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__gnu_cxx::stdio_filebuf< _CharT, _Traits > Class Template Reference
[I/O]

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>. More...

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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 49 of file stdio_filebuf.h.


Member Typedef Documentation

template<typename _CharT, typename _Traits>
typedef basic_streambuf<char_type, traits_type> std::basic_filebuf< _CharT, _Traits >::__streambuf_type [inherited]

This is a non-standard type.

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

Definition at line 77 of file fstream.

template<typename _CharT , typename _Traits = std::char_traits<_CharT>>
typedef _CharT __gnu_cxx::stdio_filebuf< _CharT, _Traits >::char_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

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

Definition at line 53 of file stdio_filebuf.h.

template<typename _CharT , typename _Traits = std::char_traits<_CharT>>
typedef traits_type::int_type __gnu_cxx::stdio_filebuf< _CharT, _Traits >::int_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

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

Definition at line 55 of file stdio_filebuf.h.

template<typename _CharT , typename _Traits = std::char_traits<_CharT>>
typedef traits_type::off_type __gnu_cxx::stdio_filebuf< _CharT, _Traits >::off_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

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

Definition at line 57 of file stdio_filebuf.h.

template<typename _CharT , typename _Traits = std::char_traits<_CharT>>
typedef traits_type::pos_type __gnu_cxx::stdio_filebuf< _CharT, _Traits >::pos_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

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

Definition at line 56 of file stdio_filebuf.h.

template<typename _CharT , typename _Traits = std::char_traits<_CharT>>
typedef _Traits __gnu_cxx::stdio_filebuf< _CharT, _Traits >::traits_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

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

Definition at line 54 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 64 of file stdio_filebuf.h.

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 126 of file stdio_filebuf.h.

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

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 142 of file stdio_filebuf.h.

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

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 121 of file stdio_filebuf.h.


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 172 of file fstream.

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

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

Definition at line 189 of file fstream.

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

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 387 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue(), std::basic_filebuf< _CharT, _Traits >::open(), __gnu_cxx::stdio_filebuf< _CharT, _Traits >::stdio_filebuf(), and std::basic_filebuf< _CharT, _Traits >::underflow().

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 128 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::is_open().

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

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 460 of file streambuf.

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue(), and std::basic_filebuf< _CharT, _Traits >::underflow().

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 466 of file streambuf.

Referenced by std::basic_filebuf< _CharT, _Traits >::showmanyc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::underflow(), and std::basic_filebuf< _CharT, _Traits >::underflow().

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 513 of file streambuf.

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

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 107 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 117 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 476 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 222 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 463 of file streambuf.

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue(), std::basic_filebuf< _CharT, _Traits >::showmanyc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::underflow(), and std::basic_filebuf< _CharT, _Traits >::underflow().

template<typename _CharT , typename _Traits >
void std::basic_filebuf< _CharT, _Traits >::imbue ( const locale  )  [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.

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

Definition at line 855 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_ext_buf, std::basic_filebuf< _CharT, _Traits >::_M_ext_next, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::ios_base::cur, std::basic_streambuf< _CharT, _Traits >::eback(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_filebuf< _CharT, _Traits >::is_open().

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 262 of file streambuf.

template<typename _CharT, typename _Traits>
bool std::basic_filebuf< _CharT, _Traits >::is_open (  )  const throw () [inline, inherited]
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 94 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::ios_base::ate, std::basic_filebuf< _CharT, _Traits >::close(), std::ios_base::end, and std::basic_filebuf< _CharT, _Traits >::is_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 275 of file fstream.

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

template<typename _CharT, typename _Traits>
virtual int_type std::basic_streambuf< _CharT, _Traits >::overflow ( int_type  = 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().

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

Definition at line 746 of file streambuf.

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

template<typename _CharT, typename _Traits>
virtual int_type std::basic_streambuf< _CharT, _Traits >::pbackfail ( int_type  = 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().

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

Definition at line 702 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 507 of file streambuf.

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

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 523 of file streambuf.

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

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 510 of file streambuf.

Referenced by std::basic_filebuf< _CharT, _Traits >::sync(), and std::basic_streambuf< _CharT, _Traits >::xsputn().

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 205 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]

Entry point for imbue().

Parameters:
loc The new locale.
Returns:
The previous locale.

Calls the derived imbue(loc).

Definition at line 239 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]

Entry point for imbue().

Parameters:
loc The new locale.
Returns:
The previous locale.

Calls the derived imbue(loc).

Definition at line 244 of file streambuf.

template<typename _CharT, typename _Traits>
__streambuf_type* 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 235 of file streambuf.

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

Entry point for imbue().

Parameters:
loc The new locale.
Returns:
The previous locale.

Calls the derived imbue(loc).

Definition at line 249 of file streambuf.

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

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 294 of file streambuf.

Referenced by std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), and std::istreambuf_iterator< _CharT, _Traits >::operator++().

template<typename _CharT, typename _Traits>
virtual pos_type std::basic_streambuf< _CharT, _Traits >::seekoff ( off_type  ,
ios_base::seekdir  ,
ios_base::openmode  = ios_base::in | ios_base::out 
) [inline, 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.

Definition at line 580 of file streambuf.

template<typename _CharT, typename _Traits>
virtual pos_type std::basic_streambuf< _CharT, _Traits >::seekpos ( pos_type  ,
ios_base::openmode  = ios_base::in | ios_base::out 
) [inline, 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.

Definition at line 592 of file streambuf.

template<typename _CharT, typename _Traits>
virtual basic_streambuf<char_type,_Traits>* std::basic_streambuf< _CharT, _Traits >::setbuf ( char_type ,
streamsize   
) [inline, protected, virtual, inherited]

Manipulates the buffer.

Each derived class provides its own appropriate behavior. See the next-to-last paragraph of http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html for more on this function.

Note:
Base class version does nothing, returns this.

Definition at line 569 of file streambuf.

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 http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html for more.

Definition at line 657 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_buf, std::basic_filebuf< _CharT, _Traits >::_M_buf_size, and std::basic_filebuf< _CharT, _Traits >::is_open().

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 487 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 533 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 316 of file streambuf.

Referenced by std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), and std::basic_istream< _CharT, _Traits >::sentry::sentry().

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 335 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 178 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_mode, std::ios_base::binary, std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gptr(), std::ios_base::in, and std::basic_filebuf< _CharT, _Traits >::is_open().

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 276 of file streambuf.

Referenced by std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), and std::basic_istream< _CharT, _Traits >::sentry::sentry().

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 350 of file streambuf.

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

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 402 of file streambuf.

Referenced by std::basic_istream< _CharT, _Traits >::get(), and 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 428 of file streambuf.

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

Tosses a character.

Advances the read pointer, ignoring the character that would have been read.

See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html

Definition at line 761 of file streambuf.

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 375 of file streambuf.

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

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 838 of file fstream.tcc.

References std::basic_streambuf< _CharT, _Traits >::pbase(), and std::basic_streambuf< _CharT, _Traits >::pptr().

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 678 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 http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25.html

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

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

Definition at line 204 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_buf_size, std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback(), std::basic_filebuf< _CharT, _Traits >::_M_ext_buf, std::basic_filebuf< _CharT, _Traits >::_M_ext_buf_size, std::basic_filebuf< _CharT, _Traits >::_M_ext_next, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::basic_streambuf< _CharT, _Traits >::eback(), std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gptr(), std::__codecvt_abstract_base< _InternT, _ExternT, _StateT >::in(), std::ios_base::in, and std::min().

template<typename _CharT , typename _Traits >
streamsize std::basic_streambuf< _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 in __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.

Definition at line 45 of file streambuf.tcc.

References std::min().

template<typename _CharT , typename _Traits >
streamsize std::basic_streambuf< _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 in __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.

Definition at line 79 of file streambuf.tcc.

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


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 109 of file fstream.

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

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

Current locale setting.

Definition at line 188 of file streambuf.

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

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 116 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::setbuf(), __gnu_cxx::stdio_filebuf< _CharT, _Traits >::stdio_filebuf(), and std::basic_filebuf< _CharT, _Traits >::underflow().

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 151 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue(), and std::basic_filebuf< _CharT, _Traits >::underflow().

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 156 of file fstream.

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

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 163 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue(), and std::basic_filebuf< _CharT, _Traits >::underflow().

template<typename _CharT, typename _Traits>
char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_beg [protected, inherited]

This is based on _IO_FILE, just reordered to be more consistent, and is intended to be the most minimal abstraction for an internal buffer.

  • get == input == read
  • put == output == write

Definition at line 180 of file streambuf.

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

Entry point for imbue().

Parameters:
loc The new locale.
Returns:
The previous locale.

Calls the derived imbue(loc).

Definition at line 181 of file streambuf.

template<typename _CharT, typename _Traits>
char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_end [protected, inherited]

Entry point for imbue().

Parameters:
loc The new locale.
Returns:
The previous locale.

Calls the derived imbue(loc).

Definition at line 182 of file streambuf.

template<typename _CharT, typename _Traits>
ios_base::openmode std::basic_filebuf< _CharT, _Traits >::_M_mode [protected, inherited]
template<typename _CharT, typename _Traits>
char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_beg [protected, inherited]

Entry point for imbue().

Parameters:
loc The new locale.
Returns:
The previous locale.

Calls the derived imbue(loc).

Definition at line 183 of file streambuf.

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

Entry point for imbue().

Parameters:
loc The new locale.
Returns:
The previous locale.

Calls the derived imbue(loc).

Definition at line 184 of file streambuf.

template<typename _CharT, typename _Traits>
char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_end [protected, inherited]

Entry point for imbue().

Parameters:
loc The new locale.
Returns:
The previous locale.

Calls the derived imbue(loc).

Definition at line 185 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 137 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 138 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 139 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 140 of file fstream.

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 128 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue(), std::basic_filebuf< _CharT, _Traits >::open(), __gnu_cxx::stdio_filebuf< _CharT, _Traits >::stdio_filebuf(), and std::basic_filebuf< _CharT, _Traits >::underflow().


The documentation for this class was generated from the following file: