Protected Member Functions |
void | _M_allocate_internal_buffer () |
bool | _M_convert_to_external (char_type *, streamsize) |
void | _M_create_pback () |
void | _M_destroy_internal_buffer () throw () |
void | _M_destroy_pback () throw () |
pos_type | _M_seek (off_type __off, ios_base::seekdir __way, __state_type __state) |
void | _M_set_buffer (streamsize __off) |
bool | _M_terminate_output () |
void | gbump (int __n) |
virtual void | imbue (const locale &__loc) |
virtual int_type | overflow (int_type __c=_Traits::eof()) |
virtual int_type | pbackfail (int_type __c=_Traits::eof()) |
void | pbump (int __n) |
virtual pos_type | seekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out) |
virtual pos_type | seekpos (pos_type __pos, ios_base::openmode __mode=ios_base::in|ios_base::out) |
virtual __streambuf_type * | setbuf (char_type *__s, streamsize __n) |
void | setg (char_type *__gbeg, char_type *__gnext, char_type *__gend) |
void | setp (char_type *__pbeg, char_type *__pend) |
virtual streamsize | showmanyc () |
virtual int | sync () |
virtual int_type | uflow () |
virtual int_type | underflow () |
virtual streamsize | xsgetn (char_type *__s, streamsize __n) |
virtual streamsize | xsputn (const char_type *__s, streamsize __n) |
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char_type * | eback () const |
char_type * | gptr () const |
char_type * | egptr () const |
|
char_type * | pbase () const |
char_type * | pptr () const |
char_type * | epptr () const |
template<typename _CharT, typename _Traits>
class std::basic_filebuf< _CharT, _Traits >
The actual work of input and output (for files).
This class associates both its input and output sequence with an external disk file, and maintains a joint file position for both sequences. Many of its semantics are described in terms of similar behavior in the Standard C Library's FILE
streams.
Definition at line 67 of file fstream.
template<typename _CharT, typename _Traits>
template<typename _CharT, typename _Traits>
template<typename _CharT, typename _Traits>
template<typename _CharT, typename _Traits>
template<typename _CharT, typename _Traits>
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 386 of file fstream.
template<typename _CharT , typename _Traits >
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.
template<typename _CharT , typename _Traits >
Changes translations.
- Parameters:
-
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::ios_base::cur.
template<typename _CharT , typename _Traits >
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::ios_base::ate, std::ios_base::end, and std::basic_filebuf< _CharT, _Traits >::open().
Referenced by std::basic_filebuf< _CharT, _Traits >::open().
template<typename _CharT , typename _Traits >
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 from std::basic_streambuf< _CharT, _Traits >.
Definition at line 408 of file fstream.tcc.
References std::ios_base::out.
template<typename _CharT, typename _Traits>
template<typename _CharT, typename _Traits>
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 315 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 >
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 @c 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::ios_base::binary, and std::ios_base::in.
template<typename _CharT, typename _Traits>
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 348 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::putback().
template<typename _CharT, typename _Traits>
template<typename _CharT, typename _Traits>
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 426 of file streambuf.
template<typename _CharT, typename _Traits>
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 373 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::unget().
template<typename _CharT , typename _Traits >
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.
template<typename _CharT, typename _Traits>
|
inlineprotectedvirtualinherited |
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 676 of file streambuf.
template<typename _CharT , typename _Traits >
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::ios_base::in, and std::min().
template<typename _CharT , typename _Traits >
Multiple character extraction.
- Parameters:
-
s | A buffer area. |
n | Maximum number of characters to assign. |
- Returns:
- The number of characters assigned.
Fills s[0] through s[n-1] with characters from the input sequence, as if by sbumpc()
. Stops when either n characters have been copied, or when traits::eof()
would be copied.
It is expected that derived classes provide a more efficient implementation by overriding this definition.
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 527 of file fstream.tcc.
References std::ios_base::in.
template<typename _CharT , typename _Traits >
Multiple character insertion.
- Parameters:
-
s | A buffer area. |
n | Maximum number of characters to write. |
- Returns:
- The number of characters written.
Writes s[0] through s[n-1] to the output sequence, as if by sputc()
. Stops when either n characters have been copied, or when sputc()
would return traits::eof()
.
It is expected that derived classes provide a more efficient implementation by overriding this definition.
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 610 of file fstream.tcc.
References std::min(), and std::ios_base::out.