basic_ios.h

symbian上STL模板库的实现

// Iostreams base classes -*- C++ -*-

// Copyright (C) 1997, 1998, 1999, 2001, 2002, 2003, 2004
// Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

/** @file basic_ios.h
 *  This is an internal header file, included by other library headers.
 *  You should not attempt to use it directly.
 */

#ifndef _BASIC_IOS_H
#define _BASIC_IOS_H 1

//#pragma GCC system_header

#include <bits/streambuf_iterator.h>
#include <bits/localefwd.h>
#include <bits/locale_classes.h>
#include <bits/locale_facets.h>

namespace std
{
    // 27.4.5  Template class basic_ios
    /**
     *  @brief  Virtual base class for all stream classes.
     *
     *  Most of the member functions called dispatched on stream objects
     *  (e.g., @c std::cout.foo(bar);) are consolidated in this class.
     */
    template<typename _CharT, typename _Traits>
        class basic_ios : public ios_base
    {
        public:
            //@{
            /**
             *  These are standard types.  They permit a standardized way of
             *  referring to names of (or names dependant on) the template
             *  parameters, which are specific to the implementation.
             */
            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;
            //@}

            //@{
            /**
             *  @if maint
             *  These are non-standard types.
             *  @endif
             */
            typedef ctype<_CharT>                          __ctype_type;
            typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> >
                __num_put_type;
            typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >
                __num_get_type;
            //@}

            // Data members:
        protected:
            basic_ostream<_CharT, _Traits>*                _M_tie;
            mutable char_type                              _M_fill;
            mutable bool                                   _M_fill_init;
            basic_streambuf<_CharT, _Traits>*              _M_streambuf;

            // Cached use_facet<ctype>, which is based on the current locale info.
            const __ctype_type*                            _M_ctype;
            // For ostream.
            const __num_put_type*                          _M_num_put;
            // For istream.
            const __num_get_type*                          _M_num_get;

        public:
            //@{
            /**
             *  @brief  The quick-and-easy status check.
             *
             *  This allows you to write constructs such as
             *  "if (!a_stream) ..." and "while (a_stream) ..."
             */
            operator void*() const
            { return this->fail() ? 0 : const_cast<basic_ios*>(this); }

            bool
                operator!() const
                { return this->fail(); }
            //@}

            /**
             *  @brief  Returns the error state of the stream buffer.
             *  @return  A bit pattern (well, isn't everything?)
             *
             *  See std::ios_base::iostate for the possible bit values.  Most
             *  users will call one of the interpreting wrappers, e.g., good().
             */
            iostate
                rdstate() const
                { return _M_streambuf_state; }

            /**
             *  @brief  [Re]sets the error state.
             *  @param  state  The new state flag(s) to set.
             *
             *  See std::ios_base::iostate for the possible bit values.  Most
             *  users will not need to pass an argument.
             */
            void
                clear(iostate __state = goodbit);

            /**
             *  @brief  Sets additional flags in the error state.
             *  @param  state  The additional state flag(s) to set.
             *
             *  See std::ios_base::iostate for the possible bit values.
             */
            void
                setstate(iostate __state)
                { this->clear(this->rdstate() | __state); }

            // Flip the internal state on for the proper state bits, then re
            // throws the propagated exception if bit also set in
            // exceptions().
            void
                _M_setstate(iostate __state)
                {
                    // 27.6.1.2.1 Common requirements.
                    // Turn this on without causing an ios::failure to be thrown.
                    _M_streambuf_state |= __state;
                    if (this->exceptions() & __state)
                        __throw_exception_again;
                }

            /**
             *  @brief  Fast error checking.
             *  @return  True if no error flags are set.
             *
             *  A wrapper around rdstate.
             */
            bool
                good() const
                { return this->rdstate() == 0; }

            /**
             *  @brief  Fast error checking.
             *  @return  True if the eofbit is set.
             *
             *  Note that other iostate flags may also be set.
             */
            bool
                eof() const
                { return (this->rdstate() & eofbit) != 0; }

            /**
             *  @brief  Fast error checking.
             *  @return  True if either the badbit or the failbit is set.
             *
             *  Checking the badbit in fail() is historical practice.
             *  Note that other iostate flags may also be set.
             */
            bool
                fail() const
                { return (this->rdstate() & (badbit | failbit)) != 0; }

            /**
             *  @brief  Fast error checking.
             *  @return  True if the badbit is set.
             *
             *  Note that other iostate flags may also be set.
             */
            bool
                bad() const
                { return (this->rdstate() & badbit) != 0; }

            /**
             *  @brief  Throwing exceptions on errors.
             *  @return  The current exceptions mask.
             *
             *  This changes nothing in the stream.  See the one-argument version
             *  of exceptions(iostate) for the meaning of the return value.
             */
            iostate
                exceptions() const
                { return _M_exception; }

            /**
             *  @brief  Throwing exceptions on errors.
             *  @param  except  The new exceptions mask.
             *
             *  By default, error flags are set silently.  You can set an
             *  exceptions mask for each stream; if a bit in the mask becomes set
             *  in the error flags, then an exception of type
             *  std::ios_base::failure is thrown.
             *
             *  If the error flage is already set when the exceptions mask is
             *  added, the exception is immediately thrown.  Try running the
             *  following under GCC 3.1 or later:
             *  @code
             *  #include <iostream>
             *  #include <fstream>
             *  #include <exception>
             *
             *  int main()
             *  {
             *      std::set_terminate (__gnu_cxx::__verbose_terminate_handler);
             *
             *      std::ifstream f ("/etc/motd");
             *
             *      std::cerr << "Setting badbit\n";