istream

Go to the documentation of this file.
00001 // Input streams -*- C++ -*-
00002 
00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
00004 // 2006, 2007, 2008
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 2, 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 // You should have received a copy of the GNU General Public License
00019 // along with this library; see the file COPYING.  If not, write to
00020 // the Free Software Foundation, 51 Franklin Street, Fifth Floor,
00021 // Boston, MA 02110-1301, USA.
00022 
00023 // As a special exception, you may use this file as part of a free software
00024 // library without restriction.  Specifically, if other files instantiate
00025 // templates or use macros or inline functions from this file, or you compile
00026 // this file and link it with other files to produce an executable, this
00027 // file does not by itself cause the resulting executable to be covered by
00028 // the GNU General Public License.  This exception does not however
00029 // invalidate any other reasons why the executable file might be covered by
00030 // the GNU General Public License.
00031 
00032 //
00033 // ISO C++ 14882: 27.6.1  Input streams
00034 //
00035 
00036 /** @file istream
00037  *  This is a Standard C++ Library header.
00038  */
00039 
00040 #ifndef _GLIBCXX_ISTREAM
00041 #define _GLIBCXX_ISTREAM 1
00042 
00043 #pragma GCC system_header
00044 
00045 #include <ios>
00046 #include <ostream>
00047 
00048 _GLIBCXX_BEGIN_NAMESPACE(std)
00049 
00050   // [27.6.1.1] Template class basic_istream
00051   /**
00052    *  @brief  Controlling input.
00053    *
00054    *  This is the base class for all input streams.  It provides text
00055    *  formatting of all builtin types, and communicates with any class
00056    *  derived from basic_streambuf to do the actual input.
00057   */
00058   template<typename _CharT, typename _Traits>
00059     class basic_istream : virtual public basic_ios<_CharT, _Traits>
00060     {
00061     public:
00062       // Types (inherited from basic_ios (27.4.4)):
00063       typedef _CharT                            char_type;
00064       typedef typename _Traits::int_type        int_type;
00065       typedef typename _Traits::pos_type        pos_type;
00066       typedef typename _Traits::off_type        off_type;
00067       typedef _Traits                           traits_type;
00068       
00069       // Non-standard Types:
00070       typedef basic_streambuf<_CharT, _Traits>      __streambuf_type;
00071       typedef basic_ios<_CharT, _Traits>        __ios_type;
00072       typedef basic_istream<_CharT, _Traits>        __istream_type;
00073       typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >        
00074                             __num_get_type;
00075       typedef ctype<_CharT>                     __ctype_type;
00076 
00077     protected:
00078       // Data Members:
00079       /**
00080        *  The number of characters extracted in the previous unformatted
00081        *  function; see gcount().
00082       */
00083       streamsize        _M_gcount;
00084 
00085     public:
00086       // [27.6.1.1.1] constructor/destructor
00087       /**
00088        *  @brief  Base constructor.
00089        *
00090        *  This ctor is almost never called by the user directly, rather from
00091        *  derived classes' initialization lists, which pass a pointer to
00092        *  their own stream buffer.
00093       */
00094       explicit
00095       basic_istream(__streambuf_type* __sb)
00096       : _M_gcount(streamsize(0))
00097       { this->init(__sb); }
00098 
00099       /**
00100        *  @brief  Base destructor.
00101        *
00102        *  This does very little apart from providing a virtual base dtor.
00103       */
00104       virtual 
00105       ~basic_istream() 
00106       { _M_gcount = streamsize(0); }
00107 
00108       // [27.6.1.1.2] prefix/suffix
00109       class sentry;
00110       friend class sentry;
00111 
00112       // [27.6.1.2] formatted input
00113       // [27.6.1.2.3] basic_istream::operator>>
00114       //@{
00115       /**
00116        *  @brief  Interface for manipulators.
00117        *
00118        *  Manipulators such as @c std::ws and @c std::dec use these
00119        *  functions in constructs like "std::cin >> std::ws".  For more
00120        *  information, see the iomanip header.
00121       */
00122       __istream_type&
00123       operator>>(__istream_type& (*__pf)(__istream_type&))
00124       { return __pf(*this); }
00125 
00126       __istream_type&
00127       operator>>(__ios_type& (*__pf)(__ios_type&))
00128       { 
00129     __pf(*this);
00130     return *this;
00131       }
00132 
00133       __istream_type&
00134       operator>>(ios_base& (*__pf)(ios_base&))
00135       {
00136     __pf(*this);
00137     return *this;
00138       }
00139       //@}
00140       
00141       // [27.6.1.2.2] arithmetic extractors
00142       /**
00143        *  @name Arithmetic Extractors
00144        *
00145        *  All the @c operator>> functions (aka <em>formatted input
00146        *  functions</em>) have some common behavior.  Each starts by
00147        *  constructing a temporary object of type std::basic_istream::sentry
00148        *  with the second argument (noskipws) set to false.  This has several
00149        *  effects, concluding with the setting of a status flag; see the
00150        *  sentry documentation for more.
00151        *
00152        *  If the sentry status is good, the function tries to extract
00153        *  whatever data is appropriate for the type of the argument.
00154        *
00155        *  If an exception is thrown during extraction, ios_base::badbit
00156        *  will be turned on in the stream's error state without causing an
00157        *  ios_base::failure to be thrown.  The original exception will then
00158        *  be rethrown.
00159       */
00160       //@{
00161       /**
00162        *  @brief  Basic arithmetic extractors
00163        *  @param  A variable of builtin type.
00164        *  @return  @c *this if successful
00165        *
00166        *  These functions use the stream's current locale (specifically, the
00167        *  @c num_get facet) to parse the input data.
00168       */
00169       __istream_type& 
00170       operator>>(bool& __n)
00171       { return _M_extract(__n); }
00172       
00173       __istream_type& 
00174       operator>>(short& __n);
00175       
00176       __istream_type& 
00177       operator>>(unsigned short& __n)
00178       { return _M_extract(__n); }
00179 
00180       __istream_type& 
00181       operator>>(int& __n);
00182     
00183       __istream_type& 
00184       operator>>(unsigned int& __n)
00185       { return _M_extract(__n); }
00186 
00187       __istream_type& 
00188       operator>>(long& __n)
00189       { return _M_extract(__n); }
00190       
00191       __istream_type& 
00192       operator>>(unsigned long& __n)
00193       { return _M_extract(__n); }
00194 
00195 #ifdef _GLIBCXX_USE_LONG_LONG
00196       __istream_type& 
00197       operator>>(long long& __n)
00198       { return _M_extract(__n); }
00199 
00200       __istream_type& 
00201       operator>>(unsigned long long& __n)
00202       { return _M_extract(__n); }
00203 #endif
00204 
00205       __istream_type& 
00206       operator>>(float& __f)
00207       { return _M_extract(__f); }
00208 
00209       __istream_type& 
00210       operator>>(double& __f)
00211       { return _M_extract(__f); }
00212 
00213       __istream_type& 
00214       operator>>(long double& __f)
00215       { return _M_extract(__f); }
00216 
00217       __istream_type& 
00218       operator>>(void*& __p)
00219       { return _M_extract(__p); }
00220 
00221       /**
00222        *  @brief  Extracting into another streambuf.
00223        *  @param  sb  A pointer to a streambuf
00224        *
00225        *  This function behaves like one of the basic arithmetic extractors,
00226        *  in that it also constructs a sentry object and has the same error
00227        *  handling behavior.
00228        *
00229        *  If @a sb is NULL, the stream will set failbit in its error state.
00230        *
00231        *  Characters are extracted from this stream and inserted into the
00232        *  @a sb streambuf until one of the following occurs:
00233        *
00234        *  - the input stream reaches end-of-file,
00235        *  - insertion into the output buffer fails (in this case, the
00236        *    character that would have been inserted is not extracted), or
00237        *  - an exception occurs (and in this case is caught)
00238        *
00239        *  If the function inserts no characters, failbit is set.
00240       */
00241       __istream_type& 
00242       operator>>(__streambuf_type* __sb);
00243       //@}
00244       
00245       // [27.6.1.3] unformatted input
00246       /**
00247        *  @brief  Character counting
00248        *  @return  The number of characters extracted by the previous
00249        *           unformatted input function dispatched for this stream.
00250       */
00251       streamsize 
00252       gcount() const 
00253       { return _M_gcount; }
00254       
00255       /**
00256        *  @name Unformatted Input Functions
00257        *
00258        *  All the unformatted input functions have some common behavior.
00259        *  Each starts by constructing a temporary object of type
00260        *  std::basic_istream::sentry with the second argument (noskipws)
00261        *  set to true.  This has several effects, concluding with the
00262        *  setting of a status flag; see the sentry documentation for more.
00263        *
00264        *  If the sentry status is good, the function tries to extract
00265        *  whatever data is appropriate for the type of the argument.
00266        *
00267        *  The number of characters extracted is stored for later retrieval
00268        *  by gcount().
00269        *
00270        *  If an exception is thrown during extraction, ios_base::badbit
00271        *  will be turned on in the stream's error state without causing an
00272        *  ios_base::failure to be thrown.  The original exception will then
00273        *  be rethrown.
00274       */
00275       //@{
00276       /**
00277        *  @brief  Simple extraction.
00278        *  @return  A character, or eof().
00279        *
00280        *  Tries to extract a character.  If none are available, sets failbit
00281        *  and returns traits::eof().
00282       */
00283       int_type 
00284       get();
00285 
00286       /**
00287        *  @brief  Simple extraction.
00288        *  @param  c  The character in which to store data.
00289        *  @return  *this
00290        *
00291        *  Tries to extract a character and store it in @a c.  If none are
00292        *  available, sets failbit and returns traits::eof().
00293        *
00294        *  @note  This function is not overloaded on signed char and
00295        *         unsigned char.
00296       */
00297       __istream_type& 
00298       get(char_type& __c);
00299 
00300       /**
00301        *  @brief  Simple multiple-character extraction.
00302        *  @param  s  Pointer to an array.
00303        *  @param  n  Maximum number of characters to store in @a s.
00304        *  @param  delim  A "stop" character.
00305        *  @return  *this
00306        *
00307        *  Characters are extracted and stored into @a s until one of the
00308        *  following happens:
00309        *
00310        *  - @c n-1 characters are stored
00311        *  - the input sequence reaches EOF
00312        *  - the next character equals @a delim, in which case the character
00313        *    is not extracted
00314        *
00315        * If no characters are stored, failbit is set in the stream's error
00316        * state.
00317        *
00318        * In any case, a null character is stored into the next location in
00319        * the array.
00320        *
00321        *  @note  This function is not overloaded on signed char and
00322        *         unsigned char.
00323       */
00324       __istream_type& 
00325       get(char_type* __s, streamsize __n, char_type __delim);
00326 
00327       /**
00328        *  @brief  Simple multiple-character extraction.
00329        *  @param  s  Pointer to an array.
00330        *  @param  n  Maximum number of characters to store in @a s.
00331        *  @return  *this
00332        *
00333        *  Returns @c get(s,n,widen('\n')).
00334       */
00335       __istream_type& 
00336       get(char_type* __s, streamsize __n)
00337       { return this->get(__s, __n, this->widen('\n')); }
00338 
00339       /**
00340        *  @brief  Extraction into another streambuf.
00341        *  @param  sb  A streambuf in which to store data.
00342        *  @param  delim  A "stop" character.
00343        *  @return  *this
00344        *
00345        *  Characters are extracted and inserted into @a sb until one of the
00346        *  following happens:
00347        *
00348        *  - the input sequence reaches EOF
00349        *  - insertion into the output buffer fails (in this case, the
00350        *    character that would have been inserted is not extracted)
00351        *  - the next character equals @a delim (in this case, the character
00352        *    is not extracted)
00353        *  - an exception occurs (and in this case is caught)
00354        *
00355        * If no characters are stored, failbit is set in the stream's error
00356        * state.
00357       */
00358       __istream_type&
00359       get(__streambuf_type& __sb, char_type __delim);
00360 
00361       /**
00362        *  @brief  Extraction into another streambuf.
00363        *  @param  sb  A streambuf in which to store data.
00364        *  @return  *this
00365        *
00366        *  Returns @c get(sb,widen('\n')).
00367       */
00368       __istream_type&
00369       get(__streambuf_type& __sb)
00370       { return this->get(__sb, this->widen('\n')); }
00371 
00372       /**
00373        *  @brief  String extraction.
00374        *  @param  s  A character array in which to store the data.
00375        *  @param  n  Maximum number of characters to extract.
00376        *  @param  delim  A "stop" character.
00377        *  @return  *this
00378        *
00379        *  Extracts and stores characters into @a s until one of the
00380        *  following happens.  Note that these criteria are required to be
00381        *  tested in the order listed here, to allow an input line to exactly
00382        *  fill the @a s array without setting failbit.
00383        *
00384        *  -# the input sequence reaches end-of-file, in which case eofbit
00385        *     is set in the stream error state
00386        *  -# the next character equals @c delim, in which case the character
00387        *     is extracted (and therefore counted in @c gcount()) but not stored
00388        *  -# @c n-1 characters are stored, in which case failbit is set
00389        *     in the stream error state
00390        *
00391        *  If no characters are extracted, failbit is set.  (An empty line of
00392        *  input should therefore not cause failbit to be set.)
00393        *
00394        *  In any case, a null character is stored in the next location in
00395        *  the array.
00396       */
00397       __istream_type& 
00398       getline(char_type* __s, streamsize __n, char_type __delim);
00399 
00400       /**
00401        *  @brief  String extraction.
00402        *  @param  s  A character array in which to store the data.
00403        *  @param  n  Maximum number of characters to extract.
00404        *  @return  *this
00405        *
00406        *  Returns @c getline(s,n,widen('\n')).
00407       */
00408       __istream_type& 
00409       getline(char_type* __s, streamsize __n)
00410       { return this->getline(__s, __n, this->widen('\n')); }
00411 
00412       /**
00413        *  @brief  Discarding characters
00414        *  @param  n  Number of characters to discard.
00415        *  @param  delim  A "stop" character.
00416        *  @return  *this
00417        *
00418        *  Extracts characters and throws them away until one of the
00419        *  following happens:
00420        *  - if @a n @c != @c std::numeric_limits<int>::max(), @a n
00421        *    characters are extracted
00422        *  - the input sequence reaches end-of-file
00423        *  - the next character equals @a delim (in this case, the character
00424        *    is extracted); note that this condition will never occur if
00425        *    @a delim equals @c traits::eof().
00426        *
00427        *  NB: Provide three overloads, instead of the single function
00428        *  (with defaults) mandated by the Standard: this leads to a
00429        *  better performing implementation, while still conforming to
00430        *  the Standard.
00431       */
00432       __istream_type& 
00433       ignore();
00434 
00435       __istream_type& 
00436       ignore(streamsize __n);
00437 
00438       __istream_type& 
00439       ignore(streamsize __n, int_type __delim);
00440       
00441       /**
00442        *  @brief  Looking ahead in the stream
00443        *  @return  The next character, or eof().
00444        *
00445        *  If, after constructing the sentry object, @c good() is false,
00446        *  returns @c traits::eof().  Otherwise reads but does not extract
00447        *  the next input character.
00448       */
00449       int_type 
00450       peek();
00451       
00452       /**
00453        *  @brief  Extraction without delimiters.
00454        *  @param  s  A character array.
00455        *  @param  n  Maximum number of characters to store.
00456        *  @return  *this
00457        *
00458        *  If the stream state is @c good(), extracts characters and stores
00459        *  them into @a s until one of the following happens:
00460        *  - @a n characters are stored
00461        *  - the input sequence reaches end-of-file, in which case the error
00462        *    state is set to @c failbit|eofbit.
00463        *
00464        *  @note  This function is not overloaded on signed char and
00465        *         unsigned char.
00466       */
00467       __istream_type& 
00468       read(char_type* __s, streamsize __n);
00469 
00470       /**
00471        *  @brief  Extraction until the buffer is exhausted, but no more.
00472        *  @param  s  A character array.
00473        *  @param  n  Maximum number of characters to store.
00474        *  @return  The number of characters extracted.
00475        *
00476        *  Extracts characters and stores them into @a s depending on the
00477        *  number of characters remaining in the streambuf's buffer,
00478        *  @c rdbuf()->in_avail(), called @c A here:
00479        *  - if @c A @c == @c -1, sets eofbit and extracts no characters
00480        *  - if @c A @c == @c 0, extracts no characters
00481        *  - if @c A @c > @c 0, extracts @c min(A,n)
00482        *
00483        *  The goal is to empty the current buffer, and to not request any
00484        *  more from the external input sequence controlled by the streambuf.
00485       */
00486       streamsize 
00487       readsome(char_type* __s, streamsize __n);
00488       
00489       /**
00490        *  @brief  Unextracting a single character.
00491        *  @param  c  The character to push back into the input stream.
00492        *  @return  *this
00493        *
00494        *  If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c).
00495        *
00496        *  If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in
00497        *  the error state.
00498        *
00499        *  @note  Since no characters are extracted, the next call to
00500        *         @c gcount() will return 0, as required by DR 60.
00501       */
00502       __istream_type& 
00503       putback(char_type __c);
00504 
00505       /**
00506        *  @brief  Unextracting the previous character.
00507        *  @return  *this
00508        *
00509        *  If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c).
00510        *
00511        *  If @c rdbuf() is null or if @c sungetc() fails, sets badbit in
00512        *  the error state.
00513        *
00514        *  @note  Since no characters are extracted, the next call to
00515        *         @c gcount() will return 0, as required by DR 60.
00516       */
00517       __istream_type& 
00518       unget();
00519 
00520       /**
00521        *  @brief  Synchronizing the stream buffer.
00522        *  @return  0 on success, -1 on failure
00523        *
00524        *  If @c rdbuf() is a null pointer, returns -1.
00525        *
00526        *  Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
00527        *  sets badbit and returns -1.
00528        *
00529        *  Otherwise, returns 0.
00530        *
00531        *  @note  This function does not count the number of characters
00532        *         extracted, if any, and therefore does not affect the next
00533        *         call to @c gcount().
00534       */
00535       int 
00536       sync();
00537 
00538       /**
00539        *  @brief  Getting the current read position.
00540        *  @return  A file position object.
00541        *
00542        *  If @c fail() is not false, returns @c pos_type(-1) to indicate
00543        *  failure.  Otherwise returns @c rdbuf()->pubseekoff(0,cur,in).
00544        *
00545        *  @note  This function does not count the number of characters
00546        *         extracted, if any, and therefore does not affect the next
00547        *         call to @c gcount().
00548       */
00549       pos_type 
00550       tellg();
00551 
00552       /**
00553        *  @brief  Changing the current read position.
00554        *  @param  pos  A file position object.
00555        *  @return  *this
00556        *
00557        *  If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos).  If
00558        *  that function fails, sets failbit.
00559        *
00560        *  @note  This function does not count the number of characters
00561        *         extracted, if any, and therefore does not affect the next
00562        *         call to @c gcount().
00563       */
00564       __istream_type& 
00565       seekg(pos_type);
00566 
00567       /**
00568        *  @brief  Changing the current read position.
00569        *  @param  off  A file offset object.
00570        *  @param  dir  The direction in which to seek.
00571        *  @return  *this
00572        *
00573        *  If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir).
00574        *  If that function fails, sets failbit.
00575        *
00576        *  @note  This function does not count the number of characters
00577        *         extracted, if any, and therefore does not affect the next
00578        *         call to @c gcount().
00579       */
00580       __istream_type& 
00581       seekg(off_type, ios_base::seekdir);
00582       //@}
00583 
00584     protected:
00585       basic_istream()
00586       : _M_gcount(streamsize(0))
00587       { this->init(0); }
00588 
00589       template<typename _ValueT>
00590         __istream_type&
00591         _M_extract(_ValueT& __v);
00592     };
00593 
00594   // Explicit specialization declarations, defined in src/istream.cc.
00595   template<> 
00596     basic_istream<char>& 
00597     basic_istream<char>::
00598     getline(char_type* __s, streamsize __n, char_type __delim);
00599   
00600   template<>
00601     basic_istream<char>&
00602     basic_istream<char>::
00603     ignore(streamsize __n);
00604   
00605   template<>
00606     basic_istream<char>&
00607     basic_istream<char>::
00608     ignore(streamsize __n, int_type __delim);
00609 
00610 #ifdef _GLIBCXX_USE_WCHAR_T
00611   template<> 
00612     basic_istream<wchar_t>& 
00613     basic_istream<wchar_t>::
00614     getline(char_type* __s, streamsize __n, char_type __delim);
00615 
00616   template<>
00617     basic_istream<wchar_t>&
00618     basic_istream<wchar_t>::
00619     ignore(streamsize __n);
00620   
00621   template<>
00622     basic_istream<wchar_t>&
00623     basic_istream<wchar_t>::
00624     ignore(streamsize __n, int_type __delim);
00625 #endif
00626 
00627   /**
00628    *  @brief  Performs setup work for input streams.
00629    *
00630    *  Objects of this class are created before all of the standard
00631    *  extractors are run.  It is responsible for "exception-safe prefix and
00632    *  suffix operations," although only prefix actions are currently required
00633    *  by the standard.  Additional actions may be added by the
00634    *  implementation, and we list them in
00635    *  http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#5
00636    *  under [27.6] notes.
00637   */
00638   template<typename _CharT, typename _Traits>
00639     class basic_istream<_CharT, _Traits>::sentry
00640     {
00641     public:
00642       /// Easy access to dependant types.
00643       typedef _Traits                   traits_type;
00644       typedef basic_streambuf<_CharT, _Traits>      __streambuf_type;
00645       typedef basic_istream<_CharT, _Traits>        __istream_type;
00646       typedef typename __istream_type::__ctype_type     __ctype_type;
00647       typedef typename _Traits::int_type        __int_type;
00648 
00649       /**
00650        *  @brief  The constructor performs all the work.
00651        *  @param  is  The input stream to guard.
00652        *  @param  noskipws  Whether to consume whitespace or not.
00653        *
00654        *  If the stream state is good (@a is.good() is true), then the
00655        *  following actions are performed, otherwise the sentry state is
00656        *  false ("not okay") and failbit is set in the stream state.
00657        *
00658        *  The sentry's preparatory actions are:
00659        *
00660        *  -# if the stream is tied to an output stream, @c is.tie()->flush()
00661        *     is called to synchronize the output sequence
00662        *  -# if @a noskipws is false, and @c ios_base::skipws is set in
00663        *     @c is.flags(), the sentry extracts and discards whitespace
00664        *     characters from the stream.  The currently imbued locale is
00665        *     used to determine whether each character is whitespace.
00666        *
00667        *  If the stream state is still good, then the sentry state becomes
00668        *  true ("okay").
00669       */
00670       explicit
00671       sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false);
00672 
00673       /**
00674        *  @brief  Quick status checking.
00675        *  @return  The sentry state.
00676        *
00677        *  For ease of use, sentries may be converted to booleans.  The
00678        *  return value is that of the sentry state (true == okay).
00679       */
00680       operator bool() const
00681       { return _M_ok; }
00682 
00683     private:
00684       bool _M_ok;
00685     };
00686 
00687   // [27.6.1.2.3] character extraction templates
00688   //@{
00689   /**
00690    *  @brief  Character extractors
00691    *  @param  in  An input stream.
00692    *  @param  c  A character reference.
00693    *  @return  in
00694    *
00695    *  Behaves like one of the formatted arithmetic extractors described in
00696    *  std::basic_istream.  After constructing a sentry object with good
00697    *  status, this function extracts a character (if one is available) and
00698    *  stores it in @a c.  Otherwise, sets failbit in the input stream.
00699   */
00700   template<typename _CharT, typename _Traits>
00701     basic_istream<_CharT, _Traits>&
00702     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c);
00703 
00704   template<class _Traits>
00705     inline basic_istream<char, _Traits>&
00706     operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
00707     { return (__in >> reinterpret_cast<char&>(__c)); }
00708 
00709   template<class _Traits>
00710     inline basic_istream<char, _Traits>&
00711     operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
00712     { return (__in >> reinterpret_cast<char&>(__c)); }
00713   //@}
00714 
00715   //@{
00716   /**
00717    *  @brief  Character string extractors
00718    *  @param  in  An input stream.
00719    *  @param  s  A pointer to a character array.
00720    *  @return  in
00721    *
00722    *  Behaves like one of the formatted arithmetic extractors described in
00723    *  std::basic_istream.  After constructing a sentry object with good
00724    *  status, this function extracts up to @c n characters and stores them
00725    *  into the array starting at @a s.  @c n is defined as:
00726    *
00727    *  - if @c width() is greater than zero, @c n is width()
00728    *  - otherwise @c n is "the number of elements of the largest array of
00729    *    @c char_type that can store a terminating @c eos." [27.6.1.2.3]/6
00730    *
00731    *  Characters are extracted and stored until one of the following happens:
00732    *  - @c n-1 characters are stored
00733    *  - EOF is reached
00734    *  - the next character is whitespace according to the current locale
00735    *  - the next character is a null byte (i.e., @c charT() )
00736    *
00737    *  @c width(0) is then called for the input stream.
00738    *
00739    *  If no characters are extracted, sets failbit.
00740   */
00741   template<typename _CharT, typename _Traits>
00742     basic_istream<_CharT, _Traits>&
00743     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s);
00744 
00745   // Explicit specialization declaration, defined in src/istream.cc.
00746   template<>
00747     basic_istream<char>&
00748     operator>>(basic_istream<char>& __in, char* __s);
00749 
00750   template<class _Traits>
00751     inline basic_istream<char, _Traits>&
00752     operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
00753     { return (__in >> reinterpret_cast<char*>(__s)); }
00754 
00755   template<class _Traits>
00756     inline basic_istream<char, _Traits>&
00757     operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
00758     { return (__in >> reinterpret_cast<char*>(__s)); }
00759   //@}
00760 
00761   // 27.6.1.5 Template class basic_iostream
00762   /**
00763    *  @brief  Merging istream and ostream capabilities.
00764    *
00765    *  This class multiply inherits from the input and output stream classes
00766    *  simply to provide a single interface.
00767   */
00768   template<typename _CharT, typename _Traits>
00769     class basic_iostream
00770     : public basic_istream<_CharT, _Traits>, 
00771       public basic_ostream<_CharT, _Traits>
00772     {
00773     public:
00774       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00775       // 271. basic_iostream missing typedefs
00776       // Types (inherited):
00777       typedef _CharT                            char_type;
00778       typedef typename _Traits::int_type        int_type;
00779       typedef typename _Traits::pos_type        pos_type;
00780       typedef typename _Traits::off_type        off_type;
00781       typedef _Traits                           traits_type;
00782 
00783       // Non-standard Types:
00784       typedef basic_istream<_CharT, _Traits>        __istream_type;
00785       typedef basic_ostream<_CharT, _Traits>        __ostream_type;
00786 
00787       /**
00788        *  @brief  Constructor does nothing.
00789        *
00790        *  Both of the parent classes are initialized with the same
00791        *  streambuf pointer passed to this constructor.
00792       */
00793       explicit
00794       basic_iostream(basic_streambuf<_CharT, _Traits>* __sb)
00795       : __istream_type(__sb), __ostream_type(__sb) { }
00796 
00797       /**
00798        *  @brief  Destructor does nothing.
00799       */
00800       virtual 
00801       ~basic_iostream() { }
00802 
00803     protected:
00804       basic_iostream()
00805       : __istream_type(), __ostream_type() { }
00806     };
00807 
00808   // [27.6.1.4] standard basic_istream manipulators
00809   /**
00810    *  @brief  Quick and easy way to eat whitespace
00811    *
00812    *  This manipulator extracts whitespace characters, stopping when the
00813    *  next character is non-whitespace, or when the input sequence is empty.
00814    *  If the sequence is empty, @c eofbit is set in the stream, but not
00815    *  @c failbit.
00816    *
00817    *  The current locale is used to distinguish whitespace characters.
00818    *
00819    *  Example:
00820    *  @code
00821    *     MyClass   mc;
00822    *
00823    *     std::cin >> std::ws >> mc;
00824    *  @endcode
00825    *  will skip leading whitespace before calling operator>> on cin and your
00826    *  object.  Note that the same effect can be achieved by creating a
00827    *  std::basic_istream::sentry inside your definition of operator>>.
00828   */
00829   template<typename _CharT, typename _Traits>
00830     basic_istream<_CharT, _Traits>& 
00831     ws(basic_istream<_CharT, _Traits>& __is);
00832 
00833 _GLIBCXX_END_NAMESPACE
00834 
00835 #ifndef _GLIBCXX_EXPORT_TEMPLATE
00836 # include <bits/istream.tcc>
00837 #endif
00838 
00839 #endif  /* _GLIBCXX_ISTREAM */

Generated on Wed Dec 31 12:48:55 2008 for libstdc++ by  doxygen 1.5.6