istream

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00001 // Input streams -*- C++ -*-
00002 
00003 // Copyright (C) 1997, 1998, 1999, 2001, 2002, 2003, 2004, 2005
00004 // Free Software Foundation, Inc.
00005 //
00006 // This file is part of the GNU ISO C++ Library.  This library is free
00007 // software; you can redistribute it and/or modify it under the
00008 // terms of the GNU General Public License as published by the
00009 // Free Software Foundation; either version 2, or (at your option)
00010 // any later version.
00011 
00012 // This library is distributed in the hope that it will be useful,
00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015 // GNU General Public License for more details.
00016 
00017 // You should have received a copy of the GNU General Public License along
00018 // with this library; see the file COPYING.  If not, write to the Free
00019 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
00020 // USA.
00021 
00022 // As a special exception, you may use this file as part of a free software
00023 // library without restriction.  Specifically, if other files instantiate
00024 // templates or use macros or inline functions from this file, or you compile
00025 // this file and link it with other files to produce an executable, this
00026 // file does not by itself cause the resulting executable to be covered by
00027 // the GNU General Public License.  This exception does not however
00028 // invalidate any other reasons why the executable file might be covered by
00029 // the GNU General Public License.
00030 
00031 //
00032 // ISO C++ 14882: 27.6.1  Input streams
00033 //
00034 
00035 /** @file istream
00036  *  This is a Standard C++ Library header.
00037  */
00038 
00039 #ifndef _GLIBCXX_ISTREAM
00040 #define _GLIBCXX_ISTREAM 1
00041 
00042 #pragma GCC system_header
00043 
00044 #include <ios>
00045 #include <limits> // For numeric_limits
00046 
00047 namespace std
00048 {
00049   // [27.6.1.1] Template class basic_istream
00050   /**
00051    *  @brief  Controlling input.
00052    *
00053    *  This is the base class for all input streams.  It provides text
00054    *  formatting of all builtin types, and communicates with any class
00055    *  derived from basic_streambuf to do the actual input.
00056   */
00057   template<typename _CharT, typename _Traits>
00058     class basic_istream : virtual public basic_ios<_CharT, _Traits>
00059     {
00060     public:
00061       // Types (inherited from basic_ios (27.4.4)):
00062       typedef _CharT                            char_type;
00063       typedef typename _Traits::int_type        int_type;
00064       typedef typename _Traits::pos_type        pos_type;
00065       typedef typename _Traits::off_type        off_type;
00066       typedef _Traits                           traits_type;
00067       
00068       // Non-standard Types:
00069       typedef basic_streambuf<_CharT, _Traits>      __streambuf_type;
00070       typedef basic_ios<_CharT, _Traits>        __ios_type;
00071       typedef basic_istream<_CharT, _Traits>        __istream_type;
00072       typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >        
00073                             __num_get_type;
00074       typedef ctype<_CharT>                     __ctype_type;
00075 
00076       template<typename _CharT2, typename _Traits2>
00077         friend basic_istream<_CharT2, _Traits2>&
00078         operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2&);
00079  
00080       template<typename _CharT2, typename _Traits2>
00081         friend basic_istream<_CharT2, _Traits2>&
00082         operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*);
00083  
00084     protected:
00085       // Data Members:
00086       /**
00087        *  @if maint
00088        *  The number of characters extracted in the previous unformatted
00089        *  function; see gcount().
00090        *  @endif
00091       */
00092       streamsize        _M_gcount;
00093 
00094     public:
00095       // [27.6.1.1.1] constructor/destructor
00096       /**
00097        *  @brief  Base constructor.
00098        *
00099        *  This ctor is almost never called by the user directly, rather from
00100        *  derived classes' initialization lists, which pass a pointer to
00101        *  their own stream buffer.
00102       */
00103       explicit 
00104       basic_istream(__streambuf_type* __sb): _M_gcount(streamsize(0))
00105       { this->init(__sb); }
00106 
00107       /**
00108        *  @brief  Base destructor.
00109        *
00110        *  This does very little apart from providing a virtual base dtor.
00111       */
00112       virtual 
00113       ~basic_istream() 
00114       { _M_gcount = streamsize(0); }
00115 
00116       // [27.6.1.1.2] prefix/suffix
00117       class sentry;
00118       friend class sentry;
00119 
00120       // [27.6.1.2] formatted input
00121       // [27.6.1.2.3] basic_istream::operator>>
00122       //@{
00123       /**
00124        *  @brief  Interface for manipulators.
00125        *
00126        *  Manuipulators such as @c std::ws and @c std::dec use these
00127        *  functions in constructs like "std::cin >> std::ws".  For more
00128        *  information, see the iomanip header.
00129       */
00130       inline __istream_type&
00131       operator>>(__istream_type& (*__pf)(__istream_type&));
00132 
00133       inline __istream_type&
00134       operator>>(__ios_type& (*__pf)(__ios_type&));
00135 
00136       inline __istream_type&
00137       operator>>(ios_base& (*__pf)(ios_base&));
00138       //@}
00139       
00140       // [27.6.1.2.2] arithmetic extractors
00141       /**
00142        *  @name Arithmetic Extractors
00143        *
00144        *  All the @c operator>> functions (aka <em>formatted input
00145        *  functions</em>) have some common behavior.  Each starts by
00146        *  constructing a temporary object of type std::basic_istream::sentry
00147        *  with the second argument (noskipws) set to false.  This has several
00148        *  effects, concluding with the setting of a status flag; see the
00149        *  sentry documentation for more.
00150        *
00151        *  If the sentry status is good, the function tries to extract
00152        *  whatever data is appropriate for the type of the argument.
00153        *
00154        *  If an exception is thrown during extraction, ios_base::badbit
00155        *  will be turned on in the stream's error state without causing an
00156        *  ios_base::failure to be thrown.  The original exception will then
00157        *  be rethrown.
00158       */
00159       //@{
00160       /**
00161        *  @brief  Basic arithmetic extractors
00162        *  @param  A variable of builtin type.
00163        *  @return  @c *this if successful
00164        *
00165        *  These functions use the stream's current locale (specifically, the
00166        *  @c num_get facet) to parse the input data.
00167       */
00168       __istream_type& 
00169       operator>>(bool& __n);
00170       
00171       __istream_type& 
00172       operator>>(short& __n);
00173       
00174       __istream_type& 
00175       operator>>(unsigned short& __n);
00176 
00177       __istream_type& 
00178       operator>>(int& __n);
00179       
00180       __istream_type& 
00181       operator>>(unsigned int& __n);
00182 
00183       __istream_type& 
00184       operator>>(long& __n);
00185       
00186       __istream_type& 
00187       operator>>(unsigned long& __n);
00188 
00189 #ifdef _GLIBCXX_USE_LONG_LONG
00190       __istream_type& 
00191       operator>>(long long& __n);
00192 
00193       __istream_type& 
00194       operator>>(unsigned long long& __n);
00195 #endif
00196 
00197       __istream_type& 
00198       operator>>(float& __f);
00199 
00200       __istream_type& 
00201       operator>>(double& __f);
00202 
00203       __istream_type& 
00204       operator>>(long double& __f);
00205 
00206       __istream_type& 
00207       operator>>(void*& __p);
00208 
00209       /**
00210        *  @brief  Extracting into another streambuf.
00211        *  @param  sb  A pointer to a streambuf
00212        *
00213        *  This function behaves like one of the basic arithmetic extractors,
00214        *  in that it also constructs a sentry object and has the same error
00215        *  handling behavior.
00216        *
00217        *  If @a sb is NULL, the stream will set failbit in its error state.
00218        *
00219        *  Characters are extracted from this stream and inserted into the
00220        *  @a sb streambuf until one of the following occurs:
00221        *
00222        *  - the input stream reaches end-of-file,
00223        *  - insertion into the output buffer fails (in this case, the
00224        *    character that would have been inserted is not extracted), or
00225        *  - an exception occurs (and in this case is caught)
00226        *
00227        *  If the function inserts no characters, failbit is set.
00228       */
00229       __istream_type& 
00230       operator>>(__streambuf_type* __sb);
00231       //@}
00232       
00233       // [27.6.1.3] unformatted input
00234       /**
00235        *  @brief  Character counting
00236        *  @return  The number of characters extracted by the previous
00237        *           unformatted input function dispatched for this stream.
00238       */
00239       inline streamsize 
00240       gcount() const 
00241       { return _M_gcount; }
00242       
00243       /**
00244        *  @name Unformatted Input Functions
00245        *
00246        *  All the unformatted input functions have some common behavior.
00247        *  Each starts by constructing a temporary object of type
00248        *  std::basic_istream::sentry with the second argument (noskipws)
00249        *  set to true.  This has several effects, concluding with the
00250        *  setting of a status flag; see the sentry documentation for more.
00251        *
00252        *  If the sentry status is good, the function tries to extract
00253        *  whatever data is appropriate for the type of the argument.
00254        *
00255        *  The number of characters extracted is stored for later retrieval
00256        *  by gcount().
00257        *
00258        *  If an exception is thrown during extraction, ios_base::badbit
00259        *  will be turned on in the stream's error state without causing an
00260        *  ios_base::failure to be thrown.  The original exception will then
00261        *  be rethrown.
00262       */
00263       //@{
00264       /**
00265        *  @brief  Simple extraction.
00266        *  @return  A character, or eof().
00267        *
00268        *  Tries to extract a character.  If none are available, sets failbit
00269        *  and returns traits::eof().
00270       */
00271       int_type 
00272       get();
00273 
00274       /**
00275        *  @brief  Simple extraction.
00276        *  @param  c  The character in which to store data.
00277        *  @return  *this
00278        *
00279        *  Tries to extract a character and store it in @a c.  If none are
00280        *  available, sets failbit and returns traits::eof().
00281        *
00282        *  @note  This function is not overloaded on signed char and
00283        *         unsigned char.
00284       */
00285       __istream_type& 
00286       get(char_type& __c);
00287 
00288       /**
00289        *  @brief  Simple multiple-character extraction.
00290        *  @param  s  Pointer to an array.
00291        *  @param  n  Maximum number of characters to store in @a s.
00292        *  @param  delim  A "stop" character.
00293        *  @return  *this
00294        *
00295        *  Characters are extracted and stored into @a s until one of the
00296        *  following happens:
00297        *
00298        *  - @c n-1 characters are stored
00299        *  - the input sequence reaches EOF
00300        *  - the next character equals @a delim, in which case the character
00301        *    is not extracted
00302        *
00303        * If no characters are stored, failbit is set in the stream's error
00304        * state.
00305        *
00306        * In any case, a null character is stored into the next location in
00307        * the array.
00308        *
00309        *  @note  This function is not overloaded on signed char and
00310        *         unsigned char.
00311       */
00312       __istream_type& 
00313       get(char_type* __s, streamsize __n, char_type __delim);
00314 
00315       /**
00316        *  @brief  Simple multiple-character extraction.
00317        *  @param  s  Pointer to an array.
00318        *  @param  n  Maximum number of characters to store in @a s.
00319        *  @return  *this
00320        *
00321        *  Returns @c get(s,n,widen('\n')).
00322       */
00323       inline __istream_type& 
00324       get(char_type* __s, streamsize __n)
00325       { return this->get(__s, __n, this->widen('\n')); }
00326 
00327       /**
00328        *  @brief  Extraction into another streambuf.
00329        *  @param  sb  A streambuf in which to store data.
00330        *  @param  delim  A "stop" character.
00331        *  @return  *this
00332        *
00333        *  Characters are extracted and inserted into @a sb until one of the
00334        *  following happens:
00335        *
00336        *  - the input sequence reaches EOF
00337        *  - insertion into the output buffer fails (in this case, the
00338        *    character that would have been inserted is not extracted)
00339        *  - the next character equals @a delim (in this case, the character
00340        *    is not extracted)
00341        *  - an exception occurs (and in this case is caught)
00342        *
00343        * If no characters are stored, failbit is set in the stream's error
00344        * state.
00345       */
00346       __istream_type&
00347       get(__streambuf_type& __sb, char_type __delim);
00348 
00349       /**
00350        *  @brief  Extraction into another streambuf.
00351        *  @param  sb  A streambuf in which to store data.
00352        *  @return  *this
00353        *
00354        *  Returns @c get(sb,widen('\n')).
00355       */
00356       inline __istream_type&
00357       get(__streambuf_type& __sb)
00358       { return this->get(__sb, this->widen('\n')); }
00359 
00360       /**
00361        *  @brief  String extraction.
00362        *  @param  s  A character array in which to store the data.
00363        *  @param  n  Maximum number of characters to extract.
00364        *  @param  delim  A "stop" character.
00365        *  @return  *this
00366        *
00367        *  Extracts and stores characters into @a s until one of the
00368        *  following happens.  Note that these criteria are required to be
00369        *  tested in the order listed here, to allow an input line to exactly
00370        *  fill the @a s array without setting failbit.
00371        *
00372        *  -# the input sequence reaches end-of-file, in which case eofbit
00373        *     is set in the stream error state
00374        *  -# the next character equals @c delim, in which case the character
00375        *     is extracted (and therefore counted in @c gcount()) but not stored
00376        *  -# @c n-1 characters are stored, in which case failbit is set
00377        *     in the stream error state
00378        *
00379        *  If no characters are extracted, failbit is set.  (An empty line of
00380        *  input should therefore not cause failbit to be set.)
00381        *
00382        *  In any case, a null character is stored in the next location in
00383        *  the array.
00384       */
00385       __istream_type& 
00386       getline(char_type* __s, streamsize __n, char_type __delim);
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        *  @return  *this
00393        *
00394        *  Returns @c getline(s,n,widen('\n')).
00395       */
00396       inline __istream_type& 
00397       getline(char_type* __s, streamsize __n)
00398       { return this->getline(__s, __n, this->widen('\n')); }
00399 
00400       /**
00401        *  @brief  Discarding characters
00402        *  @param  n  Number of characters to discard.
00403        *  @param  delim  A "stop" character.
00404        *  @return  *this
00405        *
00406        *  Extracts characters and throws them away until one of the
00407        *  following happens:
00408        *  - if @a n @c != @c std::numeric_limits<int>::max(), @a n
00409        *    characters are extracted
00410        *  - the input sequence reaches end-of-file
00411        *  - the next character equals @a delim (in this case, the character
00412        *    is extracted); note that this condition will never occur if
00413        *    @a delim equals @c traits::eof().
00414        *
00415        *  NB: Provide three overloads, instead of the single function
00416        *  (with defaults) mandated by the Standard: this leads to a
00417        *  better performing implementation, while still conforming to
00418        *  the Standard.
00419       */
00420       __istream_type& 
00421       ignore();
00422 
00423       __istream_type& 
00424       ignore(streamsize __n);
00425 
00426       __istream_type& 
00427       ignore(streamsize __n, int_type __delim);
00428       
00429       /**
00430        *  @brief  Looking ahead in the stream
00431        *  @return  The next character, or eof().
00432        *
00433        *  If, after constructing the sentry object, @c good() is false,
00434        *  returns @c traits::eof().  Otherwise reads but does not extract
00435        *  the next input character.
00436       */
00437       int_type 
00438       peek();
00439       
00440       /**
00441        *  @brief  Extraction without delimiters.
00442        *  @param  s  A character array.
00443        *  @param  n  Maximum number of characters to store.
00444        *  @return  *this
00445        *
00446        *  If the stream state is @c good(), extracts characters and stores
00447        *  them into @a s until one of the following happens:
00448        *  - @a n characters are stored
00449        *  - the input sequence reaches end-of-file, in which case the error
00450        *    state is set to @c failbit|eofbit.
00451        *
00452        *  @note  This function is not overloaded on signed char and
00453        *         unsigned char.
00454       */
00455       __istream_type& 
00456       read(char_type* __s, streamsize __n);
00457 
00458       /**
00459        *  @brief  Extraction until the buffer is exhausted, but no more.
00460        *  @param  s  A character array.
00461        *  @param  n  Maximum number of characters to store.
00462        *  @return  The number of characters extracted.
00463        *
00464        *  Extracts characters and stores them into @a s depending on the
00465        *  number of characters remaining in the streambuf's buffer,
00466        *  @c rdbuf()->in_avail(), called @c A here:
00467        *  - if @c A @c == @c -1, sets eofbit and extracts no characters
00468        *  - if @c A @c == @c 0, extracts no characters
00469        *  - if @c A @c > @c 0, extracts @c min(A,n)
00470        *
00471        *  The goal is to empty the current buffer, and to not request any
00472        *  more from the external input sequence controlled by the streambuf.
00473       */
00474       streamsize 
00475       readsome(char_type* __s, streamsize __n);
00476       
00477       /**
00478        *  @brief  Unextracting a single character.
00479        *  @param  c  The character to push back into the input stream.
00480        *  @return  *this
00481        *
00482        *  If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c).
00483        *
00484        *  If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in
00485        *  the error state.
00486        *
00487        *  @note  Since no characters are extracted, the next call to
00488        *         @c gcount() will return 0, as required by DR 60.
00489       */
00490       __istream_type& 
00491       putback(char_type __c);
00492 
00493       /**
00494        *  @brief  Unextracting the previous character.
00495        *  @return  *this
00496        *
00497        *  If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c).
00498        *
00499        *  If @c rdbuf() is null or if @c sungetc() fails, sets badbit in
00500        *  the error state.
00501        *
00502        *  @note  Since no characters are extracted, the next call to
00503        *         @c gcount() will return 0, as required by DR 60.
00504       */
00505       __istream_type& 
00506       unget();
00507 
00508       /**
00509        *  @brief  Synchronizing the stream buffer.
00510        *  @return  0 on success, -1 on failure
00511        *
00512        *  If @c rdbuf() is a null pointer, returns -1.
00513        *
00514        *  Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
00515        *  sets badbit and returns -1.
00516        *
00517        *  Otherwise, returns 0.
00518        *
00519        *  @note  This function does not count the number of characters
00520        *         extracted, if any, and therefore does not affect the next
00521        *         call to @c gcount().
00522       */
00523       int 
00524       sync();
00525 
00526       /**
00527        *  @brief  Getting the current read position.
00528        *  @return  A file position object.
00529        *
00530        *  If @c fail() is not false, returns @c pos_type(-1) to indicate
00531        *  failure.  Otherwise returns @c rdbuf()->pubseekoff(0,cur,in).
00532        *
00533        *  @note  This function does not count the number of characters
00534        *         extracted, if any, and therefore does not affect the next
00535        *         call to @c gcount().
00536       */
00537       pos_type 
00538       tellg();
00539 
00540       /**
00541        *  @brief  Changing the current read position.
00542        *  @param  pos  A file position object.
00543        *  @return  *this
00544        *
00545        *  If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos).  If
00546        *  that function fails, sets failbit.
00547        *
00548        *  @note  This function does not count the number of characters
00549        *         extracted, if any, and therefore does not affect the next
00550        *         call to @c gcount().
00551       */
00552       __istream_type& 
00553       seekg(pos_type);
00554 
00555       /**
00556        *  @brief  Changing the current read position.
00557        *  @param  off  A file offset object.
00558        *  @param  dir  The direction in which to seek.
00559        *  @return  *this
00560        *
00561        *  If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir).
00562        *  If that function fails, sets failbit.
00563        *
00564        *  @note  This function does not count the number of characters
00565        *         extracted, if any, and therefore does not affect the next
00566        *         call to @c gcount().
00567       */
00568       __istream_type& 
00569       seekg(off_type, ios_base::seekdir);
00570       //@}
00571 
00572     protected:
00573       explicit 
00574       basic_istream(): _M_gcount(streamsize(0)) { }
00575     };
00576 
00577   // Explicit specialization declarations, defined in src/istream.cc.
00578   template<> 
00579     basic_istream<char>& 
00580     basic_istream<char>::
00581     getline(char_type* __s, streamsize __n, char_type __delim);
00582   
00583   template<>
00584     basic_istream<char>&
00585     basic_istream<char>::
00586     ignore(streamsize __n);
00587   
00588   template<>
00589     basic_istream<char>&
00590     basic_istream<char>::
00591     ignore(streamsize __n, int_type __delim);
00592 
00593 #ifdef _GLIBCXX_USE_WCHAR_T
00594   template<> 
00595     basic_istream<wchar_t>& 
00596     basic_istream<wchar_t>::
00597     getline(char_type* __s, streamsize __n, char_type __delim);
00598 
00599   template<>
00600     basic_istream<wchar_t>&
00601     basic_istream<wchar_t>::
00602     ignore(streamsize __n);
00603   
00604   template<>
00605     basic_istream<wchar_t>&
00606     basic_istream<wchar_t>::
00607     ignore(streamsize __n, int_type __delim);
00608 #endif
00609 
00610   /**
00611    *  @brief  Performs setup work for input streams.
00612    *
00613    *  Objects of this class are created before all of the standard
00614    *  extractors are run.  It is responsible for "exception-safe prefix and
00615    *  suffix operations," although only prefix actions are currently required
00616    *  by the standard.  Additional actions may be added by the
00617    *  implementation, and we list them in
00618    *  http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#5
00619    *  under [27.6] notes.
00620   */
00621   template<typename _CharT, typename _Traits>
00622     class basic_istream<_CharT, _Traits>::sentry
00623     {
00624     public:
00625       /// Easy access to dependant types.
00626       typedef _Traits                   traits_type;
00627       typedef basic_streambuf<_CharT, _Traits>      __streambuf_type;
00628       typedef basic_istream<_CharT, _Traits>        __istream_type;
00629       typedef typename __istream_type::__ctype_type     __ctype_type;
00630       typedef typename _Traits::int_type        __int_type;
00631 
00632       /**
00633        *  @brief  The constructor performs all the work.
00634        *  @param  is  The input stream to guard.
00635        *  @param  noskipws  Whether to consume whitespace or not.
00636        *
00637        *  If the stream state is good (@a is.good() is true), then the
00638        *  following actions are performed, otherwise the sentry state is
00639        *  false ("not okay") and failbit is set in the stream state.
00640        *
00641        *  The sentry's preparatory actions are:
00642        *
00643        *  -# if the stream is tied to an output stream, @c is.tie()->flush()
00644        *     is called to synchronize the output sequence
00645        *  -# if @a noskipws is false, and @c ios_base::skipws is set in
00646        *     @c is.flags(), the sentry extracts and discards whitespace
00647        *     characters from the stream.  The currently imbued locale is
00648        *     used to determine whether each character is whitespace.
00649        *
00650        *  If the stream state is still good, then the sentry state becomes
00651        *  true ("okay").
00652       */
00653       explicit 
00654       sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false);
00655 
00656       /**
00657        *  @brief  Quick status checking.
00658        *  @return  The sentry state.
00659        *
00660        *  For ease of use, sentries may be converted to booleans.  The
00661        *  return value is that of the sentry state (true == okay).
00662       */
00663       operator bool() const { return _M_ok; }
00664 
00665     private:
00666       bool _M_ok;
00667     };
00668 
00669   // [27.6.1.2.3] character extraction templates
00670   //@{
00671   /**
00672    *  @brief  Character extractors
00673    *  @param  in  An input stream.
00674    *  @param  c  A character reference.
00675    *  @return  in
00676    *
00677    *  Behaves like one of the formatted arithmetic extractors described in
00678    *  std::basic_istream.  After constructing a sentry object with good
00679    *  status, this function extracts a character (if one is available) and
00680    *  stores it in @a c.  Otherwise, sets failbit in the input stream.
00681   */
00682   template<typename _CharT, typename _Traits>
00683     basic_istream<_CharT, _Traits>&
00684     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c);
00685 
00686   template<class _Traits>
00687     basic_istream<char, _Traits>&
00688     operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
00689     { return (__in >> reinterpret_cast<char&>(__c)); }
00690 
00691   template<class _Traits>
00692     basic_istream<char, _Traits>&
00693     operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
00694     { return (__in >> reinterpret_cast<char&>(__c)); }
00695   //@}
00696 
00697   //@{
00698   /**
00699    *  @brief  Character string extractors
00700    *  @param  in  An input stream.
00701    *  @param  s  A pointer to a character array.
00702    *  @return  in
00703    *
00704    *  Behaves like one of the formatted arithmetic extractors described in
00705    *  std::basic_istream.  After constructing a sentry object with good
00706    *  status, this function extracts up to @c n characters and stores them
00707    *  into the array starting at @a s.  @c n is defined as:
00708    *
00709    *  - if @c width() is greater than zero, @c n is width()
00710    *  - otherwise @c n is "the number of elements of the largest array of
00711    *    @c char_type that can store a terminating @c eos." [27.6.1.2.3]/6
00712    *
00713    *  Characters are extracted and stored until one of the following happens:
00714    *  - @c n-1 characters are stored
00715    *  - EOF is reached
00716    *  - the next character is whitespace according to the current locale
00717    *  - the next character is a null byte (i.e., @c charT() )
00718    *
00719    *  @c width(0) is then called for the input stream.
00720    *
00721    *  If no characters are extracted, sets failbit.
00722   */
00723   template<typename _CharT, typename _Traits>
00724     basic_istream<_CharT, _Traits>&
00725     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s);
00726 
00727   // Explicit specialization declaration, defined in src/istream.cc.
00728   template<>
00729     basic_istream<char>&
00730     operator>>(basic_istream<char>& __in, char* __s);
00731 
00732   template<class _Traits>
00733     basic_istream<char, _Traits>&
00734     operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
00735     { return (__in >> reinterpret_cast<char*>(__s)); }
00736 
00737   template<class _Traits>
00738     basic_istream<char, _Traits>&
00739     operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
00740     { return (__in >> reinterpret_cast<char*>(__s)); }
00741   //@}
00742 
00743   // 27.6.1.5 Template class basic_iostream
00744   /**
00745    *  @brief  Merging istream and ostream capabilities.
00746    *
00747    *  This class multiply inherits from the input and output stream classes
00748    *  simply to provide a single interface.
00749   */
00750   template<typename _CharT, typename _Traits>
00751     class basic_iostream
00752     : public basic_istream<_CharT, _Traits>, 
00753       public basic_ostream<_CharT, _Traits>
00754     {
00755     public:
00756       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00757       // 271. basic_iostream missing typedefs
00758       // Types (inherited):
00759       typedef _CharT                            char_type;
00760       typedef typename _Traits::int_type        int_type;
00761       typedef typename _Traits::pos_type        pos_type;
00762       typedef typename _Traits::off_type        off_type;
00763       typedef _Traits                           traits_type;
00764 
00765       // Non-standard Types:
00766       typedef basic_istream<_CharT, _Traits>        __istream_type;
00767       typedef basic_ostream<_CharT, _Traits>        __ostream_type;
00768 
00769       /**
00770        *  @brief  Constructor does nothing.
00771        *
00772        *  Both of the parent classes are initialized with the same
00773        *  streambuf pointer passed to this constructor.
00774       */
00775       explicit 
00776       basic_iostream(basic_streambuf<_CharT, _Traits>* __sb)
00777       : __istream_type(), __ostream_type()
00778       { this->init(__sb); }
00779 
00780       /**
00781        *  @brief  Destructor does nothing.
00782       */
00783       virtual 
00784       ~basic_iostream() { }
00785 
00786     protected:
00787       explicit 
00788       basic_iostream() : __istream_type(), __ostream_type()
00789       { }
00790     };
00791 
00792   // [27.6.1.4] standard basic_istream manipulators
00793   /**
00794    *  @brief  Quick and easy way to eat whitespace
00795    *
00796    *  This manipulator extracts whitespace characters, stopping when the
00797    *  next character is non-whitespace, or when the input sequence is empty.
00798    *  If the sequence is empty, @c eofbit is set in the stream, but not
00799    *  @c failbit.
00800    *
00801    *  The current locale is used to distinguish whitespace characters.
00802    *
00803    *  Example:
00804    *  @code
00805    *     MyClass   mc;
00806    *
00807    *     std::cin >> std::ws >> mc;
00808    *  @endcode
00809    *  will skip leading whitespace before calling operator>> on cin and your
00810    *  object.  Note that the same effect can be achieved by creating a
00811    *  std::basic_istream::sentry inside your definition of operator>>.
00812   */
00813   template<typename _CharT, typename _Traits>
00814     basic_istream<_CharT, _Traits>& 
00815     ws(basic_istream<_CharT, _Traits>& __is);
00816 } // namespace std
00817 
00818 #ifndef _GLIBCXX_EXPORT_TEMPLATE
00819 # include <bits/istream.tcc>
00820 #endif
00821 
00822 #endif  /* _GLIBCXX_ISTREAM */

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