/****************************************************************************

** libebml : parse EBML files, see http://embl.sourceforge.net/

**

** <file/class description>

**

** Copyright (C) 2002-2004 Ingo Ralf Blum.  All rights reserved.

**

** This library is free software; you can redistribute it and/or

** modify it under the terms of the GNU Lesser General Public

** License as published by the Free Software Foundation; either

** version 2.1 of the License, 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

** Lesser General Public License for more details.

**

** You should have received a copy of the GNU Lesser General Public

** License along with this library; if not, write to the Free Software

** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

**

** See http://www.gnu.org/licenses/lgpl-2.1.html for LGPL licensing information.

**

** Contact license@matroska.org if any conditions of this licensing are

** not clear to you.

**

**********************************************************************/

/*!

  \file

  \version \$Id: IOCallback.h 639 2004-07-09 20:59:14Z mosu $

*/

#ifndef MATROSKA_IOCALLBACK_H

#define MATROSKA_IOCALLBACK_H

#include "EbmlTypes.h"

#include <cassert>

#include <exception>

#include <cstdio>

// #include <iostream>

namespace libebml {

enum seek_mode

{

  seek_beginning=SEEK_SET

  ,seek_end=SEEK_END

  ,seek_current=SEEK_CUR

};

class EBML_DLL_API IOCallback

{

public:

  virtual ~IOCallback() = default;

  // The read callback works like most other read functions. You specify the

  // file, the buffer and the size and the function returns the bytes read.

  // If an error occurs or the file pointer points to the end of the file 0 is returned.

  // Users are encouraged to throw a descriptive exception, when an error occurs.

  virtual uint32 read(void*Buffer,size_t Size)=0;

  // Seek to the specified position. The mode can have either SEEK_SET, SEEK_CUR

  // or SEEK_END. The callback should return true(1) if the seek operation succeeded

  // or false (0), when the seek fails.

  virtual void setFilePointer(int64 Offset,seek_mode Mode=seek_beginning)=0;

  // This callback just works like its read pendant. It returns the number of bytes written.

  virtual size_t write(const void*Buffer,size_t Size)=0;

  // Although the position is always positive, the return value of this callback is signed to

  // easily allow negative values for returning errors. When an error occurs, the implementor

  // should return -1 and the file pointer otherwise.

  //

  // If an error occurs, an exception should be thrown.

  virtual uint64 getFilePointer()=0;

  // The close callback flushes the file buffers to disk and closes the file. When using the stdio

  // library, this is equivalent to calling fclose. When the close is not successful, an exception

  // should be thrown.

  virtual void close()=0;

  // The readFully is made virtual to allow derived classes to use another

  // implementation for this method, which e.g. does not read any data

  // unlike this does

  void readFully(void*Buffer,size_t Size);

  template<class STRUCT> void readStruct(STRUCT&Struct){readFully(&Struct,sizeof(Struct));}

  void writeFully(const void*Buffer,size_t Size);

  template<class STRUCT> void writeStruct(const STRUCT&Struct){writeFully(&Struct,sizeof(Struct));}

};

/* cygwin incompatible

template<class TRAITS> std::basic_ostream<char,TRAITS>&operator<<(std::basic_ostream<char,TRAITS>&Stream,seek_mode Mode)

{

  switch(Mode)

  {

#define x(y) case seek_##y: Stream<<"seek_" #y; break

    x(beginning);

    x(current);

    x(end);

#undef x

  default:

    assert(false);

  }

  return Stream;

}

*/

} // namespace libebml

#endif // MATROSKA_IOCALLBACK_H