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| | basic_streambuf () |
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| basic_streambuf (const basic_streambuf &) |
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| void | __safe_gbump (streamsize __n) |
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| void | __safe_pbump (streamsize __n) |
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| void | gbump (int __n) |
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| virtual void | imbue (const locale &__loc) |
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basic_streambuf & | operator= (const basic_streambuf &) |
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| virtual int_type | overflow (int_type __c=traits_type::eof()) |
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| virtual int_type | pbackfail (int_type __c=traits_type::eof()) |
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| void | pbump (int __n) |
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| virtual pos_type | seekoff (off_type, ios_base::seekdir, ios_base::openmode=ios_base::in|ios_base::out) |
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| virtual pos_type | seekpos (pos_type, ios_base::openmode=ios_base::in|ios_base::out) |
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| virtual basic_streambuf< char_type, _Traits > * | setbuf (char_type *, streamsize) |
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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<bool _IsMove, typename _CharT2 > |
| __gnu_cxx::__enable_if< __is_char< _CharT2 >::__value, _CharT2 * >::__type | __copy_move_a2 (istreambuf_iterator< _CharT2 >, istreambuf_iterator< _CharT2 >, _CharT2 *) |
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| streamsize | __copy_streambufs_eof (basic_streambuf *, basic_streambuf *, bool &) |
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void | __istream_extract (istream &, char *, streamsize) |
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template<typename _CharT2 , typename _Distance > |
| __gnu_cxx::__enable_if< __is_char< _CharT2 >::__value, void >::__type | advance (istreambuf_iterator< _CharT2 > &, _Distance) |
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| class | basic_ios< char_type, traits_type > |
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| class | basic_istream< char_type, traits_type > |
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| class | basic_ostream< char_type, traits_type > |
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template<typename _CharT2 > |
| __gnu_cxx::__enable_if< __is_char< _CharT2 >::__value, istreambuf_iterator< _CharT2 > >::__type | find (istreambuf_iterator< _CharT2 >, istreambuf_iterator< _CharT2 >, const _CharT2 &) |
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template<typename _CharT2 , typename _Traits2 , typename _Alloc > |
| basic_istream< _CharT2, _Traits2 > & | getline (basic_istream< _CharT2, _Traits2 > &, basic_string< _CharT2, _Traits2, _Alloc > &, _CharT2) |
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| class | istreambuf_iterator< char_type, traits_type > |
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template<typename _CharT2 , typename _Traits2 , typename _Alloc > |
| basic_istream< _CharT2, _Traits2 > & | operator>> (basic_istream< _CharT2, _Traits2 > &, basic_string< _CharT2, _Traits2, _Alloc > &) |
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| class | ostreambuf_iterator< char_type, traits_type > |
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template<typename _CharT, typename _Traits>
class std::basic_streambuf< _CharT, _Traits >
The actual work of input and output (interface).
- Template Parameters
-
| _CharT | Type of character stream. |
| _Traits | Traits for character type, defaults to char_traits<_CharT>. |
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
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:
- 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
charT array, 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).
Definition at line 122 of file streambuf.
template<typename _CharT , typename _Traits >
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 468 of file streambuf.
template<typename _CharT , typename _Traits >
template<typename _CharT , typename _Traits >
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 289 of file streambuf.
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 in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >, std::basic_stringbuf< _CharT, _Traits, _Alloc >, and std::wbuffer_convert< _Codecvt, _Elem, _Tr >.
Definition at line 773 of file streambuf.
template<typename _CharT , typename _Traits >
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 >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.
Definition at line 729 of file streambuf.
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.
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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.
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The standard adds that the morphemes of
showmanyc are 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< _CharT, std::char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.
Definition at line 654 of file streambuf.
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 377 of file streambuf.
Referenced by std::basic_istream< _CharT, _Traits >::putback().
template<typename _CharT , typename _Traits >
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::ostreambuf_iterator< _CharT, _Traits >::operator=(), and std::wbuffer_convert< _Codecvt, _Elem, _Tr >::overflow().
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 455 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 402 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 in std::wbuffer_convert< _Codecvt, _Elem, _Tr >, __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.
Definition at line 632 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 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.
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 https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html
- Note
- Base class version does nothing, returns eof().
Reimplemented in std::wbuffer_convert< _Codecvt, _Elem, _Tr >, __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.
Definition at line 692 of file streambuf.
template<typename _CharT , typename _Traits >
template<typename _CharT , typename _Traits >
1.9.7