std_fstream.h

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      bool
      _M_is_indeterminate(void)
      { 
	bool __ret = false;
	// Don't return true if unbuffered.
	if (_M_buf)
	  {
	    if (_M_mode & ios_base::in)
	      __ret = _M_in_beg == _M_in_cur && _M_in_cur == _M_in_end;
	    if (_M_mode & ios_base::out)
	      __ret = _M_out_beg == _M_out_cur && _M_out_cur == _M_out_end;
	  }
	return __ret;
      }
    };

  // Explicit specialization declarations, defined in src/fstream.cc.
  template<> 
    basic_filebuf<char>::int_type 
    basic_filebuf<char>::_M_underflow_common(bool __bump);

 #ifdef _GLIBCPP_USE_WCHAR_T
  template<> 
    basic_filebuf<wchar_t>::int_type 
    basic_filebuf<wchar_t>::_M_underflow_common(bool __bump);
 #endif

  // Generic definitions.
  template <typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::int_type
    basic_filebuf<_CharT, _Traits>::underflow() 
    { return _M_underflow_common(false); }

  template <typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::int_type
    basic_filebuf<_CharT, _Traits>::uflow() 
    { return _M_underflow_common(true); }


  // [27.8.1.5] Template class basic_ifstream
  /**
   *  @brief  Controlling input for files.
   *
   *  This class supports reading from named files, using the inherited
   *  functions from std::basic_istream.  To control the associated
   *  sequence, an instance of std::basic_filebuf is used, which this page
   *  refers to as @c sb.
  */
  template<typename _CharT, typename _Traits>
    class basic_ifstream : public basic_istream<_CharT, _Traits>
    {
    public:
      // Types:
      typedef _CharT 					char_type;
      typedef _Traits 					traits_type;
      typedef typename traits_type::int_type 		int_type;
      typedef typename traits_type::pos_type 		pos_type;
      typedef typename traits_type::off_type 		off_type;

      // Non-standard types:
      typedef basic_filebuf<char_type, traits_type> 	__filebuf_type;
      typedef basic_istream<char_type, traits_type>	__istream_type;

    private:
      /**
       *  @if maint
       *  @doctodo
       *  @endif
      */
      __filebuf_type	_M_filebuf;

    public:
      // Constructors/Destructors:
      /**
       *  @brief  Default constructor.
       *
       *  Initializes @c sb using its default constructor, and passes
       *  @c &sb to the base class initializer.  Does not open any files
       *  (you haven't given it a filename to open).
      */
      basic_ifstream()
      : __istream_type(NULL), _M_filebuf()
      { this->init(&_M_filebuf); }

      /**
       *  @brief  Create an input file stream.
       *  @param  s  Null terminated string specifying the filename.
       *  @param  mode  Open file in specified mode (see std::ios_base).
       *
       *  @c ios_base::in is automatically included in @a mode.
       *
       *  Tip:  When using std::string to hold the filename, you must use
       *  .c_str() before passing it to this constructor.
      */
      explicit
      basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
      : __istream_type(NULL), _M_filebuf()
      {
	this->init(&_M_filebuf);
	this->open(__s, __mode);
      }

      /**
       *  @brief  The destructor does nothing.
       *
       *  The file is closed by the filebuf object, not the formatting
       *  stream.
      */
      ~basic_ifstream()
      { }

      // Members:
      /**
       *  @brief  Accessing the underlying buffer.
       *  @return  The current basic_filebuf buffer.
       *
       *  This hides both signatures of std::basic_ios::rdbuf().
      */
      __filebuf_type*
      rdbuf() const
      { return const_cast<__filebuf_type*>(&_M_filebuf); }

      /**
       *  @brief  Wrapper to test for an open file.
       *  @return  @c rdbuf()->is_open()
      */
      bool
      is_open() { return _M_filebuf.is_open(); }

      /**
       *  @brief  Opens an external file.
       *  @param  s  The name of the file.
       *  @param  mode  The open mode flags.
       *
       *  Calls @c std::basic_filebuf::open(s,mode|in).  If that function
       *  fails, @c failbit is set in the stream's error state.
       *
       *  Tip:  When using std::string to hold the filename, you must use
       *  .c_str() before passing it to this constructor.
      */
      void
      open(const char* __s, ios_base::openmode __mode = ios_base::in)
      {
	if (!_M_filebuf.open(__s, __mode | ios_base::in))
	  this->setstate(ios_base::failbit);
      }

      /**
       *  @brief  Close the file.
       *
       *  Calls @c std::basic_filebuf::close().  If that function
       *  fails, @c failbit is set in the stream's error state.
      */
      void
      close()
      {
	if (!_M_filebuf.close())
	  this->setstate(ios_base::failbit);
      }
    };


  // [27.8.1.8] Template class basic_ofstream
  /**
   *  @brief  Controlling output for files.
   *
   *  This class supports reading from named files, using the inherited
   *  functions from std::basic_ostream.  To control the associated
   *  sequence, an instance of std::basic_filebuf is used, which this page
   *  refers to as @c sb.
  */
  template<typename _CharT, typename _Traits>
    class basic_ofstream : public basic_ostream<_CharT,_Traits>
    {
    public:
      // Types:
      typedef _CharT 					char_type;
      typedef _Traits 					traits_type;
      typedef typename traits_type::int_type 		int_type;
      typedef typename traits_type::pos_type 		pos_type;
      typedef typename traits_type::off_type 		off_type;

      // Non-standard types:
      typedef basic_filebuf<char_type, traits_type> 	__filebuf_type;
      typedef basic_ostream<char_type, traits_type>	__ostream_type;

    private:
      /**
       *  @if maint
       *  @doctodo
       *  @endif
      */
      __filebuf_type	_M_filebuf;

    public:
      // Constructors:
      /**
       *  @brief  Default constructor.
       *
       *  Initializes @c sb using its default constructor, and passes
       *  @c &sb to the base class initializer.  Does not open any files
       *  (you haven't given it a filename to open).
      */
      basic_ofstream()
      : __ostream_type(NULL), _M_filebuf()
      { this->init(&_M_filebuf); }

      /**
       *  @brief  Create an output file stream.
       *  @param  s  Null terminated string specifying the filename.
       *  @param  mode  Open file in specified mode (see std::ios_base).
       *
       *  @c ios_base::out|ios_base::trunc is automatically included in
       *  @a mode.
       *
       *  Tip:  When using std::string to hold the filename, you must use
       *  .c_str() before passing it to this constructor.
      */
      explicit
      basic_ofstream(const char* __s,
		     ios_base::openmode __mode = ios_base::out|ios_base::trunc)
      : __ostream_type(NULL), _M_filebuf()
      {
	this->init(&_M_filebuf);
	this->open(__s, __mode);
      }

      /**
       *  @brief  The destructor does nothing.
       *
       *  The file is closed by the filebuf object, not the formatting
       *  stream.
      */
      ~basic_ofstream()
      { }

      // Members:
      /**
       *  @brief  Accessing the underlying buffer.
       *  @return  The current basic_filebuf buffer.
       *
       *  This hides both signatures of std::basic_ios::rdbuf().
      */
      __filebuf_type*
      rdbuf() const
      { return const_cast<__filebuf_type*>(&_M_filebuf); }

      /**
       *  @brief  Wrapper to test for an open file.
       *  @return  @c rdbuf()->is_open()
      */
      bool
      is_open() { return _M_filebuf.is_open(); }

      /**
       *  @brief  Opens an external file.
       *  @param  s  The name of the file.
       *  @param  mode  The open mode flags.
       *
       *  Calls @c std::basic_filebuf::open(s,mode|out|trunc).  If that
       *  function fails, @c failbit is set in the stream's error state.
       *
       *  Tip:  When using std::string to hold the filename, you must use
       *  .c_str() before passing it to this constructor.
      */
      void
      open(const char* __s,
	   ios_base::openmode __mode = ios_base::out | ios_base::trunc)
      {
	if (!_M_filebuf.open(__s, __mode | ios_base::out))
	  this->setstate(ios_base::failbit);
      }

      /**
       *  @brief  Close the file.
       *
       *  Calls @c std::basic_filebuf::close().  If that function
       *  fails, @c failbit is set in the stream's error state.
      */
      void
      close()
      {
	if (!_M_filebuf.close())
	  this->setstate(ios_base::failbit);
      }
    };


  // [27.8.1.11] Template class basic_fstream
  /**
   *  @brief  Controlling intput and output for files.
   *
   *  This class supports reading from and writing to named files, using
   *  the inherited functions from std::basic_iostream.  To control the
   *  associated sequence, an instance of std::basic_filebuf is used, which
   *  this page refers to as @c sb.
  */
  template<typename _CharT, typename _Traits>
    class basic_fstream : public basic_iostream<_CharT, _Traits>
    {
    public:
      // Types:
      typedef _CharT 					char_type;
      typedef _Traits 					traits_type;
      typedef typename traits_type::int_type 		int_type;
      typedef typename traits_type::pos_type 		pos_type;
      typedef typename traits_type::off_type 		off_type;

      // Non-standard types:
      typedef basic_filebuf<char_type, traits_type> 	__filebuf_type;
      typedef basic_ios<char_type, traits_type>		__ios_type;
      typedef basic_iostream<char_type, traits_type>	__iostream_type;

    private:
      /**
       *  @if maint
       *  @doctodo
       *  @endif
      */
      __filebuf_type	_M_filebuf;

    public:
      // Constructors/destructor:
      /**
       *  @brief  Default constructor.
       *
       *  Initializes @c sb using its default constructor, and passes
       *  @c &sb to the base class initializer.  Does not open any files
       *  (you haven't given it a filename to open).
      */
      basic_fstream()
      : __iostream_type(NULL), _M_filebuf()
      { this->init(&_M_filebuf); }

      /**
       *  @brief  Create an input/output file stream.
       *  @param  s  Null terminated string specifying the filename.
       *  @param  mode  Open file in specified mode (see std::ios_base).
       *
       *  Tip:  When using std::string to hold the filename, you must use
       *  .c_str() before passing it to this constructor.
      */
      explicit
      basic_fstream(const char* __s,
		    ios_base::openmode __mode = ios_base::in | ios_base::out)
      : __iostream_type(NULL), _M_filebuf()
      {
	this->init(&_M_filebuf);
	this->open(__s, __mode);
      }

      /**
       *  @brief  The destructor does nothing.
       *
       *  The file is closed by the filebuf object, not the formatting
       *  stream.
      */
      ~basic_fstream()
      { }

      // Members:
      /**
       *  @brief  Accessing the underlying buffer.
       *  @return  The current basic_filebuf buffer.
       *
       *  This hides both signatures of std::basic_ios::rdbuf().
      */
      __filebuf_type*
      rdbuf() const
      { return const_cast<__filebuf_type*>(&_M_filebuf); }

      /**
       *  @brief  Wrapper to test for an open file.
       *  @return  @c rdbuf()->is_open()
      */
      bool
      is_open() { return _M_filebuf.is_open(); }

      /**
       *  @brief  Opens an external file.
       *  @param  s  The name of the file.
       *  @param  mode  The open mode flags.
       *
       *  Calls @c std::basic_filebuf::open(s,mode).  If that
       *  function fails, @c failbit is set in the stream's error state.
       *
       *  Tip:  When using std::string to hold the filename, you must use
       *  .c_str() before passing it to this constructor.
      */
      void
      open(const char* __s,
	   ios_base::openmode __mode = ios_base::in | ios_base::out)
      {
	if (!_M_filebuf.open(__s, __mode))
	  setstate(ios_base::failbit);
      }

      /**
       *  @brief  Close the file.
       *
       *  Calls @c std::basic_filebuf::close().  If that function
       *  fails, @c failbit is set in the stream's error state.
      */
      void
      close()
      {
	if (!_M_filebuf.close())
	  setstate(ios_base::failbit);
      }
    };
} // namespace std

#ifdef _GLIBCPP_NO_TEMPLATE_EXPORT
# define export
#endif
#ifdef  _GLIBCPP_FULLY_COMPLIANT_HEADERS
# include <bits/fstream.tcc>
#endif

#endif