src/add-ons/media/plugins/matroska/libebml/ebml/IOCallback.h

   1 /****************************************************************************
   2 ** libebml : parse EBML files, see http://embl.sourceforge.net/
   3 **
   4 ** <file/class description>
   5 **
   6 ** Copyright (C) 2002-2004 Ingo Ralf Blum.  All rights reserved.
   7 **
   8 ** This library is free software; you can redistribute it and/or
   9 ** modify it under the terms of the GNU Lesser General Public
  10 ** License as published by the Free Software Foundation; either
  11 ** version 2.1 of the License, or (at your option) any later version.
  12 **
  13 ** This library is distributed in the hope that it will be useful,
  14 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 ** Lesser General Public License for more details.
  17 **
  18 ** You should have received a copy of the GNU Lesser General Public
  19 ** License along with this library; if not, write to the Free Software
  20 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21 **
  22 ** See http://www.matroska.org/license/lgpl/ for LGPL licensing information.
  23 **
  24 ** Contact license@matroska.org if any conditions of this licensing are
  25 ** not clear to you.
  26 **
  27 **********************************************************************/
  28
  29 /*!
  30         \file
  31         \version \$Id: IOCallback.h 639 2004-07-09 20:59:14Z mosu $
  32 */
  33 #ifndef MATROSKA_IOCALLBACK_H
  34 #define MATROSKA_IOCALLBACK_H
  35
  36 #include "EbmlTypes.h"
  37
  38 #include <exception>
  39 #include <cstdio>
  40 // #include <iostream>
  41
  42
  43 START_LIBEBML_NAMESPACE
  44
  45 enum seek_mode
  46 {
  47         seek_beginning=SEEK_SET
  48         ,seek_end=SEEK_END
  49         ,seek_current=SEEK_CUR
  50 };
  51
  52 class EBML_DLL_API IOCallback
  53 {
  54 public:
  55         virtual ~IOCallback(){}
  56
  57         // The read callback works like most other read functions. You specify the
  58         // file, the buffer and the size and the function returns the bytes read.
  59         // If an error occurs or the file pointer points to the end of the file 0 is returned.
  60         // Users are encouraged to throw a descriptive exception, when an error occurs.
  61         virtual uint32 read(void*Buffer,size_t Size)=0;
  62
  63         // Seek to the specified position. The mode can have either SEEK_SET, SEEK_CUR
  64         // or SEEK_END. The callback should return true(1) if the seek operation succeeded
  65         // or false (0), when the seek fails.
  66         virtual void setFilePointer(int64 Offset,seek_mode Mode=seek_beginning)=0;
  67
  68         // This callback just works like its read pendant. It returns the number of bytes written.
  69         virtual size_t write(const void*Buffer,size_t Size)=0;
  70
  71         // Although the position is always positive, the return value of this callback is signed to
  72         // easily allow negative values for returning errors. When an error occurs, the implementor
  73         // should return -1 and the file pointer otherwise.
  74         //
  75         // If an error occurs, an exception should be thrown.
  76         virtual uint64 getFilePointer()=0;
  77
  78         // The close callback flushes the file buffers to disk and closes the file. When using the stdio
  79         // library, this is equivalent to calling fclose. When the close is not successful, an exception
  80         // should be thrown.
  81         virtual void close()=0;
  82
  83
  84         // The readFully is made virtual to allow derived classes to use another
  85         // implementation for this method, which e.g. does not read any data
  86         // unlike this does
  87         void readFully(void*Buffer,size_t Size);
  88
  89         template<class STRUCT> void readStruct(STRUCT&Struct){readFully(&Struct,sizeof(Struct));}
  90
  91         void writeFully(const void*Buffer,size_t Size);
  92
  93         template<class STRUCT> void writeStruct(const STRUCT&Struct){writeFully(&Struct,sizeof(Struct));}
  94 };
  95
  96 /* cygwin incompatible
  97 template<class TRAITS> std::basic_ostream<char,TRAITS>&operator<<(std::basic_ostream<char,TRAITS>&Stream,seek_mode Mode)
  98 {
  99         switch(Mode)
 100         {
 101 #define x(y) case seek_##y: Stream<<"seek_" #y; break
 102                 x(beginning);
 103                 x(current);
 104                 x(end);
 105 #undef x
 106         default:
 107                 assert(false);
 108         }
 109
 110         return Stream;
 111 }
 112 */
 113
 114 END_LIBEBML_NAMESPACE
 115
 116 #endif // MATROSKA_IOCALLBACK_H