libstdc++
|
The actual work of input and output (for std::string).
This class associates either or both of its input and output sequences with a sequence of characters, which can be initialized from, or made available as, a std::basic_string
. (Paraphrased from [27.7.1]/1.)
For this class, open modes (of type ios_base::openmode
) have in
set if the input sequence can be read, and out
set if the output sequence can be written.
typedef basic_streambuf<char_type, traits_type> std::basic_stringbuf< _CharT, _Traits, _Alloc >::__streambuf_type |
This is a non-standard type.
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
typedef _CharT std::basic_stringbuf< _CharT, _Traits, _Alloc >::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_streambuf< _CharT, _Traits >.
typedef traits_type::int_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::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_streambuf< _CharT, _Traits >.
typedef traits_type::off_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::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_streambuf< _CharT, _Traits >.
typedef traits_type::pos_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::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_streambuf< _CharT, _Traits >.
typedef _Traits std::basic_stringbuf< _CharT, _Traits, _Alloc >::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_streambuf< _CharT, _Traits >.
std::basic_stringbuf< _CharT, _Traits, _Alloc >::basic_stringbuf | ( | ios_base::openmode | __mode = ios_base::in | ios_base::out | ) | [inline, explicit] |
std::basic_stringbuf< _CharT, _Traits, _Alloc >::basic_stringbuf | ( | const __string_type & | __str, |
ios_base::openmode | __mode = ios_base::in | ios_base::out |
||
) | [inline, explicit] |
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.
Definition at line 480 of file streambuf.
Referenced by std::basic_filebuf< char_type, traits_type >::_M_destroy_pback(), std::basic_streambuf< char_type, traits_type >::sputbackc(), and std::basic_streambuf< char_type, traits_type >::sungetc().
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.
Definition at line 486 of file streambuf.
Referenced by std::basic_filebuf< char_type, traits_type >::_M_create_pback(), std::basic_streambuf< char_type, traits_type >::in_avail(), std::basic_streambuf< char_type, traits_type >::sbumpc(), std::basic_streambuf< char_type, traits_type >::sgetc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc(), and std::basic_stringbuf< _CharT, _Traits, _Alloc >::str().
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.
Definition at line 533 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::sputc().
void std::basic_streambuf< _CharT, _Traits >::gbump | ( | int | __n | ) | [inline, protected, inherited] |
Moving the read position.
__n | The delta by which to move. |
This just advances the read position without returning any data.
Definition at line 496 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::sbumpc(), std::basic_streambuf< char_type, traits_type >::sputbackc(), std::basic_streambuf< char_type, traits_type >::sungetc(), and std::basic_streambuf< char_type, traits_type >::uflow().
locale std::basic_streambuf< _CharT, _Traits >::getloc | ( | ) | const [inline, inherited] |
Locale access.
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 224 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::pubimbue().
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.
Definition at line 483 of file streambuf.
Referenced by std::basic_filebuf< char_type, traits_type >::_M_create_pback(), std::basic_filebuf< char_type, traits_type >::_M_destroy_pback(), std::basic_streambuf< char_type, traits_type >::in_avail(), std::basic_streambuf< char_type, traits_type >::sbumpc(), std::basic_streambuf< char_type, traits_type >::sgetc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc(), std::basic_streambuf< char_type, traits_type >::sputbackc(), std::basic_streambuf< char_type, traits_type >::sungetc(), and std::basic_streambuf< char_type, traits_type >::uflow().
virtual void std::basic_streambuf< _CharT, _Traits >::imbue | ( | const locale & | __loc | ) | [inline, protected, virtual, inherited] |
Changes translations.
__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.
Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.
Definition at line 574 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::pubimbue().
streamsize std::basic_streambuf< _CharT, _Traits >::in_avail | ( | ) | [inline, inherited] |
Looking ahead into the stream.
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()
.
basic_stringbuf< _CharT, _Traits, _Alloc >::int_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::overflow | ( | int_type | __c = traits_type::eof() | ) | [protected, virtual] |
Consumes data from the buffer; writes to the controlled sequence.
__c | An additional character to consume. |
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).
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 82 of file sstream.tcc.
References std::basic_string< _CharT, _Traits, _Alloc >::assign(), std::max(), std::min(), std::ios_base::out, std::basic_string< _CharT, _Traits, _Alloc >::push_back(), and std::basic_string< _CharT, _Traits, _Alloc >::reserve().
basic_stringbuf< _CharT, _Traits, _Alloc >::int_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::pbackfail | ( | int_type | __c = traits_type::eof() | ) | [protected, virtual] |
Tries to back up the input sequence.
__c | The character to be inserted back into the sequence. |
gptr()
, eback()
, and pptr()
are the same as for underflow()
.Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 48 of file sstream.tcc.
References std::ios_base::out.
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.
Definition at line 527 of file streambuf.
Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::str().
void std::basic_streambuf< _CharT, _Traits >::pbump | ( | int | __n | ) | [inline, protected, inherited] |
Moving the write position.
__n | The delta by which to move. |
This just advances the write position without returning any data.
Definition at line 543 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::sputc().
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.
Definition at line 530 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::sputc(), and std::basic_stringbuf< _CharT, _Traits, _Alloc >::str().
locale std::basic_streambuf< _CharT, _Traits >::pubimbue | ( | const locale & | __loc | ) | [inline, inherited] |
pos_type std::basic_streambuf< _CharT, _Traits >::pubseekoff | ( | off_type | __off, |
ios_base::seekdir | __way, | ||
ios_base::openmode | __mode = ios_base::in | ios_base::out |
||
) | [inline, inherited] |
Alters the stream position.
__off | Offset. |
__way | Value for ios_base::seekdir. |
__mode | Value for ios_base::openmode. |
Calls virtual seekoff function.
pos_type std::basic_streambuf< _CharT, _Traits >::pubseekpos | ( | pos_type | __sp, |
ios_base::openmode | __mode = ios_base::in | ios_base::out |
||
) | [inline, inherited] |
Alters the stream position.
__sp | Position |
__mode | Value for ios_base::openmode. |
Calls virtual seekpos function.
__streambuf_type* std::basic_streambuf< _CharT, _Traits >::pubsetbuf | ( | char_type * | __s, |
streamsize | __n | ||
) | [inline, inherited] |
int std::basic_streambuf< _CharT, _Traits >::pubsync | ( | ) | [inline, inherited] |
Calls virtual sync function.
Definition at line 269 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::sync().
int_type std::basic_streambuf< _CharT, _Traits >::sbumpc | ( | ) | [inline, inherited] |
Getting the next character.
If the input read position is available, returns that character and increments the read pointer, otherwise calls and returns uflow()
.
Definition at line 314 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), std::istreambuf_iterator< _CharT, _Traits >::operator++(), and std::basic_streambuf< char_type, traits_type >::snextc().
basic_stringbuf< _CharT, _Traits, _Alloc >::pos_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff | ( | off_type | , |
ios_base::seekdir | , | ||
ios_base::openmode | = ios_base::in | ios_base::out |
||
) | [protected, virtual] |
Alters the stream positions.
Each derived class provides its own appropriate behavior.
pos_type
that represents an invalid stream position. Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 151 of file sstream.tcc.
References std::ios_base::cur, std::ios_base::end, std::ios_base::in, and std::ios_base::out.
basic_stringbuf< _CharT, _Traits, _Alloc >::pos_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekpos | ( | pos_type | , |
ios_base::openmode | = ios_base::in | ios_base::out |
||
) | [protected, virtual] |
Alters the stream positions.
Each derived class provides its own appropriate behavior.
pos_type
that represents an invalid stream position. Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 199 of file sstream.tcc.
References std::ios_base::in, and std::ios_base::out.
virtual __streambuf_type* std::basic_stringbuf< _CharT, _Traits, _Alloc >::setbuf | ( | char_type * | __s, |
streamsize | __n | ||
) | [inline, protected, virtual] |
Manipulates the buffer.
__s | Pointer to a buffer area. |
__n | Size of __s. |
this
If no buffer has already been created, and both __s and __n are non-zero, then __s
is used as a buffer; see http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html for more.
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 198 of file sstream.
References std::basic_string< _CharT, _Traits, _Alloc >::clear().
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.
__gbeg | A pointer. |
__gnext | A pointer. |
__gend | A pointer. |
Definition at line 507 of file streambuf.
Referenced by std::basic_filebuf< char_type, traits_type >::_M_create_pback(), std::basic_filebuf< char_type, traits_type >::_M_destroy_pback(), and std::basic_filebuf< char_type, traits_type >::_M_set_buffer().
void std::basic_streambuf< _CharT, _Traits >::setp | ( | char_type * | __pbeg, |
char_type * | __pend | ||
) | [inline, protected, inherited] |
int_type std::basic_streambuf< _CharT, _Traits >::sgetc | ( | ) | [inline, inherited] |
Getting the next character.
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 336 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), std::basic_istream< _CharT, _Traits >::sentry::sentry(), and std::basic_streambuf< char_type, traits_type >::snextc().
streamsize std::basic_streambuf< _CharT, _Traits >::sgetn | ( | char_type * | __s, |
streamsize | __n | ||
) | [inline, inherited] |
virtual streamsize std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc | ( | ) | [inline, protected, virtual] |
Investigating the data available.
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
eof()
but that they will return immediately. showmanyc
are es-how-many-see, not show-manic. Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 166 of file sstream.
References std::basic_stringbuf< _CharT, _Traits, _Alloc >::_M_mode, std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::ios_base::in.
int_type std::basic_streambuf< _CharT, _Traits >::snextc | ( | ) | [inline, inherited] |
Getting the next character.
Calls sbumpc()
, and if that function returns traits::eof()
, so does this function. Otherwise, sgetc()
.
Definition at line 296 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().
int_type std::basic_streambuf< _CharT, _Traits >::sputbackc | ( | char_type | __c | ) | [inline, inherited] |
Pushing characters back into the input stream.
__c | The character to push back. |
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 370 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::putback().
int_type std::basic_streambuf< _CharT, _Traits >::sputc | ( | char_type | __c | ) | [inline, inherited] |
Entry point for all single-character output functions.
__c | A character to output. |
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 422 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::get(), and std::ostreambuf_iterator< _CharT, _Traits >::operator=().
streamsize std::basic_streambuf< _CharT, _Traits >::sputn | ( | const char_type * | __s, |
streamsize | __n | ||
) | [inline, inherited] |
__string_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::str | ( | ) | const [inline] |
Copying out the string buffer.
If the buffer is only created in input mode, the underlying character sequence is equal to the input sequence; otherwise, it is equal to the output sequence. [27.7.1.2]/1
Definition at line 122 of file sstream.
References std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::pbase(), and std::basic_streambuf< _CharT, _Traits >::pptr().
void std::basic_stringbuf< _CharT, _Traits, _Alloc >::str | ( | const __string_type & | __s | ) | [inline] |
Setting a new buffer.
__s | The string to use as a new sequence. |
Deallocates any previous stored sequence, then copies s to use as a new one.
Definition at line 146 of file sstream.
References std::basic_stringbuf< _CharT, _Traits, _Alloc >::_M_mode, std::basic_string< _CharT, _Traits, _Alloc >::assign(), std::basic_string< _CharT, _Traits, _Alloc >::data(), and std::basic_string< _CharT, _Traits, _Alloc >::size().
int_type std::basic_streambuf< _CharT, _Traits >::sungetc | ( | ) | [inline, inherited] |
Moving backwards in the input stream.
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 395 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::unget().
virtual int std::basic_streambuf< _CharT, _Traits >::sync | ( | void | ) | [inline, protected, virtual, inherited] |
Synchronizes the buffer arrays with the controlled sequences.
Each derived class provides its own appropriate behavior, including the definition of failure.
Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.
Definition at line 625 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::pubsync().
virtual int_type std::basic_streambuf< _CharT, _Traits >::uflow | ( | ) | [inline, protected, virtual, inherited] |
Fetches more data from the controlled 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 698 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::sbumpc().
basic_stringbuf< _CharT, _Traits, _Alloc >::int_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::underflow | ( | ) | [protected, virtual] |
Fetches more data from the controlled 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
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 133 of file sstream.tcc.
References std::ios_base::in.
streamsize std::basic_streambuf< _CharT, _Traits >::xsgetn | ( | char_type * | __s, |
streamsize | __n | ||
) | [protected, virtual, inherited] |
Multiple character extraction.
__s | A buffer area. |
__n | Maximum number of characters to assign. |
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 >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.
Definition at line 47 of file streambuf.tcc.
References std::min().
Referenced by std::basic_streambuf< char_type, traits_type >::sgetn().
streamsize std::basic_streambuf< _CharT, _Traits >::xsputn | ( | const char_type * | __s, |
streamsize | __n | ||
) | [protected, virtual, inherited] |
Multiple character insertion.
__s | A buffer area. |
__n | Maximum number of characters to write. |
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 >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.
Definition at line 81 of file streambuf.tcc.
References std::min().
Referenced by std::basic_streambuf< char_type, traits_type >::sputn().
locale std::basic_streambuf< _CharT, _Traits >::_M_buf_locale [protected, inherited] |
Current locale setting.
Definition at line 190 of file streambuf.
Referenced by std::basic_filebuf< _CharT, _Traits >::basic_filebuf(), std::basic_streambuf< char_type, traits_type >::getloc(), and std::basic_streambuf< char_type, traits_type >::pubimbue().
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.
Definition at line 182 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::eback(), and std::basic_streambuf< char_type, traits_type >::setg().
char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_cur [protected, inherited] |
Entry point for imbue().
__loc | The new locale. |
Calls the derived imbue(__loc).
Definition at line 183 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::gbump(), std::basic_streambuf< char_type, traits_type >::gptr(), and std::basic_streambuf< char_type, traits_type >::setg().
char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_end [protected, inherited] |
Entry point for imbue().
__loc | The new locale. |
Calls the derived imbue(__loc).
Definition at line 184 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::egptr(), and std::basic_streambuf< char_type, traits_type >::setg().
ios_base::openmode std::basic_stringbuf< _CharT, _Traits, _Alloc >::_M_mode [protected] |
Place to stash in || out || in | out settings for current stringbuf.
Definition at line 79 of file sstream.
Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc(), and std::basic_stringbuf< _CharT, _Traits, _Alloc >::str().
char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_beg [protected, inherited] |
Entry point for imbue().
__loc | The new locale. |
Calls the derived imbue(__loc).
Definition at line 185 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::pbase(), and std::basic_streambuf< char_type, traits_type >::setp().
char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_cur [protected, inherited] |
Entry point for imbue().
__loc | The new locale. |
Calls the derived imbue(__loc).
Definition at line 186 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::pbump(), std::basic_streambuf< char_type, traits_type >::pptr(), and std::basic_streambuf< char_type, traits_type >::setp().
char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_end [protected, inherited] |
Entry point for imbue().
__loc | The new locale. |
Calls the derived imbue(__loc).
Definition at line 187 of file streambuf.
Referenced by std::basic_streambuf< char_type, traits_type >::epptr(), and std::basic_streambuf< char_type, traits_type >::setp().