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 |
| typedef basic_streambuf < char_type, traits_type > | __streambuf_type |
Public Member Functions | |
| virtual | ~basic_streambuf () |
| locale | getloc () const |
| streamsize | in_avail () |
| locale | pubimbue (const locale &__loc) |
| int_type | sbumpc () |
| int_type | sgetc () |
| streamsize | sgetn (char_type *__s, streamsize __n) |
| int_type | snextc () |
| int_type | sputbackc (char_type __c) |
| int_type | sputc (char_type __c) |
| streamsize | sputn (const char_type *__s, streamsize __n) |
| int_type | sungetc () |
| __streambuf_type * | pubsetbuf (char_type *__s, streamsize __n) |
| pos_type | pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out) |
| pos_type | pubseekpos (pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out) |
| int | pubsync () |
Protected Attributes | |
| locale | _M_buf_locale |
| char_type * | _M_in_beg |
| char_type * | _M_in_cur |
| char_type * | _M_in_end |
| char_type * | _M_out_beg |
| char_type * | _M_out_cur |
| char_type * | _M_out_end |
Friends | |
| template<bool _IsMove, typename _CharT2 > | |
| __gnu_cxx::__enable_if < __is_char< _CharT2 > ::__value, _CharT2 * >::__type | __copy_move_a2 (istreambuf_iterator< _CharT2 >, istreambuf_iterator< _CharT2 >, _CharT2 *) |
| streamsize | __copy_streambufs_eof (__streambuf_type *, __streambuf_type *, bool &) |
| class | basic_ios< char_type, traits_type > |
| class | basic_istream< char_type, traits_type > |
| class | basic_ostream< char_type, traits_type > |
| template<typename _CharT2 > | |
| __gnu_cxx::__enable_if < __is_char< _CharT2 > ::__value, istreambuf_iterator < _CharT2 > >::__type | find (istreambuf_iterator< _CharT2 >, istreambuf_iterator< _CharT2 >, const _CharT2 &) |
| template<typename _CharT2 , typename _Traits2 , typename _Alloc > | |
| basic_istream< _CharT2, _Traits2 > & | getline (basic_istream< _CharT2, _Traits2 > &, basic_string< _CharT2, _Traits2, _Alloc > &, _CharT2) |
| class | istreambuf_iterator< char_type, traits_type > |
| template<typename _CharT2 , typename _Traits2 > | |
| basic_istream< _CharT2, _Traits2 > & | operator>> (basic_istream< _CharT2, _Traits2 > &, _CharT2 *) |
| template<typename _CharT2 , typename _Traits2 , typename _Alloc > | |
| basic_istream< _CharT2, _Traits2 > & | operator>> (basic_istream< _CharT2, _Traits2 > &, basic_string< _CharT2, _Traits2, _Alloc > &) |
| class | ostreambuf_iterator< char_type, traits_type > |
Detailed Description
template<typename _CharT, typename _Traits = char_traits<_CharT>>
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.
- Stream buffers can impose various constraints on the sequences they control. Some constraints are:
- The controlled input sequence can be not readable.
- The controlled output sequence can be not writable.
- The controlled sequences can be associated with the contents of other representations for character sequences, such as external files.
- The controlled sequences can support operations directly to or from associated sequences.
- The controlled sequences can impose limitations on how the program can read characters from a sequence, write characters to a sequence, put characters back into an input sequence, or alter the stream position.
- Each sequence is characterized by three pointers which, if non-null, all point into the same
charTarray 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:- the beginning pointer, or lowest element address in the array (called xbeg here);
- the next pointer, or next element address that is a current candidate for reading or writing (called xnext here);
- the end pointer, or first element address beyond the end of the array (called xend here).
- The following semantic constraints shall always apply for any set of three pointers for a sequence, using the pointer names given immediately above:
- If xnext is not a null pointer, then xbeg and xend shall also be non-null pointers into the same
charTarray, as described above; otherwise, xbeg and xend shall also be null. - If xnext is not a null pointer and xnext < xend for an output sequence, then a write position is available. In this case, *xnext shall be assignable as the next element to write (to put, or to store a character value, into the sequence).
- If xnext is not a null pointer and xbeg < xnext for an input sequence, then a putback position is available. In this case, xnext[-1] shall have a defined value and is the next (preceding) element to store a character that is put back into the input sequence.
- If xnext is not a null pointer and xnext< xend for an input sequence, then a read position is available. In this case, *xnext shall have a defined value and is the next element to read (to get, or to obtain a character value, from the sequence).
- If xnext is not a null pointer, then xbeg and xend shall also be non-null pointers into the same
Member Typedef Documentation
| typedef basic_streambuf<char_type, traits_type> std::basic_streambuf< _CharT, _Traits >::__streambuf_type |
| typedef _CharT std::basic_streambuf< _CharT, _Traits >::char_type |
| typedef traits_type::int_type std::basic_streambuf< _CharT, _Traits >::int_type |
| typedef traits_type::off_type std::basic_streambuf< _CharT, _Traits >::off_type |
| typedef traits_type::pos_type std::basic_streambuf< _CharT, _Traits >::pos_type |
| typedef _Traits std::basic_streambuf< _CharT, _Traits >::traits_type |
Constructor & Destructor Documentation
|
inlinevirtual |
|
inlineprotected |
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
Member Function Documentation
|
inlineprotected |
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 461 of file streambuf.
Referenced by std::basic_filebuf< char_type, traits_type >::_M_destroy_pback(), std::basic_streambuf< char, char_traits< char > >::sputbackc(), and std::basic_streambuf< char, char_traits< char > >::sungetc().
|
inlineprotected |
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 467 of file streambuf.
Referenced by std::basic_filebuf< char_type, traits_type >::_M_create_pback(), std::basic_streambuf< char, char_traits< char > >::in_avail(), std::basic_streambuf< char, char_traits< char > >::sbumpc(), std::basic_streambuf< char, char_traits< char > >::sgetc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc(), and std::basic_stringbuf< _CharT, _Traits, _Alloc >::str().
|
inlineprotected |
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 514 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::sputc().
|
inlineprotected |
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 477 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::sbumpc(), std::basic_streambuf< char, char_traits< char > >::sputbackc(), std::basic_streambuf< char, char_traits< char > >::sungetc(), and std::basic_streambuf< char, char_traits< char > >::uflow().
|
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 223 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::pubimbue().
|
inlineprotected |
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 464 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, char_traits< char > >::in_avail(), std::basic_streambuf< char, char_traits< char > >::sbumpc(), std::basic_streambuf< char, char_traits< char > >::sgetc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc(), std::basic_streambuf< char, char_traits< char > >::sputbackc(), std::basic_streambuf< char, char_traits< char > >::sungetc(), and std::basic_streambuf< char, char_traits< char > >::uflow().
|
inlineprotectedvirtual |
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 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 555 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::pubimbue().
|
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().
|
inlineprotectedvirtual |
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 std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, std::basic_stringbuf< _CharT, _Traits, _Alloc >, and __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.
Definition at line 747 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::sputc().
|
inlineprotectedvirtual |
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(), andpptr()are the same as forunderflow().
- Note
- Base class version does nothing, returns eof().
Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, std::basic_stringbuf< _CharT, _Traits, _Alloc >, and __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.
Definition at line 703 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::sputbackc(), and std::basic_streambuf< char, char_traits< char > >::sungetc().
|
inlineprotected |
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 508 of file streambuf.
Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::str().
|
inlineprotected |
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 524 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::sputc().
|
inlineprotected |
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 511 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::sputc(), and std::basic_stringbuf< _CharT, _Traits, _Alloc >::str().
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inline |
|
inline |
|
inline |
|
inline |
|
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 250 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::sync().
|
inline |
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 295 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, char_traits< char > >::snextc().
|
inlineprotectedvirtual |
Alters the stream positions.
Each derived class provides its own appropriate behavior.
- Note
- Base class version does nothing, returns a
pos_typethat represents an invalid stream position.
Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.
Definition at line 581 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::pubseekoff().
|
inlineprotectedvirtual |
Alters the stream positions.
Each derived class provides its own appropriate behavior.
- Note
- Base class version does nothing, returns a
pos_typethat represents an invalid stream position.
Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.
Definition at line 593 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::pubseekpos().
|
inlineprotectedvirtual |
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.
Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.
Definition at line 570 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::pubsetbuf().
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inlineprotected |
Setting the three read area pointers.
- Parameters
-
gbeg A pointer. gnext A pointer. gend A pointer.
Definition at line 488 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().
|
inlineprotected |
|
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 317 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, char_traits< char > >::snextc().
|
inline |
|
inlineprotectedvirtual |
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
showmanycare es-how-many-see, not show-manic.
Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.
Definition at line 628 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::in_avail().
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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 277 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().
|
inline |
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 351 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::putback().
|
inline |
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 403 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::get(), and std::ostreambuf_iterator< _CharT, _Traits >::operator=().
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inline |
|
inline |
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 376 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::unget().
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inlineprotectedvirtual |
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 >, 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 606 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::pubsync().
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inlineprotectedvirtual |
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 679 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::sbumpc().
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inlineprotectedvirtual |
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 in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, std::basic_stringbuf< _CharT, _Traits, _Alloc >, and __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.
Definition at line 666 of file streambuf.
Referenced by std::basic_streambuf< char, char_traits< char > >::sgetc(), and std::basic_streambuf< char, char_traits< char > >::uflow().
|
protectedvirtual |
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 >, 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, char_traits< char > >::sgetn().
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protectedvirtual |
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 >, 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, char_traits< char > >::sputn().
Member Data Documentation
|
protected |
Current locale setting.
Definition at line 189 of file streambuf.
Referenced by std::basic_filebuf< _CharT, _Traits >::basic_filebuf(), std::basic_streambuf< char, char_traits< char > >::getloc(), and std::basic_streambuf< char, char_traits< char > >::pubimbue().
The documentation for this class was generated from the following files:
