std::basic_streambuf< _CharT, _Traits > Class Template Reference

The actual work of input and output (interface). More...

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List of all members.

Public Types

typedef _CharT char_type
typedef _Traits traits_type
typedef traits_type::int_type int_type
typedef traits_type::pos_type pos_type
typedef traits_type::off_type off_type

Public Methods

virtual ~basic_streambuf ()
 Destructor deallocates no buffer space.

locale pubimbue (const locale &__loc)
 Entry point for imbue().

locale getloc () const
 Locale access.

streamsize in_avail ()
 Looking ahead into the stream.

int_type snextc ()
 Getting the next character.

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 sputbackc (char_type __c)
 Pushing characters back into the input stream.

int_type sungetc ()
 Moving backwards in 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.

void stossc ()
 Tosses a character.

__streambuf_type * 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)
 Entry points for derived buffer functions.

pos_type pubseekpos (pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out)
 Entry points for derived buffer functions.

int pubsync ()
 Entry points for derived buffer functions.


Protected Methods

 basic_streambuf ()
 Base constructor.

void gbump (int __n)
 Moving the read position.

void setg (char_type *__gbeg, char_type *__gnext, char_type *__gend)
 Setting the three read area pointers.

void pbump (int __n)
 Moving the write position.

void setp (char_type *__pbeg, char_type *__pend)
 Setting the three write area pointers.

virtual void imbue (const locale &__loc)
 Changes translations.

virtual basic_streambuf< char_type,
_Traits > * 
setbuf (char_type *, streamsize)
 Maniuplates the buffer.

virtual pos_type seekoff (off_type, ios_base::seekdir, ios_base::openmode=ios_base::in|ios_base::out)
 Alters the stream positions.

virtual pos_type seekpos (pos_type, ios_base::openmode=ios_base::in|ios_base::out)
 Alters the stream positions.

virtual int sync ()
 Synchronizes the buffer arrays with the controlled sequences.

virtual streamsize showmanyc ()
 Investigating the data available.

virtual streamsize xsgetn (char_type *__s, streamsize __n)
 Multiple character extraction.

virtual int_type underflow ()
 Fetches more data from the controlled sequence.

virtual int_type uflow ()
 Fetches more data from the controlled sequence.

virtual int_type pbackfail (int_type=traits_type::eof())
 Tries to back up the input sequence.

virtual streamsize xsputn (const char_type *__s, streamsize __n)
 Multiple character insertion.

virtual int_type overflow (int_type=traits_type::eof())
 Consumes data from the buffer; writes to the controlled sequence.

char_typeeback () const
 Access to the get area.

char_typegptr () const
 Access to the get area.

char_typeegptr () const
 Access to the get area.

char_typepbase () const
 Access to the put area.

char_typepptr () const
 Access to the put area.

char_typeepptr () const
 Access to the put area.


Detailed Description

template<typename _CharT, typename _Traits>
class std::basic_streambuf< _CharT, _Traits >

The actual work of input and output (interface).

This is a base class. Derived stream buffers each control a pair of character sequences: one for input, and one for output.

Section [27.5.1] of the standard describes the requirements and behavior of stream buffer classes. That section (three paragraphs) is reproduced here, for simplicity and accuracy.

  1. Stream buffers can impose various constraints on the sequences they control. Some constraints are:
  2. Each sequence is characterized by three pointers which, if non-null, all point into the same charT array object. The array object represents, at any moment, a (sub)sequence of characters from the sequence. Operations performed on a sequence alter the values stored in these pointers, perform reads and writes directly to or from associated sequences, and alter "the stream position" and conversion state as needed to maintain this subsequence relationship. The three pointers are:
  3. The following semantic constraints shall always apply for any set of three pointers for a sequence, using the pointer names given immediately above:

Definition at line 123 of file streambuf.


Member Typedef Documentation

template<typename _CharT, typename _Traits>
typedef _CharT std::basic_streambuf< _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 in __gnu_cxx::stdio_filebuf< _CharT, _Traits > , std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 132 of file streambuf.

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

template<typename _CharT, typename _Traits>
typedef traits_type::int_type std::basic_streambuf< _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 in __gnu_cxx::stdio_filebuf< _CharT, _Traits > , std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 134 of file streambuf.

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

template<typename _CharT, typename _Traits>
typedef traits_type::off_type std::basic_streambuf< _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 in __gnu_cxx::stdio_filebuf< _CharT, _Traits > , std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 136 of file streambuf.

Referenced by std::basic_streambuf< char, char_traits< char > >::pubseekoff() , and std::basic_streambuf< _CharT, _Traits >::xsputn() .

template<typename _CharT, typename _Traits>
typedef traits_type::pos_type std::basic_streambuf< _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 in __gnu_cxx::stdio_filebuf< _CharT, _Traits > , std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 135 of file streambuf.

Referenced by std::basic_streambuf< char, char_traits< char > >::pubseekoff() , and std::basic_streambuf< char, char_traits< char > >::pubseekpos() .

template<typename _CharT, typename _Traits>
typedef _Traits std::basic_streambuf< _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 in __gnu_cxx::stdio_filebuf< _CharT, _Traits > , std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 133 of file streambuf.


Constructor & Destructor Documentation

template<typename _CharT, typename _Traits>
virtual std::basic_streambuf< _CharT, _Traits >::~basic_streambuf   [inline, virtual]
 

Destructor deallocates no buffer space.

Definition at line 359 of file streambuf.

template<typename _CharT, typename _Traits>
std::basic_streambuf< _CharT, _Traits >::basic_streambuf   [inline, protected]
 

Base constructor.

Only called from derived constructors, and sets up all the buffer data to zero, including the pointers described in the basic_streambuf class description. Note that, as a result,

  • the class starts with no read nor write positions available,
  • this is not an error

Definition at line 580 of file streambuf.


Member Function Documentation

template<typename _CharT, typename _Traits>
char_type* std::basic_streambuf< _CharT, _Traits >::eback   const [inline, protected]
 

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 602 of file streambuf.

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

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

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 608 of file streambuf.

Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff() , and std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekpos() .

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

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 657 of file streambuf.

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

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

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 618 of file streambuf.

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

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 393 of file streambuf.

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

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 605 of file streambuf.

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue() , std::basic_streambuf< _CharT, _Traits >::sbumpc() , and std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff() .

template<typename _CharT, typename _Traits>
virtual void std::basic_streambuf< _CharT, _Traits >::imbue const locale &    __loc [inline, protected, virtual]
 

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." This function simply stores the new locale for use by derived classes.

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

Definition at line 699 of file streambuf.

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

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 438 of file streambuf.

template<typename _CharT, typename _Traits>
virtual int_type std::basic_streambuf< _CharT, _Traits >::overflow int_type    = traits_type::eof() [inline, 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 definiton 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 std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 896 of file streambuf.

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

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 std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 853 of file streambuf.

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

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

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 651 of file streambuf.

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

template<typename _CharT, typename _Traits>
void std::basic_streambuf< _CharT, _Traits >::pbump int    __n [inline, protected]
 

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 667 of file streambuf.

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

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 654 of file streambuf.

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

template<typename _CharT, typename _Traits>
locale std::basic_streambuf< _CharT, _Traits >::pubimbue const locale &    __loc [inline]
 

Entry point for imbue().

Parameters:
loc The new locale.
Returns:
The previous locale.
Calls the derived imbue(loc).

Definition at line 377 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]
 

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 415 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]
 

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 420 of file streambuf.

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

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 411 of file streambuf.

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

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 425 of file streambuf.

template<typename _CharT, typename _Traits>
basic_streambuf< _CharT, _Traits >::int_type std::basic_streambuf< _CharT, _Traits >::sbumpc  
 

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 49 of file streambuf.tcc.

References std::basic_streambuf< _CharT, _Traits >::char_type , std::basic_streambuf< _CharT, _Traits >::gptr() , std::basic_streambuf< _CharT, _Traits >::int_type , and std::basic_streambuf< _CharT, _Traits >::uflow() .

Referenced by std::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]
 

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 in std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 729 of file streambuf.

Referenced by std::basic_streambuf< char, char_traits< char > >::pubseekoff() .

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]
 

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 in std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 741 of file streambuf.

Referenced by std::basic_streambuf< char, char_traits< char > >::pubseekpos() .

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

Maniuplates the buffer.

Each derived class provides its own appropriate behavior. See the next-to-last paragraph of http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for more on this function.

Note:
Base class version does nothing, returns this.

Reimplemented in std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 718 of file streambuf.

template<typename _CharT, typename _Traits>
void std::basic_streambuf< _CharT, _Traits >::setg char_type   __gbeg,
char_type   __gnext,
char_type   __gend
[inline, protected]
 

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 629 of file streambuf.

template<typename _CharT, typename _Traits>
void std::basic_streambuf< _CharT, _Traits >::setp char_type   __pbeg,
char_type   __pend
[inline, protected]
 

Setting the three write area pointers.

Parameters:
pbeg A pointer.
pend A pointer.
Postcondition:
pbeg == pbase(), pbeg == pptr(), and pend == epptr()

Definition at line 677 of file streambuf.

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

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 492 of file streambuf.

template<typename _CharT, typename _Traits>
streamsize std::basic_streambuf< _CharT, _Traits >::sgetn char_type   __s,
streamsize    __n
[inline]
 

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 511 of file streambuf.

template<typename _CharT, typename _Traits>
virtual streamsize std::basic_streambuf< _CharT, _Traits >::showmanyc   [inline, protected, virtual]
 

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 in std::basic_filebuf< _CharT, _Traits > .

Definition at line 776 of file streambuf.

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

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 465 of file streambuf.

template<typename _CharT, typename _Traits>
basic_streambuf< _CharT, _Traits >::int_type std::basic_streambuf< _CharT, _Traits >::sputbackc char_type    __c
 

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 66 of file streambuf.tcc.

References std::basic_streambuf< _CharT, _Traits >::int_type , and std::basic_streambuf< _CharT, _Traits >::pbackfail() .

Referenced by std::operator>>() .

template<typename _CharT, typename _Traits>
basic_streambuf< _CharT, _Traits >::int_type std::basic_streambuf< _CharT, _Traits >::sputc char_type    __c
 

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 105 of file streambuf.tcc.

References std::basic_streambuf< _CharT, _Traits >::int_type , and std::basic_streambuf< _CharT, _Traits >::overflow() .

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

template<typename _CharT, typename _Traits>
streamsize std::basic_streambuf< _CharT, _Traits >::sputn const char_type   __s,
streamsize    __n
[inline]
 

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 567 of file streambuf.

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

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

Note:
This function has been deprecated by the standard. You must define _GLIBCPP_DEPRECATED to make this visible; see c++config.h.

Definition at line 915 of file streambuf.

template<typename _CharT, typename _Traits>
basic_streambuf< _CharT, _Traits >::int_type std::basic_streambuf< _CharT, _Traits >::sungetc  
 

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 84 of file streambuf.tcc.

References std::basic_streambuf< _CharT, _Traits >::int_type , and std::basic_streambuf< _CharT, _Traits >::pbackfail() .

template<typename _CharT, typename _Traits>
virtual int std::basic_streambuf< _CharT, _Traits >::sync void    [inline, 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 in std::basic_filebuf< _CharT, _Traits > .

Definition at line 754 of file streambuf.

Referenced by std::basic_streambuf< char, char_traits< char > >::pubsync() .

template<typename _CharT, typename _Traits>
virtual int_type std::basic_streambuf< _CharT, _Traits >::uflow   [inline, protected, virtual]
 

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 std::basic_filebuf< _CharT, _Traits > .

Definition at line 827 of file streambuf.

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

template<typename _CharT, typename _Traits>
virtual int_type std::basic_streambuf< _CharT, _Traits >::underflow   [inline, 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 definiton 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++/27_io/howto.html#6

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

Reimplemented in std::basic_filebuf< _CharT, _Traits > , and std::basic_stringbuf< _CharT, _Traits, _Alloc > .

Definition at line 814 of file streambuf.

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

Definition at line 122 of file streambuf.tcc.

References std::basic_streambuf< _CharT, _Traits >::int_type , std::min() , and std::basic_streambuf< _CharT, _Traits >::uflow() .

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

Definition at line 161 of file streambuf.tcc.

References std::basic_streambuf< _CharT, _Traits >::int_type , std::min() , std::basic_streambuf< _CharT, _Traits >::off_type , and std::basic_streambuf< _CharT, _Traits >::overflow() .


The documentation for this class was generated from the following files:
Generated on Thu Nov 21 03:13:24 2002 for libstdc++-v3 Source by doxygen1.2.18-20021030