up to @c n characters and stores them
 664    *  into the array starting at @a s.  @c n is defined as:
 665    *
 666    *  - if @c width() is greater than zero, @c n is width()
 667    *  - otherwise @c n is "the number of elements of the largest array of
 668    *    @c char_type that can store a terminating @c eos." [27.6.1.2.3]/6
 669    *
 670    *  Characters are extracted and stored until one of the following happens:
 671    *  - @c n-1 characters are stored
 672    *  - EOF is reached
 673    *  - the next character is whitespace according to the current locale
 674    *  - the next character is a null byte (i.e., @c charT() )
 675    *
 676    *  @c width(0) is then called for the input stream.
 677    *
 678    *  If no characters are extracted, sets failbit.
 679   */
 680   template<typename _CharT, typename _Traits>
 681     basic_istream<_CharT, _Traits>&
 682     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s);
 683
 684   template<class _Traits>
 685     basic_istream<char,_Traits>&
 686     operator>>(basic_istream<char,_Traits>& __in, unsigned char* __s)
 687     { return (__in >> reinterpret_cast<char*>(__s)); }
 688
 689   template<class _Traits>
 690     basic_istream<char,_Traits>&
 691     operator>>(basic_istream<char,_Traits>& __in, signed char* __s)
 692     { return (__in >> reinterpret_cast<char*>(__s)); }
 693   //@}
 694
 695   // 27.6.1.5 Template class basic_iostream
 696   /**
 697    *  @brief  Merging istream and ostream capabilities.
 698    *
 699    *  This class multiply inherits from the input and output stream classes
 700    *  simply to provide a single interface.
 701   */
 702   template<typename _CharT, typename _Traits>
 703     class basic_iostream
 704     : public basic_istream<_CharT, _Traits>,
 705       public basic_ostream<_CharT, _Traits>
 706     {
 707     public:
 708 #ifdef _GLIBCXX_RESOLVE_LIB_DEFECTS
 709 // 271. basic_iostream missing typedefs
 710       // Types (inherited):
 711       typedef _CharT                                    char_type;
 712       typedef typename _Traits::int_type                int_type;
 713       typedef typename _Traits::pos_type                pos_type;
 714       typedef typename _Traits::off_type                off_type;
 715       typedef _Traits                                   traits_type;
 716 #endif
 717
 718       // Non-standard Types:
 719       typedef basic_istream<_CharT, _Traits>            __istream_type;
 720       typedef basic_ostream<_CharT, _Traits>            __ostream_type;
 721
 722       /**
 723        *  @brief  Constructor does nothing.
 724        *
 725        *  Both of the parent classes are initialized with the same
 726        *  streambuf pointer passed to this constructor.
 727       */
 728       explicit
 729       basic_iostream(basic_streambuf<_CharT, _Traits>* __sb)
 730       : __istream_type(), __ostream_type()
 731       { this->init(__sb); }
 732
 733       /**
 734        *  @brief  Destructor does nothing.
 735       */
 736       virtual
 737       ~basic_iostream() { }
 738
 739     protected:
 740       explicit
 741       basic_iostream() : __istream_type(), __ostream_type()
 742       { }
 743     };
 744
 745   // [27.6.1.4] standard basic_istream manipulators
 746   /**
 747    *  @brief  Quick and easy way to eat whitespace
 748    *
 749    *  This manipulator extracts whitespace characters, stopping when the
 750    *  next character is non-whitespace, or when the input sequence is empty.
 751    *  If the sequence is empty, @c eofbit is set in the stream, but not
 752    *  @c failbit.
 753    *
 754    *  The current locale is used to distinguish whitespace characters.
 755    *
 756    *  Example:
 757    *  @code
 758    *     MyClass   mc;
 759    *
 760    *     std::cin >> std::ws >> mc;
 761    *  @endcode
 762    *  will skip leading whitespace before calling operator>> on cin and your
 763    *  object.  Note that the same effect can be achieved by creating a
 764    *  std::basic_istream::sentry inside your definition of operator>>.
 765   */
 766   template<typename _CharT, typename _Traits>
 767     basic_istream<_CharT, _Traits>&
 768     ws(basic_istream<_CharT, _Traits>& __is);
 769 } // namespace std
 770
 771 #ifdef _GLIBCXX_NO_TEMPLATE_EXPORT
 772 # define export
 773 #endif
 774 #ifdef  _GLIBCXX_FULLY_COMPLIANT_HEADERS
 775 # include <bits/istream.tcc>
 776 #endif
 777
 778 #endif  /* _ISTREAM */