_fstream.h

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/*
 * Copyright (c) 1999
 * Silicon Graphics Computer Systems, Inc.
 *
 * Copyright (c) 1999
 * Boris Fomitchev
 *
 * This material is provided "as is", with absolutely no warranty expressed
 * or implied. Any use is at your own risk.
 *
 * Permission to use or copy this software for any purpose is hereby granted
 * without fee, provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 *
 */
// This header defines classes basic_filebuf, basic_ifstream,
// basic_ofstream, and basic_fstream.  These classes represent
// streambufs and streams whose sources or destinations are files.

#ifndef _STLP_INTERNAL_FSTREAM_H
#define _STLP_INTERNAL_FSTREAM_H

#if defined(__sgi) && !defined(__GNUC__) && !defined(_STANDARD_C_PLUS_PLUS)
#  error This header file requires the -LANG:std option
#endif

#ifndef _STLP_INTERNAL_STREAMBUF
#  include <stl/_streambuf.h>
#endif

#ifndef _STLP_INTERNAL_ISTREAM
#  include <stl/_istream.h>
#endif

#ifndef _STLP_INTERNAL_CODECVT_H
#  include <stl/_codecvt.h>
#endif

#if defined (_STLP_USE_WIN32_IO)
typedef void* _STLP_fd;
#elif defined (_STLP_USE_UNIX_EMULATION_IO) || defined (_STLP_USE_STDIO_IO) || defined (_STLP_USE_UNIX_IO)
typedef int _STLP_fd;
#else
#  error "Configure i/o !"
#endif

_STLP_BEGIN_NAMESPACE

//----------------------------------------------------------------------
// Class _Filebuf_base, a private base class to factor out the system-
// dependent code from basic_filebuf<>.

class _STLP_CLASS_DECLSPEC _Filebuf_base {
public:                      // Opening and closing files.
  _Filebuf_base();

  bool _M_open(const char*, ios_base::openmode, long __protection);
  bool _M_open(const char*, ios_base::openmode);
  bool _M_open(int __id, ios_base::openmode = ios_base::__default_mode);
#if defined (_STLP_USE_WIN32_IO)
  bool _M_open(_STLP_fd __id, ios_base::openmode = ios_base::__default_mode);
#endif /* _STLP_USE_WIN32_IO */
  bool _M_close();

public:                      // Low-level I/O, like Unix read/write
  ptrdiff_t _M_read(char* __buf,  ptrdiff_t __n);
  streamoff _M_seek(streamoff __offset, ios_base::seekdir __dir);
  streamoff _M_file_size();
  bool _M_write(char* __buf,  ptrdiff_t __n);

public:                      // Memory-mapped I/O.
  void* _M_mmap(streamoff __offset, streamoff __len);
  void _M_unmap(void* __mmap_base, streamoff __len);

public:
  // Returns a value n such that, if pos is the file pointer at the
  // beginning of the range [first, last), pos + n is the file pointer at
  // the end.  On many operating systems n == __last - __first.
  // In Unix, writing n characters always bumps the file position by n.
  // In Windows text mode, however, it bumps the file position by n + m,
  // where m is the number of newlines in the range.  That's because an
  // internal \n corresponds to an external two-character sequence.
  streamoff _M_get_offset(char* __first, char* __last) {
#if defined (_STLP_UNIX) || defined (_STLP_MAC)
    return __last - __first;
#else // defined (_STLP_WIN32)
    return ( (_M_openmode & ios_base::binary) != 0 )
      ? (__last - __first)
      : count(__first, __last, '\n') + (__last - __first);
#endif
  }

  // Returns true if we're in binary mode or if we're using an OS or file
  // system where there is no distinction between text and binary mode.
  bool _M_in_binary_mode() const {
#if defined (_STLP_UNIX) || defined (_STLP_MAC) || defined(__BEOS__) || defined (__amigaos__)
    return true;
#elif defined (_STLP_WIN32) || defined (_STLP_VM)
    return (_M_openmode & ios_base::binary) != 0;
#else
#  error "Port!"
#endif
  }

  static void _S_initialize();

protected:                      // Static data members.
  static size_t _M_page_size;

protected:                      // Data members.
  _STLP_fd _M_file_id;
#if defined (_STLP_USE_STDIO_IO)
  // for stdio, the whole FILE* is being kept here
  FILE* _M_file;
#endif
  ios_base::openmode _M_openmode     ;
  unsigned char      _M_is_open      ;
  unsigned char      _M_should_close ;
  unsigned char      _M_regular_file ;

#if defined (_STLP_USE_WIN32_IO)
  _STLP_fd _M_view_id;
#endif

public :
  static size_t  _STLP_CALL __page_size() { return _M_page_size; }
  int  __o_mode() const { return (int)_M_openmode; }
  bool __is_open()      const { return (_M_is_open !=0 ); }
  bool __should_close() const { return (_M_should_close != 0); }
  bool __regular_file() const { return (_M_regular_file != 0); }
  _STLP_fd __get_fd() const { return _M_file_id; }
};

//----------------------------------------------------------------------
// Class basic_filebuf<>.

// Forward declaration of two helper classes.
template <class _Traits> class _Noconv_input;
template <class _Traits> class _Noconv_output;

// There is a specialized version of underflow, for basic_filebuf<char>,
// in fstream.cpp.
template <class _CharT, class _Traits>
class _Underflow;

template <class _CharT, class _Traits>
class basic_filebuf : public basic_streambuf<_CharT, _Traits> {
public:                         // Types.
  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;

  typedef typename _Traits::state_type _State_type;
  typedef basic_streambuf<_CharT, _Traits> _Base;
  typedef basic_filebuf<_CharT, _Traits> _Self;

public:                         // Constructors, destructor.
  basic_filebuf();
  ~basic_filebuf();

public:                         // Opening and closing files.
  bool is_open() const { return _M_base.__is_open(); }

  _Self* open(const char* __s, ios_base::openmode __m) {
    return _M_base._M_open(__s, __m) ? this : 0;
  }

#if !defined (_STLP_NO_EXTENSIONS)
  // These two version of open() and file descriptor getter are extensions.
  _Self* open(const char* __s, ios_base::openmode __m,
              long __protection) {
    return _M_base._M_open(__s, __m, __protection) ? this : 0;
  }

  _STLP_fd fd() const { return _M_base.__get_fd(); }

  _Self* open(int __id, ios_base::openmode _Init_mode = ios_base::__default_mode) {
    return this->_M_open(__id, _Init_mode);
  }

#  if defined (_STLP_USE_WIN32_IO)
  _Self* open(_STLP_fd __id, ios_base::openmode _Init_mode = ios_base::__default_mode) {
    return _M_base._M_open(__id, _Init_mode) ? this : 0;
  }
#  endif /* _STLP_USE_WIN32_IO */

#endif

  _Self* _M_open(int __id, ios_base::openmode _Init_mode = ios_base::__default_mode) {
    return _M_base._M_open(__id, _Init_mode) ? this : 0;
  }

  _Self* close();

protected:                      // Virtual functions from basic_streambuf.
  virtual streamsize showmanyc();
  virtual int_type underflow();

  virtual int_type pbackfail(int_type = traits_type::eof());
  virtual int_type overflow(int_type = traits_type::eof());

  virtual basic_streambuf<_CharT, _Traits>* setbuf(char_type*, streamsize);
  virtual pos_type seekoff(off_type, ios_base::seekdir,
                           ios_base::openmode = ios_base::in | ios_base::out);
  virtual pos_type seekpos(pos_type,
                           ios_base::openmode = ios_base::in | ios_base::out);

  virtual int sync();
  virtual void imbue(const locale&);

private:                        // Helper functions.

  // Precondition: we are currently in putback input mode.  Effect:
  // switches back to ordinary input mode.
  void _M_exit_putback_mode() {
    this->setg(_M_saved_eback, _M_saved_gptr, _M_saved_egptr);
    _M_in_putback_mode = false;
  }
  bool _M_switch_to_input_mode();
  void _M_exit_input_mode();
  bool _M_switch_to_output_mode();

  int_type _M_input_error();
  int_type _M_underflow_aux();
  friend class _Underflow<_CharT, _Traits>;

  int_type _M_output_error();
  bool _M_unshift();

  bool _M_allocate_buffers(_CharT* __buf, streamsize __n);
  bool _M_allocate_buffers();
  void _M_deallocate_buffers();

  pos_type _M_seek_return(off_type __off, _State_type __state) {
    if (__off != -1) {
      if (_M_in_input_mode)
        _M_exit_input_mode();
      _M_in_input_mode = false;
      _M_in_output_mode = false;
      _M_in_putback_mode = false;
      _M_in_error_mode = false;
      this->setg(0, 0, 0);
      this->setp(0, 0);
    }

    pos_type __result(__off);
    __result.state(__state);
    return __result;
  }

  bool _M_seek_init(bool __do_unshift);

  void _M_setup_codecvt(const locale&, bool __on_imbue = true);

private:                        // Data members used in all modes.

  _Filebuf_base _M_base;

private:                        // Locale-related information.

  unsigned char _M_constant_width;
  unsigned char _M_always_noconv;

  // private:                        // Mode flags.
  unsigned char _M_int_buf_dynamic;  // True if internal buffer is heap allocated,
  // false if it was supplied by the user.
  unsigned char _M_in_input_mode;
  unsigned char _M_in_output_mode;
  unsigned char _M_in_error_mode;
  unsigned char _M_in_putback_mode;

  // Internal buffer: characters seen by the filebuf's clients.
  _CharT* _M_int_buf;
  _CharT* _M_int_buf_EOS;

  // External buffer: characters corresponding to the external file.
  char* _M_ext_buf;
  char* _M_ext_buf_EOS;

  // The range [_M_ext_buf, _M_ext_buf_converted) contains the external
  // characters corresponding to the sequence in the internal buffer.  The
  // range [_M_ext_buf_converted, _M_ext_buf_end) contains characters that
  // have been read into the external buffer but have not been converted
  // to an internal sequence.
  char* _M_ext_buf_converted;
  char* _M_ext_buf_end;

  // State corresponding to beginning of internal buffer.
  _State_type _M_state;

private:                        // Data members used only in input mode.

  // Similar to _M_state except that it corresponds to
  // the end of the internal buffer instead of the beginning.
  _State_type _M_end_state;

  // This is a null pointer unless we are in mmap input mode.
  void*     _M_mmap_base;
  streamoff _M_mmap_len;

private:                        // Data members used only in putback mode.
  _CharT* _M_saved_eback;
  _CharT* _M_saved_gptr;
  _CharT* _M_saved_egptr;

  typedef codecvt<_CharT, char, _State_type> _Codecvt;
  const _Codecvt* _M_codecvt;

  int _M_width;                 // Width of the encoding (if constant), else 1
  int _M_max_width;             // Largest possible width of single character.


  enum { _S_pback_buf_size = 8 };
  _CharT _M_pback_buf[_S_pback_buf_size];

  // for _Noconv_output
public:
  bool _M_write(char* __buf,  ptrdiff_t __n) {return _M_base._M_write(__buf, __n); }

public:
  int_type
  _M_do_noconv_input() {
    _M_ext_buf_converted = _M_ext_buf_end;
    /* this-> */ _Base::setg((char_type*)_M_ext_buf, (char_type*)_M_ext_buf, (char_type*)_M_ext_buf_end);
    return traits_type::to_int_type(*_M_ext_buf);
  }
};

#if defined (_STLP_USE_TEMPLATE_EXPORT)
_STLP_EXPORT_TEMPLATE_CLASS basic_filebuf<char, char_traits<char> >;
#  if ! defined (_STLP_NO_WCHAR_T)
_STLP_EXPORT_TEMPLATE_CLASS basic_filebuf<wchar_t, char_traits<wchar_t> >;
#  endif
#endif /* _STLP_USE_TEMPLATE_EXPORT */

//
// This class had to be designed very carefully to work
// with Visual C++.
//
template <class _Traits>
class _Noconv_output {
public:
  typedef typename _Traits::char_type char_type;
  static bool  _STLP_CALL _M_doit(basic_filebuf<char_type, _Traits >*,
                                  char_type*, char_type*)
  { return false; }
};

_STLP_TEMPLATE_NULL
class _STLP_CLASS_DECLSPEC _Noconv_output< char_traits<char> > {
public:
  static bool  _STLP_CALL
  _M_doit(basic_filebuf<char, char_traits<char> >* __buf,
          char* __first, char* __last) {