streambuf

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00001 // Stream buffer classes -*- C++ -*-
00002 
00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
00004 // Free Software Foundation, Inc.
00005 //
00006 // This file is part of the GNU ISO C++ Library.  This library is free
00007 // software; you can redistribute it and/or modify it under the
00008 // terms of the GNU General Public License as published by the
00009 // Free Software Foundation; either version 2, or (at your option)
00010 // any later version.
00011 
00012 // This library is distributed in the hope that it will be useful,
00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015 // GNU General Public License for more details.
00016 
00017 // You should have received a copy of the GNU General Public License along
00018 // with this library; see the file COPYING.  If not, write to the Free
00019 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
00020 // USA.
00021 
00022 // As a special exception, you may use this file as part of a free software
00023 // library without restriction.  Specifically, if other files instantiate
00024 // templates or use macros or inline functions from this file, or you compile
00025 // this file and link it with other files to produce an executable, this
00026 // file does not by itself cause the resulting executable to be covered by
00027 // the GNU General Public License.  This exception does not however
00028 // invalidate any other reasons why the executable file might be covered by
00029 // the GNU General Public License.
00030 
00031 //
00032 // ISO C++ 14882: 27.5  Stream buffers
00033 //
00034 
00040 #ifndef _CPP_STREAMBUF
00041 #define _CPP_STREAMBUF  1
00042 
00043 #pragma GCC system_header
00044 
00045 #include <bits/c++config.h>
00046 #include <iosfwd>
00047 #include <cstdio>   // For SEEK_SET, SEEK_CUR, SEEK_END
00048 #include <bits/localefwd.h>
00049 #include <bits/ios_base.h>
00050 
00051 namespace std
00052 {
00058   template<typename _CharT, typename _Traits>
00059     streamsize
00060     __copy_streambufs(basic_ios<_CharT, _Traits>& _ios,
00061               basic_streambuf<_CharT, _Traits>* __sbin,
00062               basic_streambuf<_CharT, _Traits>* __sbout);
00063   
00124   template<typename _CharT, typename _Traits>
00125     class basic_streambuf 
00126     {
00127     public:
00129 
00134       typedef _CharT                    char_type;
00135       typedef _Traits                   traits_type;
00136       typedef typename traits_type::int_type        int_type;
00137       typedef typename traits_type::pos_type        pos_type;
00138       typedef typename traits_type::off_type        off_type;
00140 
00142 
00147       typedef ctype<char_type>                  __ctype_type;
00148       typedef basic_streambuf<char_type, traits_type>   __streambuf_type;
00149       typedef typename traits_type::state_type      __state_type;
00151       
00152       friend class basic_ios<char_type, traits_type>;
00153       friend class basic_istream<char_type, traits_type>;
00154       friend class basic_ostream<char_type, traits_type>;
00155       friend class istreambuf_iterator<char_type, traits_type>;
00156       friend class ostreambuf_iterator<char_type, traits_type>;
00157 
00158       friend streamsize
00159       __copy_streambufs<>(basic_ios<char_type, traits_type>& __ios,
00160               __streambuf_type* __sbin,__streambuf_type* __sbout);
00161       
00162     protected:
00171       char_type*        _M_buf;     
00172 
00178       size_t            _M_buf_size;
00179 
00185       size_t            _M_buf_size_opt;
00186 
00193       bool          _M_buf_unified; 
00194 
00196 
00205       char_type*        _M_in_beg;      // Start of get area. 
00206       char_type*        _M_in_cur;  // Current read area. 
00207       char_type*        _M_in_end;  // End of get area. 
00208       char_type*        _M_out_beg;     // Start of put area. 
00209       char_type*        _M_out_cur;     // Current put area. 
00210       char_type*        _M_out_end;     // End of put area. 
00212 
00218       ios_base::openmode    _M_mode;    
00219 
00225       locale            _M_buf_locale;  
00226 
00232       bool          _M_buf_locale_init;
00233 
00235 
00245       static const size_t       _S_pback_size = 1; 
00246       char_type         _M_pback[_S_pback_size]; 
00247       char_type*        _M_pback_cur_save;
00248       char_type*        _M_pback_end_save;
00249       bool          _M_pback_init; 
00251 
00257       fpos<__state_type>    _M_pos;
00258 
00259       // Initializes pback buffers, and moves normal buffers to safety.
00260       // Assumptions:
00261       // _M_in_cur has already been moved back
00262       void
00263       _M_pback_create()
00264       {
00265     if (!_M_pback_init)
00266       {
00267         size_t __dist = _M_in_end - _M_in_cur;
00268         size_t __len = min(_S_pback_size, __dist);
00269         traits_type::copy(_M_pback, _M_in_cur, __len);
00270         _M_pback_cur_save = _M_in_cur;
00271         _M_pback_end_save = _M_in_end;
00272         this->setg(_M_pback, _M_pback, _M_pback + __len);
00273         _M_pback_init = true;
00274       }
00275       }
00276 
00277       // Deactivates pback buffer contents, and restores normal buffer.
00278       // Assumptions:
00279       // The pback buffer has only moved forward.
00280       void
00281       _M_pback_destroy() throw()
00282       {
00283     if (_M_pback_init)
00284       {
00285         // Length _M_in_cur moved in the pback buffer.
00286         size_t __off_cur = _M_in_cur - _M_pback;
00287         
00288         // For in | out buffers, the end can be pushed back...
00289         size_t __off_end = 0;
00290         size_t __pback_len = _M_in_end - _M_pback;
00291         size_t __save_len = _M_pback_end_save - _M_buf;
00292         if (__pback_len > __save_len)
00293           __off_end = __pback_len - __save_len;
00294 
00295         this->setg(_M_buf, _M_pback_cur_save + __off_cur, 
00296                _M_pback_end_save + __off_end);
00297         _M_pback_cur_save = NULL;
00298         _M_pback_end_save = NULL;
00299         _M_pback_init = false;
00300       }
00301       }
00302 
00303       // Correctly sets the _M_in_cur pointer, and bumps the
00304       // _M_out_cur pointer as well if necessary.
00305       void 
00306       _M_in_cur_move(off_type __n) // argument needs to be +-
00307       {
00308     bool __testout = _M_out_cur;
00309     _M_in_cur += __n;
00310     if (__testout && _M_buf_unified)
00311       _M_out_cur += __n;
00312       }
00313 
00314       // Correctly sets the _M_out_cur pointer, and bumps the
00315       // appropriate _M_*_end pointers as well. Necessary for the
00316       // un-tied stringbufs, in in|out mode.
00317       // Invariant:
00318       // __n + _M_out_[cur, end] <= _M_buf + _M_buf_size
00319       // Assuming all _M_*_[beg, cur, end] pointers are operating on
00320       // the same range:
00321       // _M_buf <= _M_*_ <= _M_buf + _M_buf_size
00322       void 
00323       _M_out_cur_move(off_type __n) // argument needs to be +-
00324       {
00325     bool __testin = _M_in_cur;
00326 
00327     _M_out_cur += __n;
00328     if (__testin && _M_buf_unified)
00329       _M_in_cur += __n;
00330     if (_M_out_cur > _M_out_end)
00331       {
00332         _M_out_end = _M_out_cur;
00333         // NB: in | out buffers drag the _M_in_end pointer along...
00334         if (__testin)
00335           _M_in_end += __n;
00336       }
00337       }
00338 
00339       // Return the size of the output buffer.  This depends on the
00340       // buffer in use: allocated buffers have a stored size in
00341       // _M_buf_size and setbuf() buffers don't.
00342       off_type
00343       _M_out_buf_size()
00344       {
00345     off_type __ret = 0;
00346     if (_M_out_cur)
00347       {
00348         // Using allocated buffer.
00349         if (_M_out_beg == _M_buf)
00350           __ret = _M_out_beg + _M_buf_size - _M_out_cur;
00351         // Using non-allocated buffer.
00352         else
00353           __ret = _M_out_end - _M_out_cur;
00354       }
00355     return __ret;
00356       }
00357 
00358   public:
00360       virtual 
00361       ~basic_streambuf() 
00362       {
00363     _M_buf_unified = false;
00364     _M_buf_size = 0;
00365     _M_buf_size_opt = 0;
00366     _M_mode = ios_base::openmode(0);
00367       }
00368 
00369       // [27.5.2.2.1] locales
00377       locale 
00378       pubimbue(const locale &__loc)
00379       {
00380     locale __tmp(this->getloc());
00381     this->imbue(__loc);
00382     return __tmp;
00383       }
00384 
00393       locale   
00394       getloc() const
00395       { return _M_buf_locale; } 
00396 
00397       // [27.5.2.2.2] buffer management and positioning
00399 
00406       __streambuf_type* 
00407       pubsetbuf(char_type* __s, streamsize __n) 
00408       { return this->setbuf(__s, __n); }
00409 
00410       pos_type 
00411       pubseekoff(off_type __off, ios_base::seekdir __way, 
00412          ios_base::openmode __mode = ios_base::in | ios_base::out)
00413       { return this->seekoff(__off, __way, __mode); }
00414 
00415       pos_type 
00416       pubseekpos(pos_type __sp,
00417          ios_base::openmode __mode = ios_base::in | ios_base::out)
00418       { return this->seekpos(__sp, __mode); }
00419 
00420       int 
00421       pubsync() { return this->sync(); }
00423 
00424       // [27.5.2.2.3] get area
00433       streamsize 
00434       in_avail() 
00435       { 
00436     streamsize __ret;
00437     if (_M_in_cur && _M_in_cur < _M_in_end)
00438       {
00439         if (_M_pback_init)
00440           {
00441         size_t __save_len =  _M_pback_end_save - _M_pback_cur_save;
00442         size_t __pback_len = _M_in_cur - _M_pback;
00443         __ret = __save_len - __pback_len;
00444           }
00445         else
00446           __ret = this->egptr() - this->gptr();
00447       }
00448     else
00449       __ret = this->showmanyc();
00450     return __ret;
00451       }
00452 
00460       int_type 
00461       snextc()
00462       {
00463     int_type __eof = traits_type::eof();
00464     return (traits_type::eq_int_type(this->sbumpc(), __eof) 
00465         ? __eof : this->sgetc());
00466       }
00467 
00476       int_type 
00477       sbumpc();
00478 
00487       int_type 
00488       sgetc()
00489       {
00490     int_type __ret;
00491     if (_M_in_cur && _M_in_cur < _M_in_end)
00492       __ret = traits_type::to_int_type(*(this->gptr()));
00493     else 
00494       __ret = this->underflow();
00495     return __ret;
00496       }
00497 
00506       streamsize 
00507       sgetn(char_type* __s, streamsize __n)
00508       { return this->xsgetn(__s, __n); }
00509 
00510       // [27.5.2.2.4] putback
00520       int_type 
00521       sputbackc(char_type __c);
00522 
00532       int_type 
00533       sungetc();
00534 
00535       // [27.5.2.2.5] put area
00548       int_type 
00549       sputc(char_type __c);
00550 
00562       streamsize 
00563       sputn(const char_type* __s, streamsize __n)
00564       { return this->xsputn(__s, __n); }
00565 
00566     protected:
00576       basic_streambuf()
00577       : _M_buf(NULL), _M_buf_size(0), _M_buf_size_opt(BUFSIZ), 
00578       _M_buf_unified(false), _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 
00579       _M_out_beg(0), _M_out_cur(0), _M_out_end(0), 
00580       _M_mode(ios_base::openmode(0)), _M_buf_locale(locale()), 
00581       _M_pback_cur_save(0), _M_pback_end_save(0), 
00582       _M_pback_init(false)
00583       { }
00584 
00585       // [27.5.2.3.1] get area access
00587 
00597       char_type* 
00598       eback() const { return _M_in_beg; }
00599 
00600       char_type* 
00601       gptr()  const { return _M_in_cur;  }
00602 
00603       char_type* 
00604       egptr() const { return _M_in_end; }
00606 
00613       void 
00614       gbump(int __n) { _M_in_cur += __n; }
00615 
00624       void 
00625       setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)
00626       {
00627     _M_in_beg = __gbeg;
00628     _M_in_cur = __gnext;
00629     _M_in_end = __gend;
00630     if (!(_M_mode & ios_base::in) && __gbeg && __gnext && __gend)
00631       _M_mode = _M_mode | ios_base::in;
00632       }
00633 
00634       // [27.5.2.3.2] put area access
00636 
00646       char_type* 
00647       pbase() const { return _M_out_beg; }
00648 
00649       char_type* 
00650       pptr() const { return _M_out_cur; }
00651 
00652       char_type* 
00653       epptr() const { return _M_out_end; }
00655 
00662       void 
00663       pbump(int __n) { _M_out_cur += __n; }
00664 
00672       void 
00673       setp(char_type* __pbeg, char_type* __pend)
00674       { 
00675     _M_out_beg = _M_out_cur = __pbeg; 
00676     _M_out_end = __pend; 
00677     if (!(_M_mode & ios_base::out) && __pbeg && __pend)
00678       _M_mode = _M_mode | ios_base::out;
00679       }
00680 
00681       // [27.5.2.4] virtual functions
00682       // [27.5.2.4.1] locales
00694       virtual void 
00695       imbue(const locale& __loc) 
00696       { 
00697     if (_M_buf_locale != __loc)
00698       _M_buf_locale = __loc;
00699       }
00700 
00701       // [27.5.2.4.2] buffer management and positioning
00712       virtual basic_streambuf<char_type,_Traits>* 
00713       setbuf(char_type*, streamsize)
00714       { return this; }
00715       
00723       virtual pos_type 
00724       seekoff(off_type, ios_base::seekdir,
00725           ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
00726       { return pos_type(off_type(-1)); } 
00727 
00735       virtual pos_type 
00736       seekpos(pos_type, 
00737           ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out)
00738       { return pos_type(off_type(-1)); } 
00739 
00748       virtual int 
00749       sync() { return 0; }
00750 
00751       // [27.5.2.4.3] get area
00770       virtual streamsize 
00771       showmanyc() { return 0; }
00772 
00786       virtual streamsize 
00787       xsgetn(char_type* __s, streamsize __n);
00788 
00808       virtual int_type 
00809       underflow()
00810       { return traits_type::eof(); }
00811 
00821       virtual int_type 
00822       uflow() 
00823       {
00824     int_type __ret = traits_type::eof();
00825     bool __testeof = traits_type::eq_int_type(this->underflow(), __ret);
00826     bool __testpending = _M_in_cur && _M_in_cur < _M_in_end;
00827     if (!__testeof && __testpending)
00828       {
00829         __ret = traits_type::to_int_type(*_M_in_cur);
00830         ++_M_in_cur;
00831         if (_M_buf_unified && _M_mode & ios_base::out)
00832           ++_M_out_cur;
00833       }
00834     return __ret;    
00835       }
00836 
00837       // [27.5.2.4.4] putback
00847       virtual int_type 
00848       pbackfail(int_type /* __c */  = traits_type::eof())
00849       { return traits_type::eof(); }
00850 
00851       // Put area:
00865       virtual streamsize 
00866       xsputn(const char_type* __s, streamsize __n);
00867 
00890       virtual int_type 
00891       overflow(int_type /* __c */ = traits_type::eof())
00892       { return traits_type::eof(); }
00893 
00894 #ifdef _GLIBCPP_DEPRECATED
00895     // Annex D.6
00896     public:
00909       void 
00910       stossc() 
00911       {
00912     if (_M_in_cur < _M_in_end) 
00913       ++_M_in_cur;
00914     else 
00915       this->uflow();
00916       }
00917 #endif
00918 
00919 #ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
00920     // Side effect of DR 50. 
00921     private:
00922       basic_streambuf(const __streambuf_type&) { }; 
00923 
00924       __streambuf_type& 
00925       operator=(const __streambuf_type&) { return *this; };
00926 #endif
00927     };
00928 } // namespace std
00929 
00930 #ifdef _GLIBCPP_NO_TEMPLATE_EXPORT
00931 # define export
00932 #endif
00933 #ifdef  _GLIBCPP_FULLY_COMPLIANT_HEADERS
00934 #include <bits/streambuf.tcc>
00935 #endif
00936 
00937 #endif  

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