libstdc++
istream
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00001 // Input streams -*- C++ -*-
00002 
00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
00004 // 2006, 2007, 2008, 2009, 2010, 2011
00005 // Free Software Foundation, Inc.
00006 //
00007 // This file is part of the GNU ISO C++ Library.  This library is free
00008 // software; you can redistribute it and/or modify it under the
00009 // terms of the GNU General Public License as published by the
00010 // Free Software Foundation; either version 3, or (at your option)
00011 // any later version.
00012 
00013 // This library is distributed in the hope that it will be useful,
00014 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00015 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016 // GNU General Public License for more details.
00017 
00018 // Under Section 7 of GPL version 3, you are granted additional
00019 // permissions described in the GCC Runtime Library Exception, version
00020 // 3.1, as published by the Free Software Foundation.
00021 
00022 // You should have received a copy of the GNU General Public License and
00023 // a copy of the GCC Runtime Library Exception along with this program;
00024 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00025 // <http://www.gnu.org/licenses/>.
00026 
00027 //
00028 // ISO C++ 14882: 27.6.1  Input streams
00029 //
00030 
00031 /** @file include/istream
00032  *  This is a Standard C++ Library header.
00033  */
00034 
00035 #ifndef _GLIBCXX_ISTREAM
00036 #define _GLIBCXX_ISTREAM 1
00037 
00038 #pragma GCC system_header
00039 
00040 #include <ios>
00041 #include <ostream>
00042 
00043 namespace std _GLIBCXX_VISIBILITY(default)
00044 {
00045 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00046 
00047   /**
00048    *  @brief  Template class basic_istream.
00049    *  @ingroup io
00050    *
00051    *  This is the base class for all input streams.  It provides text
00052    *  formatting of all builtin types, and communicates with any class
00053    *  derived from basic_streambuf to do the actual input.
00054   */
00055   template<typename _CharT, typename _Traits>
00056     class basic_istream : virtual public basic_ios<_CharT, _Traits>
00057     {
00058     public:
00059       // Types (inherited from basic_ios (27.4.4)):
00060       typedef _CharT                    char_type;
00061       typedef typename _Traits::int_type        int_type;
00062       typedef typename _Traits::pos_type        pos_type;
00063       typedef typename _Traits::off_type        off_type;
00064       typedef _Traits                   traits_type;
00065 
00066       // Non-standard Types:
00067       typedef basic_streambuf<_CharT, _Traits>      __streambuf_type;
00068       typedef basic_ios<_CharT, _Traits>        __ios_type;
00069       typedef basic_istream<_CharT, _Traits>        __istream_type;
00070       typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >
00071                             __num_get_type;
00072       typedef ctype<_CharT>                 __ctype_type;
00073 
00074     protected:
00075       // Data Members:
00076       /**
00077        *  The number of characters extracted in the previous unformatted
00078        *  function; see gcount().
00079       */
00080       streamsize        _M_gcount;
00081 
00082     public:
00083       /**
00084        *  @brief  Base constructor.
00085        *
00086        *  This ctor is almost never called by the user directly, rather from
00087        *  derived classes' initialization lists, which pass a pointer to
00088        *  their own stream buffer.
00089       */
00090       explicit
00091       basic_istream(__streambuf_type* __sb)
00092       : _M_gcount(streamsize(0))
00093       { this->init(__sb); }
00094 
00095       /**
00096        *  @brief  Base destructor.
00097        *
00098        *  This does very little apart from providing a virtual base dtor.
00099       */
00100       virtual
00101       ~basic_istream()
00102       { _M_gcount = streamsize(0); }
00103 
00104       /// Safe prefix/suffix operations.
00105       class sentry;
00106       friend class sentry;
00107 
00108       //@{
00109       /**
00110        *  @brief  Interface for manipulators.
00111        *
00112        *  Manipulators such as @c std::ws and @c std::dec use these
00113        *  functions in constructs like
00114        *  <code>std::cin >> std::ws</code>.
00115        *  For more information, see the iomanip header.
00116       */
00117       __istream_type&
00118       operator>>(__istream_type& (*__pf)(__istream_type&))
00119       { return __pf(*this); }
00120 
00121       __istream_type&
00122       operator>>(__ios_type& (*__pf)(__ios_type&))
00123       {
00124     __pf(*this);
00125     return *this;
00126       }
00127 
00128       __istream_type&
00129       operator>>(ios_base& (*__pf)(ios_base&))
00130       {
00131     __pf(*this);
00132     return *this;
00133       }
00134       //@}
00135 
00136       //@{
00137       /**
00138        *  @name Extractors
00139        *
00140        *  All the @c operator>> functions (aka <em>formatted input
00141        *  functions</em>) have some common behavior.  Each starts by
00142        *  constructing a temporary object of type std::basic_istream::sentry
00143        *  with the second argument (noskipws) set to false.  This has several
00144        *  effects, concluding with the setting of a status flag; see the
00145        *  sentry documentation for more.
00146        *
00147        *  If the sentry status is good, the function tries to extract
00148        *  whatever data is appropriate for the type of the argument.
00149        *
00150        *  If an exception is thrown during extraction, ios_base::badbit
00151        *  will be turned on in the stream's error state without causing an
00152        *  ios_base::failure to be thrown.  The original exception will then
00153        *  be rethrown.
00154       */
00155 
00156       //@{
00157       /**
00158        *  @brief  Integer arithmetic extractors
00159        *  @param  __n A variable of builtin integral type.
00160        *  @return  @c *this if successful
00161        *
00162        *  These functions use the stream's current locale (specifically, the
00163        *  @c num_get facet) to parse the input data.
00164       */
00165       __istream_type&
00166       operator>>(bool& __n)
00167       { return _M_extract(__n); }
00168 
00169       __istream_type&
00170       operator>>(short& __n);
00171 
00172       __istream_type&
00173       operator>>(unsigned short& __n)
00174       { return _M_extract(__n); }
00175 
00176       __istream_type&
00177       operator>>(int& __n);
00178 
00179       __istream_type&
00180       operator>>(unsigned int& __n)
00181       { return _M_extract(__n); }
00182 
00183       __istream_type&
00184       operator>>(long& __n)
00185       { return _M_extract(__n); }
00186 
00187       __istream_type&
00188       operator>>(unsigned long& __n)
00189       { return _M_extract(__n); }
00190 
00191 #ifdef _GLIBCXX_USE_LONG_LONG
00192       __istream_type&
00193       operator>>(long long& __n)
00194       { return _M_extract(__n); }
00195 
00196       __istream_type&
00197       operator>>(unsigned long long& __n)
00198       { return _M_extract(__n); }
00199 #endif
00200       //@}
00201 
00202       //@{
00203       /**
00204        *  @brief  Floating point arithmetic extractors
00205        *  @param  __f A variable of builtin floating point type.
00206        *  @return  @c *this if successful
00207        *
00208        *  These functions use the stream's current locale (specifically, the
00209        *  @c num_get facet) to parse the input data.
00210       */
00211       __istream_type&
00212       operator>>(float& __f)
00213       { return _M_extract(__f); }
00214 
00215       __istream_type&
00216       operator>>(double& __f)
00217       { return _M_extract(__f); }
00218 
00219       __istream_type&
00220       operator>>(long double& __f)
00221       { return _M_extract(__f); }
00222       //@}
00223 
00224       /**
00225        *  @brief  Basic arithmetic extractors
00226        *  @param  __p A variable of pointer type.
00227        *  @return  @c *this if successful
00228        *
00229        *  These functions use the stream's current locale (specifically, the
00230        *  @c num_get facet) to parse the input data.
00231       */
00232       __istream_type&
00233       operator>>(void*& __p)
00234       { return _M_extract(__p); }
00235 
00236       /**
00237        *  @brief  Extracting into another streambuf.
00238        *  @param  __sb  A pointer to a streambuf
00239        *
00240        *  This function behaves like one of the basic arithmetic extractors,
00241        *  in that it also constructs a sentry object and has the same error
00242        *  handling behavior.
00243        *
00244        *  If @p __sb is NULL, the stream will set failbit in its error state.
00245        *
00246        *  Characters are extracted from this stream and inserted into the
00247        *  @p __sb streambuf until one of the following occurs:
00248        *
00249        *  - the input stream reaches end-of-file,
00250        *  - insertion into the output buffer fails (in this case, the
00251        *    character that would have been inserted is not extracted), or
00252        *  - an exception occurs (and in this case is caught)
00253        *
00254        *  If the function inserts no characters, failbit is set.
00255       */
00256       __istream_type&
00257       operator>>(__streambuf_type* __sb);
00258       //@}
00259 
00260       // [27.6.1.3] unformatted input
00261       /**
00262        *  @brief  Character counting
00263        *  @return  The number of characters extracted by the previous
00264        *           unformatted input function dispatched for this stream.
00265       */
00266       streamsize
00267       gcount() const
00268       { return _M_gcount; }
00269 
00270       //@{
00271       /**
00272        *  @name Unformatted Input Functions
00273        *
00274        *  All the unformatted input functions have some common behavior.
00275        *  Each starts by constructing a temporary object of type
00276        *  std::basic_istream::sentry with the second argument (noskipws)
00277        *  set to true.  This has several effects, concluding with the
00278        *  setting of a status flag; see the sentry documentation for more.
00279        *
00280        *  If the sentry status is good, the function tries to extract
00281        *  whatever data is appropriate for the type of the argument.
00282        *
00283        *  The number of characters extracted is stored for later retrieval
00284        *  by gcount().
00285        *
00286        *  If an exception is thrown during extraction, ios_base::badbit
00287        *  will be turned on in the stream's error state without causing an
00288        *  ios_base::failure to be thrown.  The original exception will then
00289        *  be rethrown.
00290       */
00291 
00292       /**
00293        *  @brief  Simple extraction.
00294        *  @return  A character, or eof().
00295        *
00296        *  Tries to extract a character.  If none are available, sets failbit
00297        *  and returns traits::eof().
00298       */
00299       int_type
00300       get();
00301 
00302       /**
00303        *  @brief  Simple extraction.
00304        *  @param  __c  The character in which to store data.
00305        *  @return  *this
00306        *
00307        *  Tries to extract a character and store it in @a __c.  If none are
00308        *  available, sets failbit and returns traits::eof().
00309        *
00310        *  @note  This function is not overloaded on signed char and
00311        *         unsigned char.
00312       */
00313       __istream_type&
00314       get(char_type& __c);
00315 
00316       /**
00317        *  @brief  Simple multiple-character extraction.
00318        *  @param  __s  Pointer to an array.
00319        *  @param  __n  Maximum number of characters to store in @a __s.
00320        *  @param  __delim  A "stop" character.
00321        *  @return  *this
00322        *
00323        *  Characters are extracted and stored into @a __s until one of the
00324        *  following happens:
00325        *
00326        *  - @c __n-1 characters are stored
00327        *  - the input sequence reaches EOF
00328        *  - the next character equals @a __delim, in which case the character
00329        *    is not extracted
00330        *
00331        * If no characters are stored, failbit is set in the stream's error
00332        * state.
00333        *
00334        * In any case, a null character is stored into the next location in
00335        * the array.
00336        *
00337        *  @note  This function is not overloaded on signed char and
00338        *         unsigned char.
00339       */
00340       __istream_type&
00341       get(char_type* __s, streamsize __n, char_type __delim);
00342 
00343       /**
00344        *  @brief  Simple multiple-character extraction.
00345        *  @param  __s  Pointer to an array.
00346        *  @param  __n  Maximum number of characters to store in @a s.
00347        *  @return  *this
00348        *
00349        *  Returns @c get(__s,__n,widen(&apos;\\n&apos;)).
00350       */
00351       __istream_type&
00352       get(char_type* __s, streamsize __n)
00353       { return this->get(__s, __n, this->widen('\n')); }
00354 
00355       /**
00356        *  @brief  Extraction into another streambuf.
00357        *  @param  __sb  A streambuf in which to store data.
00358        *  @param  __delim  A "stop" character.
00359        *  @return  *this
00360        *
00361        *  Characters are extracted and inserted into @a __sb until one of the
00362        *  following happens:
00363        *
00364        *  - the input sequence reaches EOF
00365        *  - insertion into the output buffer fails (in this case, the
00366        *    character that would have been inserted is not extracted)
00367        *  - the next character equals @a __delim (in this case, the character
00368        *    is not extracted)
00369        *  - an exception occurs (and in this case is caught)
00370        *
00371        * If no characters are stored, failbit is set in the stream's error
00372        * state.
00373       */
00374       __istream_type&
00375       get(__streambuf_type& __sb, char_type __delim);
00376 
00377       /**
00378        *  @brief  Extraction into another streambuf.
00379        *  @param  __sb  A streambuf in which to store data.
00380        *  @return  *this
00381        *
00382        *  Returns @c get(__sb,widen(&apos;\\n&apos;)).
00383       */
00384       __istream_type&
00385       get(__streambuf_type& __sb)
00386       { return this->get(__sb, this->widen('\n')); }
00387 
00388       /**
00389        *  @brief  String extraction.
00390        *  @param  __s  A character array in which to store the data.
00391        *  @param  __n  Maximum number of characters to extract.
00392        *  @param  __delim  A "stop" character.
00393        *  @return  *this
00394        *
00395        *  Extracts and stores characters into @a __s until one of the
00396        *  following happens.  Note that these criteria are required to be
00397        *  tested in the order listed here, to allow an input line to exactly
00398        *  fill the @a __s array without setting failbit.
00399        *
00400        *  -# the input sequence reaches end-of-file, in which case eofbit
00401        *     is set in the stream error state
00402        *  -# the next character equals @c __delim, in which case the character
00403        *     is extracted (and therefore counted in @c gcount()) but not stored
00404        *  -# @c __n-1 characters are stored, in which case failbit is set
00405        *     in the stream error state
00406        *
00407        *  If no characters are extracted, failbit is set.  (An empty line of
00408        *  input should therefore not cause failbit to be set.)
00409        *
00410        *  In any case, a null character is stored in the next location in
00411        *  the array.
00412       */
00413       __istream_type&
00414       getline(char_type* __s, streamsize __n, char_type __delim);
00415 
00416       /**
00417        *  @brief  String extraction.
00418        *  @param  __s  A character array in which to store the data.
00419        *  @param  __n  Maximum number of characters to extract.
00420        *  @return  *this
00421        *
00422        *  Returns @c getline(__s,__n,widen(&apos;\\n&apos;)).
00423       */
00424       __istream_type&
00425       getline(char_type* __s, streamsize __n)
00426       { return this->getline(__s, __n, this->widen('\n')); }
00427 
00428       /**
00429        *  @brief  Discarding characters
00430        *  @param  __n  Number of characters to discard.
00431        *  @param  __delim  A "stop" character.
00432        *  @return  *this
00433        *
00434        *  Extracts characters and throws them away until one of the
00435        *  following happens:
00436        *  - if @a __n @c != @c std::numeric_limits<int>::max(), @a __n
00437        *    characters are extracted
00438        *  - the input sequence reaches end-of-file
00439        *  - the next character equals @a __delim (in this case, the character
00440        *    is extracted); note that this condition will never occur if
00441        *    @a __delim equals @c traits::eof().
00442        *
00443        *  NB: Provide three overloads, instead of the single function
00444        *  (with defaults) mandated by the Standard: this leads to a
00445        *  better performing implementation, while still conforming to
00446        *  the Standard.
00447       */
00448       __istream_type&
00449       ignore(streamsize __n, int_type __delim);
00450 
00451       __istream_type&
00452       ignore(streamsize __n);
00453 
00454       __istream_type&
00455       ignore();
00456 
00457       /**
00458        *  @brief  Looking ahead in the stream
00459        *  @return  The next character, or eof().
00460        *
00461        *  If, after constructing the sentry object, @c good() is false,
00462        *  returns @c traits::eof().  Otherwise reads but does not extract
00463        *  the next input character.
00464       */
00465       int_type
00466       peek();
00467 
00468       /**
00469        *  @brief  Extraction without delimiters.
00470        *  @param  __s  A character array.
00471        *  @param  __n  Maximum number of characters to store.
00472        *  @return  *this
00473        *
00474        *  If the stream state is @c good(), extracts characters and stores
00475        *  them into @a __s until one of the following happens:
00476        *  - @a __n characters are stored
00477        *  - the input sequence reaches end-of-file, in which case the error
00478        *    state is set to @c failbit|eofbit.
00479        *
00480        *  @note  This function is not overloaded on signed char and
00481        *         unsigned char.
00482       */
00483       __istream_type&
00484       read(char_type* __s, streamsize __n);
00485 
00486       /**
00487        *  @brief  Extraction until the buffer is exhausted, but no more.
00488        *  @param  __s  A character array.
00489        *  @param  __n  Maximum number of characters to store.
00490        *  @return  The number of characters extracted.
00491        *
00492        *  Extracts characters and stores them into @a __s depending on the
00493        *  number of characters remaining in the streambuf's buffer,
00494        *  @c rdbuf()->in_avail(), called @c A here:
00495        *  - if @c A @c == @c -1, sets eofbit and extracts no characters
00496        *  - if @c A @c == @c 0, extracts no characters
00497        *  - if @c A @c > @c 0, extracts @c min(A,n)
00498        *
00499        *  The goal is to empty the current buffer, and to not request any
00500        *  more from the external input sequence controlled by the streambuf.
00501       */
00502       streamsize
00503       readsome(char_type* __s, streamsize __n);
00504 
00505       /**
00506        *  @brief  Unextracting a single character.
00507        *  @param  __c  The character to push back into the input stream.
00508        *  @return  *this
00509        *
00510        *  If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c).
00511        *
00512        *  If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in
00513        *  the error state.
00514        *
00515        *  @note  This function first clears eofbit.  Since no characters
00516        *         are extracted, the next call to @c gcount() will return 0,
00517        *         as required by DR 60.
00518       */
00519       __istream_type&
00520       putback(char_type __c);
00521 
00522       /**
00523        *  @brief  Unextracting the previous character.
00524        *  @return  *this
00525        *
00526        *  If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c).
00527        *
00528        *  If @c rdbuf() is null or if @c sungetc() fails, sets badbit in
00529        *  the error state.
00530        *
00531        *  @note  This function first clears eofbit.  Since no characters
00532        *         are extracted, the next call to @c gcount() will return 0,
00533        *         as required by DR 60.
00534       */
00535       __istream_type&
00536       unget();
00537 
00538       /**
00539        *  @brief  Synchronizing the stream buffer.
00540        *  @return  0 on success, -1 on failure
00541        *
00542        *  If @c rdbuf() is a null pointer, returns -1.
00543        *
00544        *  Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
00545        *  sets badbit and returns -1.
00546        *
00547        *  Otherwise, returns 0.
00548        *
00549        *  @note  This function does not count the number of characters
00550        *         extracted, if any, and therefore does not affect the next
00551        *         call to @c gcount().
00552       */
00553       int
00554       sync();
00555 
00556       /**
00557        *  @brief  Getting the current read position.
00558        *  @return  A file position object.
00559        *
00560        *  If @c fail() is not false, returns @c pos_type(-1) to indicate
00561        *  failure.  Otherwise returns @c rdbuf()->pubseekoff(0,cur,in).
00562        *
00563        *  @note  This function does not count the number of characters
00564        *         extracted, if any, and therefore does not affect the next
00565        *         call to @c gcount().  At variance with putback, unget and
00566        *         seekg, eofbit is not cleared first.
00567       */
00568       pos_type
00569       tellg();
00570 
00571       /**
00572        *  @brief  Changing the current read position.
00573        *  @param  __pos  A file position object.
00574        *  @return  *this
00575        *
00576        *  If @c fail() is not true, calls @c rdbuf()->pubseekpos(__pos).  If
00577        *  that function fails, sets failbit.
00578        *
00579        *  @note  This function first clears eofbit.  It does not count the
00580        *         number of characters extracted, if any, and therefore does
00581        *         not affect the next call to @c gcount().
00582       */
00583       __istream_type&
00584       seekg(pos_type);
00585 
00586       /**
00587        *  @brief  Changing the current read position.
00588        *  @param  __off  A file offset object.
00589        *  @param  __dir  The direction in which to seek.
00590        *  @return  *this
00591        *
00592        *  If @c fail() is not true, calls @c rdbuf()->pubseekoff(__off,__dir).
00593        *  If that function fails, sets failbit.
00594        *
00595        *  @note  This function first clears eofbit.  It does not count the
00596        *         number of characters extracted, if any, and therefore does
00597        *         not affect the next call to @c gcount().
00598       */
00599       __istream_type&
00600       seekg(off_type, ios_base::seekdir);
00601       //@}
00602 
00603     protected:
00604       basic_istream()
00605       : _M_gcount(streamsize(0))
00606       { this->init(0); }
00607 
00608       template<typename _ValueT>
00609     __istream_type&
00610     _M_extract(_ValueT& __v);
00611     };
00612 
00613   /// Explicit specialization declarations, defined in src/istream.cc.
00614   template<>
00615     basic_istream<char>&
00616     basic_istream<char>::
00617     getline(char_type* __s, streamsize __n, char_type __delim);
00618 
00619   template<>
00620     basic_istream<char>&
00621     basic_istream<char>::
00622     ignore(streamsize __n);
00623 
00624   template<>
00625     basic_istream<char>&
00626     basic_istream<char>::
00627     ignore(streamsize __n, int_type __delim);
00628 
00629 #ifdef _GLIBCXX_USE_WCHAR_T
00630   template<>
00631     basic_istream<wchar_t>&
00632     basic_istream<wchar_t>::
00633     getline(char_type* __s, streamsize __n, char_type __delim);
00634 
00635   template<>
00636     basic_istream<wchar_t>&
00637     basic_istream<wchar_t>::
00638     ignore(streamsize __n);
00639 
00640   template<>
00641     basic_istream<wchar_t>&
00642     basic_istream<wchar_t>::
00643     ignore(streamsize __n, int_type __delim);
00644 #endif
00645 
00646   /**
00647    *  @brief  Performs setup work for input streams.
00648    *
00649    *  Objects of this class are created before all of the standard
00650    *  extractors are run.  It is responsible for <em>exception-safe
00651    *  prefix and suffix operations,</em> although only prefix actions
00652    *  are currently required by the standard.
00653   */
00654   template<typename _CharT, typename _Traits>
00655     class basic_istream<_CharT, _Traits>::sentry
00656     {
00657       // Data Members.
00658       bool _M_ok;
00659 
00660     public:
00661       /// Easy access to dependant types.
00662       typedef _Traits                   traits_type;
00663       typedef basic_streambuf<_CharT, _Traits>      __streambuf_type;
00664       typedef basic_istream<_CharT, _Traits>        __istream_type;
00665       typedef typename __istream_type::__ctype_type     __ctype_type;
00666       typedef typename _Traits::int_type        __int_type;
00667 
00668       /**
00669        *  @brief  The constructor performs all the work.
00670        *  @param  __is  The input stream to guard.
00671        *  @param  __noskipws  Whether to consume whitespace or not.
00672        *
00673        *  If the stream state is good (@a __is.good() is true), then the
00674        *  following actions are performed, otherwise the sentry state
00675        *  is false (<em>not okay</em>) and failbit is set in the
00676        *  stream state.
00677        *
00678        *  The sentry's preparatory actions are:
00679        *
00680        *  -# if the stream is tied to an output stream, @c is.tie()->flush()
00681        *     is called to synchronize the output sequence
00682        *  -# if @a __noskipws is false, and @c ios_base::skipws is set in
00683        *     @c is.flags(), the sentry extracts and discards whitespace
00684        *     characters from the stream.  The currently imbued locale is
00685        *     used to determine whether each character is whitespace.
00686        *
00687        *  If the stream state is still good, then the sentry state becomes
00688        *  true (@a okay).
00689       */
00690       explicit
00691       sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false);
00692 
00693       /**
00694        *  @brief  Quick status checking.
00695        *  @return  The sentry state.
00696        *
00697        *  For ease of use, sentries may be converted to booleans.  The
00698        *  return value is that of the sentry state (true == okay).
00699       */
00700 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00701       explicit
00702 #endif
00703       operator bool() const
00704       { return _M_ok; }
00705     };
00706 
00707   //@{
00708   /**
00709    *  @brief  Character extractors
00710    *  @param  __in  An input stream.
00711    *  @param  __c  A character reference.
00712    *  @return  in
00713    *
00714    *  Behaves like one of the formatted arithmetic extractors described in
00715    *  std::basic_istream.  After constructing a sentry object with good
00716    *  status, this function extracts a character (if one is available) and
00717    *  stores it in @a __c.  Otherwise, sets failbit in the input stream.
00718   */
00719   template<typename _CharT, typename _Traits>
00720     basic_istream<_CharT, _Traits>&
00721     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c);
00722 
00723   template<class _Traits>
00724     inline basic_istream<char, _Traits>&
00725     operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
00726     { return (__in >> reinterpret_cast<char&>(__c)); }
00727 
00728   template<class _Traits>
00729     inline basic_istream<char, _Traits>&
00730     operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
00731     { return (__in >> reinterpret_cast<char&>(__c)); }
00732   //@}
00733 
00734   //@{
00735   /**
00736    *  @brief  Character string extractors
00737    *  @param  __in  An input stream.
00738    *  @param  __s  A pointer to a character array.
00739    *  @return  __in
00740    *
00741    *  Behaves like one of the formatted arithmetic extractors described in
00742    *  std::basic_istream.  After constructing a sentry object with good
00743    *  status, this function extracts up to @c n characters and stores them
00744    *  into the array starting at @a __s.  @c n is defined as:
00745    *
00746    *  - if @c width() is greater than zero, @c n is width() otherwise
00747    *  - @c n is <em>the number of elements of the largest array of *
00748    *  - @c char_type that can store a terminating @c eos.</em>
00749    *  - [27.6.1.2.3]/6
00750    *
00751    *  Characters are extracted and stored until one of the following happens:
00752    *  - @c n-1 characters are stored
00753    *  - EOF is reached
00754    *  - the next character is whitespace according to the current locale
00755    *  - the next character is a null byte (i.e., @c charT() )
00756    *
00757    *  @c width(0) is then called for the input stream.
00758    *
00759    *  If no characters are extracted, sets failbit.
00760   */
00761   template<typename _CharT, typename _Traits>
00762     basic_istream<_CharT, _Traits>&
00763     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s);
00764 
00765   // Explicit specialization declaration, defined in src/istream.cc.
00766   template<>
00767     basic_istream<char>&
00768     operator>>(basic_istream<char>& __in, char* __s);
00769 
00770   template<class _Traits>
00771     inline basic_istream<char, _Traits>&
00772     operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
00773     { return (__in >> reinterpret_cast<char*>(__s)); }
00774 
00775   template<class _Traits>
00776     inline basic_istream<char, _Traits>&
00777     operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
00778     { return (__in >> reinterpret_cast<char*>(__s)); }
00779   //@}
00780 
00781   /**
00782    *  @brief  Template class basic_iostream
00783    *  @ingroup io
00784    *
00785    *  This class multiply inherits from the input and output stream classes
00786    *  simply to provide a single interface.
00787   */
00788   template<typename _CharT, typename _Traits>
00789     class basic_iostream
00790     : public basic_istream<_CharT, _Traits>,
00791       public basic_ostream<_CharT, _Traits>
00792     {
00793     public:
00794       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00795       // 271. basic_iostream missing typedefs
00796       // Types (inherited):
00797       typedef _CharT                    char_type;
00798       typedef typename _Traits::int_type        int_type;
00799       typedef typename _Traits::pos_type        pos_type;
00800       typedef typename _Traits::off_type        off_type;
00801       typedef _Traits                   traits_type;
00802 
00803       // Non-standard Types:
00804       typedef basic_istream<_CharT, _Traits>        __istream_type;
00805       typedef basic_ostream<_CharT, _Traits>        __ostream_type;
00806 
00807       /**
00808        *  @brief  Constructor does nothing.
00809        *
00810        *  Both of the parent classes are initialized with the same
00811        *  streambuf pointer passed to this constructor.
00812       */
00813       explicit
00814       basic_iostream(basic_streambuf<_CharT, _Traits>* __sb)
00815       : __istream_type(__sb), __ostream_type(__sb) { }
00816 
00817       /**
00818        *  @brief  Destructor does nothing.
00819       */
00820       virtual
00821       ~basic_iostream() { }
00822 
00823     protected:
00824       basic_iostream()
00825       : __istream_type(), __ostream_type() { }
00826     };
00827 
00828   /**
00829    *  @brief  Quick and easy way to eat whitespace
00830    *
00831    *  This manipulator extracts whitespace characters, stopping when the
00832    *  next character is non-whitespace, or when the input sequence is empty.
00833    *  If the sequence is empty, @c eofbit is set in the stream, but not
00834    *  @c failbit.
00835    *
00836    *  The current locale is used to distinguish whitespace characters.
00837    *
00838    *  Example:
00839    *  @code
00840    *     MyClass   mc;
00841    *
00842    *     std::cin >> std::ws >> mc;
00843    *  @endcode
00844    *  will skip leading whitespace before calling operator>> on cin and your
00845    *  object.  Note that the same effect can be achieved by creating a
00846    *  std::basic_istream::sentry inside your definition of operator>>.
00847   */
00848   template<typename _CharT, typename _Traits>
00849     basic_istream<_CharT, _Traits>&
00850     ws(basic_istream<_CharT, _Traits>& __is);
00851 
00852 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00853   // [27.7.1.6] Rvalue stream extraction
00854   /**
00855    *  @brief  Generic extractor for rvalue stream
00856    *  @param  __is  An input stream.
00857    *  @param  __x  A reference to the extraction target.
00858    *  @return  is
00859    *
00860    *  This is just a forwarding function to allow extraction from
00861    *  rvalue streams since they won't bind to the extractor functions
00862    *  that take an lvalue reference.
00863   */
00864   template<typename _CharT, typename _Traits, typename _Tp>
00865     inline basic_istream<_CharT, _Traits>&
00866     operator>>(basic_istream<_CharT, _Traits>&& __is, _Tp& __x)
00867     { return (__is >> __x); }
00868 #endif // __GXX_EXPERIMENTAL_CXX0X__
00869 
00870 _GLIBCXX_END_NAMESPACE_VERSION
00871 } // namespace
00872 
00873 #include <bits/istream.tcc>
00874 
00875 #endif  /* _GLIBCXX_ISTREAM */