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| basic_filebuf () |
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| basic_filebuf (basic_filebuf &&) |
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| basic_filebuf (const basic_filebuf &)=delete |
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virtual | ~basic_filebuf () |
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__filebuf_type * | close () |
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locale | getloc () const |
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streamsize | in_avail () |
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bool | is_open () const throw () |
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template<typename _Path > |
_If_fs_path< _Path, __filebuf_type * > | open (const _Path &__s, ios_base::openmode __mode) |
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__filebuf_type * | open (const char *__s, ios_base::openmode __mode) |
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__filebuf_type * | open (const std::string &__s, ios_base::openmode __mode) |
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basic_filebuf & | operator= (basic_filebuf &&) |
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basic_filebuf & | operator= (const basic_filebuf &)=delete |
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locale | pubimbue (const locale &__loc) |
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int_type | sbumpc () |
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int_type | sgetc () |
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streamsize | sgetn (char_type *__s, streamsize __n) |
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int_type | snextc () |
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int_type | sputbackc (char_type __c) |
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int_type | sputc (char_type __c) |
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streamsize | sputn (const char_type *__s, streamsize __n) |
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int_type | sungetc () |
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void | swap (basic_filebuf &) |
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basic_streambuf * | pubsetbuf (char_type *__s, streamsize __n) |
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pos_type | pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out) |
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pos_type | pubseekpos (pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out) |
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int | pubsync () |
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void | __safe_gbump (streamsize __n) |
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void | __safe_pbump (streamsize __n) |
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void | _M_allocate_internal_buffer () |
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bool | _M_convert_to_external (char_type *, streamsize) |
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void | _M_create_pback () |
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void | _M_destroy_internal_buffer () throw () |
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void | _M_destroy_pback () throw () |
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int | _M_get_ext_pos (__state_type &__state) |
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pos_type | _M_seek (off_type __off, ios_base::seekdir __way, __state_type __state) |
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void | _M_set_buffer (streamsize __off) |
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bool | _M_terminate_output () |
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void | gbump (int __n) |
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virtual void | imbue (const locale &__loc) |
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virtual int_type | overflow (int_type __c=_Traits::eof()) |
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virtual int_type | pbackfail (int_type __c=_Traits::eof()) |
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void | pbump (int __n) |
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virtual pos_type | seekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out) |
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virtual pos_type | seekpos (pos_type __pos, ios_base::openmode __mode=ios_base::in|ios_base::out) |
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virtual __streambuf_type * | setbuf (char_type *__s, streamsize __n) |
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void | setg (char_type *__gbeg, char_type *__gnext, char_type *__gend) |
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void | setp (char_type *__pbeg, char_type *__pend) |
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virtual streamsize | showmanyc () |
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void | swap (basic_streambuf &__sb) |
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virtual int | sync () |
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virtual int_type | uflow () |
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virtual int_type | underflow () |
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virtual streamsize | xsgetn (char_type *__s, streamsize __n) |
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virtual streamsize | xsputn (const char_type *__s, streamsize __n) |
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char_type * | eback () const |
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char_type * | gptr () const |
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char_type * | egptr () const |
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char_type * | pbase () const |
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char_type * | pptr () const |
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char_type * | epptr () const |
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template<
typename _CharT,
typename _Traits>
class std::basic_filebuf< _CharT, _Traits >
The actual work of input and output (for files).
- Template Parameters
-
_CharT | Type of character stream. |
_Traits | Traits for character type, defaults to char_traits<_CharT>. |
This class associates both its input and output sequence with an external disk file, and maintains a joint file position for both sequences. Many of its semantics are described in terms of similar behavior in the Standard C Library's FILE
streams.
Requirements on traits_type, specific to this class:
- traits_type::pos_type must be fpos<traits_type::state_type>
- traits_type::off_type must be streamoff
- traits_type::state_type must be Assignable and DefaultConstructible,
- traits_type::state_type() must be the initial state for codecvt.
Definition at line 85 of file fstream.
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 464 of file fstream.
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 249 of file fstream.tcc.
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 179 of file fstream.tcc.
References std::ios_base::ate, and std::ios_base::end.
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 541 of file fstream.tcc.
References std::ios_base::app, std::ios_base::cur, and std::ios_base::out.
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 297 of file fstream.tcc.
References std::ios_base::binary, and std::ios_base::in.
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 429 of file streambuf.
Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::overflow().
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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 705 of file streambuf.
Fetches more data from the controlled sequence.
- Returns
- The first character from the pending sequence.
Informally, this function is called when the input buffer is exhausted (or does not exist, as buffering need not actually be done). If a buffer exists, it is refilled. In either case, the next available character is returned, or traits::eof()
to indicate a null pending sequence.
For a formal definition of the pending sequence, see a good text such as Langer & Kreft, or [27.5.2.4.3]/7-14.
A functioning input streambuf can be created by overriding only this function (no buffer area will be used). For an example, see https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html
- Note
- Base class version does nothing, returns eof().
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Definition at line 323 of file fstream.tcc.
References std::ios_base::in.
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 669 of file fstream.tcc.
References std::ios_base::in.
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 755 of file fstream.tcc.
References std::ios_base::app, std::min(), and std::ios_base::out.