// File based streams -*- C++ -*-

// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003

// 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.

//

// ISO C++ 14882: 27.8  File-based streams

//

/** @file fstream

 *  This is a Standard C++ Library header.  You should @c #include this header

 *  in your programs, rather than any of the "st[dl]_*.h" implementation files.

 */

#ifndef _GLIBCXX_FSTREAM

#define _GLIBCXX_FSTREAM 1

#pragma GCC system_header

#include <istream>

#include <ostream>

#include <locale>	// For codecvt

#include <cstdio>       // For SEEK_SET, SEEK_CUR, SEEK_END, BUFSIZ     

#include <bits/basic_file.h>

#include <bits/gthr.h>

namespace std

{

  // [27.8.1.1] template class basic_filebuf

  /**

   *  @brief  The actual work of input and output (for files).

   *

   *  This class associates both its input and output sequence with an

   *  external disk file, and maintains a joint file position for both

   *  sequences.  Many of its sematics are described in terms of similar

   *  behavior in the Standard C Library's @c FILE streams.

  */

  // Requirements on traits_type, specific to this class:

  // traits_type::pos_type must be fpos<traits_type::state_type>

  // traits_type::off_type must be streamoff

  // traits_type::state_type must be Assignable and DefaultConstructable,

  // and traits_type::state_type() must be the initial state for codecvt.

  template<typename _CharT, typename _Traits>

    class basic_filebuf : public basic_streambuf<_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;

      //@{

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      typedef basic_streambuf<char_type, traits_type>  	__streambuf_type;

      typedef basic_filebuf<char_type, traits_type>     __filebuf_type;

      typedef __basic_file<char>		        __file_type;

      typedef typename traits_type::state_type          __state_type;

      typedef codecvt<char_type, char, __state_type>    __codecvt_type;

      //@}

      friend class ios_base; // For sync_with_stdio.

    protected:

      // Data Members:

      // MT lock inherited from libio or other low-level io library.

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      __c_lock          	_M_lock;

      // External buffer.

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      __file_type 		_M_file;

      /**

       *  @if maint

       *  Place to stash in || out || in | out settings for current filebuf.

       *  @endif

      */

      ios_base::openmode 	_M_mode;

      // Beginning state type for codecvt.

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      __state_type 		_M_state_beg;

      // During output, the state that corresponds to pptr(),

      // during input, the state that corresponds to egptr() and

      // _M_ext_next.

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      __state_type		_M_state_cur;

      // Not used for output. During input, the state that corresponds

      // to eback() and _M_ext_buf.

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      __state_type		_M_state_last;

      /**

       *  @if maint

       *  Pointer to the beginning of internal buffer.

       *  @endif

      */

      char_type*		_M_buf; 	

      /**

       *  @if maint

       *  Actual size of internal buffer. This number is equal to the size

       *  of the put area + 1 position, reserved for the overflow char of

       *  a full area.

       *  @endif

      */

      size_t			_M_buf_size;

      // Set iff _M_buf is allocated memory from _M_allocate_internal_buffer.

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      bool			_M_buf_allocated;

      /**

       *  @if maint

       *  _M_reading == false && _M_writing == false for 'uncommitted' mode;  

       *  _M_reading == true for 'read' mode;

       *  _M_writing == true for 'write' mode;

       *

       *  NB: _M_reading == true && _M_writing == true is unused.

       *  @endif

      */ 

      bool                      _M_reading;

      bool                      _M_writing;

      //@{

      /**

       *  @if maint

       *  Necessary bits for putback buffer management.

       *

       *  @note pbacks of over one character are not currently supported.

       *  @endif

      */

      char_type			_M_pback; 

      char_type*		_M_pback_cur_save;

      char_type*		_M_pback_end_save;

      bool			_M_pback_init; 

      //@}

      // Cached codecvt facet.

      const __codecvt_type* 	_M_codecvt;

      /**

       *  @if maint

       *  Buffer for external characters. Used for input when

       *  codecvt::always_noconv() == false. When valid, this corresponds

       *  to eback().

       *  @endif

      */ 

      char*			_M_ext_buf;

      /**

       *  @if maint

       *  Size of buffer held by _M_ext_buf.

       *  @endif

      */ 

      streamsize		_M_ext_buf_size;

      /**

       *  @if maint

       *  Pointers into the buffer held by _M_ext_buf that delimit a

       *  subsequence of bytes that have been read but not yet converted.

       *  When valid, _M_ext_next corresponds to egptr().

       *  @endif

      */ 

      const char*		_M_ext_next;

      char*			_M_ext_end;

      /**

       *  @if maint

       *  Initializes pback buffers, and moves normal buffers to safety.

       *  Assumptions:

       *  _M_in_cur has already been moved back

       *  @endif

      */

      void

      _M_create_pback()

      {

	if (!_M_pback_init)

	  {

	    _M_pback_cur_save = this->gptr();

	    _M_pback_end_save = this->egptr();

	    this->setg(&_M_pback, &_M_pback, &_M_pback + 1);

	    _M_pback_init = true;

	  }

      }

      /**

       *  @if maint

       *  Deactivates pback buffer contents, and restores normal buffer.

       *  Assumptions:

       *  The pback buffer has only moved forward.

       *  @endif

      */ 

      void

      _M_destroy_pback() throw()

      {

	if (_M_pback_init)

	  {

	    // Length _M_in_cur moved in the pback buffer.

	    _M_pback_cur_save += this->gptr() != this->eback();

	    this->setg(this->_M_buf, _M_pback_cur_save, _M_pback_end_save);

	    _M_pback_init = false;

	  }

      }

    public:

      // Constructors/destructor:

      /**

       *  @brief  Does not open any files.

       *

       *  The default constructor initializes the parent class using its

       *  own default ctor.

      */

      basic_filebuf();

      /**

       *  @brief  The destructor closes the file first.

      */

      virtual

      ~basic_filebuf()

      { this->close(); }

      // Members:

      /**

       *  @brief  Returns true if the external file is open.

      */

      bool

      is_open() const throw() { return _M_file.is_open(); }

      /**

       *  @brief  Opens an external file.

       *  @param  s  The name of the file.

       *  @param  mode  The open mode flags.

       *  @return  @c this on success, NULL on failure

       *

       *  If a file is already open, this function immediately fails.

       *  Otherwise it tries to open the file named @a s using the flags

       *  given in @a mode.

       *

       *  [Table 92 gives the relation between openmode combinations and the

       *  equivalent fopen() flags, but the table has not been copied yet.]

      */

      __filebuf_type*

      open(const char* __s, ios_base::openmode __mode);

      /**

       *  @brief  Closes the currently associated file.

       *  @return  @c this on success, NULL on failure

       *

       *  If no file is currently open, this function immediately fails.

       *

       *  If a "put buffer area" exists, @c overflow(eof) is called to flush

       *  all the characters.  The file is then closed.

       *

       *  If any operations fail, this function also fails.

      */

      __filebuf_type*

      close() throw();

    protected:

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      void

      _M_allocate_internal_buffer();

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      void

      _M_destroy_internal_buffer() throw();

      // [27.8.1.4] overridden virtual functions

      // [documentation is inherited]

      virtual streamsize

      showmanyc();

      // Stroustrup, 1998, p. 628

      // underflow() and uflow() functions are called to get the next

      // charater from the real input source when the buffer is empty.

      // Buffered input uses underflow()

      // [documentation is inherited]

      virtual int_type

      underflow();

      // [documentation is inherited]

      virtual int_type

      pbackfail(int_type __c = _Traits::eof());

      // Stroustrup, 1998, p 648

      // The overflow() function is called to transfer characters to the

      // real output destination when the buffer is full. A call to

      // overflow(c) outputs the contents of the buffer plus the

      // character c.

      // 27.5.2.4.5

      // Consume some sequence of the characters in the pending sequence.

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      virtual int_type

      overflow(int_type __c = _Traits::eof());

      // Convert internal byte sequence to external, char-based

      // sequence via codecvt.

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      bool

      _M_convert_to_external(char_type*, streamsize);

      /**

       *  @brief  Manipulates the buffer.

       *  @param  s  Pointer to a buffer area.

       *  @param  n  Size of @a s.

       *  @return  @c this

       *

       *  If no file has been opened, and both @a s and @a n are zero, then

       *  the stream becomes unbuffered.  Otherwise, @c s is used as a

       *  buffer; see

       *  http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2

       *  for more.

      */

      virtual __streambuf_type*

      setbuf(char_type* __s, streamsize __n);

      // [documentation is inherited]

      virtual pos_type

      seekoff(off_type __off, ios_base::seekdir __way,

	      ios_base::openmode __mode = ios_base::in | ios_base::out);

      // [documentation is inherited]

      virtual pos_type

      seekpos(pos_type __pos,

	      ios_base::openmode __mode = ios_base::in | ios_base::out);

      // Common code for seekoff and seekpos

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      pos_type

      _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state);

      // [documentation is inherited]

      virtual int

      sync();

      // [documentation is inherited]

      virtual void

      imbue(const locale& __loc);

      // [documentation is inherited]

      virtual streamsize

      xsgetn(char_type* __s, streamsize __n);

      // [documentation is inherited]

      virtual streamsize

      xsputn(const char_type* __s, streamsize __n);

      // Flushes output buffer, then writes unshift sequence.

      /**

       *  @if maint

       *  @doctodo

       *  @endif

      */

      bool

      _M_terminate_output();

      /**

       *  @if maint 

       *  This function sets the pointers of the internal buffer, both get

       *  and put areas. Typically:

       *

       *   __off == egptr() - eback() upon underflow/uflow ('read' mode);

       *   __off == 0 upon overflow ('write' mode);

       *   __off == -1 upon open, setbuf, seekoff/pos ('uncommitted' mode).

       * 

       *  NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size

       *  reflects the actual allocated memory and the last cell is reserved

       *  for the overflow char of a full put area.

       *  @endif

      */

      void

      _M_set_buffer(streamsize __off)

      {

 	const bool __testin = this->_M_mode & ios_base::in;

 	const bool __testout = this->_M_mode & ios_base::out;

	if (__testin && __off > 0)

	  this->setg(this->_M_buf, this->_M_buf, this->_M_buf + __off);

	else

	  this->setg(this->_M_buf, this->_M_buf, this->_M_buf);

	if (__testout && __off == 0 && this->_M_buf_size > 1 )

	  this->setp(this->_M_buf, this->_M_buf + this->_M_buf_size - 1);

	else

	  this->setp(NULL, NULL);

      }

    };

  // [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(), _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(), _M_filebuf()

      {

	this->init(&_M_filebuf);

	this->open(__s, __mode);

      }