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