fstream

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00001 // File based streams -*- C++ -*-
00002 
00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
00004 // 2006, 2007, 2008, 2009, 2010
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 /** @file fstream
00028  *  This is a Standard C++ Library header.
00029  */
00030 
00031 //
00032 // ISO C++ 14882: 27.8  File-based streams
00033 //
00034 
00035 #ifndef _GLIBCXX_FSTREAM
00036 #define _GLIBCXX_FSTREAM 1
00037 
00038 #pragma GCC system_header
00039 
00040 #include <istream>
00041 #include <ostream>
00042 #include <bits/codecvt.h>
00043 #include <cstdio>             // For BUFSIZ
00044 #include <bits/basic_file.h>  // For __basic_file, __c_lock
00045 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00046 #include <string>             // For std::string overloads.
00047 #endif
00048 
00049 _GLIBCXX_BEGIN_NAMESPACE(std)
00050 
00051   // [27.8.1.1] template class basic_filebuf
00052   /**
00053    *  @brief  The actual work of input and output (for files).
00054    *  @ingroup io
00055    *
00056    *  This class associates both its input and output sequence with an
00057    *  external disk file, and maintains a joint file position for both
00058    *  sequences.  Many of its semantics are described in terms of similar
00059    *  behavior in the Standard C Library's @c FILE streams.
00060    */
00061   // Requirements on traits_type, specific to this class:
00062   // traits_type::pos_type must be fpos<traits_type::state_type>
00063   // traits_type::off_type must be streamoff
00064   // traits_type::state_type must be Assignable and DefaultConstructible,
00065   // and traits_type::state_type() must be the initial state for codecvt.
00066   template<typename _CharT, typename _Traits>
00067     class basic_filebuf : public basic_streambuf<_CharT, _Traits>
00068     {
00069     public:
00070       // Types:
00071       typedef _CharT                                char_type;
00072       typedef _Traits                               traits_type;
00073       typedef typename traits_type::int_type        int_type;
00074       typedef typename traits_type::pos_type        pos_type;
00075       typedef typename traits_type::off_type        off_type;
00076 
00077       typedef basic_streambuf<char_type, traits_type>   __streambuf_type;
00078       typedef basic_filebuf<char_type, traits_type>     __filebuf_type;
00079       typedef __basic_file<char>                __file_type;
00080       typedef typename traits_type::state_type          __state_type;
00081       typedef codecvt<char_type, char, __state_type>    __codecvt_type;
00082 
00083       friend class ios_base; // For sync_with_stdio.
00084 
00085     protected:
00086       // Data Members:
00087       // MT lock inherited from libio or other low-level io library.
00088       __c_lock              _M_lock;
00089 
00090       // External buffer.
00091       __file_type       _M_file;
00092 
00093       /// Place to stash in || out || in | out settings for current filebuf.
00094       ios_base::openmode    _M_mode;
00095 
00096       // Beginning state type for codecvt.
00097       __state_type      _M_state_beg;
00098 
00099       // During output, the state that corresponds to pptr(),
00100       // during input, the state that corresponds to egptr() and
00101       // _M_ext_next.
00102       __state_type      _M_state_cur;
00103 
00104       // Not used for output. During input, the state that corresponds
00105       // to eback() and _M_ext_buf.
00106       __state_type      _M_state_last;
00107 
00108       /// Pointer to the beginning of internal buffer.
00109       char_type*        _M_buf;     
00110 
00111       /**
00112        *  Actual size of internal buffer. This number is equal to the size
00113        *  of the put area + 1 position, reserved for the overflow char of
00114        *  a full area.
00115        */
00116       size_t            _M_buf_size;
00117 
00118       // Set iff _M_buf is allocated memory from _M_allocate_internal_buffer.
00119       bool          _M_buf_allocated;
00120 
00121       /**
00122        *  _M_reading == false && _M_writing == false for @b uncommitted mode;
00123        *  _M_reading == true for @b read mode;
00124        *  _M_writing == true for @b write mode;
00125        *
00126        *  NB: _M_reading == true && _M_writing == true is unused.
00127        */
00128       bool                      _M_reading;
00129       bool                      _M_writing;
00130 
00131       //@{
00132       /**
00133        *  Necessary bits for putback buffer management.
00134        *
00135        *  @note pbacks of over one character are not currently supported.
00136        */
00137       char_type         _M_pback;
00138       char_type*        _M_pback_cur_save;
00139       char_type*        _M_pback_end_save;
00140       bool          _M_pback_init;
00141       //@}
00142 
00143       // Cached codecvt facet.
00144       const __codecvt_type*     _M_codecvt;
00145 
00146       /**
00147        *  Buffer for external characters. Used for input when
00148        *  codecvt::always_noconv() == false. When valid, this corresponds
00149        *  to eback().
00150        */
00151       char*         _M_ext_buf;
00152 
00153       /**
00154        *  Size of buffer held by _M_ext_buf.
00155        */
00156       streamsize        _M_ext_buf_size;
00157 
00158       /**
00159        *  Pointers into the buffer held by _M_ext_buf that delimit a
00160        *  subsequence of bytes that have been read but not yet converted.
00161        *  When valid, _M_ext_next corresponds to egptr().
00162        */
00163       const char*       _M_ext_next;
00164       char*         _M_ext_end;
00165 
00166       /**
00167        *  Initializes pback buffers, and moves normal buffers to safety.
00168        *  Assumptions:
00169        *  _M_in_cur has already been moved back
00170        */
00171       void
00172       _M_create_pback()
00173       {
00174     if (!_M_pback_init)
00175       {
00176         _M_pback_cur_save = this->gptr();
00177         _M_pback_end_save = this->egptr();
00178         this->setg(&_M_pback, &_M_pback, &_M_pback + 1);
00179         _M_pback_init = true;
00180       }
00181       }
00182 
00183       /**
00184        *  Deactivates pback buffer contents, and restores normal buffer.
00185        *  Assumptions:
00186        *  The pback buffer has only moved forward.
00187        */
00188       void
00189       _M_destroy_pback() throw()
00190       {
00191     if (_M_pback_init)
00192       {
00193         // Length _M_in_cur moved in the pback buffer.
00194         _M_pback_cur_save += this->gptr() != this->eback();
00195         this->setg(_M_buf, _M_pback_cur_save, _M_pback_end_save);
00196         _M_pback_init = false;
00197       }
00198       }
00199 
00200     public:
00201       // Constructors/destructor:
00202       /**
00203        *  @brief  Does not open any files.
00204        *
00205        *  The default constructor initializes the parent class using its
00206        *  own default ctor.
00207        */
00208       basic_filebuf();
00209 
00210       /**
00211        *  @brief  The destructor closes the file first.
00212        */
00213       virtual
00214       ~basic_filebuf()
00215       { this->close(); }
00216 
00217       // Members:
00218       /**
00219        *  @brief  Returns true if the external file is open.
00220        */
00221       bool
00222       is_open() const throw()
00223       { return _M_file.is_open(); }
00224 
00225       /**
00226        *  @brief  Opens an external file.
00227        *  @param  s  The name of the file.
00228        *  @param  mode  The open mode flags.
00229        *  @return  @c this on success, NULL on failure
00230        *
00231        *  If a file is already open, this function immediately fails.
00232        *  Otherwise it tries to open the file named @a s using the flags
00233        *  given in @a mode.
00234        *
00235        *  Table 92, adapted here, gives the relation between openmode
00236        *  combinations and the equivalent fopen() flags.
00237        *  (NB: lines app, in|out|app, in|app, binary|app, binary|in|out|app,
00238        *  and binary|in|app per DR 596)
00239        *  +---------------------------------------------------------+
00240        *  | ios_base Flag combination            stdio equivalent   |
00241        *  |binary  in  out  trunc  app                              |
00242        *  +---------------------------------------------------------+
00243        *  |             +                        w                  |
00244        *  |             +           +            a                  |
00245        *  |                         +            a                  |
00246        *  |             +     +                  w                  |
00247        *  |         +                            r                  |
00248        *  |         +   +                        r+                 |
00249        *  |         +   +     +                  w+                 |
00250        *  |         +   +           +            a+                 |
00251        *  |         +               +            a+                 |
00252        *  +---------------------------------------------------------+
00253        *  |   +         +                        wb                 |
00254        *  |   +         +           +            ab                 |
00255        *  |   +                     +            ab                 |
00256        *  |   +         +     +                  wb                 |
00257        *  |   +     +                            rb                 |
00258        *  |   +     +   +                        r+b                |
00259        *  |   +     +   +     +                  w+b                |
00260        *  |   +     +   +           +            a+b                |
00261        *  |   +     +               +            a+b                |
00262        *  +---------------------------------------------------------+
00263        */
00264       __filebuf_type*
00265       open(const char* __s, ios_base::openmode __mode);
00266 
00267 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00268       /**
00269        *  @brief  Opens an external file.
00270        *  @param  s  The name of the file.
00271        *  @param  mode  The open mode flags.
00272        *  @return  @c this on success, NULL on failure
00273        */
00274       __filebuf_type*
00275       open(const std::string& __s, ios_base::openmode __mode)
00276       { return open(__s.c_str(), __mode); }
00277 #endif
00278 
00279       /**
00280        *  @brief  Closes the currently associated file.
00281        *  @return  @c this on success, NULL on failure
00282        *
00283        *  If no file is currently open, this function immediately fails.
00284        *
00285        *  If a <em>put buffer area</em> exists, @c overflow(eof) is
00286        *  called to flush all the characters.  The file is then
00287        *  closed.
00288        *
00289        *  If any operations fail, this function also fails.
00290        */
00291       __filebuf_type*
00292       close();
00293 
00294     protected:
00295       void
00296       _M_allocate_internal_buffer();
00297 
00298       void
00299       _M_destroy_internal_buffer() throw();
00300 
00301       // [27.8.1.4] overridden virtual functions
00302       virtual streamsize
00303       showmanyc();
00304 
00305       // Stroustrup, 1998, p. 628
00306       // underflow() and uflow() functions are called to get the next
00307       // character from the real input source when the buffer is empty.
00308       // Buffered input uses underflow()
00309 
00310       virtual int_type
00311       underflow();
00312 
00313       virtual int_type
00314       pbackfail(int_type __c = _Traits::eof());
00315 
00316       // Stroustrup, 1998, p 648
00317       // The overflow() function is called to transfer characters to the
00318       // real output destination when the buffer is full. A call to
00319       // overflow(c) outputs the contents of the buffer plus the
00320       // character c.
00321       // 27.5.2.4.5
00322       // Consume some sequence of the characters in the pending sequence.
00323       virtual int_type
00324       overflow(int_type __c = _Traits::eof());
00325 
00326       // Convert internal byte sequence to external, char-based
00327       // sequence via codecvt.
00328       bool
00329       _M_convert_to_external(char_type*, streamsize);
00330 
00331       /**
00332        *  @brief  Manipulates the buffer.
00333        *  @param  s  Pointer to a buffer area.
00334        *  @param  n  Size of @a s.
00335        *  @return  @c this
00336        *
00337        *  If no file has been opened, and both @a s and @a n are zero, then
00338        *  the stream becomes unbuffered.  Otherwise, @c s is used as a
00339        *  buffer; see
00340        *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html
00341        *  for more.
00342        */
00343       virtual __streambuf_type*
00344       setbuf(char_type* __s, streamsize __n);
00345 
00346       virtual pos_type
00347       seekoff(off_type __off, ios_base::seekdir __way,
00348           ios_base::openmode __mode = ios_base::in | ios_base::out);
00349 
00350       virtual pos_type
00351       seekpos(pos_type __pos,
00352           ios_base::openmode __mode = ios_base::in | ios_base::out);
00353 
00354       // Common code for seekoff, seekpos, and overflow
00355       pos_type
00356       _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state);
00357       
00358       int
00359       _M_get_ext_pos(__state_type &__state);
00360 
00361       virtual int
00362       sync();
00363 
00364       virtual void
00365       imbue(const locale& __loc);
00366 
00367       virtual streamsize
00368       xsgetn(char_type* __s, streamsize __n);
00369 
00370       virtual streamsize
00371       xsputn(const char_type* __s, streamsize __n);
00372 
00373       // Flushes output buffer, then writes unshift sequence.
00374       bool
00375       _M_terminate_output();
00376 
00377       /**
00378        *  This function sets the pointers of the internal buffer, both get
00379        *  and put areas. Typically:
00380        *
00381        *   __off == egptr() - eback() upon underflow/uflow (@b read mode);
00382        *   __off == 0 upon overflow (@b write mode);
00383        *   __off == -1 upon open, setbuf, seekoff/pos (@b uncommitted mode).
00384        *
00385        *  NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size
00386        *  reflects the actual allocated memory and the last cell is reserved
00387        *  for the overflow char of a full put area.
00388        */
00389       void
00390       _M_set_buffer(streamsize __off)
00391       {
00392     const bool __testin = _M_mode & ios_base::in;
00393     const bool __testout = _M_mode & ios_base::out;
00394     
00395     if (__testin && __off > 0)
00396       this->setg(_M_buf, _M_buf, _M_buf + __off);
00397     else
00398       this->setg(_M_buf, _M_buf, _M_buf);
00399 
00400     if (__testout && __off == 0 && _M_buf_size > 1 )
00401       this->setp(_M_buf, _M_buf + _M_buf_size - 1);
00402     else
00403       this->setp(0, 0);
00404       }
00405     };
00406 
00407   // [27.8.1.5] Template class basic_ifstream
00408   /**
00409    *  @brief  Controlling input for files.
00410    *  @ingroup io
00411    *
00412    *  This class supports reading from named files, using the inherited
00413    *  functions from std::basic_istream.  To control the associated
00414    *  sequence, an instance of std::basic_filebuf is used, which this page
00415    *  refers to as @c sb.
00416    */
00417   template<typename _CharT, typename _Traits>
00418     class basic_ifstream : public basic_istream<_CharT, _Traits>
00419     {
00420     public:
00421       // Types:
00422       typedef _CharT                    char_type;
00423       typedef _Traits                   traits_type;
00424       typedef typename traits_type::int_type        int_type;
00425       typedef typename traits_type::pos_type        pos_type;
00426       typedef typename traits_type::off_type        off_type;
00427 
00428       // Non-standard types:
00429       typedef basic_filebuf<char_type, traits_type>     __filebuf_type;
00430       typedef basic_istream<char_type, traits_type> __istream_type;
00431 
00432     private:
00433       __filebuf_type    _M_filebuf;
00434 
00435     public:
00436       // Constructors/Destructors:
00437       /**
00438        *  @brief  Default constructor.
00439        *
00440        *  Initializes @c sb using its default constructor, and passes
00441        *  @c &sb to the base class initializer.  Does not open any files
00442        *  (you haven't given it a filename to open).
00443        */
00444       basic_ifstream() : __istream_type(), _M_filebuf()
00445       { this->init(&_M_filebuf); }
00446 
00447       /**
00448        *  @brief  Create an input file stream.
00449        *  @param  s  Null terminated string specifying the filename.
00450        *  @param  mode  Open file in specified mode (see std::ios_base).
00451        *
00452        *  @c ios_base::in is automatically included in @a mode.
00453        *
00454        *  Tip:  When using std::string to hold the filename, you must use
00455        *  .c_str() before passing it to this constructor.
00456        */
00457       explicit
00458       basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
00459       : __istream_type(), _M_filebuf()
00460       {
00461     this->init(&_M_filebuf);
00462     this->open(__s, __mode);
00463       }
00464 
00465 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00466       /**
00467        *  @brief  Create an input file stream.
00468        *  @param  s  std::string specifying the filename.
00469        *  @param  mode  Open file in specified mode (see std::ios_base).
00470        *
00471        *  @c ios_base::in is automatically included in @a mode.
00472        */
00473       explicit
00474       basic_ifstream(const std::string& __s,
00475              ios_base::openmode __mode = ios_base::in)
00476       : __istream_type(), _M_filebuf()
00477       {
00478     this->init(&_M_filebuf);
00479     this->open(__s, __mode);
00480       }
00481 #endif
00482 
00483       /**
00484        *  @brief  The destructor does nothing.
00485        *
00486        *  The file is closed by the filebuf object, not the formatting
00487        *  stream.
00488        */
00489       ~basic_ifstream()
00490       { }
00491 
00492       // Members:
00493       /**
00494        *  @brief  Accessing the underlying buffer.
00495        *  @return  The current basic_filebuf buffer.
00496        *
00497        *  This hides both signatures of std::basic_ios::rdbuf().
00498        */
00499       __filebuf_type*
00500       rdbuf() const
00501       { return const_cast<__filebuf_type*>(&_M_filebuf); }
00502 
00503       /**
00504        *  @brief  Wrapper to test for an open file.
00505        *  @return  @c rdbuf()->is_open()
00506        */
00507       bool
00508       is_open()
00509       { return _M_filebuf.is_open(); }
00510 
00511       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00512       // 365. Lack of const-qualification in clause 27
00513       bool
00514       is_open() const
00515       { return _M_filebuf.is_open(); }
00516 
00517       /**
00518        *  @brief  Opens an external file.
00519        *  @param  s  The name of the file.
00520        *  @param  mode  The open mode flags.
00521        *
00522        *  Calls @c std::basic_filebuf::open(s,mode|in).  If that function
00523        *  fails, @c failbit is set in the stream's error state.
00524        *
00525        *  Tip:  When using std::string to hold the filename, you must use
00526        *  .c_str() before passing it to this constructor.
00527        */
00528       void
00529       open(const char* __s, ios_base::openmode __mode = ios_base::in)
00530       {
00531     if (!_M_filebuf.open(__s, __mode | ios_base::in))
00532       this->setstate(ios_base::failbit);
00533     else
00534       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00535       // 409. Closing an fstream should clear error state
00536       this->clear();
00537       }
00538 
00539 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00540       /**
00541        *  @brief  Opens an external file.
00542        *  @param  s  The name of the file.
00543        *  @param  mode  The open mode flags.
00544        *
00545        *  Calls @c std::basic_filebuf::open(s,mode|in).  If that function
00546        *  fails, @c failbit is set in the stream's error state.
00547        */
00548       void
00549       open(const std::string& __s, ios_base::openmode __mode = ios_base::in)
00550       {
00551     if (!_M_filebuf.open(__s, __mode | ios_base::in))
00552       this->setstate(ios_base::failbit);
00553     else
00554       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00555       // 409. Closing an fstream should clear error state
00556       this->clear();
00557       }
00558 #endif
00559 
00560       /**
00561        *  @brief  Close the file.
00562        *
00563        *  Calls @c std::basic_filebuf::close().  If that function
00564        *  fails, @c failbit is set in the stream's error state.
00565        */
00566       void
00567       close()
00568       {
00569     if (!_M_filebuf.close())
00570       this->setstate(ios_base::failbit);
00571       }
00572     };
00573 
00574 
00575   // [27.8.1.8] Template class basic_ofstream
00576   /**
00577    *  @brief  Controlling output for files.
00578    *  @ingroup io
00579    *
00580    *  This class supports reading from named files, using the inherited
00581    *  functions from std::basic_ostream.  To control the associated
00582    *  sequence, an instance of std::basic_filebuf is used, which this page
00583    *  refers to as @c sb.
00584    */
00585   template<typename _CharT, typename _Traits>
00586     class basic_ofstream : public basic_ostream<_CharT,_Traits>
00587     {
00588     public:
00589       // Types:
00590       typedef _CharT                    char_type;
00591       typedef _Traits                   traits_type;
00592       typedef typename traits_type::int_type        int_type;
00593       typedef typename traits_type::pos_type        pos_type;
00594       typedef typename traits_type::off_type        off_type;
00595 
00596       // Non-standard types:
00597       typedef basic_filebuf<char_type, traits_type>     __filebuf_type;
00598       typedef basic_ostream<char_type, traits_type> __ostream_type;
00599 
00600     private:
00601       __filebuf_type    _M_filebuf;
00602 
00603     public:
00604       // Constructors:
00605       /**
00606        *  @brief  Default constructor.
00607        *
00608        *  Initializes @c sb using its default constructor, and passes
00609        *  @c &sb to the base class initializer.  Does not open any files
00610        *  (you haven't given it a filename to open).
00611        */
00612       basic_ofstream(): __ostream_type(), _M_filebuf()
00613       { this->init(&_M_filebuf); }
00614 
00615       /**
00616        *  @brief  Create an output file stream.
00617        *  @param  s  Null terminated string specifying the filename.
00618        *  @param  mode  Open file in specified mode (see std::ios_base).
00619        *
00620        *  @c ios_base::out|ios_base::trunc is automatically included in
00621        *  @a mode.
00622        *
00623        *  Tip:  When using std::string to hold the filename, you must use
00624        *  .c_str() before passing it to this constructor.
00625        */
00626       explicit
00627       basic_ofstream(const char* __s,
00628              ios_base::openmode __mode = ios_base::out|ios_base::trunc)
00629       : __ostream_type(), _M_filebuf()
00630       {
00631     this->init(&_M_filebuf);
00632     this->open(__s, __mode);
00633       }
00634 
00635 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00636       /**
00637        *  @brief  Create an output file stream.
00638        *  @param  s  std::string specifying the filename.
00639        *  @param  mode  Open file in specified mode (see std::ios_base).
00640        *
00641        *  @c ios_base::out|ios_base::trunc is automatically included in
00642        *  @a mode.
00643        */
00644       explicit
00645       basic_ofstream(const std::string& __s,
00646              ios_base::openmode __mode = ios_base::out|ios_base::trunc)
00647       : __ostream_type(), _M_filebuf()
00648       {
00649     this->init(&_M_filebuf);
00650     this->open(__s, __mode);
00651       }
00652 #endif
00653 
00654       /**
00655        *  @brief  The destructor does nothing.
00656        *
00657        *  The file is closed by the filebuf object, not the formatting
00658        *  stream.
00659        */
00660       ~basic_ofstream()
00661       { }
00662 
00663       // Members:
00664       /**
00665        *  @brief  Accessing the underlying buffer.
00666        *  @return  The current basic_filebuf buffer.
00667        *
00668        *  This hides both signatures of std::basic_ios::rdbuf().
00669        */
00670       __filebuf_type*
00671       rdbuf() const
00672       { return const_cast<__filebuf_type*>(&_M_filebuf); }
00673 
00674       /**
00675        *  @brief  Wrapper to test for an open file.
00676        *  @return  @c rdbuf()->is_open()
00677        */
00678       bool
00679       is_open()
00680       { return _M_filebuf.is_open(); }
00681 
00682       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00683       // 365. Lack of const-qualification in clause 27
00684       bool
00685       is_open() const
00686       { return _M_filebuf.is_open(); }
00687 
00688       /**
00689        *  @brief  Opens an external file.
00690        *  @param  s  The name of the file.
00691        *  @param  mode  The open mode flags.
00692        *
00693        *  Calls @c std::basic_filebuf::open(s,mode|out|trunc).  If that
00694        *  function fails, @c failbit is set in the stream's error state.
00695        *
00696        *  Tip:  When using std::string to hold the filename, you must use
00697        *  .c_str() before passing it to this constructor.
00698        */
00699       void
00700       open(const char* __s,
00701        ios_base::openmode __mode = ios_base::out | ios_base::trunc)
00702       {
00703     if (!_M_filebuf.open(__s, __mode | ios_base::out))
00704       this->setstate(ios_base::failbit);
00705     else
00706       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00707       // 409. Closing an fstream should clear error state
00708       this->clear();
00709       }
00710 
00711 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00712       /**
00713        *  @brief  Opens an external file.
00714        *  @param  s  The name of the file.
00715        *  @param  mode  The open mode flags.
00716        *
00717        *  Calls @c std::basic_filebuf::open(s,mode|out|trunc).  If that
00718        *  function fails, @c failbit is set in the stream's error state.
00719        */
00720       void
00721       open(const std::string& __s,
00722        ios_base::openmode __mode = ios_base::out | ios_base::trunc)
00723       {
00724     if (!_M_filebuf.open(__s, __mode | ios_base::out))
00725       this->setstate(ios_base::failbit);
00726     else
00727       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00728       // 409. Closing an fstream should clear error state
00729       this->clear();
00730       }
00731 #endif
00732 
00733       /**
00734        *  @brief  Close the file.
00735        *
00736        *  Calls @c std::basic_filebuf::close().  If that function
00737        *  fails, @c failbit is set in the stream's error state.
00738        */
00739       void
00740       close()
00741       {
00742     if (!_M_filebuf.close())
00743       this->setstate(ios_base::failbit);
00744       }
00745     };
00746 
00747 
00748   // [27.8.1.11] Template class basic_fstream
00749   /**
00750    *  @brief  Controlling input and output for files.
00751    *  @ingroup io
00752    *
00753    *  This class supports reading from and writing to named files, using
00754    *  the inherited functions from std::basic_iostream.  To control the
00755    *  associated sequence, an instance of std::basic_filebuf is used, which
00756    *  this page refers to as @c sb.
00757    */
00758   template<typename _CharT, typename _Traits>
00759     class basic_fstream : public basic_iostream<_CharT, _Traits>
00760     {
00761     public:
00762       // Types:
00763       typedef _CharT                    char_type;
00764       typedef _Traits                   traits_type;
00765       typedef typename traits_type::int_type        int_type;
00766       typedef typename traits_type::pos_type        pos_type;
00767       typedef typename traits_type::off_type        off_type;
00768 
00769       // Non-standard types:
00770       typedef basic_filebuf<char_type, traits_type>     __filebuf_type;
00771       typedef basic_ios<char_type, traits_type>     __ios_type;
00772       typedef basic_iostream<char_type, traits_type>    __iostream_type;
00773 
00774     private:
00775       __filebuf_type    _M_filebuf;
00776 
00777     public:
00778       // Constructors/destructor:
00779       /**
00780        *  @brief  Default constructor.
00781        *
00782        *  Initializes @c sb using its default constructor, and passes
00783        *  @c &sb to the base class initializer.  Does not open any files
00784        *  (you haven't given it a filename to open).
00785        */
00786       basic_fstream()
00787       : __iostream_type(), _M_filebuf()
00788       { this->init(&_M_filebuf); }
00789 
00790       /**
00791        *  @brief  Create an input/output file stream.
00792        *  @param  s  Null terminated string specifying the filename.
00793        *  @param  mode  Open file in specified mode (see std::ios_base).
00794        *
00795        *  Tip:  When using std::string to hold the filename, you must use
00796        *  .c_str() before passing it to this constructor.
00797        */
00798       explicit
00799       basic_fstream(const char* __s,
00800             ios_base::openmode __mode = ios_base::in | ios_base::out)
00801       : __iostream_type(0), _M_filebuf()
00802       {
00803     this->init(&_M_filebuf);
00804     this->open(__s, __mode);
00805       }
00806 
00807 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00808       /**
00809        *  @brief  Create an input/output file stream.
00810        *  @param  s  Null terminated string specifying the filename.
00811        *  @param  mode  Open file in specified mode (see std::ios_base).
00812        */
00813       explicit
00814       basic_fstream(const std::string& __s,
00815             ios_base::openmode __mode = ios_base::in | ios_base::out)
00816       : __iostream_type(0), _M_filebuf()
00817       {
00818     this->init(&_M_filebuf);
00819     this->open(__s, __mode);
00820       }
00821 #endif
00822 
00823       /**
00824        *  @brief  The destructor does nothing.
00825        *
00826        *  The file is closed by the filebuf object, not the formatting
00827        *  stream.
00828        */
00829       ~basic_fstream()
00830       { }
00831 
00832       // Members:
00833       /**
00834        *  @brief  Accessing the underlying buffer.
00835        *  @return  The current basic_filebuf buffer.
00836        *
00837        *  This hides both signatures of std::basic_ios::rdbuf().
00838        */
00839       __filebuf_type*
00840       rdbuf() const
00841       { return const_cast<__filebuf_type*>(&_M_filebuf); }
00842 
00843       /**
00844        *  @brief  Wrapper to test for an open file.
00845        *  @return  @c rdbuf()->is_open()
00846        */
00847       bool
00848       is_open()
00849       { return _M_filebuf.is_open(); }
00850 
00851       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00852       // 365. Lack of const-qualification in clause 27
00853       bool
00854       is_open() const
00855       { return _M_filebuf.is_open(); }
00856 
00857       /**
00858        *  @brief  Opens an external file.
00859        *  @param  s  The name of the file.
00860        *  @param  mode  The open mode flags.
00861        *
00862        *  Calls @c std::basic_filebuf::open(s,mode).  If that
00863        *  function fails, @c failbit is set in the stream's error state.
00864        *
00865        *  Tip:  When using std::string to hold the filename, you must use
00866        *  .c_str() before passing it to this constructor.
00867        */
00868       void
00869       open(const char* __s,
00870        ios_base::openmode __mode = ios_base::in | ios_base::out)
00871       {
00872     if (!_M_filebuf.open(__s, __mode))
00873       this->setstate(ios_base::failbit);
00874     else
00875       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00876       // 409. Closing an fstream should clear error state
00877       this->clear();
00878       }
00879 
00880 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00881       /**
00882        *  @brief  Opens an external file.
00883        *  @param  s  The name of the file.
00884        *  @param  mode  The open mode flags.
00885        *
00886        *  Calls @c std::basic_filebuf::open(s,mode).  If that
00887        *  function fails, @c failbit is set in the stream's error state.
00888        */
00889       void
00890       open(const std::string& __s,
00891        ios_base::openmode __mode = ios_base::in | ios_base::out)
00892       {
00893     if (!_M_filebuf.open(__s, __mode))
00894       this->setstate(ios_base::failbit);
00895     else
00896       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00897       // 409. Closing an fstream should clear error state
00898       this->clear();
00899       }
00900 #endif
00901 
00902       /**
00903        *  @brief  Close the file.
00904        *
00905        *  Calls @c std::basic_filebuf::close().  If that function
00906        *  fails, @c failbit is set in the stream's error state.
00907        */
00908       void
00909       close()
00910       {
00911     if (!_M_filebuf.close())
00912       this->setstate(ios_base::failbit);
00913       }
00914     };
00915 
00916 _GLIBCXX_END_NAMESPACE
00917 
00918 #ifndef _GLIBCXX_EXPORT_TEMPLATE
00919 # include <bits/fstream.tcc>
00920 #endif
00921 
00922 #endif /* _GLIBCXX_FSTREAM */