eabstractdata.h

#ifndef EABSTRACTDATA_H
#define EABSTRACTDATA_H
#include <QtCore>
#include <memory>
#include "emetadata.h"
#include "eexception.h"
#include "global.h"
//



class EAbstractData : public QObject
{
   Q_OBJECT
public:
   virtual qint64 dataEnd() const = 0;
   virtual void readData() = 0;
   virtual void writeNewData() = 0;
   virtual void finish();
   virtual QAbstractTableModel* model() = 0;
public:
   template<class T> const T* cast() const;
   template<class T> T* cast();
protected:
   const EMetadata& systemMeta() const;
   const EMetadata& meta() const;
   void setMeta(const EMetadata& newMeta);
   const EDataStream& stream() const;
   EDataStream& stream();
   void seek(qint64 index) const;
   void allocate(qint64 size);
};






template<class T> const T* EAbstractData::cast() const
{
   // Use qt object cast to cast this object to the given template type as read only. 
   // If the cast fails then throw an exception, else return the cast read only 
   // pointer. 
   const T* ret {qobject_cast<const T*>(this)};
   if ( !ret )
   {
      E_MAKE_EXCEPTION(e);
      e.setTitle(tr("Logic Error"));
      e.setDetails(tr("Cannot convert abstract data object to given type."));
      throw e;
   }
   return ret;
}






template<class T> T* EAbstractData::cast()
{
   // Use qt object cast to cast this object to the given template type. If the cast 
   // fails then throw an exception, else return the cast pointer. 
   T* ret {qobject_cast<T*>(this)};
   if ( !ret )
   {
      E_MAKE_EXCEPTION(e);
      e.setTitle(tr("Logic Error"));
      e.setDetails(tr("Cannot convert abstract data object to given type."));
      throw e;
   }
   return ret;
}



#endif