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Whole document tree                   std_streambuf.h Go to the documentation of this file. // Stream buffer classes -*- C++ -*- // Copyright (C) 1997, 1998, 1999, 2000, 2001 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 // #ifndef _CPP_STREAMBUF #define _CPP_STREAMBUF 1 #pragma GCC system_header #include <bits/c++config.h> #include <bits/std_iosfwd.h> #include <bits/std_cstdio.h> // For SEEK_SET, SEEK_CUR, SEEK_END #include <bits/localefwd.h> #include <bits/ios_base.h> namespace std { template<typename _CharT, typename _Traits> streamsize __copy_streambufs(basic_ios<_CharT, _Traits>& _ios, basic_streambuf<_CharT, _Traits>* __sbin, basic_streambuf<_CharT, _Traits>* __sbout); // 27.5.2 Template class basic_streambuf<_CharT, _Traits> template<typename _CharT, typename _Traits> class basic_streambuf { public: // Types: 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; // Non-standard Types: typedef ctype<char_type> __ctype_type; typedef basic_streambuf<char_type, traits_type> __streambuf_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: // 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. char_type* _M_buf; // Actual size of allocated internal buffer, in bytes. int_type _M_buf_size; // Optimal or preferred size of internal buffer, in bytes. int_type _M_buf_size_opt; // True iff _M_in_* and _M_out_* buffers should always point to // the same place. True for fstreams, false for sstreams. bool _M_buf_unified; // 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 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. // Place to stash in || out || in | out settings for current streambuf. ios_base::openmode _M_mode; // Current locale setting. locale _M_buf_locale; // True iff locale is initialized. bool _M_buf_locale_init; // 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... // NB: pbacks of over one character are not currently supported. int_type _M_pback_size; char_type* _M_pback; char_type* _M_pback_cur_save; char_type* _M_pback_end_save; bool _M_pback_init; // 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) { int_type __dist = _M_in_end - _M_in_cur; int_type __len = min(_M_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() { if (_M_pback_init) { // Length _M_in_cur moved in the pback buffer. int_type __off_cur = _M_in_cur - _M_pback; // For in | out buffers, the end can be pushed back... int_type __off_end = 0; int_type __pback_len = _M_in_end - _M_pback; int_type __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; } // These three functions are used to clarify internal buffer // maintenance. After an overflow, or after a seekoff call that // started at beg or end, or possibly when the stream becomes // unbuffered, and a myrid other obscure corner cases, the // internal buffer does not truly reflect the contents of the // external buffer. At this point, for whatever reason, it is in // an indeterminate state. void _M_set_indeterminate(void) { if (_M_mode & ios_base::in) this->setg(_M_buf, _M_buf, _M_buf); if (_M_mode & ios_base::out) this->setp(_M_buf, _M_buf); } void _M_set_determinate(off_type __off) { bool __testin = _M_mode & ios_base::in; bool __testout = _M_mode & ios_base::out; if (__testin) this->setg(_M_buf, _M_buf, _M_buf + __off); if (__testout) this->setp(_M_buf, _M_buf + __off); } bool _M_is_indeterminate(void) { bool __ret = false; // Don't return true if unbuffered. if (_M_buf) { if (_M_mode & ios_base::in) __ret = _M_in_beg == _M_in_cur && _M_in_cur == _M_in_end; if (_M_mode & ios_base::out) __ret = _M_out_beg == _M_out_cur && _M_out_cur == _M_out_end; } return __ret; } public: virtual ~basic_streambuf() { _M_buf_unified = false; _M_buf_size = 0; _M_buf_size_opt = 0; _M_mode = ios_base::openmode(0); _M_buf_locale_init = false; } // Locales: locale pubimbue(const locale &__loc) { locale __tmp(this->getloc()); this->imbue(__loc); return __tmp; } locale getloc() const { if (_M_buf_locale_init) return _M_buf_locale; else return locale(); } // Buffer and positioning: __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(); } // Get and put areas: // Get area: streamsize in_avail() { streamsize __ret; if (_M_in_cur && _M_in_cur < _M_in_end) { if (_M_pback_init) { int_type __save_len = _M_pback_end_save - _M_pback_cur_save; int_type __pback_len = _M_in_cur - _M_pback; __ret = __save_len - __pback_len; } else __ret = this->egptr() - this->gptr(); } else __ret = this->showmanyc(); return __ret; } int_type snextc() { int_type __eof = traits_type::eof(); return (this->sbumpc() == __eof ? __eof : this->sgetc()); } int_type sbumpc(); 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; } streamsize sgetn(char_type* __s, streamsize __n) { return this->xsgetn(__s, __n); } // Putback: int_type sputbackc(char_type __c); int_type sungetc(); // Put area: int_type sputc(char_type __c); streamsize sputn(const char_type* __s, streamsize __n) { return this->xsputn(__s, __n); } protected: basic_streambuf() : _M_buf(NULL), _M_buf_size(0), _M_buf_size_opt(static_cast<int_type>(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_buf_locale_init(false), _M_pback_size(1), _M_pback(NULL), _M_pback_cur_save(NULL), _M_pback_end_save(NULL), _M_pback_init(false) { } // Get area: char_type* eback() const { return _M_in_beg; } char_type* gptr() const { return _M_in_cur; } char_type* egptr() const { return _M_in_end; } void gbump(int __n) { _M_in_cur += __n; } 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; } // Put area: char_type* pbase() const { return _M_out_beg; } char_type* pptr() const { return _M_out_cur; } char_type* epptr() const { return _M_out_end; } void pbump(int __n) { _M_out_cur += __n; } 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; } // Virtual functions: // Locales: virtual void imbue(const locale& __loc) { _M_buf_locale_init = true; if (_M_buf_locale != __loc) _M_buf_locale = __loc; } // Buffer management and positioning: virtual basic_streambuf<char_type,_Traits>* setbuf(char_type*, streamsize) { return this; } 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)); } virtual pos_type seekpos(pos_type, ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) { return pos_type(off_type(-1)); } virtual int sync() { return 0; } // Get area: virtual streamsize showmanyc() { return 0; } virtual streamsize xsgetn(char_type* __s, streamsize __n); virtual int_type underflow() { return traits_type::eof(); } virtual int_type uflow() { int_type __ret = traits_type::eof(); bool __testeof = 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; } // Putback: virtual int_type pbackfail(int_type /* __c */ = traits_type::eof()) { return traits_type::eof(); } // Put area: virtual streamsize xsputn(const char_type* __s, streamsize __n); virtual int_type overflow(int_type /* __c */ = traits_type::eof()) { return traits_type::eof(); } #ifdef _GLIBCPP_DEPRECATED public: void stossc() { if (_M_in_cur < _M_in_end) ++_M_in_cur; else this->uflow(); } #endif #ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS private: basic_streambuf(const __streambuf_type&); __streambuf_type& operator=(const __streambuf_type&); #endif }; } // namespace std #ifdef _GLIBCPP_NO_TEMPLATE_EXPORT # define export #ifdef _GLIBCPP_FULLY_COMPLIANT_HEADERS #include <bits/streambuf.tcc> #endif #endif #endif /* _CPP_STREAMBUF */