LCOV - code coverage report
Current view: directory - tools/gcc-4.5/include/c++/4.5.2 - streambuf (source / functions) Found Hit Coverage
Test: app.info Lines: 42 0 0.0 %
Date: 2012-06-02 Functions: 18 0 0.0 %

       1                 : // Stream buffer classes -*- C++ -*-
       2                 : 
       3                 : // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
       4                 : // 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
       5                 : //
       6                 : // This file is part of the GNU ISO C++ Library.  This library is free
       7                 : // software; you can redistribute it and/or modify it under the
       8                 : // terms of the GNU General Public License as published by the
       9                 : // Free Software Foundation; either version 3, or (at your option)
      10                 : // any later version.
      11                 : 
      12                 : // This library is distributed in the hope that it will be useful,
      13                 : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      14                 : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      15                 : // GNU General Public License for more details.
      16                 : 
      17                 : // Under Section 7 of GPL version 3, you are granted additional
      18                 : // permissions described in the GCC Runtime Library Exception, version
      19                 : // 3.1, as published by the Free Software Foundation.
      20                 : 
      21                 : // You should have received a copy of the GNU General Public License and
      22                 : // a copy of the GCC Runtime Library Exception along with this program;
      23                 : // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      24                 : // <http://www.gnu.org/licenses/>.
      25                 : 
      26                 : /** @file streambuf
      27                 :  *  This is a Standard C++ Library header.
      28                 :  */
      29                 : 
      30                 : //
      31                 : // ISO C++ 14882: 27.5  Stream buffers
      32                 : //
      33                 : 
      34                 : #ifndef _GLIBXX_STREAMBUF
      35                 : #define _GLIBXX_STREAMBUF 1
      36                 : 
      37                 : #pragma GCC system_header
      38                 : 
      39                 : #include <bits/c++config.h>
      40                 : #include <iosfwd>
      41                 : #include <bits/localefwd.h>
      42                 : #include <bits/ios_base.h>
      43                 : #include <bits/cpp_type_traits.h>
      44                 : #include <ext/type_traits.h>
      45                 : 
      46                 : _GLIBCXX_BEGIN_NAMESPACE(std)
      47                 : 
      48                 :   template<typename _CharT, typename _Traits>
      49                 :     streamsize
      50                 :     __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>*,
      51                 :                           basic_streambuf<_CharT, _Traits>*, bool&);
      52                 : 
      53                 :   /**
      54                 :    *  @brief  The actual work of input and output (interface).
      55                 :    *  @ingroup io
      56                 :    *
      57                 :    *  This is a base class.  Derived stream buffers each control a
      58                 :    *  pair of character sequences:  one for input, and one for output.
      59                 :    *
      60                 :    *  Section [27.5.1] of the standard describes the requirements and
      61                 :    *  behavior of stream buffer classes.  That section (three paragraphs)
      62                 :    *  is reproduced here, for simplicity and accuracy.
      63                 :    *
      64                 :    *  -# Stream buffers can impose various constraints on the sequences
      65                 :    *     they control.  Some constraints are:
      66                 :    *     - The controlled input sequence can be not readable.
      67                 :    *     - The controlled output sequence can be not writable.
      68                 :    *     - The controlled sequences can be associated with the contents of
      69                 :    *       other representations for character sequences, such as external
      70                 :    *       files.
      71                 :    *     - The controlled sequences can support operations @e directly to or
      72                 :    *       from associated sequences.
      73                 :    *     - The controlled sequences can impose limitations on how the
      74                 :    *       program can read characters from a sequence, write characters to
      75                 :    *       a sequence, put characters back into an input sequence, or alter
      76                 :    *       the stream position.
      77                 :    *     .
      78                 :    *  -# Each sequence is characterized by three pointers which, if non-null,
      79                 :    *     all point into the same @c charT array object.  The array object
      80                 :    *     represents, at any moment, a (sub)sequence of characters from the
      81                 :    *     sequence.  Operations performed on a sequence alter the values
      82                 :    *     stored in these pointers, perform reads and writes directly to or
      83                 :    *     from associated sequences, and alter <em>the stream position</em> and
      84                 :    *     conversion state as needed to maintain this subsequence relationship.
      85                 :    *     The three pointers are:
      86                 :    *     - the <em>beginning pointer</em>, or lowest element address in the
      87                 :    *       array (called @e xbeg here);
      88                 :    *     - the <em>next pointer</em>, or next element address that is a
      89                 :    *       current candidate for reading or writing (called @e xnext here);
      90                 :    *     - the <em>end pointer</em>, or first element address beyond the
      91                 :    *       end of the array (called @e xend here).
      92                 :    *     .
      93                 :    *  -# The following semantic constraints shall always apply for any set
      94                 :    *     of three pointers for a sequence, using the pointer names given
      95                 :    *     immediately above:
      96                 :    *     - If @e xnext is not a null pointer, then @e xbeg and @e xend shall
      97                 :    *       also be non-null pointers into the same @c charT array, as
      98                 :    *       described above; otherwise, @e xbeg and @e xend shall also be null.
      99                 :    *     - If @e xnext is not a null pointer and @e xnext < @e xend for an
     100                 :    *       output sequence, then a <em>write position</em> is available.
     101                 :    *       In this case, @e *xnext shall be assignable as the next element
     102                 :    *       to write (to put, or to store a character value, into the sequence).
     103                 :    *     - If @e xnext is not a null pointer and @e xbeg < @e xnext for an
     104                 :    *       input sequence, then a <em>putback position</em> is available.
     105                 :    *       In this case, @e xnext[-1] shall have a defined value and is the
     106                 :    *       next (preceding) element to store a character that is put back
     107                 :    *       into the input sequence.
     108                 :    *     - If @e xnext is not a null pointer and @e xnext< @e xend for an
     109                 :    *       input sequence, then a <em>read position</em> is available.
     110                 :    *       In this case, @e *xnext shall have a defined value and is the
     111                 :    *       next element to read (to get, or to obtain a character value,
     112                 :    *       from the sequence).
     113                 :   */
     114                 :   template<typename _CharT, typename _Traits>
     115                 :     class basic_streambuf 
     116                 :     {
     117                 :     public:
     118                 :       //@{
     119                 :       /**
     120                 :        *  These are standard types.  They permit a standardized way of
     121                 :        *  referring to names of (or names dependant on) the template
     122                 :        *  parameters, which are specific to the implementation.
     123                 :       */
     124                 :       typedef _CharT                                    char_type;
     125                 :       typedef _Traits                                   traits_type;
     126                 :       typedef typename traits_type::int_type            int_type;
     127                 :       typedef typename traits_type::pos_type            pos_type;
     128                 :       typedef typename traits_type::off_type            off_type;
     129                 :       //@}
     130                 : 
     131                 :       //@{
     132                 :       /// This is a non-standard type.
     133                 :       typedef basic_streambuf<char_type, traits_type>     __streambuf_type;
     134                 :       //@}
     135                 :       
     136                 :       friend class basic_ios<char_type, traits_type>;
     137                 :       friend class basic_istream<char_type, traits_type>;
     138                 :       friend class basic_ostream<char_type, traits_type>;
     139                 :       friend class istreambuf_iterator<char_type, traits_type>;
     140                 :       friend class ostreambuf_iterator<char_type, traits_type>;
     141                 : 
     142                 :       friend streamsize
     143                 :       __copy_streambufs_eof<>(__streambuf_type*, __streambuf_type*, bool&);
     144                 : 
     145                 :       template<bool _IsMove, typename _CharT2>
     146                 :         friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, 
     147                 :                                                _CharT2*>::__type
     148                 :         __copy_move_a2(istreambuf_iterator<_CharT2>,
     149                 :                        istreambuf_iterator<_CharT2>, _CharT2*);
     150                 : 
     151                 :       template<typename _CharT2>
     152                 :         friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value,
     153                 :                                   istreambuf_iterator<_CharT2> >::__type
     154                 :         find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>,
     155                 :              const _CharT2&);
     156                 : 
     157                 :       template<typename _CharT2, typename _Traits2>
     158                 :         friend basic_istream<_CharT2, _Traits2>&
     159                 :         operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*);
     160                 : 
     161                 :       template<typename _CharT2, typename _Traits2, typename _Alloc>
     162                 :         friend basic_istream<_CharT2, _Traits2>&
     163                 :         operator>>(basic_istream<_CharT2, _Traits2>&,
     164                 :                    basic_string<_CharT2, _Traits2, _Alloc>&);
     165                 : 
     166                 :       template<typename _CharT2, typename _Traits2, typename _Alloc>
     167                 :         friend basic_istream<_CharT2, _Traits2>&
     168                 :         getline(basic_istream<_CharT2, _Traits2>&,
     169                 :                 basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2);
     170                 : 
     171                 :     protected:
     172                 :       //@{
     173                 :       /**
     174                 :        *  This is based on _IO_FILE, just reordered to be more consistent,
     175                 :        *  and is intended to be the most minimal abstraction for an
     176                 :        *  internal buffer.
     177                 :        *  -  get == input == read
     178                 :        *  -  put == output == write
     179                 :       */
     180                 :       char_type*                _M_in_beg;     // Start of get area. 
     181                 :       char_type*                _M_in_cur;     // Current read area. 
     182                 :       char_type*                _M_in_end;     // End of get area. 
     183                 :       char_type*                _M_out_beg;    // Start of put area. 
     184                 :       char_type*                _M_out_cur;    // Current put area. 
     185                 :       char_type*                _M_out_end;    // End of put area.
     186                 : 
     187                 :       /// Current locale setting.
     188                 :       locale                    _M_buf_locale;  
     189                 : 
     190                 :   public:
     191                 :       /// Destructor deallocates no buffer space.
     192                 :       virtual 
     193               0 :       ~basic_streambuf() 
     194               0 :       { }
     195                 : 
     196                 :       // [27.5.2.2.1] locales
     197                 :       /**
     198                 :        *  @brief  Entry point for imbue().
     199                 :        *  @param  loc  The new locale.
     200                 :        *  @return  The previous locale.
     201                 :        *
     202                 :        *  Calls the derived imbue(loc).
     203                 :       */
     204                 :       locale 
     205                 :       pubimbue(const locale &__loc)
     206                 :       {
     207                 :         locale __tmp(this->getloc());
     208                 :         this->imbue(__loc);
     209                 :         _M_buf_locale = __loc;
     210                 :         return __tmp;
     211                 :       }
     212                 : 
     213                 :       /**
     214                 :        *  @brief  Locale access.
     215                 :        *  @return  The current locale in effect.
     216                 :        *
     217                 :        *  If pubimbue(loc) has been called, then the most recent @c loc
     218                 :        *  is returned.  Otherwise the global locale in effect at the time
     219                 :        *  of construction is returned.
     220                 :       */
     221                 :       locale   
     222                 :       getloc() const
     223                 :       { return _M_buf_locale; } 
     224                 : 
     225                 :       // [27.5.2.2.2] buffer management and positioning
     226                 :       //@{
     227                 :       /**
     228                 :        *  @brief  Entry points for derived buffer functions.
     229                 :        *
     230                 :        *  The public versions of @c pubfoo dispatch to the protected
     231                 :        *  derived @c foo member functions, passing the arguments (if any)
     232                 :        *  and returning the result unchanged.
     233                 :       */
     234                 :       __streambuf_type* 
     235                 :       pubsetbuf(char_type* __s, streamsize __n) 
     236                 :       { return this->setbuf(__s, __n); }
     237                 : 
     238                 :       pos_type 
     239                 :       pubseekoff(off_type __off, ios_base::seekdir __way, 
     240                 :                  ios_base::openmode __mode = ios_base::in | ios_base::out)
     241                 :       { return this->seekoff(__off, __way, __mode); }
     242                 : 
     243                 :       pos_type 
     244                 :       pubseekpos(pos_type __sp,
     245                 :                  ios_base::openmode __mode = ios_base::in | ios_base::out)
     246                 :       { return this->seekpos(__sp, __mode); }
     247                 : 
     248                 :       int 
     249               0 :       pubsync() { return this->sync(); }
     250                 :       //@}
     251                 : 
     252                 :       // [27.5.2.2.3] get area
     253                 :       /**
     254                 :        *  @brief  Looking ahead into the stream.
     255                 :        *  @return  The number of characters available.
     256                 :        *
     257                 :        *  If a read position is available, returns the number of characters
     258                 :        *  available for reading before the buffer must be refilled.
     259                 :        *  Otherwise returns the derived @c showmanyc().
     260                 :       */
     261                 :       streamsize 
     262                 :       in_avail() 
     263                 :       { 
     264                 :         const streamsize __ret = this->egptr() - this->gptr();
     265                 :         return __ret ? __ret : this->showmanyc();
     266                 :       }
     267                 : 
     268                 :       /**
     269                 :        *  @brief  Getting the next character.
     270                 :        *  @return  The next character, or eof.
     271                 :        *
     272                 :        *  Calls @c sbumpc(), and if that function returns
     273                 :        *  @c traits::eof(), so does this function.  Otherwise, @c sgetc().
     274                 :       */
     275                 :       int_type 
     276                 :       snextc()
     277                 :       {
     278                 :         int_type __ret = traits_type::eof();
     279                 :         if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), 
     280                 :                                                        __ret), true))
     281                 :           __ret = this->sgetc();
     282                 :         return __ret;
     283                 :       }
     284                 : 
     285                 :       /**
     286                 :        *  @brief  Getting the next character.
     287                 :        *  @return  The next character, or eof.
     288                 :        *
     289                 :        *  If the input read position is available, returns that character
     290                 :        *  and increments the read pointer, otherwise calls and returns
     291                 :        *  @c uflow().
     292                 :       */
     293                 :       int_type 
     294                 :       sbumpc()
     295                 :       {
     296                 :         int_type __ret;
     297                 :         if (__builtin_expect(this->gptr() < this->egptr(), true))
     298                 :           {
     299                 :             __ret = traits_type::to_int_type(*this->gptr());
     300                 :             this->gbump(1);
     301                 :           }
     302                 :         else 
     303                 :           __ret = this->uflow();
     304                 :         return __ret;
     305                 :       }
     306                 : 
     307                 :       /**
     308                 :        *  @brief  Getting the next character.
     309                 :        *  @return  The next character, or eof.
     310                 :        *
     311                 :        *  If the input read position is available, returns that character,
     312                 :        *  otherwise calls and returns @c underflow().  Does not move the 
     313                 :        *  read position after fetching the character.
     314                 :       */
     315                 :       int_type 
     316                 :       sgetc()
     317                 :       {
     318                 :         int_type __ret;
     319                 :         if (__builtin_expect(this->gptr() < this->egptr(), true))
     320                 :           __ret = traits_type::to_int_type(*this->gptr());
     321                 :         else 
     322                 :           __ret = this->underflow();
     323                 :         return __ret;
     324                 :       }
     325                 : 
     326                 :       /**
     327                 :        *  @brief  Entry point for xsgetn.
     328                 :        *  @param  s  A buffer area.
     329                 :        *  @param  n  A count.
     330                 :        *
     331                 :        *  Returns xsgetn(s,n).  The effect is to fill @a s[0] through
     332                 :        *  @a s[n-1] with characters from the input sequence, if possible.
     333                 :       */
     334                 :       streamsize 
     335                 :       sgetn(char_type* __s, streamsize __n)
     336                 :       { return this->xsgetn(__s, __n); }
     337                 : 
     338                 :       // [27.5.2.2.4] putback
     339                 :       /**
     340                 :        *  @brief  Pushing characters back into the input stream.
     341                 :        *  @param  c  The character to push back.
     342                 :        *  @return  The previous character, if possible.
     343                 :        *
     344                 :        *  Similar to sungetc(), but @a c is pushed onto the stream
     345                 :        *  instead of <em>the previous character.</em> If successful,
     346                 :        *  the next character fetched from the input stream will be @a
     347                 :        *  c.
     348                 :       */
     349                 :       int_type 
     350                 :       sputbackc(char_type __c)
     351                 :       {
     352                 :         int_type __ret;
     353                 :         const bool __testpos = this->eback() < this->gptr();
     354                 :         if (__builtin_expect(!__testpos || 
     355                 :                              !traits_type::eq(__c, this->gptr()[-1]), false))
     356                 :           __ret = this->pbackfail(traits_type::to_int_type(__c));
     357                 :         else 
     358                 :           {
     359                 :             this->gbump(-1);
     360                 :             __ret = traits_type::to_int_type(*this->gptr());
     361                 :           }
     362                 :         return __ret;
     363                 :       }
     364                 : 
     365                 :       /**
     366                 :        *  @brief  Moving backwards in the input stream.
     367                 :        *  @return  The previous character, if possible.
     368                 :        *
     369                 :        *  If a putback position is available, this function decrements
     370                 :        *  the input pointer and returns that character.  Otherwise,
     371                 :        *  calls and returns pbackfail().  The effect is to @a unget
     372                 :        *  the last character @a gotten.
     373                 :       */
     374                 :       int_type 
     375                 :       sungetc()
     376                 :       {
     377                 :         int_type __ret;
     378                 :         if (__builtin_expect(this->eback() < this->gptr(), true))
     379                 :           {
     380                 :             this->gbump(-1);
     381                 :             __ret = traits_type::to_int_type(*this->gptr());
     382                 :           }
     383                 :         else 
     384                 :           __ret = this->pbackfail();
     385                 :         return __ret;
     386                 :       }
     387                 : 
     388                 :       // [27.5.2.2.5] put area
     389                 :       /**
     390                 :        *  @brief  Entry point for all single-character output functions.
     391                 :        *  @param  c  A character to output.
     392                 :        *  @return  @a c, if possible.
     393                 :        *
     394                 :        *  One of two public output functions.
     395                 :        *
     396                 :        *  If a write position is available for the output sequence (i.e.,
     397                 :        *  the buffer is not full), stores @a c in that position, increments
     398                 :        *  the position, and returns @c traits::to_int_type(c).  If a write
     399                 :        *  position is not available, returns @c overflow(c).
     400                 :       */
     401                 :       int_type 
     402               0 :       sputc(char_type __c)
     403                 :       {
     404                 :         int_type __ret;
     405               0 :         if (__builtin_expect(this->pptr() < this->epptr(), true))
     406                 :           {
     407               0 :             *this->pptr() = __c;
     408               0 :             this->pbump(1);
     409               0 :             __ret = traits_type::to_int_type(__c);
     410                 :           }
     411                 :         else
     412               0 :           __ret = this->overflow(traits_type::to_int_type(__c));
     413               0 :         return __ret;
     414                 :       }
     415                 : 
     416                 :       /**
     417                 :        *  @brief  Entry point for all single-character output functions.
     418                 :        *  @param  s  A buffer read area.
     419                 :        *  @param  n  A count.
     420                 :        *
     421                 :        *  One of two public output functions.
     422                 :        *
     423                 :        *
     424                 :        *  Returns xsputn(s,n).  The effect is to write @a s[0] through
     425                 :        *  @a s[n-1] to the output sequence, if possible.
     426                 :       */
     427                 :       streamsize 
     428               0 :       sputn(const char_type* __s, streamsize __n)
     429               0 :       { return this->xsputn(__s, __n); }
     430                 : 
     431                 :     protected:
     432                 :       /**
     433                 :        *  @brief  Base constructor.
     434                 :        *
     435                 :        *  Only called from derived constructors, and sets up all the
     436                 :        *  buffer data to zero, including the pointers described in the
     437                 :        *  basic_streambuf class description.  Note that, as a result,
     438                 :        *  - the class starts with no read nor write positions available,
     439                 :        *  - this is not an error
     440                 :       */
     441               0 :       basic_streambuf()
     442                 :       : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 
     443                 :       _M_out_beg(0), _M_out_cur(0), _M_out_end(0),
     444               0 :       _M_buf_locale(locale()) 
     445               0 :       { }
     446                 : 
     447                 :       // [27.5.2.3.1] get area access
     448                 :       //@{
     449                 :       /**
     450                 :        *  @brief  Access to the get area.
     451                 :        *
     452                 :        *  These functions are only available to other protected functions,
     453                 :        *  including derived classes.
     454                 :        *
     455                 :        *  - eback() returns the beginning pointer for the input sequence
     456                 :        *  - gptr() returns the next pointer for the input sequence
     457                 :        *  - egptr() returns the end pointer for the input sequence
     458                 :       */
     459                 :       char_type* 
     460               0 :       eback() const { return _M_in_beg; }
     461                 : 
     462                 :       char_type* 
     463               0 :       gptr()  const { return _M_in_cur;  }
     464                 : 
     465                 :       char_type* 
     466               0 :       egptr() const { return _M_in_end; }
     467                 :       //@}
     468                 : 
     469                 :       /**
     470                 :        *  @brief  Moving the read position.
     471                 :        *  @param  n  The delta by which to move.
     472                 :        *
     473                 :        *  This just advances the read position without returning any data.
     474                 :       */
     475                 :       void 
     476               0 :       gbump(int __n) { _M_in_cur += __n; }
     477                 : 
     478                 :       /**
     479                 :        *  @brief  Setting the three read area pointers.
     480                 :        *  @param  gbeg  A pointer.
     481                 :        *  @param  gnext  A pointer.
     482                 :        *  @param  gend  A pointer.
     483                 :        *  @post  @a gbeg == @c eback(), @a gnext == @c gptr(), and
     484                 :        *         @a gend == @c egptr()
     485                 :       */
     486                 :       void 
     487               0 :       setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
     488                 :       {
     489               0 :         _M_in_beg = __gbeg;
     490               0 :         _M_in_cur = __gnext;
     491               0 :         _M_in_end = __gend;
     492               0 :       }
     493                 : 
     494                 :       // [27.5.2.3.2] put area access
     495                 :       //@{
     496                 :       /**
     497                 :        *  @brief  Access to the put area.
     498                 :        *
     499                 :        *  These functions are only available to other protected functions,
     500                 :        *  including derived classes.
     501                 :        *
     502                 :        *  - pbase() returns the beginning pointer for the output sequence
     503                 :        *  - pptr() returns the next pointer for the output sequence
     504                 :        *  - epptr() returns the end pointer for the output sequence
     505                 :       */
     506                 :       char_type* 
     507               0 :       pbase() const { return _M_out_beg; }
     508                 : 
     509                 :       char_type* 
     510               0 :       pptr() const { return _M_out_cur; }
     511                 : 
     512                 :       char_type* 
     513               0 :       epptr() const { return _M_out_end; }
     514                 :       //@}
     515                 : 
     516                 :       /**
     517                 :        *  @brief  Moving the write position.
     518                 :        *  @param  n  The delta by which to move.
     519                 :        *
     520                 :        *  This just advances the write position without returning any data.
     521                 :       */
     522                 :       void 
     523               0 :       pbump(int __n) { _M_out_cur += __n; }
     524                 : 
     525                 :       /**
     526                 :        *  @brief  Setting the three write area pointers.
     527                 :        *  @param  pbeg  A pointer.
     528                 :        *  @param  pend  A pointer.
     529                 :        *  @post  @a pbeg == @c pbase(), @a pbeg == @c pptr(), and
     530                 :        *         @a pend == @c epptr()
     531                 :       */
     532                 :       void 
     533               0 :       setp(char_type* __pbeg, char_type* __pend)
     534                 :       { 
     535               0 :         _M_out_beg = _M_out_cur = __pbeg; 
     536               0 :         _M_out_end = __pend;
     537               0 :       }
     538                 : 
     539                 :       // [27.5.2.4] virtual functions
     540                 :       // [27.5.2.4.1] locales
     541                 :       /**
     542                 :        *  @brief  Changes translations.
     543                 :        *  @param  loc  A new locale.
     544                 :        *
     545                 :        *  Translations done during I/O which depend on the current
     546                 :        *  locale are changed by this call.  The standard adds,
     547                 :        *  <em>Between invocations of this function a class derived
     548                 :        *  from streambuf can safely cache results of calls to locale
     549                 :        *  functions and to members of facets so obtained.</em>
     550                 :        *
     551                 :        *  @note  Base class version does nothing.
     552                 :       */
     553                 :       virtual void 
     554               0 :       imbue(const locale&) 
     555               0 :       { }
     556                 : 
     557                 :       // [27.5.2.4.2] buffer management and positioning
     558                 :       /**
     559                 :        *  @brief  Manipulates the buffer.
     560                 :        *
     561                 :        *  Each derived class provides its own appropriate behavior.  See
     562                 :        *  the next-to-last paragraph of 
     563                 :        *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html
     564                 :        *  for more on this function.
     565                 :        *
     566                 :        *  @note  Base class version does nothing, returns @c this.
     567                 :       */
     568                 :       virtual basic_streambuf<char_type,_Traits>* 
     569                 :       setbuf(char_type*, streamsize)
     570                 :       { return this; }
     571                 :       
     572                 :       /**
     573                 :        *  @brief  Alters the stream positions.
     574                 :        *
     575                 :        *  Each derived class provides its own appropriate behavior.
     576                 :        *  @note  Base class version does nothing, returns a @c pos_type
     577                 :        *         that represents an invalid stream position.
     578                 :       */
     579                 :       virtual pos_type 
     580                 :       seekoff(off_type, ios_base::seekdir,
     581                 :               ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
     582                 :       { return pos_type(off_type(-1)); } 
     583                 : 
     584                 :       /**
     585                 :        *  @brief  Alters the stream positions.
     586                 :        *
     587                 :        *  Each derived class provides its own appropriate behavior.
     588                 :        *  @note  Base class version does nothing, returns a @c pos_type
     589                 :        *         that represents an invalid stream position.
     590                 :       */
     591                 :       virtual pos_type 
     592                 :       seekpos(pos_type, 
     593                 :               ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
     594                 :       { return pos_type(off_type(-1)); } 
     595                 : 
     596                 :       /**
     597                 :        *  @brief  Synchronizes the buffer arrays with the controlled sequences.
     598                 :        *  @return  -1 on failure.
     599                 :        *
     600                 :        *  Each derived class provides its own appropriate behavior,
     601                 :        *  including the definition of @a failure.
     602                 :        *  @note  Base class version does nothing, returns zero.
     603                 :       */
     604                 :       virtual int 
     605               0 :       sync() { return 0; }
     606                 : 
     607                 :       // [27.5.2.4.3] get area
     608                 :       /**
     609                 :        *  @brief  Investigating the data available.
     610                 :        *  @return  An estimate of the number of characters available in the
     611                 :        *           input sequence, or -1.
     612                 :        *
     613                 :        *  <em>If it returns a positive value, then successive calls to
     614                 :        *  @c underflow() will not return @c traits::eof() until at
     615                 :        *  least that number of characters have been supplied.  If @c
     616                 :        *  showmanyc() returns -1, then calls to @c underflow() or @c
     617                 :        *  uflow() will fail.</em> [27.5.2.4.3]/1
     618                 :        *
     619                 :        *  @note  Base class version does nothing, returns zero.
     620                 :        *  @note  The standard adds that <em>the intention is not only that the
     621                 :        *         calls [to underflow or uflow] will not return @c eof() but
     622                 :        *         that they will return immediately.</em>
     623                 :        *  @note  The standard adds that <em>the morphemes of @c showmanyc are
     624                 :        *         @b es-how-many-see, not @b show-manic.</em>
     625                 :       */
     626                 :       virtual streamsize 
     627                 :       showmanyc() { return 0; }
     628                 : 
     629                 :       /**
     630                 :        *  @brief  Multiple character extraction.
     631                 :        *  @param  s  A buffer area.
     632                 :        *  @param  n  Maximum number of characters to assign.
     633                 :        *  @return  The number of characters assigned.
     634                 :        *
     635                 :        *  Fills @a s[0] through @a s[n-1] with characters from the input
     636                 :        *  sequence, as if by @c sbumpc().  Stops when either @a n characters
     637                 :        *  have been copied, or when @c traits::eof() would be copied.
     638                 :        *
     639                 :        *  It is expected that derived classes provide a more efficient
     640                 :        *  implementation by overriding this definition.
     641                 :       */
     642                 :       virtual streamsize 
     643                 :       xsgetn(char_type* __s, streamsize __n);
     644                 : 
     645                 :       /**
     646                 :        *  @brief  Fetches more data from the controlled sequence.
     647                 :        *  @return  The first character from the <em>pending sequence</em>.
     648                 :        *
     649                 :        *  Informally, this function is called when the input buffer is
     650                 :        *  exhausted (or does not exist, as buffering need not actually be
     651                 :        *  done).  If a buffer exists, it is @a refilled.  In either case, the
     652                 :        *  next available character is returned, or @c traits::eof() to
     653                 :        *  indicate a null pending sequence.
     654                 :        *
     655                 :        *  For a formal definition of the pending sequence, see a good text
     656                 :        *  such as Langer & Kreft, or [27.5.2.4.3]/7-14.
     657                 :        *
     658                 :        *  A functioning input streambuf can be created by overriding only
     659                 :        *  this function (no buffer area will be used).  For an example, see
     660                 :        *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25.html
     661                 :        *
     662                 :        *  @note  Base class version does nothing, returns eof().
     663                 :       */
     664                 :       virtual int_type 
     665                 :       underflow()
     666                 :       { return traits_type::eof(); }
     667                 : 
     668                 :       /**
     669                 :        *  @brief  Fetches more data from the controlled sequence.
     670                 :        *  @return  The first character from the <em>pending sequence</em>.
     671                 :        *
     672                 :        *  Informally, this function does the same thing as @c underflow(),
     673                 :        *  and in fact is required to call that function.  It also returns
     674                 :        *  the new character, like @c underflow() does.  However, this
     675                 :        *  function also moves the read position forward by one.
     676                 :       */
     677                 :       virtual int_type 
     678               0 :       uflow() 
     679                 :       {
     680               0 :         int_type __ret = traits_type::eof();
     681                 :         const bool __testeof = traits_type::eq_int_type(this->underflow(), 
     682               0 :                                                         __ret);
     683               0 :         if (!__testeof)
     684                 :           {
     685               0 :             __ret = traits_type::to_int_type(*this->gptr());
     686               0 :             this->gbump(1);
     687                 :           }
     688               0 :         return __ret;    
     689                 :       }
     690                 : 
     691                 :       // [27.5.2.4.4] putback
     692                 :       /**
     693                 :        *  @brief  Tries to back up the input sequence.
     694                 :        *  @param  c  The character to be inserted back into the sequence.
     695                 :        *  @return  eof() on failure, <em>some other value</em> on success
     696                 :        *  @post  The constraints of @c gptr(), @c eback(), and @c pptr()
     697                 :        *         are the same as for @c underflow().
     698                 :        *
     699                 :        *  @note  Base class version does nothing, returns eof().
     700                 :       */
     701                 :       virtual int_type 
     702                 :       pbackfail(int_type /* __c */  = traits_type::eof())
     703                 :       { return traits_type::eof(); }
     704                 : 
     705                 :       // Put area:
     706                 :       /**
     707                 :        *  @brief  Multiple character insertion.
     708                 :        *  @param  s  A buffer area.
     709                 :        *  @param  n  Maximum number of characters to write.
     710                 :        *  @return  The number of characters written.
     711                 :        *
     712                 :        *  Writes @a s[0] through @a s[n-1] to the output sequence, as if
     713                 :        *  by @c sputc().  Stops when either @a n characters have been
     714                 :        *  copied, or when @c sputc() would return @c traits::eof().
     715                 :        *
     716                 :        *  It is expected that derived classes provide a more efficient
     717                 :        *  implementation by overriding this definition.
     718                 :       */
     719                 :       virtual streamsize 
     720                 :       xsputn(const char_type* __s, streamsize __n);
     721                 : 
     722                 :       /**
     723                 :        *  @brief  Consumes data from the buffer; writes to the
     724                 :        *          controlled sequence.
     725                 :        *  @param  c  An additional character to consume.
     726                 :        *  @return  eof() to indicate failure, something else (usually
     727                 :        *           @a c, or not_eof())
     728                 :        *
     729                 :        *  Informally, this function is called when the output buffer
     730                 :        *  is full (or does not exist, as buffering need not actually
     731                 :        *  be done).  If a buffer exists, it is @a consumed, with
     732                 :        *  <em>some effect</em> on the controlled sequence.
     733                 :        *  (Typically, the buffer is written out to the sequence
     734                 :        *  verbatim.)  In either case, the character @a c is also
     735                 :        *  written out, if @a c is not @c eof().
     736                 :        *
     737                 :        *  For a formal definition of this function, see a good text
     738                 :        *  such as Langer & Kreft, or [27.5.2.4.5]/3-7.
     739                 :        *
     740                 :        *  A functioning output streambuf can be created by overriding only
     741                 :        *  this function (no buffer area will be used).
     742                 :        *
     743                 :        *  @note  Base class version does nothing, returns eof().
     744                 :       */
     745                 :       virtual int_type 
     746                 :       overflow(int_type /* __c */ = traits_type::eof())
     747                 :       { return traits_type::eof(); }
     748                 : 
     749                 : #if _GLIBCXX_DEPRECATED
     750                 :     // Annex D.6
     751                 :     public:
     752                 :       /**
     753                 :        *  @brief  Tosses a character.
     754                 :        *
     755                 :        *  Advances the read pointer, ignoring the character that would have
     756                 :        *  been read.
     757                 :        *
     758                 :        *  See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html
     759                 :        */
     760                 :       void 
     761                 :       stossc() 
     762                 :       {
     763                 :         if (this->gptr() < this->egptr()) 
     764                 :           this->gbump(1);
     765                 :         else 
     766                 :           this->uflow();
     767                 :       }
     768                 : #endif
     769                 : 
     770                 :     private:
     771                 :       // _GLIBCXX_RESOLVE_LIB_DEFECTS
     772                 :       // Side effect of DR 50. 
     773                 :       basic_streambuf(const __streambuf_type& __sb)
     774                 :       : _M_in_beg(__sb._M_in_beg), _M_in_cur(__sb._M_in_cur), 
     775                 :       _M_in_end(__sb._M_in_end), _M_out_beg(__sb._M_out_beg), 
     776                 :       _M_out_cur(__sb._M_out_cur), _M_out_end(__sb._M_out_cur),
     777                 :       _M_buf_locale(__sb._M_buf_locale) 
     778                 :       { }
     779                 : 
     780                 :       __streambuf_type& 
     781                 :       operator=(const __streambuf_type&) { return *this; };
     782                 :     };
     783                 : 
     784                 :   // Explicit specialization declarations, defined in src/streambuf.cc.
     785                 :   template<>
     786                 :     streamsize
     787                 :     __copy_streambufs_eof(basic_streambuf<char>* __sbin,
     788                 :                           basic_streambuf<char>* __sbout, bool& __ineof);
     789                 : #ifdef _GLIBCXX_USE_WCHAR_T
     790                 :   template<>
     791                 :     streamsize
     792                 :     __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin,
     793                 :                           basic_streambuf<wchar_t>* __sbout, bool& __ineof);
     794                 : #endif
     795                 : 
     796                 : _GLIBCXX_END_NAMESPACE
     797                 : 
     798                 : #ifndef _GLIBCXX_EXPORT_TEMPLATE
     799                 : # include <bits/streambuf.tcc>
     800                 : #endif
     801                 : 
     802                 : #endif /* _GLIBCXX_STREAMBUF */

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