libstdc++-v3/include/std/istream

   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       // Data Members.
 635       bool _M_ok;
 636
 637     public:
 638       /// Easy access to dependant types.
 639       typedef _Traits                                   traits_type;
 640       typedef basic_streambuf<_CharT, _Traits>          __streambuf_type;
 641       typedef basic_istream<_CharT, _Traits>            __istream_type;
 642       typedef typename __istream_type::__ctype_type     __ctype_type;
 643       typedef typename _Traits::int_type                __int_type;
 644
 645       /**
 646        *  @brief  The constructor performs all the work.
 647        *  @param  is  The input stream to guard.
 648        *  @param  noskipws  Whether to consume whitespace or not.
 649        *
 650        *  If the stream state is good (@a is.good() is true), then the
 651        *  following actions are performed, otherwise the sentry state is
 652        *  false ("not okay") and failbit is set in the stream state.
 653        *
 654        *  The sentry's preparatory actions are:
 655        *
 656        *  -# if the stream is tied to an output stream, @c is.tie()->flush()
 657        *     is called to synchronize the output sequence
 658        *  -# if @a noskipws is false, and @c ios_base::skipws is set in
 659        *     @c is.flags(), the sentry extracts and discards whitespace
 660        *     characters from the stream.  The currently imbued locale is
 661        *     used to determine whether each character is whitespace.
 662        *
 663        *  If the stream state is still good, then the sentry state becomes
 664        *  true ("okay").
 665       */
 666       explicit
 667       sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false);
 668
 669       /**
 670        *  @brief  Quick status checking.
 671        *  @return  The sentry state.
 672        *
 673        *  For ease of use, sentries may be converted to booleans.  The
 674        *  return value is that of the sentry state (true == okay).
 675       */
 676 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 677       explicit
 678 #endif
 679       operator bool() const
 680       { return _M_ok; }
 681     };
 682
 683   // [27.6.1.2.3] character extraction templates
 684   //@{
 685   /**
 686    *  @brief  Character extractors
 687    *  @param  in  An input stream.
 688    *  @param  c  A character reference.
 689    *  @return  in
 690    *
 691    *  Behaves like one of the formatted arithmetic extractors described in
 692    *  std::basic_istream.  After constructing a sentry object with good
 693    *  status, this function extracts a character (if one is available) and
 694    *  stores it in @a c.  Otherwise, sets failbit in the input stream.
 695   */
 696   template<typename _CharT, typename _Traits>
 697     basic_istream<_CharT, _Traits>&
 698     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c);
 699
 700   template<class _Traits>
 701     inline basic_istream<char, _Traits>&
 702     operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
 703     { return (__in >> reinterpret_cast<char&>(__c)); }
 704
 705   template<class _Traits>
 706     inline basic_istream<char, _Traits>&
 707     operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
 708     { return (__in >> reinterpret_cast<char&>(__c)); }
 709   //@}
 710
 711   //@{
 712   /**
 713    *  @brief  Character string extractors
 714    *  @param  in  An input stream.
 715    *  @param  s  A pointer to a character array.
 716    *  @return  in
 717    *
 718    *  Behaves like one of the formatted arithmetic extractors described in
 719    *  std::basic_istream.  After constructing a sentry object with good
 720    *  status, this function extracts up to @c n characters and stores them
 721    *  into the array starting at @a s.  @c n is defined as:
 722    *
 723    *  - if @c width() is greater than zero, @c n is width()
 724    *  - otherwise @c n is "the number of elements of the largest array of
 725    *    @c char_type that can store a terminating @c eos." [27.6.1.2.3]/6
 726    *
 727    *  Characters are extracted and stored until one of the following happens:
 728    *  - @c n-1 characters are stored
 729    *  - EOF is reached
 730    *  - the next character is whitespace according to the current locale
 731    *  - the next character is a null byte (i.e., @c charT() )
 732    *
 733    *  @c width(0) is then called for the input stream.
 734    *
 735    *  If no characters are extracted, sets failbit.
 736   */
 737   template<typename _CharT, typename _Traits>
 738     basic_istream<_CharT, _Traits>&
 739     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s);
 740
 741   // Explicit specialization declaration, defined in src/istream.cc.
 742   template<>
 743     basic_istream<char>&
 744     operator>>(basic_istream<char>& __in, char* __s);
 745
 746   template<class _Traits>
 747     inline basic_istream<char, _Traits>&
 748     operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
 749     { return (__in >> reinterpret_cast<char*>(__s)); }
 750
 751   template<class _Traits>
 752     inline basic_istream<char, _Traits>&
 753     operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
 754     { return (__in >> reinterpret_cast<char*>(__s)); }
 755   //@}
 756
 757   // 27.6.1.5 Template class basic_iostream
 758   /**
 759    *  @brief  Merging istream and ostream capabilities.
 760    *  @ingroup io
 761    *
 762    *  This class multiply inherits from the input and output stream classes
 763    *  simply to provide a single interface.
 764   */
 765   template<typename _CharT, typename _Traits>
 766     class basic_iostream
 767     : public basic_istream<_CharT, _Traits>,
 768       public basic_ostream<_CharT, _Traits>
 769     {
 770     public:
 771       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 772       // 271. basic_iostream missing typedefs
 773       // Types (inherited):
 774       typedef _CharT                                    char_type;
 775       typedef typename _Traits::int_type                int_type;
 776       typedef typename _Traits::pos_type                pos_type;
 777       typedef typename _Traits::off_type                off_type;
 778       typedef _Traits                                   traits_type;
 779
 780       // Non-standard Types:
 781       typedef basic_istream<_CharT, _Traits>            __istream_type;
 782       typedef basic_ostream<_CharT, _Traits>            __ostream_type;
 783
 784       /**
 785        *  @brief  Constructor does nothing.
 786        *
 787        *  Both of the parent classes are initialized with the same
 788        *  streambuf pointer passed to this constructor.
 789       */
 790       explicit
 791       basic_iostream(basic_streambuf<_CharT, _Traits>* __sb)
 792       : __istream_type(__sb), __ostream_type(__sb) { }
 793
 794       /**
 795        *  @brief  Destructor does nothing.
 796       */
 797       virtual
 798       ~basic_iostream() { }
 799
 800     protected:
 801       basic_iostream()
 802       : __istream_type(), __ostream_type() { }
 803     };
 804
 805   // [27.6.1.4] standard basic_istream manipulators
 806   /**
 807    *  @brief  Quick and easy way to eat whitespace
 808    *
 809    *  This manipulator extracts whitespace characters, stopping when the
 810    *  next character is non-whitespace, or when the input sequence is empty.
 811    *  If the sequence is empty, @c eofbit is set in the stream, but not
 812    *  @c failbit.
 813    *
 814    *  The current locale is used to distinguish whitespace characters.
 815    *
 816    *  Example:
 817    *  @code
 818    *     MyClass   mc;
 819    *
 820    *     std::cin >> std::ws >> mc;
 821    *  @endcode
 822    *  will skip leading whitespace before calling operator>> on cin and your
 823    *  object.  Note that the same effect can be achieved by creating a
 824    *  std::basic_istream::sentry inside your definition of operator>>.
 825   */
 826   template<typename _CharT, typename _Traits>
 827     basic_istream<_CharT, _Traits>&
 828     ws(basic_istream<_CharT, _Traits>& __is);
 829
 830 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 831   // [27.7.1.6] Rvalue stream extraction
 832   /**
 833    *  @brief  Generic extractor for rvalue stream
 834    *  @param  is  An input stream.
 835    *  @param  x  A reference to the extraction target.
 836    *  @return  is
 837    *
 838    *  This is just a forwarding function to allow extraction from
 839    *  rvalue streams since they won't bind to the extractor functions
 840    *  that take an lvalue reference.
 841   */
 842   template<typename _CharT, typename _Traits, typename _Tp>
 843     inline basic_istream<_CharT, _Traits>&
 844     operator>>(basic_istream<_CharT, _Traits>&& __is, _Tp& __x)
 845     { return (__is >> __x); }
 846 #endif // __GXX_EXPERIMENTAL_CXX0X__
 847
 848 _GLIBCXX_END_NAMESPACE
 849
 850 #ifndef _GLIBCXX_EXPORT_TEMPLATE
 851 # include <bits/istream.tcc>
 852 #endif
 853
 854 #endif  /* _GLIBCXX_ISTREAM */