Provided by: libstdc++-9-doc_9.2.1-9ubuntu2_all bug

NAME

       __gnu_cxx::stdio_filebuf< _CharT, _Traits > - Provides a layer of compatibility for
       C/POSIX.

       This GNU extension provides extensions for working with standard C FILE*'s and POSIX file
       descriptors. It must be instantiated by the user with the type of character used in the
       file stream, e.g., stdio_filebuf<char>.

SYNOPSIS

       Inherits std::basic_filebuf< _CharT, _Traits >.

   Public Types
       typedef codecvt< char_type, char, __state_type > __codecvt_type
       typedef __basic_file< char > __file_type
       typedef basic_filebuf< char_type, traits_type > __filebuf_type
       typedef traits_type::state_type __state_type
       typedef basic_streambuf< char_type, traits_type > __streambuf_type
       typedef _CharT char_type
       typedef traits_type::int_type int_type
       typedef traits_type::off_type off_type
       typedef traits_type::pos_type pos_type
       typedef std::size_t size_t
       typedef _Traits traits_type

   Public Member Functions
       stdio_filebuf ()
       stdio_filebuf (int __fd, std::ios_base::openmode __mode, size_t __size=static_cast< size_t
           >(BUFSIZ))
       stdio_filebuf (std::__c_file *__f, std::ios_base::openmode __mode, size_t
           __size=static_cast< size_t >(BUFSIZ))
       stdio_filebuf (stdio_filebuf &&)=default
       virtual ~stdio_filebuf ()
       __filebuf_type * close ()
           Closes the currently associated file.
       int fd ()
       std::__c_file * file ()
       locale getloc () const
           Locale access.
       streamsize in_avail ()
           Looking ahead into the stream.
       bool is_open () const  throw ()
           Returns true if the external file is open.
       __filebuf_type * open (const char *__s, ios_base::openmode __mode)
           Opens an external file.
       __filebuf_type * open (const std::string &__s, ios_base::openmode __mode)
           Opens an external file.
       stdio_filebuf & operator= (stdio_filebuf &&)=default
       locale pubimbue (const locale &__loc)
           Entry point for imbue().
       int_type sbumpc ()
           Getting the next character.
       int_type sgetc ()
           Getting the next character.
       streamsize sgetn (char_type *__s, streamsize __n)
           Entry point for xsgetn.
       int_type snextc ()
           Getting the next character.
       int_type sputbackc (char_type __c)
           Pushing characters back into the input stream.
       int_type sputc (char_type __c)
           Entry point for all single-character output functions.
       streamsize sputn (const char_type *__s, streamsize __n)
           Entry point for all single-character output functions.
       int_type sungetc ()
           Moving backwards in the input stream.
       void swap (stdio_filebuf &__fb)
       void swap (basic_filebuf &)

           basic_streambuf * pubsetbuf (char_type *__s, streamsize __n)
               Entry points for derived buffer functions.
           pos_type pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode
               __mode=ios_base::in|ios_base::out)
               Alters the stream position.
           pos_type pubseekpos (pos_type __sp, ios_base::openmode
               __mode=ios_base::in|ios_base::out)
               Alters the stream position.
           int pubsync ()
               Calls virtual sync function.

   Protected Member Functions
       void __safe_gbump (streamsize __n)
       void __safe_pbump (streamsize __n)
       void _M_allocate_internal_buffer ()
       bool _M_convert_to_external (char_type *, streamsize)
       void _M_create_pback ()
       void _M_destroy_internal_buffer ()  throw ()
       void _M_destroy_pback ()  throw ()
       int _M_get_ext_pos (__state_type &__state)
       pos_type _M_seek (off_type __off, ios_base::seekdir __way, __state_type __state)
       void _M_set_buffer (streamsize __off)
       bool _M_terminate_output ()
       void gbump (int __n)
           Moving the read position.
       virtual void imbue (const locale &__loc)
       virtual void imbue (const locale &__loc __attribute__((__unused__)))
           Changes translations.
       virtual int_type overflow (int_type __c=_Traits::eof())
       virtual int_type overflow (int_type __c __attribute__((__unused__))=traits_type::eof())
           Consumes data from the buffer; writes to the controlled sequence.
       virtual int_type pbackfail (int_type __c=_Traits::eof())
       virtual int_type pbackfail (int_type __c __attribute__((__unused__))=traits_type::eof())
           Tries to back up the input sequence.
       void pbump (int __n)
           Moving the write position.
       virtual pos_type seekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode
           __mode=ios_base::in|ios_base::out)
           Alters the stream positions.
       virtual pos_type seekpos (pos_type __pos, ios_base::openmode
           __mode=ios_base::in|ios_base::out)
           Alters the stream positions.
       virtual __streambuf_type * setbuf (char_type *__s, streamsize __n)
           Manipulates the buffer.
       void setg (char_type *__gbeg, char_type *__gnext, char_type *__gend)
           Setting the three read area pointers.
       void setp (char_type *__pbeg, char_type *__pend)
           Setting the three write area pointers.
       virtual streamsize showmanyc ()
           Investigating the data available.
       void swap (basic_streambuf &__sb)
       virtual int sync ()
           Synchronizes the buffer arrays with the controlled sequences.
       virtual int_type uflow ()
           Fetches more data from the controlled sequence.
       virtual int_type underflow ()
           Fetches more data from the controlled sequence.
       virtual streamsize xsgetn (char_type *__s, streamsize __n)
           Multiple character extraction.
       virtual streamsize xsputn (const char_type *__s, streamsize __n)
           Multiple character insertion.

           char_type * eback () const
               Access to the get area.
           char_type * gptr () const
               Access to the get area.
           char_type * egptr () const
               Access to the get area.

           char_type * pbase () const
               Access to the put area.
           char_type * pptr () const
               Access to the put area.
           char_type * epptr () const
               Access to the put area.

   Protected Attributes
       char_type * _M_buf
           Pointer to the beginning of internal buffer.
       bool _M_buf_allocated
       locale _M_buf_locale
           Current locale setting.
       size_t _M_buf_size
       const __codecvt_type * _M_codecvt
       char * _M_ext_buf
       streamsize _M_ext_buf_size
       char * _M_ext_end
       const char * _M_ext_next
       __file_type _M_file
       char_type * _M_in_beg
           Start of get area.
       char_type * _M_in_cur
           Current read area.
       char_type * _M_in_end
           End of get area.
       __c_lock _M_lock
       ios_base::openmode _M_mode
           Place to stash in || out || in | out settings for current filebuf.
       char_type * _M_out_beg
           Start of put area.
       char_type * _M_out_cur
           Current put area.
       char_type * _M_out_end
           End of put area.
       bool _M_reading
       __state_type _M_state_beg
       __state_type _M_state_cur
       __state_type _M_state_last
       bool _M_writing

           char_type _M_pback
           char_type * _M_pback_cur_save
           char_type * _M_pback_end_save
           bool _M_pback_init

Detailed Description

   template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
       class __gnu_cxx::stdio_filebuf< _CharT, _Traits >" Provides a layer of compatibility for
       C/POSIX.

       This GNU extension provides extensions for working with standard C FILE*'s and POSIX file
       descriptors. It must be instantiated by the user with the type of character used in the
       file stream, e.g., stdio_filebuf<char>.

       Definition at line 50 of file stdio_filebuf.h.

Constructor & Destructor Documentation

   template<typename _CharT , typename _Traits  = std::char_traits<_CharT>>
       __gnu_cxx::stdio_filebuf< _CharT, _Traits >::stdio_filebuf () [inline]
       deferred initialization

       Definition at line 65 of file stdio_filebuf.h.

       Referenced by __gnu_cxx::stdio_filebuf< _CharT, _Traits >::~stdio_filebuf().

   template<typename _CharT , typename _Traits > __gnu_cxx::stdio_filebuf< _CharT, _Traits
       >::stdio_filebuf (int __fd, std::ios_base::openmode __mode, size_t __size =
       static_cast<size_t>(BUFSIZ))
       Parameters:
           __fd An open file descriptor.
           __mode Same meaning as in a standard filebuf.
           __size Optimal or preferred size of internal buffer, in chars.

       This constructor associates a file stream buffer with an open POSIX file descriptor. The
       file descriptor will be automatically closed when the stdio_filebuf is closed/destroyed.

       Definition at line 137 of file stdio_filebuf.h.

   template<typename _CharT , typename _Traits > __gnu_cxx::stdio_filebuf< _CharT, _Traits
       >::stdio_filebuf (std::__c_file * __f, std::ios_base::openmode __mode, size_t __size =
       static_cast<size_t>(BUFSIZ))
       Parameters:
           __f An open FILE*.
           __mode Same meaning as in a standard filebuf.
           __size Optimal or preferred size of internal buffer, in chars. Defaults to system's
           BUFSIZ.

       This constructor associates a file stream buffer with an open C FILE*. The FILE* will not
       be automatically closed when the stdio_filebuf is closed/destroyed.

       Definition at line 153 of file stdio_filebuf.h.

   template<typename _CharT , typename _Traits > __gnu_cxx::stdio_filebuf< _CharT, _Traits
       >::~stdio_filebuf () [virtual]
       Closes the external data stream if the file descriptor constructor was used.

       Definition at line 132 of file stdio_filebuf.h.

       References __gnu_cxx::stdio_filebuf< _CharT, _Traits >::stdio_filebuf().

Member Function Documentation

   template<typename _CharT, typename _Traits> void std::basic_filebuf< _CharT, _Traits
       >::_M_create_pback () [inline],  [protected],  [inherited]
       Initializes pback buffers, and moves normal buffers to safety. Assumptions: _M_in_cur has
       already been moved back

       Definition at line 199 of file fstream.

   template<typename _CharT, typename _Traits> void std::basic_filebuf< _CharT, _Traits
       >::_M_destroy_pback () [inline],  [protected],  [inherited]
       Deactivates pback buffer contents, and restores normal buffer. Assumptions: The pback
       buffer has only moved forward.

       Definition at line 216 of file fstream.

   template<typename _CharT, typename _Traits> void std::basic_filebuf< _CharT, _Traits
       >::_M_set_buffer (streamsize __off) [inline],  [protected],  [inherited]
       This function sets the pointers of the internal buffer, both get and put areas. Typically:

       __off == egptr() - eback() upon underflow/uflow (read mode); __off == 0 upon overflow
       (write mode); __off == -1 upon open, setbuf, seekoff/pos (uncommitted mode).

       NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size reflects the actual allocated
       memory and the last cell is reserved for the overflow char of a full put area.

       Definition at line 459 of file fstream.

       Referenced by std::basic_filebuf< char_type, traits_type >::close().

   template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits >::__filebuf_type
       * std::basic_filebuf< _CharT, _Traits >::close () [inherited]
       Closes the currently associated file.

       Returns:
           this on success, NULL on failure

       If no file is currently open, this function immediately fails.

       If a put buffer area exists, overflow(eof) is called to flush all the characters. The file
       is then closed.

       If any operations fail, this function also fails.

       Definition at line 250 of file fstream.tcc.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::eback () const [inline],  [protected],  [inherited]
       Access to the get area. These functions are only available to other protected functions,
       including derived classes.

       · eback() returns the beginning pointer for the input sequence

       · gptr() returns the next pointer for the input sequence

       · egptr() returns the end pointer for the input sequence

       Definition at line 489 of file streambuf.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::egptr () const [inline],  [protected],  [inherited]
       Access to the get area. These functions are only available to other protected functions,
       including derived classes.

       · eback() returns the beginning pointer for the input sequence

       · gptr() returns the next pointer for the input sequence

       · egptr() returns the end pointer for the input sequence

       Definition at line 495 of file streambuf.

       Referenced by std::ostreambuf_iterator< _CharT, _Traits >::failed().

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::epptr () const [inline],  [protected],  [inherited]
       Access to the put area. These functions are only available to other protected functions,
       including derived classes.

       · pbase() returns the beginning pointer for the output sequence

       · pptr() returns the next pointer for the output sequence

       · epptr() returns the end pointer for the output sequence

       Definition at line 542 of file streambuf.

   template<typename _CharT , typename _Traits  = std::char_traits<_CharT>> int
       __gnu_cxx::stdio_filebuf< _CharT, _Traits >::fd () [inline]
       Returns:
           The underlying file descriptor.

       Once associated with an external data stream, this function can be used to access the
       underlying POSIX file descriptor. Note that there is no way for the library to track what
       you do with the descriptor, so be careful.

       Definition at line 118 of file stdio_filebuf.h.

   template<typename _CharT , typename _Traits  = std::char_traits<_CharT>> std::__c_file*
       __gnu_cxx::stdio_filebuf< _CharT, _Traits >::file () [inline]
       Returns:
           The underlying FILE*.

       This function can be used to access the underlying 'C' file pointer. Note that there is no
       way for the library to track what you do with the file, so be careful.

       Definition at line 128 of file stdio_filebuf.h.

   template<typename _CharT, typename _Traits> void std::basic_streambuf< _CharT, _Traits
       >::gbump (int __n) [inline],  [protected],  [inherited]
       Moving the read position.

       Parameters:
           __n The delta by which to move.

       This just advances the read position without returning any data.

       Definition at line 505 of file streambuf.

   template<typename _CharT, typename _Traits> locale std::basic_streambuf< _CharT, _Traits
       >::getloc () const [inline],  [inherited]
       Locale access.

       Returns:
           The current locale in effect.

       If pubimbue(loc) has been called, then the most recent loc is returned. Otherwise the
       global locale in effect at the time of construction is returned.

       Definition at line 233 of file streambuf.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::gptr () const [inline],  [protected],  [inherited]
       Access to the get area. These functions are only available to other protected functions,
       including derived classes.

       · eback() returns the beginning pointer for the input sequence

       · gptr() returns the next pointer for the input sequence

       · egptr() returns the end pointer for the input sequence

       Definition at line 492 of file streambuf.

       Referenced by std::ostreambuf_iterator< _CharT, _Traits >::failed().

   template<typename _CharT, typename _Traits> virtual void std::basic_streambuf< _CharT, _Traits
       >::imbue (const locale &__loc  __attribute__(__unused__)) [inline],  [protected],
       [virtual],  [inherited]
       Changes translations.

       Parameters:
           __loc A new locale.

       Translations done during I/O which depend on the current locale are changed by this call.
       The standard adds, Between invocations of this function a class derived from streambuf can
       safely cache results of calls to locale functions and to members of facets so obtained.

       Note:
           Base class version does nothing.

       Definition at line 583 of file streambuf.

   template<typename _CharT, typename _Traits> streamsize std::basic_streambuf< _CharT, _Traits
       >::in_avail () [inline],  [inherited]
       Looking ahead into the stream.

       Returns:
           The number of characters available.

       If a read position is available, returns the number of characters available for reading
       before the buffer must be refilled. Otherwise returns the derived showmanyc().

       Definition at line 291 of file streambuf.

   template<typename _CharT, typename _Traits> bool std::basic_filebuf< _CharT, _Traits
       >::is_open () const [inline],  [inherited]
       Returns true if the external file is open.

       Definition at line 265 of file fstream.

   template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits >::__filebuf_type
       * std::basic_filebuf< _CharT, _Traits >::open (const char * __s, ios_base::openmode
       __mode) [inherited]
       Opens an external file.

       Parameters:
           __s The name of the file.
           __mode The open mode flags.

       Returns:
           this on success, NULL on failure

       If a file is already open, this function immediately fails. Otherwise it tries to open the
       file named __s using the flags given in __mode.

       Table 92, adapted here, gives the relation between openmode combinations and the
       equivalent fopen() flags. (NB: lines app, in|out|app, in|app, binary|app,
       binary|in|out|app, and binary|in|app per DR 596)

       +---------------------------------------------------------+
       | ios_base Flag combination            stdio equivalent   |
       |binary  in  out  trunc  app                              |
       +---------------------------------------------------------+
       |             +                        w                  |
       |             +           +            a                  |
       |                         +            a                  |
       |             +     +                  w                  |
       |         +                            r                  |
       |         +   +                        r+                 |
       |         +   +     +                  w+                 |
       |         +   +           +            a+                 |
       |         +               +            a+                 |
       +---------------------------------------------------------+
       |   +         +                        wb                 |
       |   +         +           +            ab                 |
       |   +                     +            ab                 |
       |   +         +     +                  wb                 |
       |   +     +                            rb                 |
       |   +     +   +                        r+b                |
       |   +     +   +     +                  w+b                |
       |   +     +   +           +            a+b                |
       |   +     +               +            a+b                |
       +---------------------------------------------------------+

       Definition at line 180 of file fstream.tcc.

       Referenced by std::basic_filebuf< char_type, traits_type >::open().

   template<typename _CharT, typename _Traits> __filebuf_type* std::basic_filebuf< _CharT,
       _Traits >::open (const std::string & __s, ios_base::openmode __mode) [inline],
       [inherited]
       Opens an external file.

       Parameters:
           __s The name of the file.
           __mode The open mode flags.

       Returns:
           this on success, NULL on failure

       Definition at line 331 of file fstream.

   template<typename _CharT, typename _Traits> virtual int_type std::basic_streambuf< _CharT,
       _Traits >::overflow (int_type __c  __attribute__(__unused__) = traits_type::eof())
       [inline],  [protected],  [virtual],  [inherited]
       Consumes data from the buffer; writes to the controlled sequence.

       Parameters:
           __c An additional character to consume.

       Returns:
           eof() to indicate failure, something else (usually __c, or not_eof())

       Informally, this function is called when the output buffer is full (or does not exist, as
       buffering need not actually be done). If a buffer exists, it is consumed, with some effect
       on the controlled sequence. (Typically, the buffer is written out to the sequence
       verbatim.) In either case, the character c is also written out, if __c is not eof().

       For a formal definition of this function, see a good text such as Langer & Kreft, or
       [27.5.2.4.5]/3-7.

       A functioning output streambuf can be created by overriding only this function (no buffer
       area will be used).

       Note:
           Base class version does nothing, returns eof().

       Definition at line 775 of file streambuf.

   template<typename _CharT, typename _Traits> virtual int_type std::basic_streambuf< _CharT,
       _Traits >::pbackfail (int_type __c  __attribute__(__unused__) = traits_type::eof())
       [inline],  [protected],  [virtual],  [inherited]
       Tries to back up the input sequence.

       Parameters:
           __c The character to be inserted back into the sequence.

       Returns:
           eof() on failure, some other value on success

       Postcondition:
           The constraints of gptr(), eback(), and pptr() are the same as for underflow().

       Note:
           Base class version does nothing, returns eof().

       Definition at line 731 of file streambuf.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::pbase () const [inline],  [protected],  [inherited]
       Access to the put area. These functions are only available to other protected functions,
       including derived classes.

       · pbase() returns the beginning pointer for the output sequence

       · pptr() returns the next pointer for the output sequence

       · epptr() returns the end pointer for the output sequence

       Definition at line 536 of file streambuf.

   template<typename _CharT, typename _Traits> void std::basic_streambuf< _CharT, _Traits
       >::pbump (int __n) [inline],  [protected],  [inherited]
       Moving the write position.

       Parameters:
           __n The delta by which to move.

       This just advances the write position without returning any data.

       Definition at line 552 of file streambuf.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::pptr () const [inline],  [protected],  [inherited]
       Access to the put area. These functions are only available to other protected functions,
       including derived classes.

       · pbase() returns the beginning pointer for the output sequence

       · pptr() returns the next pointer for the output sequence

       · epptr() returns the end pointer for the output sequence

       Definition at line 539 of file streambuf.

   template<typename _CharT, typename _Traits> locale std::basic_streambuf< _CharT, _Traits
       >::pubimbue (const locale & __loc) [inline],  [inherited]
       Entry point for imbue().

       Parameters:
           __loc The new locale.

       Returns:
           The previous locale.

       Calls the derived imbue(__loc).

       Definition at line 216 of file streambuf.

   template<typename _CharT, typename _Traits> pos_type std::basic_streambuf< _CharT, _Traits
       >::pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode =
       ios_base::in | ios_base::out) [inline],  [inherited]
       Alters the stream position.

       Parameters:
           __off Offset.
           __way Value for ios_base::seekdir.
           __mode Value for ios_base::openmode.

       Calls virtual seekoff function.

       Definition at line 258 of file streambuf.

   template<typename _CharT, typename _Traits> pos_type std::basic_streambuf< _CharT, _Traits
       >::pubseekpos (pos_type __sp, ios_base::openmode __mode = ios_base::in | ios_base::out)
       [inline],  [inherited]
       Alters the stream position.

       Parameters:
           __sp Position
           __mode Value for ios_base::openmode.

       Calls virtual seekpos function.

       Definition at line 270 of file streambuf.

   template<typename _CharT, typename _Traits> basic_streambuf* std::basic_streambuf< _CharT,
       _Traits >::pubsetbuf (char_type * __s, streamsize __n) [inline],  [inherited]
       Entry points for derived buffer functions. The public versions of pubfoo dispatch to the
       protected derived foo member functions, passing the arguments (if any) and returning the
       result unchanged.

       Definition at line 246 of file streambuf.

   template<typename _CharT, typename _Traits> int std::basic_streambuf< _CharT, _Traits
       >::pubsync () [inline],  [inherited]
       Calls virtual sync function.

       Definition at line 278 of file streambuf.

   template<typename _CharT, typename _Traits> int_type std::basic_streambuf< _CharT, _Traits
       >::sbumpc () [inline],  [inherited]
       Getting the next character.

       Returns:
           The next character, or eof.

       If the input read position is available, returns that character and increments the read
       pointer, otherwise calls and returns uflow().

       Definition at line 323 of file streambuf.

   template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits >::pos_type
       std::basic_filebuf< _CharT, _Traits >::seekoff (off_type, ios_base::seekdir,
       ios_base::openmode = ios_base::in | ios_base::out) [protected],  [virtual],  [inherited]
       Alters the stream positions. Each derived class provides its own appropriate behavior.

       Note:
           Base class version does nothing, returns a pos_type that represents an invalid stream
           position.

       Reimplemented from std::basic_streambuf< _CharT, _Traits >.

       Definition at line 833 of file fstream.tcc.

   template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits >::pos_type
       std::basic_filebuf< _CharT, _Traits >::seekpos (pos_type, ios_base::openmode =
       ios_base::in | ios_base::out) [protected],  [virtual],  [inherited]
       Alters the stream positions. Each derived class provides its own appropriate behavior.

       Note:
           Base class version does nothing, returns a pos_type that represents an invalid stream
           position.

       Reimplemented from std::basic_streambuf< _CharT, _Traits >.

       Definition at line 893 of file fstream.tcc.

   template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits
       >::__streambuf_type * std::basic_filebuf< _CharT, _Traits >::setbuf (char_type * __s,
       streamsize __n) [protected],  [virtual],  [inherited]
       Manipulates the buffer.

       Parameters:
           __s Pointer to a buffer area.
           __n Size of __s.

       Returns:
           this

       If no file has been opened, and both __s and __n are zero, then the stream becomes
       unbuffered. Otherwise, __s is used as a buffer; see
       https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering for
       more.

       Reimplemented from std::basic_streambuf< _CharT, _Traits >.

       Definition at line 804 of file fstream.tcc.

   template<typename _CharT, typename _Traits> void std::basic_streambuf< _CharT, _Traits >::setg
       (char_type * __gbeg, char_type * __gnext, char_type * __gend) [inline],  [protected],
       [inherited]
       Setting the three read area pointers.

       Parameters:
           __gbeg A pointer.
           __gnext A pointer.
           __gend A pointer.

       Postcondition:
           __gbeg == eback(), __gnext == gptr(), and __gend == egptr()

       Definition at line 516 of file streambuf.

   template<typename _CharT, typename _Traits> void std::basic_streambuf< _CharT, _Traits >::setp
       (char_type * __pbeg, char_type * __pend) [inline],  [protected],  [inherited]
       Setting the three write area pointers.

       Parameters:
           __pbeg A pointer.
           __pend A pointer.

       Postcondition:
           __pbeg == pbase(), __pbeg == pptr(), and __pend == epptr()

       Definition at line 562 of file streambuf.

   template<typename _CharT, typename _Traits> int_type std::basic_streambuf< _CharT, _Traits
       >::sgetc () [inline],  [inherited]
       Getting the next character.

       Returns:
           The next character, or eof.

       If the input read position is available, returns that character, otherwise calls and
       returns underflow(). Does not move the read position after fetching the character.

       Definition at line 345 of file streambuf.

       Referenced by std::istreambuf_iterator< _CharT, _Traits >::equal(), and
       std::ostreambuf_iterator< _CharT, _Traits >::failed().

   template<typename _CharT, typename _Traits> streamsize std::basic_streambuf< _CharT, _Traits
       >::sgetn (char_type * __s, streamsize __n) [inline],  [inherited]
       Entry point for xsgetn.

       Parameters:
           __s A buffer area.
           __n A count.

       Returns xsgetn(__s,__n). The effect is to fill __s[0] through __s[__n-1] with characters
       from the input sequence, if possible.

       Definition at line 364 of file streambuf.

   template<typename _CharT , typename _Traits > streamsize std::basic_filebuf< _CharT, _Traits
       >::showmanyc () [protected],  [virtual],  [inherited]
       Investigating the data available.

       Returns:
           An estimate of the number of characters available in the input sequence, or -1.

       If it returns a positive value, then successive calls to underflow() will not return
       traits::eof() until at least that number of characters have been supplied. If showmanyc()
       returns -1, then calls to underflow() or uflow() will fail. [27.5.2.4.3]/1

       Note:
           Base class version does nothing, returns zero.

           The standard adds that the intention is not only that the calls [to underflow or
           uflow] will not return eof() but that they will return immediately.

           The standard adds that the morphemes of showmanyc are es-how-many-see, not show-manic.

       Reimplemented from std::basic_streambuf< _CharT, _Traits >.

       Definition at line 298 of file fstream.tcc.

   template<typename _CharT, typename _Traits> int_type std::basic_streambuf< _CharT, _Traits
       >::snextc () [inline],  [inherited]
       Getting the next character.

       Returns:
           The next character, or eof.

       Calls sbumpc(), and if that function returns traits::eof(), so does this function.
       Otherwise, sgetc().

       Definition at line 305 of file streambuf.

   template<typename _CharT, typename _Traits> int_type std::basic_streambuf< _CharT, _Traits
       >::sputbackc (char_type __c) [inline],  [inherited]
       Pushing characters back into the input stream.

       Parameters:
           __c The character to push back.

       Returns:
           The previous character, if possible.

       Similar to sungetc(), but __c is pushed onto the stream instead of the previous character.
       If successful, the next character fetched from the input stream will be __c.

       Definition at line 379 of file streambuf.

   template<typename _CharT, typename _Traits> int_type std::basic_streambuf< _CharT, _Traits
       >::sputc (char_type __c) [inline],  [inherited]
       Entry point for all single-character output functions.

       Parameters:
           __c A character to output.

       Returns:
           __c, if possible.

       One of two public output functions.

       If a write position is available for the output sequence (i.e., the buffer is not full),
       stores __c in that position, increments the position, and returns
       traits::to_int_type(__c). If a write position is not available, returns overflow(__c).

       Definition at line 431 of file streambuf.

       Referenced by std::ostreambuf_iterator< _CharT, _Traits >::operator=().

   template<typename _CharT, typename _Traits> streamsize std::basic_streambuf< _CharT, _Traits
       >::sputn (const char_type * __s, streamsize __n) [inline],  [inherited]
       Entry point for all single-character output functions.

       Parameters:
           __s A buffer read area.
           __n A count.

       One of two public output functions.

       Returns xsputn(__s,__n). The effect is to write __s[0] through __s[__n-1] to the output
       sequence, if possible.

       Definition at line 457 of file streambuf.

       Referenced by std::ostreambuf_iterator< _CharT, _Traits >::failed().

   template<typename _CharT, typename _Traits> int_type std::basic_streambuf< _CharT, _Traits
       >::sungetc () [inline],  [inherited]
       Moving backwards in the input stream.

       Returns:
           The previous character, if possible.

       If a putback position is available, this function decrements the input pointer and returns
       that character. Otherwise, calls and returns pbackfail(). The effect is to unget the last
       character gotten.

       Definition at line 404 of file streambuf.

   template<typename _CharT , typename _Traits > int std::basic_filebuf< _CharT, _Traits >::sync
       () [protected],  [virtual],  [inherited]
       Synchronizes the buffer arrays with the controlled sequences.

       Returns:
           -1 on failure.

       Each derived class provides its own appropriate behavior, including the definition of
       failure.

       Note:
           Base class version does nothing, returns zero.

       Reimplemented from std::basic_streambuf< _CharT, _Traits >.

       Definition at line 1013 of file fstream.tcc.

   template<typename _CharT, typename _Traits> virtual int_type std::basic_streambuf< _CharT,
       _Traits >::uflow () [inline],  [protected],  [virtual],  [inherited]
       Fetches more data from the controlled sequence.

       Returns:
           The first character from the pending sequence.

       Informally, this function does the same thing as underflow(), and in fact is required to
       call that function. It also returns the new character, like underflow() does. However,
       this function also moves the read position forward by one.

       Reimplemented in __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.

       Definition at line 707 of file streambuf.

   template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits >::int_type
       std::basic_filebuf< _CharT, _Traits >::underflow () [protected],  [virtual],  [inherited]
       Fetches more data from the controlled sequence.

       Returns:
           The first character from the pending sequence.

       Informally, this function is called when the input buffer is exhausted (or does not exist,
       as buffering need not actually be done). If a buffer exists, it is refilled. In either
       case, the next available character is returned, or traits::eof() to indicate a null
       pending sequence.

       For a formal definition of the pending sequence, see a good text such as Langer & Kreft,
       or [27.5.2.4.3]/7-14.

       A functioning input streambuf can be created by overriding only this function (no buffer
       area will be used). For an example, see
       https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html

       Note:
           Base class version does nothing, returns eof().

       Reimplemented from std::basic_streambuf< _CharT, _Traits >.

       Definition at line 324 of file fstream.tcc.

   template<typename _CharT , typename _Traits > streamsize std::basic_filebuf< _CharT, _Traits
       >::xsgetn (char_type * __s, streamsize __n) [protected],  [virtual],  [inherited]
       Multiple character extraction.

       Parameters:
           __s A buffer area.
           __n Maximum number of characters to assign.

       Returns:
           The number of characters assigned.

       Fills __s[0] through __s[__n-1] with characters from the input sequence, as if by
       sbumpc(). Stops when either __n characters have been copied, or when traits::eof() would
       be copied.

       It is expected that derived classes provide a more efficient implementation by overriding
       this definition.

       Reimplemented from std::basic_streambuf< _CharT, _Traits >.

       Definition at line 670 of file fstream.tcc.

   template<typename _CharT , typename _Traits > streamsize std::basic_filebuf< _CharT, _Traits
       >::xsputn (const char_type * __s, streamsize __n) [protected],  [virtual],  [inherited]
       Multiple character insertion.

       Parameters:
           __s A buffer area.
           __n Maximum number of characters to write.

       Returns:
           The number of characters written.

       Writes __s[0] through __s[__n-1] to the output sequence, as if by sputc(). Stops when
       either n characters have been copied, or when sputc() would return traits::eof().

       It is expected that derived classes provide a more efficient implementation by overriding
       this definition.

       Reimplemented from std::basic_streambuf< _CharT, _Traits >.

       Definition at line 756 of file fstream.tcc.

Member Data Documentation

   template<typename _CharT, typename _Traits> char_type* std::basic_filebuf< _CharT, _Traits
       >::_M_buf [protected],  [inherited]
       Pointer to the beginning of internal buffer.

       Definition at line 136 of file fstream.

   template<typename _CharT, typename _Traits> locale std::basic_streambuf< _CharT, _Traits
       >::_M_buf_locale [protected],  [inherited]
       Current locale setting.

       Definition at line 199 of file streambuf.

   template<typename _CharT, typename _Traits> size_t std::basic_filebuf< _CharT, _Traits
       >::_M_buf_size [protected],  [inherited]
       Actual size of internal buffer. This number is equal to the size of the put area + 1
       position, reserved for the overflow char of a full area.

       Definition at line 143 of file fstream.

   template<typename _CharT, typename _Traits> char* std::basic_filebuf< _CharT, _Traits
       >::_M_ext_buf [protected],  [inherited]
       Buffer for external characters. Used for input when codecvt::always_noconv() == false.
       When valid, this corresponds to eback().

       Definition at line 178 of file fstream.

   template<typename _CharT, typename _Traits> streamsize std::basic_filebuf< _CharT, _Traits
       >::_M_ext_buf_size [protected],  [inherited]
       Size of buffer held by _M_ext_buf.

       Definition at line 183 of file fstream.

   template<typename _CharT, typename _Traits> const char* std::basic_filebuf< _CharT, _Traits
       >::_M_ext_next [protected],  [inherited]
       Pointers into the buffer held by _M_ext_buf that delimit a subsequence of bytes that have
       been read but not yet converted. When valid, _M_ext_next corresponds to egptr().

       Definition at line 190 of file fstream.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::_M_in_beg [protected],  [inherited]
       Start of get area.

       Definition at line 191 of file streambuf.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::_M_in_cur [protected],  [inherited]
       Current read area.

       Definition at line 192 of file streambuf.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::_M_in_end [protected],  [inherited]
       End of get area.

       Definition at line 193 of file streambuf.

   template<typename _CharT, typename _Traits> ios_base::openmode std::basic_filebuf< _CharT,
       _Traits >::_M_mode [protected],  [inherited]
       Place to stash in || out || in | out settings for current filebuf.

       Definition at line 121 of file fstream.

       Referenced by std::basic_filebuf< char_type, traits_type >::close().

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::_M_out_beg [protected],  [inherited]
       Start of put area.

       Definition at line 194 of file streambuf.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::_M_out_cur [protected],  [inherited]
       Current put area.

       Definition at line 195 of file streambuf.

   template<typename _CharT, typename _Traits> char_type* std::basic_streambuf< _CharT, _Traits
       >::_M_out_end [protected],  [inherited]
       End of put area.

       Definition at line 196 of file streambuf.

   template<typename _CharT, typename _Traits> char_type std::basic_filebuf< _CharT, _Traits
       >::_M_pback [protected],  [inherited]
       Necessary bits for putback buffer management.

       Note:
           pbacks of over one character are not currently supported.

       Definition at line 164 of file fstream.

   template<typename _CharT, typename _Traits> char_type* std::basic_filebuf< _CharT, _Traits
       >::_M_pback_cur_save [protected],  [inherited]
       Necessary bits for putback buffer management.

       Note:
           pbacks of over one character are not currently supported.

       Definition at line 165 of file fstream.

   template<typename _CharT, typename _Traits> char_type* std::basic_filebuf< _CharT, _Traits
       >::_M_pback_end_save [protected],  [inherited]
       Necessary bits for putback buffer management.

       Note:
           pbacks of over one character are not currently supported.

       Definition at line 166 of file fstream.

   template<typename _CharT, typename _Traits> bool std::basic_filebuf< _CharT, _Traits
       >::_M_pback_init [protected],  [inherited]
       Necessary bits for putback buffer management.

       Note:
           pbacks of over one character are not currently supported.

       Definition at line 167 of file fstream.

       Referenced by std::basic_filebuf< char_type, traits_type >::close().

   template<typename _CharT, typename _Traits> bool std::basic_filebuf< _CharT, _Traits
       >::_M_reading [protected],  [inherited]
       _M_reading == false && _M_writing == false for uncommitted mode; _M_reading == true for
       read mode; _M_writing == true for write mode;

       NB: _M_reading == true && _M_writing == true is unused.

       Definition at line 155 of file fstream.

       Referenced by std::basic_filebuf< char_type, traits_type >::close().

Author

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