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contextbase.h

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/***************************************************************************
    contextbase.h  -  Definition of ContextBase class.
                             -------------------
    begin                : June 21 2002
    copyright            : (C) 2003 by Vojtìch Toman
    email                : vtoman@lit.cz
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program 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 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef CONTEXTBASE_H
#define CONTEXTBASE_H


#include "defs.h"
#include "arithcodec.h"



enum ContextType
{
  StaticContext,

  DynamicContext
};






class ContextBase
{
public:
  ContextBase(void) { initialized = false; }

  enum OperationResult
  {
    Ok = 0,
    
    NotKnown = -1,
    
    TooManySymbols = -2,
    
    NoMemory = -3
  };

  int endOfMessage;


  virtual void setType(int, ContextType) = 0;

  virtual int initialize(void) = 0;

  virtual int lastFixedSymbol(void) = 0;

  virtual bool isInitialized(void) { return initialized; }

  virtual void setArithCodec(ArithCodec *ac) { arithCodec = ac; }

  virtual int encode(int) throw (ExaltContextNotInitializedException, ExaltIOException) = 0;

  virtual int encodeEndOfMessage() throw (ExaltContextNotInitializedException, ExaltIOException)= 0;

  virtual int decode(void) throw (ExaltContextNotInitializedException, ExaltIOException) = 0;

  virtual int installSymbol(int) = 0;

  virtual void purgeContext(void) = 0;

protected:
  ArithCodec *arithCodec;

  bool initialized;
}; //ContextBase


#endif //CONTEXTBASE_H

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