freebsd-dev/contrib/libstdc++/include/std/std_streambuf.h
2003-07-11 03:42:04 +00:00

938 lines
31 KiB
C++

// Stream buffer classes -*- C++ -*-
// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
// Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING. If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
//
// ISO C++ 14882: 27.5 Stream buffers
//
/** @file streambuf
* This is a Standard C++ Library header. You should @c #include this header
* in your programs, rather than any of the "st[dl]_*.h" implementation files.
*/
#ifndef _CPP_STREAMBUF
#define _CPP_STREAMBUF 1
#pragma GCC system_header
#include <bits/c++config.h>
#include <iosfwd>
#include <cstdio> // For SEEK_SET, SEEK_CUR, SEEK_END
#include <bits/localefwd.h>
#include <bits/ios_base.h>
namespace std
{
/**
* @if maint
* Does stuff.
* @endif
*/
template<typename _CharT, typename _Traits>
streamsize
__copy_streambufs(basic_ios<_CharT, _Traits>& _ios,
basic_streambuf<_CharT, _Traits>* __sbin,
basic_streambuf<_CharT, _Traits>* __sbout);
/**
* @brief 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 @e 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 @c 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 <em>beginning pointer</em>, or lowest element address in the
* array (called @e xbeg here);
* - the <em>next pointer</em>, or next element address that is a
* current candidate for reading or writing (called @e xnext here);
* - the <em>end pointer</em>, or first element address beyond the
* end of the array (called @e 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 @e xnext is not a null pointer, then @e xbeg and @e xend shall
* also be non-null pointers into the same @c charT array, as
* described above; otherwise, @e xbeg and @e xend shall also be null.
* - If @e xnext is not a null pointer and @e xnext < @e xend for an
* output sequence, then a <em>write position</em> is available.
* In this case, @e *xnext shall be assignable as the next element
* to write (to put, or to store a character value, into the sequence).
* - If @e xnext is not a null pointer and @e xbeg < @e xnext for an
* input sequence, then a <em>putback position</em> is available.
* In this case, @e 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 @e xnext is not a null pointer and @e xnext< @e xend for an
* input sequence, then a <em>read position</em> is available.
* In this case, @e *xnext shall have a defined value and is the
* next element to read (to get, or to obtain a character value,
* from the sequence).
*/
template<typename _CharT, typename _Traits>
class basic_streambuf
{
public:
//@{
/**
* 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.
*/
typedef _CharT char_type;
typedef _Traits traits_type;
typedef typename traits_type::int_type int_type;
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
//@}
//@{
/**
* @if maint
* These are non-standard types.
* @endif
*/
typedef ctype<char_type> __ctype_type;
typedef basic_streambuf<char_type, traits_type> __streambuf_type;
typedef typename traits_type::state_type __state_type;
//@}
friend class basic_ios<char_type, traits_type>;
friend class basic_istream<char_type, traits_type>;
friend class basic_ostream<char_type, traits_type>;
friend class istreambuf_iterator<char_type, traits_type>;
friend class ostreambuf_iterator<char_type, traits_type>;
friend streamsize
__copy_streambufs<>(basic_ios<char_type, traits_type>& __ios,
__streambuf_type* __sbin,__streambuf_type* __sbout);
protected:
/**
* @if maint
* Pointer to the beginning of internally-allocated space. Filebuf
* manually allocates/deallocates this, whereas stringstreams attempt
* to use the built-in intelligence of the string class. If you are
* managing memory, set this. If not, leave it NULL.
* @endif
*/
char_type* _M_buf;
/**
* @if maint
* Actual size of allocated internal buffer, in bytes.
* @endif
*/
size_t _M_buf_size;
/**
* @if maint
* Optimal or preferred size of internal buffer, in bytes.
* @endif
*/
size_t _M_buf_size_opt;
/**
* @if maint
* True iff _M_in_* and _M_out_* buffers should always point to
* the same place. True for fstreams, false for sstreams.
* @endif
*/
bool _M_buf_unified;
//@{
/**
* @if maint
* This is based on _IO_FILE, just reordered to be more consistent,
* and is intended to be the most minimal abstraction for an
* internal buffer.
* - get == input == read
* - put == output == write
* @endif
*/
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.
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.
//@}
/**
* @if maint
* Place to stash in || out || in | out settings for current streambuf.
* @endif
*/
ios_base::openmode _M_mode;
/**
* @if maint
* Current locale setting.
* @endif
*/
locale _M_buf_locale;
/**
* @if maint
* True iff locale is initialized.
* @endif
*/
bool _M_buf_locale_init;
//@{
/**
* @if maint
* Necessary bits for putback buffer management. Only used in
* the basic_filebuf class, as necessary for the standard
* requirements. The only basic_streambuf member function that
* needs access to these data members is in_avail...
*
* @note pbacks of over one character are not currently supported.
* @endif
*/
static const size_t _S_pback_size = 1;
char_type _M_pback[_S_pback_size];
char_type* _M_pback_cur_save;
char_type* _M_pback_end_save;
bool _M_pback_init;
//@}
/**
* @if maint
* Yet unused.
* @endif
*/
fpos<__state_type> _M_pos;
// Initializes pback buffers, and moves normal buffers to safety.
// Assumptions:
// _M_in_cur has already been moved back
void
_M_pback_create()
{
if (!_M_pback_init)
{
size_t __dist = _M_in_end - _M_in_cur;
size_t __len = min(_S_pback_size, __dist);
traits_type::copy(_M_pback, _M_in_cur, __len);
_M_pback_cur_save = _M_in_cur;
_M_pback_end_save = _M_in_end;
this->setg(_M_pback, _M_pback, _M_pback + __len);
_M_pback_init = true;
}
}
// Deactivates pback buffer contents, and restores normal buffer.
// Assumptions:
// The pback buffer has only moved forward.
void
_M_pback_destroy() throw()
{
if (_M_pback_init)
{
// Length _M_in_cur moved in the pback buffer.
size_t __off_cur = _M_in_cur - _M_pback;
// For in | out buffers, the end can be pushed back...
size_t __off_end = 0;
size_t __pback_len = _M_in_end - _M_pback;
size_t __save_len = _M_pback_end_save - _M_buf;
if (__pback_len > __save_len)
__off_end = __pback_len - __save_len;
this->setg(_M_buf, _M_pback_cur_save + __off_cur,
_M_pback_end_save + __off_end);
_M_pback_cur_save = NULL;
_M_pback_end_save = NULL;
_M_pback_init = false;
}
}
// Correctly sets the _M_in_cur pointer, and bumps the
// _M_out_cur pointer as well if necessary.
void
_M_in_cur_move(off_type __n) // argument needs to be +-
{
bool __testout = _M_out_cur;
_M_in_cur += __n;
if (__testout && _M_buf_unified)
_M_out_cur += __n;
}
// Correctly sets the _M_out_cur pointer, and bumps the
// appropriate _M_*_end pointers as well. Necessary for the
// un-tied stringbufs, in in|out mode.
// Invariant:
// __n + _M_out_[cur, end] <= _M_buf + _M_buf_size
// Assuming all _M_*_[beg, cur, end] pointers are operating on
// the same range:
// _M_buf <= _M_*_ <= _M_buf + _M_buf_size
void
_M_out_cur_move(off_type __n) // argument needs to be +-
{
bool __testin = _M_in_cur;
_M_out_cur += __n;
if (__testin && _M_buf_unified)
_M_in_cur += __n;
if (_M_out_cur > _M_out_end)
{
_M_out_end = _M_out_cur;
// NB: in | out buffers drag the _M_in_end pointer along...
if (__testin)
_M_in_end += __n;
}
}
// Return the size of the output buffer. This depends on the
// buffer in use: allocated buffers have a stored size in
// _M_buf_size and setbuf() buffers don't.
off_type
_M_out_buf_size()
{
off_type __ret = 0;
if (_M_out_cur)
{
// Using allocated buffer.
if (_M_out_beg == _M_buf)
__ret = _M_out_beg + _M_buf_size - _M_out_cur;
// Using non-allocated buffer.
else
__ret = _M_out_end - _M_out_cur;
}
return __ret;
}
public:
/// Destructor deallocates no buffer space.
virtual
~basic_streambuf()
{
_M_buf_unified = false;
_M_buf_size = 0;
_M_buf_size_opt = 0;
_M_mode = ios_base::openmode(0);
}
// [27.5.2.2.1] locales
/**
* @brief Entry point for imbue().
* @param loc The new locale.
* @return The previous locale.
*
* Calls the derived imbue(loc).
*/
locale
pubimbue(const locale &__loc)
{
locale __tmp(this->getloc());
this->imbue(__loc);
return __tmp;
}
/**
* @brief Locale access.
* @return The current locale in effect.
*
* If pubimbue(loc) has been called, then the most recent @c loc
* is returned. Otherwise the global locale in effect at the time
* of construction is returned.
*/
locale
getloc() const
{ return _M_buf_locale; }
// [27.5.2.2.2] buffer management and positioning
//@{
/**
* @brief Entry points for derived buffer functions.
*
* The public versions of @c pubfoo dispatch to the protected
* derived @c foo member functions, passing the arguments (if any)
* and returning the result unchanged.
*/
__streambuf_type*
pubsetbuf(char_type* __s, streamsize __n)
{ return this->setbuf(__s, __n); }
pos_type
pubseekoff(off_type __off, ios_base::seekdir __way,
ios_base::openmode __mode = ios_base::in | ios_base::out)
{ return this->seekoff(__off, __way, __mode); }
pos_type
pubseekpos(pos_type __sp,
ios_base::openmode __mode = ios_base::in | ios_base::out)
{ return this->seekpos(__sp, __mode); }
int
pubsync() { return this->sync(); }
//@}
// [27.5.2.2.3] get area
/**
* @brief Looking ahead into the stream.
* @return 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 @c showmanyc().
*/
streamsize
in_avail()
{
streamsize __ret;
if (_M_in_cur && _M_in_cur < _M_in_end)
{
if (_M_pback_init)
{
size_t __save_len = _M_pback_end_save - _M_pback_cur_save;
size_t __pback_len = _M_in_cur - _M_pback;
__ret = __save_len - __pback_len;
}
else
__ret = this->egptr() - this->gptr();
}
else
__ret = this->showmanyc();
return __ret;
}
/**
* @brief Getting the next character.
* @return The next character, or eof.
*
* Calls @c sbumpc(), and if that function returns
* @c traits::eof(), so does this function. Otherwise, @c sgetc().
*/
int_type
snextc()
{
int_type __eof = traits_type::eof();
return (traits_type::eq_int_type(this->sbumpc(), __eof)
? __eof : this->sgetc());
}
/**
* @brief Getting the next character.
* @return The next character, or eof.
*
* If the input read position is available, returns that character
* and increments the read pointer, otherwise calls and returns
* @c uflow().
*/
int_type
sbumpc();
/**
* @brief Getting the next character.
* @return The next character, or eof.
*
* If the input read position is available, returns that character,
* otherwise calls and returns @c underflow(). Does not move the
* read position after fetching the character.
*/
int_type
sgetc()
{
int_type __ret;
if (_M_in_cur && _M_in_cur < _M_in_end)
__ret = traits_type::to_int_type(*(this->gptr()));
else
__ret = this->underflow();
return __ret;
}
/**
* @brief Entry point for xsgetn.
* @param s A buffer area.
* @param n A count.
*
* Returns xsgetn(s,n). The effect is to fill @a s[0] through
* @a s[n-1] with characters from the input sequence, if possible.
*/
streamsize
sgetn(char_type* __s, streamsize __n)
{ return this->xsgetn(__s, __n); }
// [27.5.2.2.4] putback
/**
* @brief Pushing characters back into the input stream.
* @param c The character to push back.
* @return The previous character, if possible.
*
* Similar to sungetc(), but @a c is pushed onto the stream instead
* of "the previous character". If successful, the next character
* fetched from the input stream will be @a c.
*/
int_type
sputbackc(char_type __c);
/**
* @brief Moving backwards in the input stream.
* @return 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".
*/
int_type
sungetc();
// [27.5.2.2.5] put area
/**
* @brief Entry point for all single-character output functions.
* @param c A character to output.
* @return @a 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 @a c in that position, increments
* the position, and returns @c traits::to_int_type(c). If a write
* position is not available, returns @c overflow(c).
*/
int_type
sputc(char_type __c);
/**
* @brief Entry point for all single-character output functions.
* @param s A buffer read area.
* @param n A count.
*
* One of two public output functions.
*
*
* Returns xsputn(s,n). The effect is to write @a s[0] through
* @a s[n-1] to the output sequence, if possible.
*/
streamsize
sputn(const char_type* __s, streamsize __n)
{ return this->xsputn(__s, __n); }
protected:
/**
* @brief 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
*/
basic_streambuf()
: _M_buf(NULL), _M_buf_size(0), _M_buf_size_opt(BUFSIZ),
_M_buf_unified(false), _M_in_beg(0), _M_in_cur(0), _M_in_end(0),
_M_out_beg(0), _M_out_cur(0), _M_out_end(0),
_M_mode(ios_base::openmode(0)), _M_buf_locale(locale()),
_M_pback_cur_save(0), _M_pback_end_save(0),
_M_pback_init(false)
{ }
// [27.5.2.3.1] get area access
//@{
/**
* @brief 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
*/
char_type*
eback() const { return _M_in_beg; }
char_type*
gptr() const { return _M_in_cur; }
char_type*
egptr() const { return _M_in_end; }
//@}
/**
* @brief Moving the read position.
* @param n The delta by which to move.
*
* This just advances the read position without returning any data.
*/
void
gbump(int __n) { _M_in_cur += __n; }
/**
* @brief Setting the three read area pointers.
* @param gbeg A pointer.
* @param gnext A pointer.
* @param gend A pointer.
* @post @a gbeg == @c eback(), @a gnext == @c gptr(), and
* @a gend == @c egptr()
*/
void
setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
{
_M_in_beg = __gbeg;
_M_in_cur = __gnext;
_M_in_end = __gend;
if (!(_M_mode & ios_base::in) && __gbeg && __gnext && __gend)
_M_mode = _M_mode | ios_base::in;
}
// [27.5.2.3.2] put area access
//@{
/**
* @brief 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
*/
char_type*
pbase() const { return _M_out_beg; }
char_type*
pptr() const { return _M_out_cur; }
char_type*
epptr() const { return _M_out_end; }
//@}
/**
* @brief Moving the write position.
* @param n The delta by which to move.
*
* This just advances the write position without returning any data.
*/
void
pbump(int __n) { _M_out_cur += __n; }
/**
* @brief Setting the three write area pointers.
* @param pbeg A pointer.
* @param pend A pointer.
* @post @a pbeg == @c pbase(), @a pbeg == @c pptr(), and
* @a pend == @c epptr()
*/
void
setp(char_type* __pbeg, char_type* __pend)
{
_M_out_beg = _M_out_cur = __pbeg;
_M_out_end = __pend;
if (!(_M_mode & ios_base::out) && __pbeg && __pend)
_M_mode = _M_mode | ios_base::out;
}
// [27.5.2.4] virtual functions
// [27.5.2.4.1] locales
/**
* @brief Changes translations.
* @param 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." This function simply stores the new locale for use
* by derived classes.
*/
virtual void
imbue(const locale& __loc)
{
if (_M_buf_locale != __loc)
_M_buf_locale = __loc;
}
// [27.5.2.4.2] buffer management and positioning
/**
* @brief Maniuplates the buffer.
*
* Each derived class provides its own appropriate behavior. See
* the next-to-last paragraph of
* http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for
* more on this function.
*
* @note Base class version does nothing, returns @c this.
*/
virtual basic_streambuf<char_type,_Traits>*
setbuf(char_type*, streamsize)
{ return this; }
/**
* @brief Alters the stream positions.
*
* Each derived class provides its own appropriate behavior.
* @note Base class version does nothing, returns a @c pos_type
* that represents an invalid stream position.
*/
virtual pos_type
seekoff(off_type, ios_base::seekdir,
ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
{ return pos_type(off_type(-1)); }
/**
* @brief Alters the stream positions.
*
* Each derived class provides its own appropriate behavior.
* @note Base class version does nothing, returns a @c pos_type
* that represents an invalid stream position.
*/
virtual pos_type
seekpos(pos_type,
ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
{ return pos_type(off_type(-1)); }
/**
* @brief Synchronizes the buffer arrays with the controlled sequences.
* @return -1 on failure.
*
* Each derived class provides its own appropriate behavior,
* including the definition of "failure".
* @note Base class version does nothing, returns zero.
*/
virtual int
sync() { return 0; }
// [27.5.2.4.3] get area
/**
* @brief Investigating the data available.
* @return An estimate of the number of characters available in the
* input sequence, or -1.
*
* "If it returns a positive value, then successive calls to
* @c underflow() will not return @c traits::eof() until at least that
* number of characters have been supplied. If @c showmanyc()
* returns -1, then calls to @c underflow() or @c uflow() will fail."
* [27.5.2.4.3]/1
*
* @note Base class version does nothing, returns zero.
* @note The standard adds that "the intention is not only that the
* calls [to underflow or uflow] will not return @c eof() but
* that they will return "immediately".
* @note The standard adds that "the morphemes of @c showmanyc are
* "es-how-many-see", not "show-manic".
*/
virtual streamsize
showmanyc() { return 0; }
/**
* @brief Multiple character extraction.
* @param s A buffer area.
* @param n Maximum number of characters to assign.
* @return The number of characters assigned.
*
* Fills @a s[0] through @a s[n-1] with characters from the input
* sequence, as if by @c sbumpc(). Stops when either @a n characters
* have been copied, or when @c traits::eof() would be copied.
*
* It is expected that derived classes provide a more efficient
* implementation by overriding this definition.
*/
virtual streamsize
xsgetn(char_type* __s, streamsize __n);
/**
* @brief Fetches more data from the controlled sequence.
* @return The first character from the <em>pending sequence</em>.
*
* 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 @c 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().
*/
virtual int_type
underflow()
{ return traits_type::eof(); }
/**
* @brief Fetches more data from the controlled sequence.
* @return The first character from the <em>pending sequence</em>.
*
* Informally, this function does the same thing as @c underflow(),
* and in fact is required to call that function. It also returns
* the new character, like @c underflow() does. However, this
* function also moves the read position forward by one.
*/
virtual int_type
uflow()
{
int_type __ret = traits_type::eof();
bool __testeof = traits_type::eq_int_type(this->underflow(), __ret);
bool __testpending = _M_in_cur && _M_in_cur < _M_in_end;
if (!__testeof && __testpending)
{
__ret = traits_type::to_int_type(*_M_in_cur);
++_M_in_cur;
if (_M_buf_unified && _M_mode & ios_base::out)
++_M_out_cur;
}
return __ret;
}
// [27.5.2.4.4] putback
/**
* @brief Tries to back up the input sequence.
* @param c The character to be inserted back into the sequence.
* @return eof() on failure, "some other value" on success
* @post The constraints of @c gptr(), @c eback(), and @c pptr()
* are the same as for @c underflow().
*
* @note Base class version does nothing, returns eof().
*/
virtual int_type
pbackfail(int_type /* __c */ = traits_type::eof())
{ return traits_type::eof(); }
// Put area:
/**
* @brief Multiple character insertion.
* @param s A buffer area.
* @param n Maximum number of characters to write.
* @return The number of characters written.
*
* Writes @a s[0] through @a s[n-1] to the output sequence, as if
* by @c sputc(). Stops when either @a n characters have been
* copied, or when @c sputc() would return @c traits::eof().
*
* It is expected that derived classes provide a more efficient
* implementation by overriding this definition.
*/
virtual streamsize
xsputn(const char_type* __s, streamsize __n);
/**
* @brief Consumes data from the buffer; writes to the
* controlled sequence.
* @param c An additional character to consume.
* @return eof() to indicate failure, something else (usually
* @a 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 @a c is also
* written out, if @a c is not @c 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().
*/
virtual int_type
overflow(int_type /* __c */ = traits_type::eof())
{ return traits_type::eof(); }
#ifdef _GLIBCPP_DEPRECATED
// Annex D.6
public:
/**
* @brief 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 @c _GLIBCPP_DEPRECATED to make this visible; see
* c++config.h.
*/
void
stossc()
{
if (_M_in_cur < _M_in_end)
++_M_in_cur;
else
this->uflow();
}
#endif
#ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
// Side effect of DR 50.
private:
basic_streambuf(const __streambuf_type&) { };
__streambuf_type&
operator=(const __streambuf_type&) { return *this; };
#endif
};
} // namespace std
#ifdef _GLIBCPP_NO_TEMPLATE_EXPORT
# define export
#endif
#ifdef _GLIBCPP_FULLY_COMPLIANT_HEADERS
#include <bits/streambuf.tcc>
#endif
#endif