519 lines
16 KiB
C++
519 lines
16 KiB
C++
// Iostreams base classes -*- C++ -*-
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// Copyright (C) 1997-2015 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 3, 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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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file bits/basic_ios.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{ios}
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*/
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#ifndef _BASIC_IOS_H
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#define _BASIC_IOS_H 1
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#pragma GCC system_header
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#include <bits/localefwd.h>
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#include <bits/locale_classes.h>
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#include <bits/locale_facets.h>
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#include <bits/streambuf_iterator.h>
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#include <bits/move.h>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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template<typename _Facet>
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inline const _Facet&
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__check_facet(const _Facet* __f)
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{
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if (!__f)
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__throw_bad_cast();
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return *__f;
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}
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/**
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* @brief Template class basic_ios, virtual base class for all
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* stream classes.
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* @ingroup io
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*
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* @tparam _CharT Type of character stream.
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* @tparam _Traits Traits for character type, defaults to
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* char_traits<_CharT>.
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*
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* Most of the member functions called dispatched on stream objects
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* (e.g., @c std::cout.foo(bar);) are consolidated in this class.
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*/
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template<typename _CharT, typename _Traits>
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class basic_ios : public ios_base
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{
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public:
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//@{
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/**
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* These are standard types. They permit a standardized way of
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* referring to names of (or names dependent on) the template
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* parameters, which are specific to the implementation.
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*/
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typedef _CharT char_type;
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typedef typename _Traits::int_type int_type;
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typedef typename _Traits::pos_type pos_type;
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typedef typename _Traits::off_type off_type;
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typedef _Traits traits_type;
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//@}
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//@{
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/**
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* These are non-standard types.
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*/
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typedef ctype<_CharT> __ctype_type;
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typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> >
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__num_put_type;
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typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >
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__num_get_type;
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//@}
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// Data members:
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protected:
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basic_ostream<_CharT, _Traits>* _M_tie;
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mutable char_type _M_fill;
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mutable bool _M_fill_init;
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basic_streambuf<_CharT, _Traits>* _M_streambuf;
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// Cached use_facet<ctype>, which is based on the current locale info.
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const __ctype_type* _M_ctype;
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// For ostream.
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const __num_put_type* _M_num_put;
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// For istream.
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const __num_get_type* _M_num_get;
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public:
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//@{
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/**
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* @brief The quick-and-easy status check.
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*
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* This allows you to write constructs such as
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* <code>if (!a_stream) ...</code> and <code>while (a_stream) ...</code>
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*/
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#if __cplusplus >= 201103L
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explicit operator bool() const
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{ return !this->fail(); }
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#else
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operator void*() const
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{ return this->fail() ? 0 : const_cast<basic_ios*>(this); }
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#endif
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bool
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operator!() const
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{ return this->fail(); }
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//@}
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/**
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* @brief Returns the error state of the stream buffer.
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* @return A bit pattern (well, isn't everything?)
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*
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* See std::ios_base::iostate for the possible bit values. Most
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* users will call one of the interpreting wrappers, e.g., good().
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*/
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iostate
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rdstate() const
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{ return _M_streambuf_state; }
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/**
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* @brief [Re]sets the error state.
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* @param __state The new state flag(s) to set.
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*
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* See std::ios_base::iostate for the possible bit values. Most
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* users will not need to pass an argument.
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*/
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void
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clear(iostate __state = goodbit);
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/**
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* @brief Sets additional flags in the error state.
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* @param __state The additional state flag(s) to set.
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*
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* See std::ios_base::iostate for the possible bit values.
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*/
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void
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setstate(iostate __state)
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{ this->clear(this->rdstate() | __state); }
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// Flip the internal state on for the proper state bits, then re
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// throws the propagated exception if bit also set in
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// exceptions().
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void
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_M_setstate(iostate __state)
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{
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// 27.6.1.2.1 Common requirements.
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// Turn this on without causing an ios::failure to be thrown.
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_M_streambuf_state |= __state;
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if (this->exceptions() & __state)
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__throw_exception_again;
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}
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/**
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* @brief Fast error checking.
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* @return True if no error flags are set.
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*
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* A wrapper around rdstate.
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*/
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bool
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good() const
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{ return this->rdstate() == 0; }
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/**
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* @brief Fast error checking.
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* @return True if the eofbit is set.
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*
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* Note that other iostate flags may also be set.
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*/
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bool
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eof() const
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{ return (this->rdstate() & eofbit) != 0; }
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/**
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* @brief Fast error checking.
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* @return True if either the badbit or the failbit is set.
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*
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* Checking the badbit in fail() is historical practice.
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* Note that other iostate flags may also be set.
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*/
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bool
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fail() const
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{ return (this->rdstate() & (badbit | failbit)) != 0; }
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/**
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* @brief Fast error checking.
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* @return True if the badbit is set.
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*
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* Note that other iostate flags may also be set.
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*/
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bool
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bad() const
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{ return (this->rdstate() & badbit) != 0; }
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/**
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* @brief Throwing exceptions on errors.
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* @return The current exceptions mask.
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*
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* This changes nothing in the stream. See the one-argument version
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* of exceptions(iostate) for the meaning of the return value.
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*/
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iostate
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exceptions() const
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{ return _M_exception; }
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/**
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* @brief Throwing exceptions on errors.
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* @param __except The new exceptions mask.
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*
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* By default, error flags are set silently. You can set an
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* exceptions mask for each stream; if a bit in the mask becomes set
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* in the error flags, then an exception of type
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* std::ios_base::failure is thrown.
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*
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* If the error flag is already set when the exceptions mask is
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* added, the exception is immediately thrown. Try running the
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* following under GCC 3.1 or later:
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* @code
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* #include <iostream>
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* #include <fstream>
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* #include <exception>
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*
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* int main()
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* {
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* std::set_terminate (__gnu_cxx::__verbose_terminate_handler);
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*
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* std::ifstream f ("/etc/motd");
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*
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* std::cerr << "Setting badbit\n";
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* f.setstate (std::ios_base::badbit);
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*
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* std::cerr << "Setting exception mask\n";
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* f.exceptions (std::ios_base::badbit);
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* }
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* @endcode
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*/
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void
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exceptions(iostate __except)
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{
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_M_exception = __except;
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this->clear(_M_streambuf_state);
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}
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// Constructor/destructor:
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/**
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* @brief Constructor performs initialization.
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*
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* The parameter is passed by derived streams.
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*/
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explicit
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basic_ios(basic_streambuf<_CharT, _Traits>* __sb)
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: ios_base(), _M_tie(0), _M_fill(), _M_fill_init(false), _M_streambuf(0),
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_M_ctype(0), _M_num_put(0), _M_num_get(0)
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{ this->init(__sb); }
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/**
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* @brief Empty.
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*
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* The destructor does nothing. More specifically, it does not
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* destroy the streambuf held by rdbuf().
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*/
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virtual
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~basic_ios() { }
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// Members:
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/**
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* @brief Fetches the current @e tied stream.
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* @return A pointer to the tied stream, or NULL if the stream is
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* not tied.
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*
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* A stream may be @e tied (or synchronized) to a second output
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* stream. When this stream performs any I/O, the tied stream is
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* first flushed. For example, @c std::cin is tied to @c std::cout.
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*/
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basic_ostream<_CharT, _Traits>*
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tie() const
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{ return _M_tie; }
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/**
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* @brief Ties this stream to an output stream.
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* @param __tiestr The output stream.
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* @return The previously tied output stream, or NULL if the stream
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* was not tied.
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*
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* This sets up a new tie; see tie() for more.
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*/
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basic_ostream<_CharT, _Traits>*
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tie(basic_ostream<_CharT, _Traits>* __tiestr)
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{
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basic_ostream<_CharT, _Traits>* __old = _M_tie;
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_M_tie = __tiestr;
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return __old;
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}
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/**
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* @brief Accessing the underlying buffer.
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* @return The current stream buffer.
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*
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* This does not change the state of the stream.
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*/
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basic_streambuf<_CharT, _Traits>*
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rdbuf() const
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{ return _M_streambuf; }
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/**
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* @brief Changing the underlying buffer.
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* @param __sb The new stream buffer.
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* @return The previous stream buffer.
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*
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* Associates a new buffer with the current stream, and clears the
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* error state.
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*
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* Due to historical accidents which the LWG refuses to correct, the
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* I/O library suffers from a design error: this function is hidden
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* in derived classes by overrides of the zero-argument @c rdbuf(),
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* which is non-virtual for hysterical raisins. As a result, you
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* must use explicit qualifications to access this function via any
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* derived class. For example:
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*
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* @code
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* std::fstream foo; // or some other derived type
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* std::streambuf* p = .....;
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*
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* foo.ios::rdbuf(p); // ios == basic_ios<char>
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* @endcode
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*/
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basic_streambuf<_CharT, _Traits>*
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rdbuf(basic_streambuf<_CharT, _Traits>* __sb);
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/**
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* @brief Copies fields of __rhs into this.
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* @param __rhs The source values for the copies.
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* @return Reference to this object.
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*
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* All fields of __rhs are copied into this object except that rdbuf()
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* and rdstate() remain unchanged. All values in the pword and iword
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* arrays are copied. Before copying, each callback is invoked with
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* erase_event. After copying, each (new) callback is invoked with
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* copyfmt_event. The final step is to copy exceptions().
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*/
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basic_ios&
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copyfmt(const basic_ios& __rhs);
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/**
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* @brief Retrieves the @a empty character.
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* @return The current fill character.
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*
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* It defaults to a space (' ') in the current locale.
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*/
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char_type
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fill() const
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{
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if (!_M_fill_init)
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{
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_M_fill = this->widen(' ');
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_M_fill_init = true;
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}
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return _M_fill;
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}
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/**
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* @brief Sets a new @a empty character.
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* @param __ch The new character.
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* @return The previous fill character.
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*
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* The fill character is used to fill out space when P+ characters
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* have been requested (e.g., via setw), Q characters are actually
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* used, and Q<P. It defaults to a space (' ') in the current locale.
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*/
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char_type
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fill(char_type __ch)
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{
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char_type __old = this->fill();
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_M_fill = __ch;
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return __old;
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}
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// Locales:
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/**
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* @brief Moves to a new locale.
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* @param __loc The new locale.
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* @return The previous locale.
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*
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* Calls @c ios_base::imbue(loc), and if a stream buffer is associated
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* with this stream, calls that buffer's @c pubimbue(loc).
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*
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* Additional l10n notes are at
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* http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
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*/
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locale
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imbue(const locale& __loc);
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/**
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* @brief Squeezes characters.
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* @param __c The character to narrow.
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* @param __dfault The character to narrow.
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* @return The narrowed character.
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*
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* Maps a character of @c char_type to a character of @c char,
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* if possible.
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*
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* Returns the result of
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* @code
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* std::use_facet<ctype<char_type> >(getloc()).narrow(c,dfault)
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* @endcode
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*
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* Additional l10n notes are at
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* http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
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*/
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char
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narrow(char_type __c, char __dfault) const
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{ return __check_facet(_M_ctype).narrow(__c, __dfault); }
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/**
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* @brief Widens characters.
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* @param __c The character to widen.
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* @return The widened character.
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*
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* Maps a character of @c char to a character of @c char_type.
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*
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* Returns the result of
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* @code
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* std::use_facet<ctype<char_type> >(getloc()).widen(c)
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* @endcode
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*
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* Additional l10n notes are at
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* http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
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*/
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char_type
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widen(char __c) const
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{ return __check_facet(_M_ctype).widen(__c); }
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protected:
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// 27.4.5.1 basic_ios constructors
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/**
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* @brief Empty.
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*
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* The default constructor does nothing and is not normally
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* accessible to users.
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*/
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basic_ios()
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: ios_base(), _M_tie(0), _M_fill(char_type()), _M_fill_init(false),
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_M_streambuf(0), _M_ctype(0), _M_num_put(0), _M_num_get(0)
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{ }
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/**
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* @brief All setup is performed here.
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*
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* This is called from the public constructor. It is not virtual and
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* cannot be redefined.
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*/
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void
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init(basic_streambuf<_CharT, _Traits>* __sb);
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#if __cplusplus >= 201103L
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basic_ios(const basic_ios&) = delete;
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basic_ios& operator=(const basic_ios&) = delete;
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void
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move(basic_ios& __rhs)
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{
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ios_base::_M_move(__rhs);
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_M_cache_locale(_M_ios_locale);
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this->tie(__rhs.tie(nullptr));
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_M_fill = __rhs._M_fill;
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_M_fill_init = __rhs._M_fill_init;
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_M_streambuf = nullptr;
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}
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void
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move(basic_ios&& __rhs)
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{ this->move(__rhs); }
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void
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swap(basic_ios& __rhs) noexcept
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{
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ios_base::_M_swap(__rhs);
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_M_cache_locale(_M_ios_locale);
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__rhs._M_cache_locale(__rhs._M_ios_locale);
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std::swap(_M_tie, __rhs._M_tie);
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std::swap(_M_fill, __rhs._M_fill);
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std::swap(_M_fill_init, __rhs._M_fill_init);
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}
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void
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set_rdbuf(basic_streambuf<_CharT, _Traits>* __sb)
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{ _M_streambuf = __sb; }
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#endif
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void
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_M_cache_locale(const locale& __loc);
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};
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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#include <bits/basic_ios.tcc>
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#endif /* _BASIC_IOS_H */
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