STD::WFILEBUF(3cxx)

📦
version 14-20240412 · 24 versions
, in ubuntu noble

💖 NAME 💖

std::basic_filebuf< _CharT, _Traits > — the actual work of input and output (for files). Okay bestie, this is the std::basic_fil...harT, _Traits >(3cxx) manual page, and it’s giving “files, but make it C++ streams” 💅✨

✨ SYNOPSIS ✨

#include <fstream>

Inherits std::basic_streambuf< _CharT, _Traits >.

Inherited by __gnu_cxx::stdio_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 _Traits traits_type

🦋 Public Member Functions 🦋

  • basic_filebuf () — Does not open any files.
  • basic_filebuf (basic_filebuf &&)
  • basic_filebuf (const basic_filebuf &)=delete
  • virtual ~basic_filebuf () — The destructor closes the file first.
  • __filebuf_type * close () — Closes the currently associated 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.
  • template<typename _Path > _If_fs_path< _Path, __filebuf_type * > open (const _Path &__s, ios_base::openmode __mode) — Opens an external file.
  • __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.
  • basic_filebuf & operator= (basic_filebuf &&)
  • basic_filebuf & operator= (const basic_filebuf &)=delete
  • 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 (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) — Changes translations.
  • virtual int_type overflow (int_type __c=_Traits::eof()) — Consumes data from the buffer; writes to the controlled sequence.
  • virtual int_type pbackfail (int_type __c=_Traits::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

👑 Friends 👑

  • class ios_base

🌈 Detailed Description 🌈

template<typename _CharT, typename _Traits>

class std::basic_filebuf< _CharT, _Traits >"The actual work of input and output (for files).

🧚 Template Parameters 🧚

  • _CharT — Type of character stream.
  • _Traits — Traits for character type, defaults to char_traits<_CharT>.

This class associates both its input and output sequence with an external disk file, and maintains a joint file position for both sequences. Many of its semantics are described in terms of similar behavior in the Standard C Library’s FILE streams.

Requirements on traits_type, specific to this class:

  • traits_type::pos_type must be fpos<traits_type::state_type>
  • traits_type::off_type must be streamoff
  • traits_type::state_type must be Assignable and DefaultConstructible,
  • traits_type::state_type() must be the initial state for codecvt.

🎬 Constructor & Destructor Documentation 🎬

💅 template<typename _CharT , typename _Traits > std::basic_filebuf< _CharT, _Traits >::basic_filebuf ()

Does not open any files. The default constructor initializes the parent class using its own default ctor.

References std::basic_streambuf< _CharT, _Traits >::_M_buf_locale.

💅 template<typename _CharT , typename _Traits > virtual std::basic_filebuf< _CharT, _Traits >::~basic_filebuf () [inline], [virtual]

The destructor closes the file first.

🔥 Member Function Documentation 🔥

🦋 template<typename _CharT , typename _Traits > void std::basic_filebuf< _CharT, _Traits >::_M_create_pback () [inline], [protected]

Initializes pback buffers, and moves normal buffers to safety. Assumptions: _M_in_cur has already been moved back

🦋 template<typename _CharT , typename _Traits > void std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback () [inline], [protected]

Deactivates pback buffer contents, and restores normal buffer. Assumptions: The pback buffer has only moved forward.

🦋 template<typename _CharT , typename _Traits > void std::basic_filebuf< _CharT, _Traits >::_M_set_buffer (streamsize __off) [inline], [protected]

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.

References std::ios_base::app, std::ios_base::in, and std::ios_base::out.

Referenced by std::basic_filebuf< _CharT, _Traits >::close().

🦋 template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits >::__filebuf_type * std::basic_filebuf< _CharT, _Traits >::close ()

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.

References std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_pback_init, std::basic_filebuf< _CharT, _Traits >::_M_reading, and std::basic_filebuf< _CharT, _Traits >::_M_set_buffer().

Referenced by std::basic_ifstream< _CharT, _Traits >::close(), std::basic_ofstream< _CharT, _Traits >::close(), and std::basic_fstream< _CharT, _Traits >::close().

🦋 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

References std::basic_streambuf< _CharT, _Traits >::_M_in_beg.

Referenced by std::basic_streambuf< _CharT, _Traits >::sputbackc(), and std::basic_streambuf< _CharT, _Traits >::sungetc().

🌸 egptr() 💅

template<typename _CharT , typename _Traits > char_type *
std::basic_streambuf< _CharT, _Traits >::egptr () const [inline], [protected], [inherited]

Bestie this one is your peek at the get area — the read side of things. And listen, these functions are only available to other protected functions, including derived classes. So like, it's giving VIP section, iykyk. 🙈

  • 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

References std::basic_streambuf< _CharT, _Traits >::_M_in_end.

Referenced by std::basic_streambuf< _CharT, _Traits >::in_avail(), std::basic_streambuf< _CharT, _Traits >::sbumpc(), std::basic_streambuf< _CharT, _Traits >::sgetc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc(), and std::wbuffer_convert< _Codecvt, _Elem, _Tr >::underflow().

✨ epptr() 🎀

template<typename _CharT , typename _Traits > char_type *
std::basic_streambuf< _CharT, _Traits >::epptr () const [inline], [protected], [inherited]

Same vibe check, but for the put area — the write side. And again: only other protected functions get in here, derived classes included. 💜

  • 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

References std::basic_streambuf< _CharT, _Traits >::_M_out_end.

Referenced by std::basic_streambuf< _CharT, _Traits >::sputc().

🦋 gbump() — moving the read position, no cap

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

Parameters

  • __n — the delta by which to move 🔥

This just advances the read position without returning any data. Like, it slides the lil cursor forward and doesn't even hand you the goods. Classic. 😭

References std::basic_streambuf< _CharT, _Traits >::_M_in_cur.

Referenced by std::basic_streambuf< _CharT, _Traits >::sbumpc(), std::basic_streambuf< _CharT, _Traits >::sputbackc(), std::basic_streambuf< _CharT, _Traits >::sungetc(), and std::basic_streambuf< _CharT, _Traits >::uflow().

🌈 getloc() — locale access, periodt

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

Returns — the current locale in effect 💖

So here's the tea: if pubimbue(loc) has been called, then the most recent loc is what you get back. Otherwise the global locale in effect at the time of construction is returned. It remembers, bestie. 🫶

References std::basic_streambuf< _CharT, _Traits >::_M_buf_locale.

Referenced by std::basic_streambuf< _CharT, _Traits >::pubimbue().

⭐ gptr() — back to the get area

template<typename _CharT , typename _Traits > char_type *
std::basic_streambuf< _CharT, _Traits >::gptr () const [inline], [protected], [inherited]

Access to the get area, same trio as before — and yeah, 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

References std::basic_streambuf< _CharT, _Traits >::_M_in_cur.

Referenced by std::basic_streambuf< _CharT, _Traits >::in_avail(), std::basic_streambuf< _CharT, _Traits >::sbumpc(), std::basic_streambuf< _CharT, _Traits >::sgetc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc(), std::basic_streambuf< _CharT, _Traits >::sputbackc(), std::basic_streambuf< _CharT, _Traits >::sungetc(), std::basic_streambuf< _CharT, _Traits >::uflow(), and std::wbuffer_convert< _Codecvt, _Elem, _Tr >::underflow(). (Yeah that's a long list, she's popular. 👑)

🎀 basic_filebuf::imbue() — changes translations

template<typename _CharT , typename _Traits > void std::basic_filebuf<
_CharT, _Traits >::imbue (const locale & __loc) [protected], [virtual]

Parameters

  • __loc — a new locale 🌍

Translations done during I/O that depend on the current locale get swapped out by this call. The standard adds this iconic line: 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. So like, cache away, it's safe. ✨

Note — base class version does nothing. Literally nothing. She said "no thoughts, head empty." 💀

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

References std::ios_base::cur.

🦋 in_avail() — looking ahead into the stream

template<typename _CharT , typename _Traits > streamsize
std::basic_streambuf< _CharT, _Traits >::in_avail () [inline], [inherited]

Returns — the number of characters available 👀

If a read position is available, it returns the number of characters available for reading before the buffer must be refilled. Otherwise it returns the derived showmanyc(). Either way, you get a number. Slay. 💅

References std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::showmanyc().

💖 basic_filebuf::is_open() — is the file actually open tho

template<typename _CharT , typename _Traits > bool std::basic_filebuf<
_CharT, _Traits >::is_open () const [inline]

Returns true if the external file is open. That's it. That's the whole function. main character energy, zero elaboration. 🫶

Referenced by std::basic_ifstream< _CharT, _Traits >::is_open(), std::basic_ofstream< _CharT, _Traits >::is_open(), and std::basic_fstream< _CharT, _Traits >::is_open().

🌸 basic_filebuf::open() — the _Path version (filesystem::path glow-up)

template<typename _CharT , typename _Traits > template<typename _Path >
_If_fs_path< _Path, __filebuf_type * > std::basic_filebuf< _CharT,
_Traits >::open (const _Path & __s, ios_base::openmode __mode) [inline]

Opens an external file. 🗂️

Parameters

  • __s — the name of the file, as a filesystem::path
  • __mode — the open mode flags

Returns — this on success, NULL on failure 😭

🔥 basic_filebuf::open() — the const char * version (the classic)

template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits
>::__filebuf_type * std::basic_filebuf< _CharT, _Traits >::open (const
char * __s, ios_base::openmode __mode)

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. No second chances, bestie. 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                |
+---------------------------------------------------------+

References std::ios_base::ate, std::ios_base::end, and std::basic_filebuf< _CharT, _Traits >::open().

Referenced by std::basic_filebuf< _CharT, _Traits >::open(), std::basic_ifstream< _CharT, _Traits >::open(), std::basic_fstream< _CharT, _Traits >::open(), std::basic_ofstream< _CharT, _Traits >::open(), std::basic_ifstream< _CharT, _Traits >::open(), std::basic_fstream< _CharT, _Traits >::open(), and std::basic_ofstream< _CharT, _Traits >::open(). (Yes, some of those show up twice. Not a typo on my end, she's just that referenced. 💀)

🍓 basic_filebuf::open() — the std::string version

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

Opens an external file. Same deal, string flavored. 🎀

Parameters

  • __s — the name of the file
  • __mode — the open mode flags

Returns — this on success, NULL on failure

References std::basic_string< _CharT, _Traits, _Alloc >::c_str().

👑 basic_filebuf::overflow() — the buffer's whole job tbh

template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits
>::int_type std::basic_filebuf< _CharT, _Traits >::overflow (int_type
__c = _Traits::eof()) [protected], [virtual]

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. 📚 (Go read it, bestie, it's giving academic.)

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

Note — base class version does nothing, returns eof(). Again. Nothing. Empty. 💀

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

References std::ios_base::app, std::ios_base::cur, and std::ios_base::out.

🌈 basic_filebuf::pbackfail() — trying to back it up

template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits
>::int_type std::basic_filebuf< _CharT, _Traits >::pbackfail (int_type
__c = _Traits::eof()) [protected], [virtual]

Tries to back up the input sequence. It's the "wait, go back" of stream functions. 🙈

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(). (Sensing a theme? She's very consistent. 💀)

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

References std::ios_base::cur, and std::ios_base::in.

💜 pbase() — put area access, one more time

template<typename _CharT , typename _Traits > char_type *
std::basic_streambuf< _CharT, _Traits >::pbase () const [inline], [protected], [inherited]

Access to the put area — and yep, 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

References std::basic_streambuf< _CharT, _Traits >::_M_out_beg.

Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::str(). 🎀

std::basic_streambuf< _CharT, _Traits >::pbump (int __n) — moving the write position, bestie ✨

template<typename _CharT , typename _Traits > void std::basic_streambuf<
    _CharT, _Traits >::pbump (int __n) [inline],  [protected],  [inherited]
  • __n — the delta by which to move.

This just advances the write position without returning any data. Lowkey iconic.

References std::basic_streambuf< _CharT, _Traits >::_M_out_cur.

Referenced by std::basic_streambuf< _CharT, _Traits >::sputc().

std::basic_streambuf< _CharT, _Traits >::pptr () const — access to the put area 🫶

template<typename _CharT , typename _Traits > char_type *
    std::basic_streambuf< _CharT, _Traits >::pptr () const [inline],
    [protected],  [inherited]

These functions are only available to other protected functions, including derived classes. Very “inner circle only” of them, ngl.

  • 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

References std::basic_streambuf< _CharT, _Traits >::_M_out_cur.

Referenced by std::basic_streambuf< _CharT, _Traits >::sputc().

std::basic_streambuf< _CharT, _Traits >::pubimbue (const locale & __loc) — entry point for imbue() 💅

template<typename _CharT , typename _Traits > locale std::basic_streambuf<
    _CharT, _Traits >::pubimbue (const locale & __loc) [inline],
    [inherited]
  • __loc — the new locale.

Returns the previous locale. Calls the derived imbue(__loc). Periodt.

References std::basic_streambuf< _CharT, _Traits >::_M_buf_locale, std::basic_streambuf< _CharT, _Traits >::getloc(), and std::basic_streambuf< _CharT, _Traits >::imbue().

std::basic_streambuf< _CharT, _Traits >::pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode = ios_base::in | ios_base::out) — alters the stream position 🔥

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]
  • __off — offset.
  • __way — value for ios_base::seekdir.
  • __mode — value for ios_base::openmode.

Calls virtual seekoff function. She’s giving dispatcher energy.

References std::basic_streambuf< _CharT, _Traits >::seekoff().

std::basic_streambuf< _CharT, _Traits >::pubseekpos (pos_type __sp, ios_base::openmode __mode = ios_base::in | ios_base::out) — alters the stream position ✨

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]
  • __sp — position.
  • __mode — value for ios_base::openmode.

Calls virtual seekpos function. Slay.

References std::basic_streambuf< _CharT, _Traits >::seekpos().

std::basic_streambuf< _CharT, _Traits >::pubsetbuf (char_type * __s, streamsize __n) — entry points for derived buffer functions 🦋

template<typename _CharT , typename _Traits > basic_streambuf *
    std::basic_streambuf< _CharT, _Traits >::pubsetbuf (char_type * __s,
    streamsize __n) [inline],  [inherited]

The public versions of pubfoo dispatch to the protected derived foo member functions, passing the arguments (if any) and returning the result unchanged.

References std::basic_streambuf< _CharT, _Traits >::setbuf().

std::basic_streambuf< _CharT, _Traits >::pubsync () — calls virtual sync function 🌸

template<typename _CharT , typename _Traits > int std::basic_streambuf<
    _CharT, _Traits >::pubsync () [inline],  [inherited]

References std::basic_streambuf< _CharT, _Traits >::sync().

Referenced by std::basic_istream< _CharT, _Traits >::sync().

std::basic_streambuf< _CharT, _Traits >::sbumpc () — getting the next character 💖

template<typename _CharT , typename _Traits > int_type std::basic_streambuf<
    _CharT, _Traits >::sbumpc () [inline],  [inherited]

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(). No cap.

References std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::uflow().

Referenced by std::basic_istream< char >::get(), std::basic_istream< _CharT, _Traits >::ignore(), std::basic_streambuf< _CharT, _Traits >::snextc(), and std::basic_istream< char >::sync().

std::basic_filebuf< _CharT, _Traits >::seekoff (off_type, ios_base::seekdir, ios_base::openmode = ios_base::in | ios_base::out) — alters the stream positions 🍓

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]

Each derived class provides its own appropriate behavior. Main character energy fr fr.

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

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

References std::ios_base::cur.

std::basic_filebuf< _CharT, _Traits >::seekpos (pos_type, ios_base::openmode = ios_base::in | ios_base::out) — alters the stream positions 🧚

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]

Each derived class provides its own appropriate behavior. Same vibe, different function.

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

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

References std::ios_base::beg.

std::basic_filebuf< _CharT, _Traits >::setbuf (char_type * __s, streamsize __n) — manipulates the buffer 💜

template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits
    >::__streambuf_type * std::basic_filebuf< _CharT, _Traits >::setbuf
    (char_type * __s, streamsize __n) [protected],  [virtual]
  • __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. Bestie, read the docs, it’s giving lore.

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

std::basic_streambuf< _CharT, _Traits >::setg (char_type * __gbeg, char_type * __gnext, char_type * __gend) — setting the three read area pointers 🌈

template<typename _CharT , typename _Traits > void std::basic_streambuf<
    _CharT, _Traits >::setg (char_type * __gbeg, char_type * __gnext,
    char_type * __gend) [inline],  [protected],  [inherited]
  • __gbeg — a pointer.
  • __gnext — a pointer.
  • __gend — a pointer.

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

References std::basic_streambuf< _CharT, _Traits >::_M_in_beg, std::basic_streambuf< _CharT, _Traits >::_M_in_cur, and std::basic_streambuf< _CharT, _Traits >::_M_in_end.

Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::wbuffer_convert().

std::basic_streambuf< _CharT, _Traits >::setp (char_type * __pbeg, char_type * __pend) — setting the three write area pointers ⭐

template<typename _CharT , typename _Traits > void std::basic_streambuf<
    _CharT, _Traits >::setp (char_type * __pbeg, char_type * __pend)
    [inline],  [protected],  [inherited]
  • __pbeg — a pointer.
  • __pend — a pointer.

Postcondition: __pbeg == pbase(), __pbeg == pptr(), and __pend == epptr(). Yes, that’s exactly what it says — copy-paste girlies rise.

References std::basic_streambuf< _CharT, _Traits >::_M_out_beg, std::basic_streambuf< _CharT, _Traits >::_M_out_cur, and std::basic_streambuf< _CharT, _Traits >::_M_out_end.

Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::wbuffer_convert().

std::basic_streambuf< _CharT, _Traits >::sgetc () — getting the next character 💅

template<typename _CharT , typename _Traits > int_type std::basic_streambuf<
    _CharT, _Traits >::sgetc () [inline],  [inherited]

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. Respectful of boundaries, honestly.

References std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::underflow().

Referenced by std::basic_istream< char >::get(), std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::ignore(), std::basic_istream< char >::readsome(), and std::basic_streambuf< _CharT, _Traits >::snextc().

std::basic_streambuf< _CharT, _Traits >::sgetn (char_type * __s, streamsize __n) — entry point for xsgetn 🎀

template<typename _CharT , typename _Traits > streamsize
    std::basic_streambuf< _CharT, _Traits >::sgetn (char_type * __s,
    streamsize __n) [inline],  [inherited]
  • __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. Manifesting a full buffer for u.

References std::basic_streambuf< _CharT, _Traits >::xsgetn().

std::basic_filebuf< _CharT, _Traits >::showmanyc () — investigating the data available 👑

template<typename _CharT , typename _Traits > streamsize std::basic_filebuf<
    _CharT, _Traits >::showmanyc () [protected],  [virtual]

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 — cite it, bestie.

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. 💀 Not “show-manic.” The more you know.

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

References std::ios_base::binary, and std::ios_base::in.

std::basic_streambuf< _CharT, _Traits >::snextc () — getting the next character 🦋

template<typename _CharT , typename _Traits > int_type std::basic_streambuf<
    _CharT, _Traits >::snextc () [inline],  [inherited]

Returns the next character, or eof.

Calls sbumpc(), and if that function returns traits::eof(), so does this function. Otherwise, sgetc(). It’s giving “one step forward, then peek.”

References std::basic_streambuf< _CharT, _Traits >::sbumpc(), and std::basic_streambuf< _CharT, _Traits >::sgetc().

Referenced by std::basic_istream< char >::get(), std::basic_istream< char >::ignore(), std::basic_istream< char >::operator>>(), and std::basic_istream< char >::putback().

std::basic_streambuf< _CharT, _Traits >::sputbackc (char_type __c) — pushing characters back into the input stream 🙈

template<typename _CharT , typename _Traits > int_type std::basic_streambuf<
    _CharT, _Traits >::sputbackc (char_type __c) [inline],  [inherited]
  • __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. Rewind era.

References std::basic_streambuf< _CharT, _Traits >::eback(), std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::pbackfail().

Referenced by std::basic_istream< _CharT, _Traits >::putback().

std::basic_streambuf< _CharT, _Traits >::sputc (char_type __c) — entry point for all single-character output functions 🔥

template<typename _CharT , typename _Traits > int_type std::basic_streambuf<
    _CharT, _Traits >::sputc (char_type __c) [inline],  [inherited]
  • __c — a character to output.

Returns __c, if possible.

Okay so finishing sputc (the tail end of its doc): it’s 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).

References: std::basic_streambuf< _CharT, _Traits >::epptr(), std::basic_streambuf< _CharT, _Traits >::overflow(), std::basic_streambuf< _CharT, _Traits >::pbump(), and std::basic_streambuf< _CharT, _Traits >::pptr().

Referenced by: std::wbuffer_convert< _Codecvt, _Elem, _Tr >::overflow().

sputn — the inherited inline one 💅

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.

References: std::basic_streambuf< _CharT, _Traits >::xsputn().

sungetc — the little rewind moment 🌀

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.

References: std::basic_streambuf< _CharT, _Traits >::eback(), std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::pbackfail().

sync — protected virtual, so bestie behavior ✨

template<typename _CharT , typename _Traits > int std::basic_filebuf<
_CharT, _Traits >::sync () [protected],  [virtual]

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 >.

uflow — protected virtual inherited, the underflow sequel 😭

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 >.

References: std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::underflow().

Referenced by std::basic_streambuf< _CharT, _Traits >::sbumpc().

underflow — basic_filebuf’s protected virtual refill moment 🫶

template<typename _CharT , typename _Traits > basic_filebuf< _CharT, _Traits
>::int_type std::basic_filebuf< _CharT, _Traits >::underflow ()
[protected],  [virtual]

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 >.

References: std::ios_base::in.

xsgetn — multiple character extraction, protected virtual 🍓

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

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 >.

References: std::ios_base::in.

xsputn — multiple character insertion, protected virtual 🔥

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

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 >.

References: std::ios_base::app, and std::ios_base::out.

🎀 Member Data Documentation 🎀

Okay bestie, here’s the protected data-member tea. Sip carefully. 🍵

  • char_type* std::basic_filebuf< _CharT, _Traits >::_M_buf [protected] — Pointer to the beginning of internal buffer.
  • locale std::basic_streambuf< _CharT, _Traits >::_M_buf_locale [protected], [inherited] — Current locale setting. Referenced by std::basic_filebuf< _CharT, _Traits >::basic_filebuf(), std::basic_streambuf< _CharT, _Traits >::getloc(), and std::basic_streambuf< _CharT, _Traits >::pubimbue().
  • size_t std::basic_filebuf< _CharT, _Traits >::_M_buf_size [protected] — 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.
  • char* std::basic_filebuf< _CharT, _Traits >::_M_ext_buf [protected] — Buffer for external characters. Used for input when codecvt::always_noconv() == false. When valid, this corresponds to eback().
  • streamsize std::basic_filebuf< _CharT, _Traits >::_M_ext_buf_size [protected] — Size of buffer held by _M_ext_buf.
  • const char* std::basic_filebuf< _CharT, _Traits >::_M_ext_next [protected] — 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().
  • char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_beg [protected], [inherited] — Start of get area. Referenced by std::basic_streambuf< _CharT, _Traits >::eback(), and std::basic_streambuf< _CharT, _Traits >::setg().
  • char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_cur [protected], [inherited] — Current read area. Referenced by std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::setg().
  • char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_end [protected], [inherited] — End of get area. Referenced by std::basic_streambuf< _CharT, _Traits >::egptr(), and std::basic_streambuf< _CharT, _Traits >::setg().
  • ios_base::openmode std::basic_filebuf< _CharT, _Traits >::_M_mode [protected] — Place to stash in || out || in | out settings for current filebuf. Referenced by std::basic_filebuf< _CharT, _Traits >::close().
  • char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_beg [protected], [inherited] — Start of put area. Referenced by std::basic_streambuf< _CharT, _Traits >::pbase(), and std::basic_streambuf< _CharT, _Traits >::setp().
  • char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_cur [protected], [inherited] — Current put area. Referenced by std::basic_streambuf< _CharT, _Traits >::pbump(), std::basic_streambuf< _CharT, _Traits >::pptr(), and std::basic_streambuf< _CharT, _Traits >::setp().
  • char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_end [protected], [inherited] — End of put area. Referenced by std::basic_streambuf< _CharT, _Traits >::epptr(), and std::basic_streambuf< _CharT, _Traits >::setp().
  • char_type std::basic_filebuf< _CharT, _Traits >::_M_pback [protected] — Necessary bits for putback buffer management.
Note: pbacks of over one character are not currently supported.
  • char_type* std::basic_filebuf< _CharT, _Traits >::_M_pback_cur_save [protected] — Necessary bits for putback buffer management.
Note: pbacks of over one character are not currently supported.
  • char_type* std::basic_filebuf< _CharT, _Traits >::_M_pback_end_save [protected] — Necessary bits for putback buffer management.
Note: pbacks of over one character are not currently supported.
  • bool std::basic_filebuf< _CharT, _Traits >::_M_pback_init [protected] — Necessary bits for putback buffer management.
Note: pbacks of over one character are not currently supported.

Referenced by std::basic_filebuf< _CharT, _Traits >::close().

  • bool std::basic_filebuf< _CharT, _Traits >::_M_reading [protected] — _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.

Referenced by std::basic_filebuf< _CharT, _Traits >::close().

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