775 lines
27 KiB
C++
775 lines
27 KiB
C++
// Input streams -*- C++ -*-
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// Copyright (C) 1997, 1998, 1999, 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: 27.6.1 Input streams
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//
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/** @file istream
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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_ISTREAM
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#define _GLIBCXX_ISTREAM 1
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#pragma GCC system_header
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#include <ios>
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#include <limits> // For numeric_limits
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namespace std
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{
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// [27.6.1.1] Template class basic_istream
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/**
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* @brief Controlling input.
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*
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* This is the base class for all input streams. It provides text
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* formatting of all builtin types, and communicates with any class
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* derived from basic_streambuf to do the actual input.
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*/
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template<typename _CharT, typename _Traits>
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class basic_istream : virtual public basic_ios<_CharT, _Traits>
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{
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public:
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// Types (inherited from basic_ios (27.4.4)):
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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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// Non-standard Types:
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typedef basic_streambuf<_CharT, _Traits> __streambuf_type;
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typedef basic_ios<_CharT, _Traits> __ios_type;
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typedef basic_istream<_CharT, _Traits> __istream_type;
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typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >
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__num_get_type;
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typedef ctype<_CharT> __ctype_type;
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template<typename _CharT2, typename _Traits2>
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friend basic_istream<_CharT2, _Traits2>&
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operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2&);
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template<typename _CharT2, typename _Traits2>
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friend basic_istream<_CharT2, _Traits2>&
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operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*);
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protected:
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// Data Members:
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/**
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* @if maint
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* The number of characters extracted in the previous unformatted
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* function; see gcount().
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* @endif
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*/
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streamsize _M_gcount;
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public:
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// [27.6.1.1.1] constructor/destructor
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/**
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* @brief Base constructor.
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*
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* This ctor is almost never called by the user directly, rather from
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* derived classes' initialization lists, which pass a pointer to
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* their own stream buffer.
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*/
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explicit
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basic_istream(__streambuf_type* __sb): _M_gcount(streamsize(0))
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{ this->init(__sb); }
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/**
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* @brief Base destructor.
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*
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* This does very little apart from providing a virtual base dtor.
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*/
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virtual
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~basic_istream()
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{ _M_gcount = streamsize(0); }
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// [27.6.1.1.2] prefix/suffix
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class sentry;
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friend class sentry;
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// [27.6.1.2] formatted input
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// [27.6.1.2.3] basic_istream::operator>>
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//@{
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/**
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* @brief Interface for manipulators.
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*
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* Manuipulators such as @c std::ws and @c std::dec use these
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* functions in constructs like "std::cin >> std::ws". For more
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* information, see the iomanip header.
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*/
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inline __istream_type&
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operator>>(__istream_type& (*__pf)(__istream_type&));
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inline __istream_type&
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operator>>(__ios_type& (*__pf)(__ios_type&));
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inline __istream_type&
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operator>>(ios_base& (*__pf)(ios_base&));
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//@}
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// [27.6.1.2.2] arithmetic extractors
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/**
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* @name Arithmetic Extractors
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*
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* All the @c operator>> functions (aka <em>formatted input
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* functions</em>) have some common behavior. Each starts by
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* constructing a temporary object of type std::basic_istream::sentry
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* with the second argument (noskipws) set to false. This has several
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* effects, concluding with the setting of a status flag; see the
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* sentry documentation for more.
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*
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* If the sentry status is good, the function tries to extract
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* whatever data is appropriate for the type of the argument.
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*
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* If an exception is thrown during extraction, ios_base::badbit
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* will be turned on in the stream's error state without causing an
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* ios_base::failure to be thrown. The original exception will then
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* be rethrown.
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*/
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//@{
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/**
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* @brief Basic arithmetic extractors
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* @param A variable of builtin type.
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* @return @c *this if successful
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*
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* These functions use the stream's current locale (specifically, the
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* @c num_get facet) to parse the input data.
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*/
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__istream_type&
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operator>>(bool& __n);
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__istream_type&
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operator>>(short& __n);
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__istream_type&
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operator>>(unsigned short& __n);
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__istream_type&
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operator>>(int& __n);
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__istream_type&
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operator>>(unsigned int& __n);
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__istream_type&
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operator>>(long& __n);
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__istream_type&
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operator>>(unsigned long& __n);
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#ifdef _GLIBCXX_USE_LONG_LONG
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__istream_type&
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operator>>(long long& __n);
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__istream_type&
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operator>>(unsigned long long& __n);
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#endif
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__istream_type&
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operator>>(float& __f);
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__istream_type&
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operator>>(double& __f);
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__istream_type&
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operator>>(long double& __f);
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__istream_type&
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operator>>(void*& __p);
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/**
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* @brief Extracting into another streambuf.
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* @param sb A pointer to a streambuf
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*
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* This function behaves like one of the basic arithmetic extractors,
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* in that it also constructs a sentry object and has the same error
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* handling behavior.
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*
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* If @a sb is NULL, the stream will set failbit in its error state.
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*
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* Characters are extracted from this stream and inserted into the
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* @a sb streambuf until one of the following occurs:
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*
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* - the input stream reaches end-of-file,
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* - insertion into the output buffer fails (in this case, the
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* character that would have been inserted is not extracted), or
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* - an exception occurs (and in this case is caught)
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*
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* If the function inserts no characters, failbit is set.
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*/
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__istream_type&
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operator>>(__streambuf_type* __sb);
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//@}
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// [27.6.1.3] unformatted input
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/**
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* @brief Character counting
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* @return The number of characters extracted by the previous
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* unformatted input function dispatched for this stream.
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*/
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inline streamsize
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gcount() const
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{ return _M_gcount; }
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/**
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* @name Unformatted Input Functions
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*
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* All the unformatted input functions have some common behavior.
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* Each starts by constructing a temporary object of type
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* std::basic_istream::sentry with the second argument (noskipws)
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* set to true. This has several effects, concluding with the
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* setting of a status flag; see the sentry documentation for more.
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*
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* If the sentry status is good, the function tries to extract
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* whatever data is appropriate for the type of the argument.
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*
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* The number of characters extracted is stored for later retrieval
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* by gcount().
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*
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* If an exception is thrown during extraction, ios_base::badbit
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* will be turned on in the stream's error state without causing an
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* ios_base::failure to be thrown. The original exception will then
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* be rethrown.
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*/
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//@{
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/**
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* @brief Simple extraction.
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* @return A character, or eof().
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*
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* Tries to extract a character. If none are available, sets failbit
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* and returns traits::eof().
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*/
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int_type
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get();
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/**
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* @brief Simple extraction.
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* @param c The character in which to store data.
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* @return *this
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*
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* Tries to extract a character and store it in @a c. If none are
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* available, sets failbit and returns traits::eof().
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*
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* @note This function is not overloaded on signed char and
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* unsigned char.
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*/
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__istream_type&
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get(char_type& __c);
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/**
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* @brief Simple multiple-character extraction.
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* @param s Pointer to an array.
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* @param n Maximum number of characters to store in @a s.
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* @param delim A "stop" character.
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* @return *this
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*
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* Characters are extracted and stored into @a s until one of the
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* following happens:
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*
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* - @c n-1 characters are stored
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* - the input sequence reaches EOF
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* - the next character equals @a delim, in which case the character
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* is not extracted
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*
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* If no characters are stored, failbit is set in the stream's error
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* state.
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*
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* In any case, a null character is stored into the next location in
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* the array.
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*
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* @note This function is not overloaded on signed char and
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* unsigned char.
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*/
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__istream_type&
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get(char_type* __s, streamsize __n, char_type __delim);
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/**
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* @brief Simple multiple-character extraction.
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* @param s Pointer to an array.
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* @param n Maximum number of characters to store in @a s.
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* @return *this
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*
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* Returns @c get(s,n,widen('\n')).
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*/
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inline __istream_type&
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get(char_type* __s, streamsize __n)
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{ return this->get(__s, __n, this->widen('\n')); }
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/**
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* @brief Extraction into another streambuf.
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* @param sb A streambuf in which to store data.
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* @param delim A "stop" character.
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* @return *this
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*
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* Characters are extracted and inserted into @a sb until one of the
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* following happens:
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*
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* - the input sequence reaches EOF
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* - insertion into the output buffer fails (in this case, the
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* character that would have been inserted is not extracted)
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* - the next character equals @a delim (in this case, the character
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* is not extracted)
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* - an exception occurs (and in this case is caught)
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*
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* If no characters are stored, failbit is set in the stream's error
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* state.
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*/
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__istream_type&
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get(__streambuf_type& __sb, char_type __delim);
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/**
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* @brief Extraction into another streambuf.
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* @param sb A streambuf in which to store data.
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* @return *this
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*
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* Returns @c get(sb,widen('\n')).
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*/
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inline __istream_type&
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get(__streambuf_type& __sb)
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{ return this->get(__sb, this->widen('\n')); }
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/**
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* @brief String extraction.
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* @param s A character array in which to store the data.
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* @param n Maximum number of characters to extract.
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* @param delim A "stop" character.
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* @return *this
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*
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* Extracts and stores characters into @a s until one of the
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* following happens. Note that these criteria are required to be
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* tested in the order listed here, to allow an input line to exactly
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* fill the @a s array without setting failbit.
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*
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* -# the input sequence reaches end-of-file, in which case eofbit
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* is set in the stream error state
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* -# the next character equals @c delim, in which case the character
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* is extracted (and therefore counted in @c gcount()) but not stored
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* -# @c n-1 characters are stored, in which case failbit is set
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* in the stream error state
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*
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* If no characters are extracted, failbit is set. (An empty line of
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* input should therefore not cause failbit to be set.)
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*
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* In any case, a null character is stored in the next location in
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* the array.
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*/
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__istream_type&
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getline(char_type* __s, streamsize __n, char_type __delim);
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/**
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* @brief String extraction.
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* @param s A character array in which to store the data.
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* @param n Maximum number of characters to extract.
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* @return *this
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*
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* Returns @c getline(s,n,widen('\n')).
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*/
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inline __istream_type&
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getline(char_type* __s, streamsize __n)
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{ return this->getline(__s, __n, this->widen('\n')); }
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/**
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* @brief Discarding characters
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* @param n Number of characters to discard.
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* @param delim A "stop" character.
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* @return *this
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*
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* Extracts characters and throws them away until one of the
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* following happens:
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* - if @a n @c != @c std::numeric_limits<int>::max(), @a n
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* characters are extracted
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* - the input sequence reaches end-of-file
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* - the next character equals @a delim (in this case, the character
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* is extracted); note that this condition will never occur if
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* @a delim equals @c traits::eof().
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*/
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__istream_type&
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ignore(streamsize __n = 1, int_type __delim = traits_type::eof());
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/**
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* @brief Looking ahead in the stream
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* @return The next character, or eof().
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*
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* If, after constructing the sentry object, @c good() is false,
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* returns @c traits::eof(). Otherwise reads but does not extract
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* the next input character.
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*/
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int_type
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peek();
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/**
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* @brief Extraction without delimiters.
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* @param s A character array.
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* @param n Maximum number of characters to store.
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* @return *this
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*
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* If the stream state is @c good(), extracts characters and stores
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* them into @a s until one of the following happens:
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* - @a n characters are stored
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* - the input sequence reaches end-of-file, in which case the error
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* state is set to @c failbit|eofbit.
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*
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* @note This function is not overloaded on signed char and
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* unsigned char.
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*/
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__istream_type&
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read(char_type* __s, streamsize __n);
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/**
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* @brief Extraction until the buffer is exhausted, but no more.
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* @param s A character array.
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* @param n Maximum number of characters to store.
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* @return The number of characters extracted.
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*
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* Extracts characters and stores them into @a s depending on the
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* number of characters remaining in the streambuf's buffer,
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* @c rdbuf()->in_avail(), called @c A here:
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* - if @c A @c == @c -1, sets eofbit and extracts no characters
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* - if @c A @c == @c 0, extracts no characters
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* - if @c A @c > @c 0, extracts @c min(A,n)
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*
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* The goal is to empty the current buffer, and to not request any
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* more from the external input sequence controlled by the streambuf.
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*/
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streamsize
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readsome(char_type* __s, streamsize __n);
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/**
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* @brief Unextracting a single character.
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* @param c The character to push back into the input stream.
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* @return *this
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*
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* If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c).
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*
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* If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in
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* the error state.
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*
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* @note Since no characters are extracted, the next call to
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* @c gcount() will return 0, as required by DR 60.
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*/
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__istream_type&
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putback(char_type __c);
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/**
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* @brief Unextracting the previous character.
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* @return *this
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*
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* If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c).
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*
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* If @c rdbuf() is null or if @c sungetc() fails, sets badbit in
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* the error state.
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*
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* @note Since no characters are extracted, the next call to
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* @c gcount() will return 0, as required by DR 60.
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*/
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__istream_type&
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unget();
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/**
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* @brief Synchronizing the stream buffer.
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* @return 0 on success, -1 on failure
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*
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* If @c rdbuf() is a null pointer, returns -1.
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*
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* Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
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* sets badbit and returns -1.
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*
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* Otherwise, returns 0.
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*
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* @note This function does not count the number of characters
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* extracted, if any, and therefore does not affect the next
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* call to @c gcount().
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*/
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int
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sync();
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/**
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* @brief Getting the current read position.
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* @return A file position object.
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*
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* If @c fail() is not false, returns @c pos_type(-1) to indicate
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* failure. Otherwise returns @c rdbuf()->pubseekoff(0,cur,in).
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*
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* @note This function does not count the number of characters
|
|
* extracted, if any, and therefore does not affect the next
|
|
* call to @c gcount().
|
|
*/
|
|
pos_type
|
|
tellg();
|
|
|
|
/**
|
|
* @brief Changing the current read position.
|
|
* @param pos A file position object.
|
|
* @return *this
|
|
*
|
|
* If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos). If
|
|
* that function fails, sets failbit.
|
|
*
|
|
* @note This function does not count the number of characters
|
|
* extracted, if any, and therefore does not affect the next
|
|
* call to @c gcount().
|
|
*/
|
|
__istream_type&
|
|
seekg(pos_type);
|
|
|
|
/**
|
|
* @brief Changing the current read position.
|
|
* @param off A file offset object.
|
|
* @param dir The direction in which to seek.
|
|
* @return *this
|
|
*
|
|
* If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir).
|
|
* If that function fails, sets failbit.
|
|
*
|
|
* @note This function does not count the number of characters
|
|
* extracted, if any, and therefore does not affect the next
|
|
* call to @c gcount().
|
|
*/
|
|
__istream_type&
|
|
seekg(off_type, ios_base::seekdir);
|
|
//@}
|
|
|
|
protected:
|
|
explicit
|
|
basic_istream(): _M_gcount(streamsize(0)) { }
|
|
};
|
|
|
|
/**
|
|
* @brief Performs setup work for input streams.
|
|
*
|
|
* Objects of this class are created before all of the standard
|
|
* extractors are run. It is responsible for "exception-safe prefix and
|
|
* suffix operations," although only prefix actions are currently required
|
|
* by the standard. Additional actions may be added by the
|
|
* implementation, and we list them in
|
|
* http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#5
|
|
* under [27.6] notes.
|
|
*/
|
|
template<typename _CharT, typename _Traits>
|
|
class basic_istream<_CharT, _Traits>::sentry
|
|
{
|
|
public:
|
|
/// Easy access to dependant types.
|
|
typedef _Traits traits_type;
|
|
typedef basic_streambuf<_CharT, _Traits> __streambuf_type;
|
|
typedef basic_istream<_CharT, _Traits> __istream_type;
|
|
typedef typename __istream_type::__ctype_type __ctype_type;
|
|
typedef typename _Traits::int_type __int_type;
|
|
|
|
/**
|
|
* @brief The constructor performs all the work.
|
|
* @param is The input stream to guard.
|
|
* @param noskipws Whether to consume whitespace or not.
|
|
*
|
|
* If the stream state is good (@a is.good() is true), then the
|
|
* following actions are performed, otherwise the sentry state is
|
|
* false ("not okay") and failbit is set in the stream state.
|
|
*
|
|
* The sentry's preparatory actions are:
|
|
*
|
|
* -# if the stream is tied to an output stream, @c is.tie()->flush()
|
|
* is called to synchronize the output sequence
|
|
* -# if @a noskipws is false, and @c ios_base::skipws is set in
|
|
* @c is.flags(), the sentry extracts and discards whitespace
|
|
* characters from the stream. The currently imbued locale is
|
|
* used to determine whether each character is whitespace.
|
|
*
|
|
* If the stream state is still good, then the sentry state becomes
|
|
* true ("okay").
|
|
*/
|
|
explicit
|
|
sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false);
|
|
|
|
/**
|
|
* @brief Quick status checking.
|
|
* @return The sentry state.
|
|
*
|
|
* For ease of use, sentries may be converted to booleans. The
|
|
* return value is that of the sentry state (true == okay).
|
|
*/
|
|
operator bool() const { return _M_ok; }
|
|
|
|
private:
|
|
bool _M_ok;
|
|
};
|
|
|
|
// [27.6.1.2.3] character extraction templates
|
|
//@{
|
|
/**
|
|
* @brief Character extractors
|
|
* @param in An input stream.
|
|
* @param c A character reference.
|
|
* @return in
|
|
*
|
|
* Behaves like one of the formatted arithmetic extractors described in
|
|
* std::basic_istream. After constructing a sentry object with good
|
|
* status, this function extracts a character (if one is available) and
|
|
* stores it in @a c. Otherwise, sets failbit in the input stream.
|
|
*/
|
|
template<typename _CharT, typename _Traits>
|
|
basic_istream<_CharT, _Traits>&
|
|
operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c);
|
|
|
|
template<class _Traits>
|
|
basic_istream<char, _Traits>&
|
|
operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
|
|
{ return (__in >> reinterpret_cast<char&>(__c)); }
|
|
|
|
template<class _Traits>
|
|
basic_istream<char, _Traits>&
|
|
operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
|
|
{ return (__in >> reinterpret_cast<char&>(__c)); }
|
|
//@}
|
|
|
|
//@{
|
|
/**
|
|
* @brief Character string extractors
|
|
* @param in An input stream.
|
|
* @param s A pointer to a character array.
|
|
* @return in
|
|
*
|
|
* Behaves like one of the formatted arithmetic extractors described in
|
|
* std::basic_istream. After constructing a sentry object with good
|
|
* status, this function extracts up to @c n characters and stores them
|
|
* into the array starting at @a s. @c n is defined as:
|
|
*
|
|
* - if @c width() is greater than zero, @c n is width()
|
|
* - otherwise @c n is "the number of elements of the largest array of
|
|
* @c char_type that can store a terminating @c eos." [27.6.1.2.3]/6
|
|
*
|
|
* Characters are extracted and stored until one of the following happens:
|
|
* - @c n-1 characters are stored
|
|
* - EOF is reached
|
|
* - the next character is whitespace according to the current locale
|
|
* - the next character is a null byte (i.e., @c charT() )
|
|
*
|
|
* @c width(0) is then called for the input stream.
|
|
*
|
|
* If no characters are extracted, sets failbit.
|
|
*/
|
|
template<typename _CharT, typename _Traits>
|
|
basic_istream<_CharT, _Traits>&
|
|
operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s);
|
|
|
|
template<class _Traits>
|
|
basic_istream<char,_Traits>&
|
|
operator>>(basic_istream<char,_Traits>& __in, unsigned char* __s)
|
|
{ return (__in >> reinterpret_cast<char*>(__s)); }
|
|
|
|
template<class _Traits>
|
|
basic_istream<char,_Traits>&
|
|
operator>>(basic_istream<char,_Traits>& __in, signed char* __s)
|
|
{ return (__in >> reinterpret_cast<char*>(__s)); }
|
|
//@}
|
|
|
|
// 27.6.1.5 Template class basic_iostream
|
|
/**
|
|
* @brief Merging istream and ostream capabilities.
|
|
*
|
|
* This class multiply inherits from the input and output stream classes
|
|
* simply to provide a single interface.
|
|
*/
|
|
template<typename _CharT, typename _Traits>
|
|
class basic_iostream
|
|
: public basic_istream<_CharT, _Traits>,
|
|
public basic_ostream<_CharT, _Traits>
|
|
{
|
|
public:
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 271. basic_iostream missing typedefs
|
|
// Types (inherited):
|
|
typedef _CharT char_type;
|
|
typedef typename _Traits::int_type int_type;
|
|
typedef typename _Traits::pos_type pos_type;
|
|
typedef typename _Traits::off_type off_type;
|
|
typedef _Traits traits_type;
|
|
|
|
// Non-standard Types:
|
|
typedef basic_istream<_CharT, _Traits> __istream_type;
|
|
typedef basic_ostream<_CharT, _Traits> __ostream_type;
|
|
|
|
/**
|
|
* @brief Constructor does nothing.
|
|
*
|
|
* Both of the parent classes are initialized with the same
|
|
* streambuf pointer passed to this constructor.
|
|
*/
|
|
explicit
|
|
basic_iostream(basic_streambuf<_CharT, _Traits>* __sb)
|
|
: __istream_type(), __ostream_type()
|
|
{ this->init(__sb); }
|
|
|
|
/**
|
|
* @brief Destructor does nothing.
|
|
*/
|
|
virtual
|
|
~basic_iostream() { }
|
|
|
|
protected:
|
|
explicit
|
|
basic_iostream() : __istream_type(), __ostream_type()
|
|
{ }
|
|
};
|
|
|
|
// [27.6.1.4] standard basic_istream manipulators
|
|
/**
|
|
* @brief Quick and easy way to eat whitespace
|
|
*
|
|
* This manipulator extracts whitespace characters, stopping when the
|
|
* next character is non-whitespace, or when the input sequence is empty.
|
|
* If the sequence is empty, @c eofbit is set in the stream, but not
|
|
* @c failbit.
|
|
*
|
|
* The current locale is used to distinguish whitespace characters.
|
|
*
|
|
* Example:
|
|
* @code
|
|
* MyClass mc;
|
|
*
|
|
* std::cin >> std::ws >> mc;
|
|
* @endcode
|
|
* will skip leading whitespace before calling operator>> on cin and your
|
|
* object. Note that the same effect can be achieved by creating a
|
|
* std::basic_istream::sentry inside your definition of operator>>.
|
|
*/
|
|
template<typename _CharT, typename _Traits>
|
|
basic_istream<_CharT, _Traits>&
|
|
ws(basic_istream<_CharT, _Traits>& __is);
|
|
} // namespace std
|
|
|
|
#ifndef _GLIBCXX_EXPORT_TEMPLATE
|
|
# include <bits/istream.tcc>
|
|
#endif
|
|
|
|
#endif /* _GLIBCXX_ISTREAM */
|