781a529886
2003-11-15 Paolo Carlini <pcarlini@suse.de> * include/std/std_fstream.h: Tweak a comment. From-SVN: r73640
861 lines
25 KiB
C++
861 lines
25 KiB
C++
// File based streams -*- C++ -*-
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// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
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// Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 2, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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//
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// ISO C++ 14882: 27.8 File-based streams
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//
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/** @file fstream
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* This is a Standard C++ Library header. You should @c #include this header
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* in your programs, rather than any of the "st[dl]_*.h" implementation files.
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*/
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#ifndef _GLIBCXX_FSTREAM
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#define _GLIBCXX_FSTREAM 1
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#pragma GCC system_header
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#include <istream>
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#include <ostream>
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#include <locale> // For codecvt
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#include <cstdio> // For SEEK_SET, SEEK_CUR, SEEK_END, BUFSIZ
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#include <bits/basic_file.h>
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#include <bits/gthr.h>
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namespace std
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{
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// [27.8.1.1] template class basic_filebuf
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/**
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* @brief The actual work of input and output (for files).
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*
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* This class associates both its input and output sequence with an
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* external disk file, and maintains a joint file position for both
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* sequences. Many of its sematics are described in terms of similar
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* behavior in the Standard C Library's @c FILE streams.
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*/
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// Requirements on traits_type, specific to this class:
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// traits_type::pos_type must be fpos<traits_type::state_type>
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// traits_type::off_type must be streamoff
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// traits_type::state_type must be Assignable and DefaultConstructable,
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// and traits_type::state_type() must be the initial state for codecvt.
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template<typename _CharT, typename _Traits>
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class basic_filebuf : public basic_streambuf<_CharT, _Traits>
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{
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public:
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// Types:
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typedef _CharT char_type;
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typedef _Traits traits_type;
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typedef typename traits_type::int_type int_type;
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typedef typename traits_type::pos_type pos_type;
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typedef typename traits_type::off_type off_type;
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//@{
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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typedef basic_streambuf<char_type, traits_type> __streambuf_type;
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typedef basic_filebuf<char_type, traits_type> __filebuf_type;
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typedef __basic_file<char> __file_type;
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typedef typename traits_type::state_type __state_type;
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typedef codecvt<char_type, char, __state_type> __codecvt_type;
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//@}
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friend class ios_base; // For sync_with_stdio.
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protected:
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// Data Members:
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// MT lock inherited from libio or other low-level io library.
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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__c_lock _M_lock;
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// External buffer.
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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__file_type _M_file;
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/**
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* @if maint
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* Place to stash in || out || in | out settings for current filebuf.
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* @endif
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*/
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ios_base::openmode _M_mode;
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// Beginning state type for codecvt.
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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__state_type _M_state_beg;
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// During output, the state that corresponds to pptr(),
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// during input, the state that corresponds to egptr() and
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// _M_ext_next.
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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__state_type _M_state_cur;
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// Not used for output. During input, the state that corresponds
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// to eback() and _M_ext_buf.
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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__state_type _M_state_last;
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/**
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* @if maint
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* Pointer to the beginning of internal buffer.
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* @endif
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*/
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char_type* _M_buf;
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/**
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* @if maint
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* Actual size of internal buffer. This number is equal to the size
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* of the put area + 1 position, reserved for the overflow char of
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* a full area.
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* @endif
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*/
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size_t _M_buf_size;
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// Set iff _M_buf is allocated memory from _M_allocate_internal_buffer.
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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bool _M_buf_allocated;
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/**
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* @if maint
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* _M_reading == false && _M_writing == false for 'uncommitted' mode;
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* _M_reading == true for 'read' mode;
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* _M_writing == true for 'write' mode;
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*
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* NB: _M_reading == true && _M_writing == true is unused.
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* @endif
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*/
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bool _M_reading;
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bool _M_writing;
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//@{
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/**
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* @if maint
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* Necessary bits for putback buffer management.
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*
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* @note pbacks of over one character are not currently supported.
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* @endif
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*/
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char_type _M_pback;
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char_type* _M_pback_cur_save;
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char_type* _M_pback_end_save;
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bool _M_pback_init;
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//@}
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// Cached codecvt facet.
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const __codecvt_type* _M_codecvt;
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/**
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* @if maint
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* Buffer for external characters. Used for input when
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* codecvt::always_noconv() == false. When valid, this corresponds
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* to eback().
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* @endif
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*/
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char* _M_ext_buf;
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/**
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* @if maint
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* Size of buffer held by _M_ext_buf.
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* @endif
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*/
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streamsize _M_ext_buf_size;
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/**
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* @if maint
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* Pointers into the buffer held by _M_ext_buf that delimit a
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* subsequence of bytes that have been read but not yet converted.
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* When valid, _M_ext_next corresponds to egptr().
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* @endif
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*/
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const char* _M_ext_next;
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char* _M_ext_end;
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/**
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* @if maint
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* Initializes pback buffers, and moves normal buffers to safety.
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* Assumptions:
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* _M_in_cur has already been moved back
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* @endif
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*/
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void
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_M_create_pback()
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{
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if (!_M_pback_init)
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{
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_M_pback_cur_save = this->gptr();
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_M_pback_end_save = this->egptr();
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this->setg(&_M_pback, &_M_pback, &_M_pback + 1);
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_M_pback_init = true;
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}
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}
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/**
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* @if maint
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* Deactivates pback buffer contents, and restores normal buffer.
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* Assumptions:
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* The pback buffer has only moved forward.
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* @endif
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*/
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void
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_M_destroy_pback() throw()
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{
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if (_M_pback_init)
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{
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// Length _M_in_cur moved in the pback buffer.
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_M_pback_cur_save += this->gptr() != this->eback();
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this->setg(this->_M_buf, _M_pback_cur_save, _M_pback_end_save);
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_M_pback_init = false;
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}
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}
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public:
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// Constructors/destructor:
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/**
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* @brief Does not open any files.
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*
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* The default constructor initializes the parent class using its
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* own default ctor.
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*/
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basic_filebuf();
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/**
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* @brief The destructor closes the file first.
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*/
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virtual
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~basic_filebuf()
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{ this->close(); }
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// Members:
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/**
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* @brief Returns true if the external file is open.
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*/
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bool
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is_open() const throw() { return _M_file.is_open(); }
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/**
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* @brief Opens an external file.
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* @param s The name of the file.
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* @param mode The open mode flags.
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* @return @c this on success, NULL on failure
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*
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* If a file is already open, this function immediately fails.
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* Otherwise it tries to open the file named @a s using the flags
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* given in @a mode.
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*
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* [Table 92 gives the relation between openmode combinations and the
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* equivalent fopen() flags, but the table has not been copied yet.]
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*/
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__filebuf_type*
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open(const char* __s, ios_base::openmode __mode);
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/**
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* @brief Closes the currently associated file.
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* @return @c this on success, NULL on failure
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*
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* If no file is currently open, this function immediately fails.
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*
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* If a "put buffer area" exists, @c overflow(eof) is called to flush
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* all the characters. The file is then closed.
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*
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* If any operations fail, this function also fails.
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*/
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__filebuf_type*
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close() throw();
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protected:
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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void
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_M_allocate_internal_buffer();
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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void
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_M_destroy_internal_buffer() throw();
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// [27.8.1.4] overridden virtual functions
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// [documentation is inherited]
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virtual streamsize
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showmanyc();
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// Stroustrup, 1998, p. 628
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// underflow() and uflow() functions are called to get the next
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// charater from the real input source when the buffer is empty.
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// Buffered input uses underflow()
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// [documentation is inherited]
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virtual int_type
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underflow();
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// [documentation is inherited]
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virtual int_type
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pbackfail(int_type __c = _Traits::eof());
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// Stroustrup, 1998, p 648
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// The overflow() function is called to transfer characters to the
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// real output destination when the buffer is full. A call to
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// overflow(c) outputs the contents of the buffer plus the
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// character c.
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// 27.5.2.4.5
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// Consume some sequence of the characters in the pending sequence.
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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virtual int_type
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overflow(int_type __c = _Traits::eof());
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// Convert internal byte sequence to external, char-based
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// sequence via codecvt.
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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bool
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_M_convert_to_external(char_type*, streamsize);
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/**
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* @brief Manipulates the buffer.
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* @param s Pointer to a buffer area.
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* @param n Size of @a s.
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* @return @c this
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*
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* If no file has been opened, and both @a s and @a n are zero, then
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* the stream becomes unbuffered. Otherwise, @c s is used as a
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* buffer; see
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* http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2
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* for more.
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*/
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virtual __streambuf_type*
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setbuf(char_type* __s, streamsize __n);
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// [documentation is inherited]
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virtual pos_type
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seekoff(off_type __off, ios_base::seekdir __way,
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ios_base::openmode __mode = ios_base::in | ios_base::out);
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// [documentation is inherited]
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virtual pos_type
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seekpos(pos_type __pos,
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ios_base::openmode __mode = ios_base::in | ios_base::out);
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// Common code for seekoff and seekpos
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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pos_type
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_M_seek(off_type __off, ios_base::seekdir __way, __state_type __state);
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// [documentation is inherited]
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virtual int
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sync();
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// [documentation is inherited]
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virtual void
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imbue(const locale& __loc);
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// [documentation is inherited]
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virtual streamsize
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xsgetn(char_type* __s, streamsize __n)
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{
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// Clear out pback buffer before going on to the real deal...
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streamsize __ret = 0;
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if (this->_M_pback_init)
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{
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if (__n && this->gptr() == this->eback())
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{
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*__s++ = *this->gptr();
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this->gbump(1);
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__ret = 1;
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}
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_M_destroy_pback();
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}
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if (__ret < __n)
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__ret += __streambuf_type::xsgetn(__s, __n - __ret);
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return __ret;
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}
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// [documentation is inherited]
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virtual streamsize
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xsputn(const char_type* __s, streamsize __n);
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// Flushes output buffer, then writes unshift sequence.
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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bool
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_M_terminate_output();
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/**
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* @if maint
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* This function sets the pointers of the internal buffer, both get
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* and put areas. Typically:
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*
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* __off == egptr() - eback() upon underflow/uflow ('read' mode);
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* __off == 0 upon overflow ('write' mode);
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* __off == -1 upon open, setbuf, seekoff/pos ('uncommitted' mode).
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*
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* NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size
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* reflects the actual allocated memory and the last cell is reserved
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* for the overflow char of a full put area.
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* @endif
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*/
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void
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_M_set_buffer(streamsize __off)
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{
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const bool __testin = this->_M_mode & ios_base::in;
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const bool __testout = this->_M_mode & ios_base::out;
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if (__testin && __off > 0)
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this->setg(this->_M_buf, this->_M_buf, this->_M_buf + __off);
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else
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this->setg(this->_M_buf, this->_M_buf, this->_M_buf);
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if (__testout && __off == 0 && this->_M_buf_size > 1 )
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this->setp(this->_M_buf, this->_M_buf + this->_M_buf_size - 1);
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else
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this->setp(NULL, NULL);
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}
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};
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// [27.8.1.5] Template class basic_ifstream
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/**
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* @brief Controlling input for files.
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*
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* This class supports reading from named files, using the inherited
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* functions from std::basic_istream. To control the associated
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* sequence, an instance of std::basic_filebuf is used, which this page
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* refers to as @c sb.
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*/
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template<typename _CharT, typename _Traits>
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class basic_ifstream : public basic_istream<_CharT, _Traits>
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{
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public:
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// Types:
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typedef _CharT char_type;
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typedef _Traits traits_type;
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typedef typename traits_type::int_type int_type;
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typedef typename traits_type::pos_type pos_type;
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typedef typename traits_type::off_type off_type;
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// Non-standard types:
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typedef basic_filebuf<char_type, traits_type> __filebuf_type;
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typedef basic_istream<char_type, traits_type> __istream_type;
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private:
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/**
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* @if maint
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* @doctodo
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* @endif
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*/
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__filebuf_type _M_filebuf;
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public:
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// Constructors/Destructors:
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/**
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* @brief Default constructor.
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*
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* Initializes @c sb using its default constructor, and passes
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* @c &sb to the base class initializer. Does not open any files
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* (you haven't given it a filename to open).
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*/
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basic_ifstream() : __istream_type(), _M_filebuf()
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{ this->init(&_M_filebuf); }
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/**
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* @brief Create an input file stream.
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* @param s Null terminated string specifying the filename.
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* @param mode Open file in specified mode (see std::ios_base).
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*
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* @c ios_base::in is automatically included in @a mode.
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*
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* Tip: When using std::string to hold the filename, you must use
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* .c_str() before passing it to this constructor.
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*/
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explicit
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basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
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: __istream_type(), _M_filebuf()
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{
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this->init(&_M_filebuf);
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this->open(__s, __mode);
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}
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/**
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* @brief The destructor does nothing.
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*
|
|
* The file is closed by the filebuf object, not the formatting
|
|
* stream.
|
|
*/
|
|
~basic_ifstream()
|
|
{ }
|
|
|
|
// Members:
|
|
/**
|
|
* @brief Accessing the underlying buffer.
|
|
* @return The current basic_filebuf buffer.
|
|
*
|
|
* This hides both signatures of std::basic_ios::rdbuf().
|
|
*/
|
|
__filebuf_type*
|
|
rdbuf() const
|
|
{ return const_cast<__filebuf_type*>(&_M_filebuf); }
|
|
|
|
/**
|
|
* @brief Wrapper to test for an open file.
|
|
* @return @c rdbuf()->is_open()
|
|
*/
|
|
bool
|
|
is_open() { return _M_filebuf.is_open(); }
|
|
|
|
/**
|
|
* @brief Opens an external file.
|
|
* @param s The name of the file.
|
|
* @param mode The open mode flags.
|
|
*
|
|
* Calls @c std::basic_filebuf::open(s,mode|in). If that function
|
|
* fails, @c failbit is set in the stream's error state.
|
|
*
|
|
* Tip: When using std::string to hold the filename, you must use
|
|
* .c_str() before passing it to this constructor.
|
|
*/
|
|
void
|
|
open(const char* __s, ios_base::openmode __mode = ios_base::in)
|
|
{
|
|
if (!_M_filebuf.open(__s, __mode | ios_base::in))
|
|
this->setstate(ios_base::failbit);
|
|
}
|
|
|
|
/**
|
|
* @brief Close the file.
|
|
*
|
|
* Calls @c std::basic_filebuf::close(). If that function
|
|
* fails, @c failbit is set in the stream's error state.
|
|
*/
|
|
void
|
|
close()
|
|
{
|
|
if (!_M_filebuf.close())
|
|
this->setstate(ios_base::failbit);
|
|
}
|
|
};
|
|
|
|
|
|
// [27.8.1.8] Template class basic_ofstream
|
|
/**
|
|
* @brief Controlling output for files.
|
|
*
|
|
* This class supports reading from named files, using the inherited
|
|
* functions from std::basic_ostream. To control the associated
|
|
* sequence, an instance of std::basic_filebuf is used, which this page
|
|
* refers to as @c sb.
|
|
*/
|
|
template<typename _CharT, typename _Traits>
|
|
class basic_ofstream : public basic_ostream<_CharT,_Traits>
|
|
{
|
|
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 basic_filebuf<char_type, traits_type> __filebuf_type;
|
|
typedef basic_ostream<char_type, traits_type> __ostream_type;
|
|
|
|
private:
|
|
/**
|
|
* @if maint
|
|
* @doctodo
|
|
* @endif
|
|
*/
|
|
__filebuf_type _M_filebuf;
|
|
|
|
public:
|
|
// Constructors:
|
|
/**
|
|
* @brief Default constructor.
|
|
*
|
|
* Initializes @c sb using its default constructor, and passes
|
|
* @c &sb to the base class initializer. Does not open any files
|
|
* (you haven't given it a filename to open).
|
|
*/
|
|
basic_ofstream(): __ostream_type(), _M_filebuf()
|
|
{ this->init(&_M_filebuf); }
|
|
|
|
/**
|
|
* @brief Create an output file stream.
|
|
* @param s Null terminated string specifying the filename.
|
|
* @param mode Open file in specified mode (see std::ios_base).
|
|
*
|
|
* @c ios_base::out|ios_base::trunc is automatically included in
|
|
* @a mode.
|
|
*
|
|
* Tip: When using std::string to hold the filename, you must use
|
|
* .c_str() before passing it to this constructor.
|
|
*/
|
|
explicit
|
|
basic_ofstream(const char* __s,
|
|
ios_base::openmode __mode = ios_base::out|ios_base::trunc)
|
|
: __ostream_type(), _M_filebuf()
|
|
{
|
|
this->init(&_M_filebuf);
|
|
this->open(__s, __mode);
|
|
}
|
|
|
|
/**
|
|
* @brief The destructor does nothing.
|
|
*
|
|
* The file is closed by the filebuf object, not the formatting
|
|
* stream.
|
|
*/
|
|
~basic_ofstream()
|
|
{ }
|
|
|
|
// Members:
|
|
/**
|
|
* @brief Accessing the underlying buffer.
|
|
* @return The current basic_filebuf buffer.
|
|
*
|
|
* This hides both signatures of std::basic_ios::rdbuf().
|
|
*/
|
|
__filebuf_type*
|
|
rdbuf() const
|
|
{ return const_cast<__filebuf_type*>(&_M_filebuf); }
|
|
|
|
/**
|
|
* @brief Wrapper to test for an open file.
|
|
* @return @c rdbuf()->is_open()
|
|
*/
|
|
bool
|
|
is_open() { return _M_filebuf.is_open(); }
|
|
|
|
/**
|
|
* @brief Opens an external file.
|
|
* @param s The name of the file.
|
|
* @param mode The open mode flags.
|
|
*
|
|
* Calls @c std::basic_filebuf::open(s,mode|out|trunc). If that
|
|
* function fails, @c failbit is set in the stream's error state.
|
|
*
|
|
* Tip: When using std::string to hold the filename, you must use
|
|
* .c_str() before passing it to this constructor.
|
|
*/
|
|
void
|
|
open(const char* __s,
|
|
ios_base::openmode __mode = ios_base::out | ios_base::trunc)
|
|
{
|
|
if (!_M_filebuf.open(__s, __mode | ios_base::out))
|
|
this->setstate(ios_base::failbit);
|
|
}
|
|
|
|
/**
|
|
* @brief Close the file.
|
|
*
|
|
* Calls @c std::basic_filebuf::close(). If that function
|
|
* fails, @c failbit is set in the stream's error state.
|
|
*/
|
|
void
|
|
close()
|
|
{
|
|
if (!_M_filebuf.close())
|
|
this->setstate(ios_base::failbit);
|
|
}
|
|
};
|
|
|
|
|
|
// [27.8.1.11] Template class basic_fstream
|
|
/**
|
|
* @brief Controlling intput and output for files.
|
|
*
|
|
* This class supports reading from and writing to named files, using
|
|
* the inherited functions from std::basic_iostream. To control the
|
|
* associated sequence, an instance of std::basic_filebuf is used, which
|
|
* this page refers to as @c sb.
|
|
*/
|
|
template<typename _CharT, typename _Traits>
|
|
class basic_fstream : public basic_iostream<_CharT, _Traits>
|
|
{
|
|
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 basic_filebuf<char_type, traits_type> __filebuf_type;
|
|
typedef basic_ios<char_type, traits_type> __ios_type;
|
|
typedef basic_iostream<char_type, traits_type> __iostream_type;
|
|
|
|
private:
|
|
/**
|
|
* @if maint
|
|
* @doctodo
|
|
* @endif
|
|
*/
|
|
__filebuf_type _M_filebuf;
|
|
|
|
public:
|
|
// Constructors/destructor:
|
|
/**
|
|
* @brief Default constructor.
|
|
*
|
|
* Initializes @c sb using its default constructor, and passes
|
|
* @c &sb to the base class initializer. Does not open any files
|
|
* (you haven't given it a filename to open).
|
|
*/
|
|
basic_fstream()
|
|
: __iostream_type(), _M_filebuf()
|
|
{ this->init(&_M_filebuf); }
|
|
|
|
/**
|
|
* @brief Create an input/output file stream.
|
|
* @param s Null terminated string specifying the filename.
|
|
* @param mode Open file in specified mode (see std::ios_base).
|
|
*
|
|
* Tip: When using std::string to hold the filename, you must use
|
|
* .c_str() before passing it to this constructor.
|
|
*/
|
|
explicit
|
|
basic_fstream(const char* __s,
|
|
ios_base::openmode __mode = ios_base::in | ios_base::out)
|
|
: __iostream_type(NULL), _M_filebuf()
|
|
{
|
|
this->init(&_M_filebuf);
|
|
this->open(__s, __mode);
|
|
}
|
|
|
|
/**
|
|
* @brief The destructor does nothing.
|
|
*
|
|
* The file is closed by the filebuf object, not the formatting
|
|
* stream.
|
|
*/
|
|
~basic_fstream()
|
|
{ }
|
|
|
|
// Members:
|
|
/**
|
|
* @brief Accessing the underlying buffer.
|
|
* @return The current basic_filebuf buffer.
|
|
*
|
|
* This hides both signatures of std::basic_ios::rdbuf().
|
|
*/
|
|
__filebuf_type*
|
|
rdbuf() const
|
|
{ return const_cast<__filebuf_type*>(&_M_filebuf); }
|
|
|
|
/**
|
|
* @brief Wrapper to test for an open file.
|
|
* @return @c rdbuf()->is_open()
|
|
*/
|
|
bool
|
|
is_open() { return _M_filebuf.is_open(); }
|
|
|
|
/**
|
|
* @brief Opens an external file.
|
|
* @param s The name of the file.
|
|
* @param mode The open mode flags.
|
|
*
|
|
* Calls @c std::basic_filebuf::open(s,mode). If that
|
|
* function fails, @c failbit is set in the stream's error state.
|
|
*
|
|
* Tip: When using std::string to hold the filename, you must use
|
|
* .c_str() before passing it to this constructor.
|
|
*/
|
|
void
|
|
open(const char* __s,
|
|
ios_base::openmode __mode = ios_base::in | ios_base::out)
|
|
{
|
|
if (!_M_filebuf.open(__s, __mode))
|
|
this->setstate(ios_base::failbit);
|
|
}
|
|
|
|
/**
|
|
* @brief Close the file.
|
|
*
|
|
* Calls @c std::basic_filebuf::close(). If that function
|
|
* fails, @c failbit is set in the stream's error state.
|
|
*/
|
|
void
|
|
close()
|
|
{
|
|
if (!_M_filebuf.close())
|
|
this->setstate(ios_base::failbit);
|
|
}
|
|
};
|
|
} // namespace std
|
|
|
|
#ifndef _GLIBCXX_EXPORT_TEMPLATE
|
|
# include <bits/fstream.tcc>
|
|
#endif
|
|
|
|
#endif /* _GLIBCXX_FSTREAM */
|