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