Public Types¶

typedef __string_type::size_type __size_type
typedef basic_streambuf< char_type, traits_type > __streambuf_type
typedef basic_string< char_type, _Traits, _Alloc > __string_type
typedef _Alloc allocator_type
typedef _CharT char_type
typedef traits_type::int_type int_type
typedef traits_type::off_type off_type
typedef traits_type::pos_type pos_type
typedef _Traits traits_type

Public Member Functions¶

basic_stringbuf ()
Starts with an empty string buffer. basic_stringbuf (basic_stringbuf &&__rhs)
basic_stringbuf (const __string_type &__str, ios_base::openmode __mode=ios_base::in|ios_base::out)
Starts with an existing string buffer. basic_stringbuf (const basic_stringbuf &)=delete
basic_stringbuf (ios_base::openmode __mode)
Starts with an empty string buffer. locale getloc () const
Locale access. streamsize in_avail ()
Looking ahead into the stream. basic_stringbuf & operator= (basic_stringbuf &&__rhs)
basic_stringbuf & operator= (const basic_stringbuf &)=delete
locale pubimbue (const locale &__loc)
Entry point for imbue(). int_type sbumpc ()
Getting the next character. int_type sgetc ()
Getting the next character. streamsize sgetn (char_type *__s, streamsize __n)
Entry point for xsgetn. int_type snextc ()
Getting the next character. int_type sputbackc (char_type __c)
Pushing characters back into the input stream. int_type sputc (char_type __c)
Entry point for all single-character output functions. streamsize sputn (const char_type *__s, streamsize __n)
Entry point for all single-character output functions. __string_type str () const
Copying out the string buffer. void str (const __string_type &__s)
Setting a new buffer. int_type sungetc ()
Moving backwards in the input stream. void swap (basic_stringbuf &__rhs) noexcept(_Noexcept_swap::value)

basic_streambuf * pubsetbuf (char_type *__s, streamsize __n)
Entry points for derived buffer functions. pos_type pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream position. pos_type pubseekpos (pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream position. int pubsync ()
Calls virtual sync function.

Protected Member Functions¶

void __safe_gbump (streamsize __n)
void __safe_pbump (streamsize __n)
void _M_pbump (char_type *__pbeg, char_type *__pend, off_type __off)
void _M_stringbuf_init (ios_base::openmode __mode)
void _M_sync (char_type *__base, __size_type __i, __size_type __o)
void _M_update_egptr ()
void gbump (int __n)
Moving the read position. virtual void imbue (const locale &__loc)
Changes translations. virtual int_type overflow (int_type __c=traits_type::eof())
Consumes data from the buffer; writes to the controlled sequence. virtual int_type pbackfail (int_type __c=traits_type::eof())
Tries to back up the input sequence. void pbump (int __n)
Moving the write position. virtual pos_type seekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions. virtual pos_type seekpos (pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions. virtual __streambuf_type * setbuf (char_type *__s, streamsize __n)
Manipulates the buffer. void setg (char_type *__gbeg, char_type *__gnext, char_type *__gend)
Setting the three read area pointers. void setp (char_type *__pbeg, char_type *__pend)
Setting the three write area pointers. virtual streamsize showmanyc ()
Investigating the data available. void swap (basic_streambuf &__sb)
virtual int sync ()
Synchronizes the buffer arrays with the controlled sequences. virtual int_type uflow ()
Fetches more data from the controlled sequence. virtual int_type underflow ()
Fetches more data from the controlled sequence. virtual streamsize xsgetn (char_type *__s, streamsize __n)
Multiple character extraction. virtual streamsize xsputn (const char_type *__s, streamsize __n)
Multiple character insertion.

char_type * eback () const
Access to the get area. char_type * gptr () const
Access to the get area. char_type * egptr () const
Access to the get area.

char_type * pbase () const
Access to the put area. char_type * pptr () const
Access to the put area. char_type * epptr () const
Access to the put area.

Protected Attributes¶

locale _M_buf_locale
Current locale setting. char_type * _M_in_beg
Start of get area. char_type * _M_in_cur
Current read area. char_type * _M_in_end
End of get area. ios_base::openmode _M_mode
Place to stash in || out || in | out settings for current stringbuf. char_type * _M_out_beg
Start of put area. char_type * _M_out_cur
Current put area. char_type * _M_out_end
End of put area. __string_type _M_string

template<typename _CharT, typename _Traits, typename _Alloc>¶

class std::basic_stringbuf< _CharT, _Traits, _Alloc >" The actual work of input and output (for std::string).

Template Parameters

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.

template<typename _CharT , typename _Traits , typename _Alloc > std::basic_stringbuf< _CharT, _Traits, _Alloc >::basic_stringbuf () [inline]¶

Starts with an empty string buffer. The default constructor initializes the parent class using its own default ctor.

template<typename _CharT , typename _Traits , typename _Alloc > std::basic_stringbuf< _CharT, _Traits, _Alloc >::basic_stringbuf (ios_base::openmode __mode) [inline], [explicit]¶

Starts with an empty string buffer.

Parameters

The default constructor initializes the parent class using its own default ctor.

template<typename _CharT , typename _Traits , typename _Alloc > std::basic_stringbuf< _CharT, _Traits, _Alloc >::basic_stringbuf (const __string_type & __str, ios_base::openmode __mode = ios_base::in | ios_base::out) [inline], [explicit]¶

Starts with an existing string buffer.

Parameters

This constructor initializes the parent class using its own default ctor.

template<typename _CharT , typename _Traits > 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.

• 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

template<typename _CharT , typename _Traits > 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.

• 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

template<typename _CharT , typename _Traits > 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.

• 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

template<typename _CharT , typename _Traits > void std::basic_streambuf< _CharT, _Traits >::gbump (int __n) [inline], [protected], [inherited]¶

Moving the read position.

Parameters

This just advances the read position without returning any data.

template<typename _CharT , typename _Traits > locale std::basic_streambuf< _CharT, _Traits >::getloc () const [inline], [inherited]¶

Locale access.

Returns

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.

template<typename _CharT , typename _Traits > 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.

• 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

template<typename _CharT , typename _Traits > virtual void std::basic_streambuf< _CharT, _Traits >::imbue (const locale & __loc) [inline], [protected], [virtual], [inherited]¶

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

Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.

template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _CharT, _Traits >::in_avail () [inline], [inherited]¶

Looking ahead into the stream.

Returns

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().

template<class _CharT , class _Traits , class _Alloc > 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.

Parameters

Returns

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

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

References __gnu_debug::__base(), std::basic_string< _CharT, _Traits, _Alloc >::assign(), std::ios_base::in, std::max(), std::min(), std::ios_base::out, std::basic_string< _CharT, _Traits, _Alloc >::push_back(), and std::basic_string< _CharT, _Traits, _Alloc >::reserve().

template<class _CharT , class _Traits , class _Alloc > 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.

Parameters

Returns

Postcondition

Note

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

References std::ios_base::out.

template<typename _CharT , typename _Traits > 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.

• 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

template<typename _CharT , typename _Traits > void std::basic_streambuf< _CharT, _Traits >::pbump (int __n) [inline], [protected], [inherited]¶

Moving the write position.

Parameters

This just advances the write position without returning any data.

template<typename _CharT , typename _Traits > 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.

• 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

template<typename _CharT , typename _Traits > locale std::basic_streambuf< _CharT, _Traits >::pubimbue (const locale & __loc) [inline], [inherited]¶

Entry point for imbue().

Parameters

Returns

Calls the derived imbue(__loc).

template<typename _CharT , typename _Traits > 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.

Parameters

Calls virtual seekoff function.

template<typename _CharT , typename _Traits > 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.

Parameters

Calls virtual seekpos function.

template<typename _CharT , typename _Traits > basic_streambuf* std::basic_streambuf< _CharT, _Traits >::pubsetbuf (char_type * __s, streamsize __n) [inline], [inherited]¶

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.

template<typename _CharT , typename _Traits > int std::basic_streambuf< _CharT, _Traits >::pubsync () [inline], [inherited]¶

Calls virtual sync function.

Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::sync().

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sbumpc () [inline], [inherited]¶

Getting the next character.

Returns

If the input read position is available, returns that character and increments the read pointer, otherwise calls and returns uflow().

template<class _CharT , class _Traits , class _Alloc > 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.

Note

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

References std::ios_base::cur, std::ios_base::end, std::ios_base::in, and std::ios_base::out.

template<class _CharT , class _Traits , class _Alloc > 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.

Note

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

References std::ios_base::in, and std::ios_base::out.

template<typename _CharT , typename _Traits , typename _Alloc > virtual __streambuf_type* std::basic_stringbuf< _CharT, _Traits, _Alloc >::setbuf (char_type * __s, streamsize __n) [inline], [protected], [virtual]¶

Manipulates the buffer.

Parameters

Returns

If no buffer has already been created, and both __s and __n are non-zero, then __s is used as a buffer; see https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering for more.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

template<typename _CharT , typename _Traits > 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.

Parameters

Postcondition

template<typename _CharT , typename _Traits > void std::basic_streambuf< _CharT, _Traits >::setp (char_type * __pbeg, char_type * __pend) [inline], [protected], [inherited]¶

Setting the three write area pointers.

Parameters

Postcondition

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sgetc () [inline], [inherited]¶

Getting the next character.

Returns

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.

Referenced by std::basic_istream< char >::seekg().

template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _CharT, _Traits >::sgetn (char_type * __s, streamsize __n) [inline], [inherited]¶

Entry point for xsgetn.

Parameters

Returns xsgetn(__s,__n). The effect is to fill __s[0] through __s[__n-1] with characters from the input sequence, if possible.

template<typename _CharT , typename _Traits , typename _Alloc > virtual streamsize std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc () [inline], [protected], [virtual]¶

Investigating the data available.

Returns

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

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::snextc () [inline], [inherited]¶

Getting the next character.

Returns

Calls sbumpc(), and if that function returns traits::eof(), so does this function. Otherwise, sgetc().

Referenced by std::basic_istream< char >::putback(), and std::basic_istream< char >::seekg().

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sputbackc (char_type __c) [inline], [inherited]¶

Pushing characters back into the input stream.

Parameters

Returns

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.

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sputc (char_type __c) [inline], [inherited]¶

Entry point for all single-character output functions.

Parameters

Returns

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).

Referenced by std::ostreambuf_iterator< _CharT, _Traits >::operator=().

template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _CharT, _Traits >::sputn (const char_type * __s, streamsize __n) [inline], [inherited]¶

Entry point for all single-character output functions.

Parameters

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.

template<typename _CharT , typename _Traits , typename _Alloc > __string_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::str () const [inline]¶

Copying out the string buffer.

Returns

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

template<typename _CharT , typename _Traits , typename _Alloc > void std::basic_stringbuf< _CharT, _Traits, _Alloc >::str (const __string_type & __s) [inline]¶

Setting a new buffer.

Parameters

Deallocates any previous stored sequence, then copies s to use as a new one.

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sungetc () [inline], [inherited]¶

Moving backwards in the input stream.

Returns

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.

template<typename _CharT , typename _Traits > virtual int std::basic_streambuf< _CharT, _Traits >::sync (void) [inline], [protected], [virtual], [inherited]¶

Synchronizes the buffer arrays with the controlled sequences.

Returns

Each derived class provides its own appropriate behavior, including the definition of failure.

Note

Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >, and std::wbuffer_convert< _Codecvt, _Elem, _Tr >.

template<typename _CharT , typename _Traits > virtual int_type std::basic_streambuf< _CharT, _Traits >::uflow () [inline], [protected], [virtual], [inherited]¶

Fetches more data from the controlled sequence.

Returns

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 >.

template<class _CharT , class _Traits , class _Alloc > basic_stringbuf< _CharT, _Traits, _Alloc >::int_type std::basic_stringbuf< _CharT, _Traits, _Alloc >::underflow [protected], [virtual]¶

Fetches more data from the controlled sequence.

Returns

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

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

References std::ios_base::in.

template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _CharT, _Traits >::xsgetn (char_type * __s, streamsize __n) [protected], [virtual], [inherited]¶

Multiple character extraction.

Parameters

Returns

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, std::char_traits< _CharT > >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.

References std::min().

template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _CharT, _Traits >::xsputn (const char_type * __s, streamsize __n) [protected], [virtual], [inherited]¶

Multiple character insertion.

Parameters

Returns

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, std::char_traits< _CharT > >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.

References std::min().

template<typename _CharT , typename _Traits > locale std::basic_streambuf< _CharT, _Traits >::_M_buf_locale [protected], [inherited]¶

Current locale setting.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_beg [protected], [inherited]¶

Start of get area.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_cur [protected], [inherited]¶

Current read area.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_end [protected], [inherited]¶

End of get area.

template<typename _CharT , typename _Traits , typename _Alloc > ios_base::openmode std::basic_stringbuf< _CharT, _Traits, _Alloc >::_M_mode [protected]¶

Place to stash in || out || in | out settings for current stringbuf.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_beg [protected], [inherited]¶

Start of put area.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_cur [protected], [inherited]¶

Current put area.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_end [protected], [inherited]¶

End of put area.