basic_stringbuf Class Template Reference

Inheritance diagram for basic_stringbuf:

Detailed Description

template<typename _CharT, typename _Traits, typename _Alloc>
class std::basic_stringbuf< _CharT, _Traits, _Alloc >

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.

Definition at line 62 of file sstream.

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 (const __string_type &__str, ios_base::openmode __mode=ios_base::in|ios_base::out)
basic_stringbuf (ios_base::openmode __mode=ios_base::in|ios_base::out)
locale getloc () const
streamsize in_avail ()
locale pubimbue (const locale &__loc)
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)
__streambuf_type * pubsetbuf (char_type *__s, streamsize __n)
int pubsync ()
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)
void stossc ()
void str (const __string_type &__s)
__string_type str () const
int_type sungetc ()

Protected Member Functions

void _M_stringbuf_init (ios_base::openmode __mode)
void _M_sync (char_type *__base, __size_type __i, __size_type __o)
void _M_update_egptr ()
char_type * eback () const
char_type * egptr () const
char_type * epptr () const
void gbump (int __n)
char_type * gptr () const
virtual void imbue (const locale &)
virtual int_type overflow (int_type __c=traits_type::eof())
virtual int_type pbackfail (int_type __c=traits_type::eof())
char_type * pbase () const
void pbump (int __n)
char_type * pptr () const
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 __sp, 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)

Protected Attributes

locale _M_buf_locale
char_type * _M_in_beg
char_type * _M_in_cur
char_type * _M_in_end
ios_base::openmode _M_mode
char_type * _M_out_beg
char_type * _M_out_cur
char_type * _M_out_end
__string_type _M_string

Friends

streamsize __copy_streambufs (__streambuf_type *__sbin, __streambuf_type *__sbout)
class basic_ios< char_type, traits_type >
class basic_istream< char_type, traits_type >
class basic_ostream< char_type, traits_type >
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 >
class ostreambuf_iterator< char_type, traits_type >

Member Typedef Documentation

typedef _CharT char_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.
Reimplemented from basic_streambuf.
Definition at line 66 of file sstream.

Constructor & Destructor Documentation

basic_stringbuf ( ios_base::openmode __mode = ios_base::in | ios_base::out ) [inline, explicit]

Starts with an empty string buffer.

Parameters:

mode Whether the buffer can read, or write, or both.

The default constructor initializes the parent class using its own default ctor.
Definition at line 100 of file sstream.

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:

str A string to copy as a starting buffer.

mode Whether the buffer can read, or write, or both.

This constructor initializes the parent class using its own default ctor.
Definition at line 113 of file sstream.

Member Function Documentation

char_type* 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

Definition at line 456 of file streambuf.
Referenced by basic_filebuf::imbue(), basic_stringbuf::overflow(), basic_stringbuf::seekoff(), basic_filebuf::seekoff(), basic_stringbuf::seekpos(), basic_streambuf< char_type, traits_type >::sputbackc(), and basic_filebuf::underflow().

void gbump ( int __n ) [inline, protected, inherited]

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 472 of file streambuf.
Referenced by basic_stringbuf::pbackfail(), basic_filebuf::pbackfail(), basic_streambuf< char_type, traits_type >::sbumpc(), basic_stringbuf::seekoff(), basic_stringbuf::seekpos(), basic_streambuf< char_type, traits_type >::sputbackc(), basic_streambuf< char_type, traits_type >::stossc(), basic_streambuf< char_type, traits_type >::sungetc(), basic_streambuf< char_type, traits_type >::uflow(), and basic_streambuf::xsgetn().

locale getloc ( ) const [inline, inherited]

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 219 of file streambuf.

virtual void imbue ( const locale & ) [inline, protected, virtual, inherited]

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 basic_filebuf, and basic_filebuf< char_type, traits_type >.
Definition at line 550 of file streambuf.
Referenced by basic_streambuf< char_type, traits_type >::pubimbue().

streamsize in_avail ( ) [inline, inherited]

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 259 of file streambuf.

basic_stringbuf< _CharT, _Traits, _Alloc >::int_type overflow ( int_type __c = traits_type::eof() ) [protected, virtual]

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 definiton 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 basic_streambuf.
Definition at line 86 of file sstream.tcc.
References basic_string::assign(), basic_string::capacity(), basic_string::data(), basic_streambuf::eback(), std::max(), basic_string::max_size(), std::min(), ios_base::out, basic_streambuf::pbase(), basic_string::reserve(), basic_streambuf::sputc(), and basic_string::swap().

basic_stringbuf< _CharT, _Traits, _Alloc >::int_type pbackfail ( int_type __c = traits_type::eof() ) [protected, virtual]

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 from basic_streambuf.
Definition at line 52 of file sstream.tcc.
References basic_streambuf::gbump(), and ios_base::out.

char_type* 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

Definition at line 503 of file streambuf.
Referenced by basic_stringbuf::overflow(), basic_filebuf::overflow(), basic_stringbuf::seekoff(), and basic_stringbuf::seekpos().

void pbump ( int __n ) [inline, protected, inherited]

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 519 of file streambuf.
Referenced by basic_filebuf::overflow(), basic_stringbuf::seekoff(), basic_stringbuf::seekpos(), basic_streambuf< char_type, traits_type >::sputc(), and basic_streambuf::xsputn().

locale pubimbue ( const locale & __loc ) [inline, inherited]

Entry point for imbue().

Parameters:

loc The new locale.

Returns:
The previous locale.
Calls the derived imbue(loc).
Definition at line 202 of file streambuf.

__streambuf_type* 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.
Definition at line 232 of file streambuf.

int_type sbumpc ( ) [inline, inherited]

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 291 of file streambuf.
Referenced by basic_istream::getline(), basic_istream::ignore(), istreambuf_iterator::operator++(), and std::operator>>().

basic_stringbuf< _CharT, _Traits, _Alloc >::pos_type seekoff ( off_type __off,

ios_base::seekdir __way,

ios_base::openmode __mode = ios_base::in | ios_base::out

) [protected, virtual]

Alters the stream positions.
Each derived class provides its own appropriate behavior.
Note:
Base class version does nothing, returns a pos_type that represents an invalid stream position.

Reimplemented from basic_streambuf.
Definition at line 147 of file sstream.tcc.
References ios_base::cur, basic_streambuf::eback(), ios_base::end, basic_streambuf::gbump(), ios_base::in, ios_base::out, basic_streambuf::pbase(), and basic_streambuf::pbump().

basic_stringbuf< _CharT, _Traits, _Alloc >::pos_type seekpos ( pos_type __sp,

ios_base::openmode __mode = ios_base::in | ios_base::out

) [protected, virtual]

Alters the stream positions.
Each derived class provides its own appropriate behavior.
Note:
Base class version does nothing, returns a pos_type that represents an invalid stream position.

Reimplemented from basic_streambuf.
Definition at line 194 of file sstream.tcc.
References basic_streambuf::eback(), basic_streambuf::gbump(), ios_base::in, ios_base::out, basic_streambuf::pbase(), and basic_streambuf::pbump().

virtual __streambuf_type* setbuf ( char_type * __s,

streamsize __n

) [inline, protected, virtual]

Manipulates the buffer.

Parameters:

s Pointer to a buffer area.

n Size of s.

Returns:
this
If no buffer has already been created, and both s and n are non-zero, then s is used as a buffer; see http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for more.
Reimplemented from basic_streambuf.
Definition at line 191 of file sstream.
References basic_string::assign().

void setg ( char_type * __gbeg,

char_type * __gnext,

char_type * __gend

) [inline, protected, inherited]

Setting the three read area pointers.

Parameters:

gbeg A pointer.

gnext A pointer.

gend A pointer.

Postcondition:
gbeg == eback(), gnext == gptr(), and gend == egptr()

Definition at line 483 of file streambuf.

void setp ( char_type * __pbeg,

char_type * __pend

) [inline, protected, inherited]

Setting the three write area pointers.

Parameters:

pbeg A pointer.

pend A pointer.

Postcondition:
pbeg == pbase(), pbeg == pptr(), and pend == epptr()

Definition at line 529 of file streambuf.

int_type sgetc ( ) [inline, inherited]

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 313 of file streambuf.
Referenced by basic_istream::get(), basic_istream::getline(), basic_istream::ignore(), and basic_streambuf< char_type, traits_type >::snextc().

streamsize sgetn ( char_type * __s,

streamsize __n

) [inline, inherited]

Entry point for xsgetn.

Parameters:

s A buffer area.

n A count.

Returns xsgetn(s,n). The effect is to fill s[0] through s[n-1] with characters from the input sequence, if possible.
Definition at line 332 of file streambuf.

virtual streamsize showmanyc ( ) [inline, protected, virtual, inherited]

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 in basic_filebuf, and basic_filebuf< char_type, traits_type >.
Definition at line 623 of file streambuf.
Referenced by basic_streambuf< char_type, traits_type >::in_avail().

int_type snextc ( ) [inline, inherited]

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 273 of file streambuf.
Referenced by basic_istream::get(), basic_istream::getline(), and basic_istream::ignore().

int_type sputbackc ( char_type __c ) [inline, inherited]

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 346 of file streambuf.
Referenced by std::operator>>(), and basic_istream::putback().

int_type sputc ( char_type __c ) [inline, inherited]

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 398 of file streambuf.
Referenced by basic_istream::get(), ostreambuf_iterator::operator=(), and basic_stringbuf::overflow().

streamsize sputn ( const char_type * __s,

streamsize __n

) [inline, inherited]

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 424 of file streambuf.

void stossc ( ) [inline, inherited]

Tosses a character.
Advances the read pointer, ignoring the character that would have been read.
See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html

Note:
This function has been deprecated by the standard. You must define _GLIBCXX_DEPRECATED to make this visible; see c++config.h.

Definition at line 760 of file streambuf.

void str ( const __string_type & __s ) [inline]

Setting a new buffer.

Parameters:

s The string to use as a new sequence.

Deallocates any previous stored sequence, then copies s to use as a new one.
Definition at line 150 of file sstream.
References basic_string::assign(), basic_string::data(), and basic_string::size().

__string_type str ( ) const [inline]

Copying out the string buffer.

Returns:
A copy of one of the underlying sequences.
"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
Definition at line 128 of file sstream.
Referenced by basic_stringstream::str(), basic_ostringstream::str(), and basic_istringstream::str().

int_type sungetc ( ) [inline, inherited]

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 371 of file streambuf.
Referenced by basic_istream::unget().

virtual int sync ( void ) [inline, protected, virtual, inherited]

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 stdio_sync_filebuf, basic_filebuf, and basic_filebuf< char_type, traits_type >.
Definition at line 601 of file streambuf.

virtual int_type uflow ( ) [inline, protected, virtual, inherited]

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 stdio_sync_filebuf.
Definition at line 674 of file streambuf.
Referenced by basic_streambuf< char_type, traits_type >::sbumpc(), basic_streambuf< char_type, traits_type >::stossc(), and basic_streambuf::xsgetn().

basic_stringbuf< _CharT, _Traits, _Alloc >::int_type underflow ( ) [protected, virtual]

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 definiton 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++/27_io/howto.html#6

Note:
Base class version does nothing, returns eof().

Reimplemented from basic_streambuf.
Definition at line 129 of file sstream.tcc.
References ios_base::in.

streamsize xsgetn ( char_type * __s,

streamsize __n

) [protected, virtual, inherited]

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 basic_filebuf, and basic_filebuf< char_type, traits_type >.
Definition at line 50 of file streambuf.tcc.
References std::copy(), basic_streambuf::gbump(), std::min(), and basic_streambuf::uflow().
Referenced by basic_streambuf< char_type, traits_type >::sgetn().

streamsize xsputn ( const char_type * __s,

streamsize __n

) [protected, virtual, inherited]

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 basic_filebuf, and basic_filebuf< char_type, traits_type >.
Definition at line 84 of file streambuf.tcc.
References std::copy(), std::min(), basic_streambuf::overflow(), and basic_streambuf::pbump().
Referenced by basic_streambuf< char_type, traits_type >::sputn().

The documentation for this class was generated from the following files:

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