DataManAccessor.h

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// # DataManAccessor.h: Base class for the Data Manager Accessor classes
// # Copyright (C) 1996,1999
// # Associated Universities, Inc. Washington DC, USA.
// #
// # This library is free software; you can redistribute it and/or modify it
// # under the terms of the GNU Library General Public License as published by
// # the Free Software Foundation; either version 2 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 Library General Public
// # License for more details.
// #
// # You should have received a copy of the GNU Library General Public License
// # along with this library; if not, write to the Free Software Foundation,
// # Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
// #
// # Correspondence concerning AIPS++ should be addressed as follows:
// #        Internet email: casa-feedback@nrao.edu.
// #        Postal address: AIPS++ Project Office
// #                        National Radio Astronomy Observatory
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#ifndef TABLES_DATAMANACCESSOR_H
#define TABLES_DATAMANACCESSOR_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/tables/DataMan/DataManager.h>
#include <iosfwd>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// <summary>
// Base class for the Data Manager Accessor classes.
// </summary>
 
// <use visibility=local>
 
// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="" demos="">
// </reviewed>
 
// <prerequisite>
// # Classes you should understand before using this one.
// <li> <linkto class=DataManager>DataManager</linkto>
// </prerequisite>
 
// <synopsis>
// The Table system has one or more data managers underneath.
// Once a table is constructed, these data managers are invisible
// and there is no way to get access to them.
// However, sometimes limited access to them is needed (e.g. to
// set the size of an internal cache).
// <p>
// This class should be used as the base class for specialized
// Data Manager Accessor classes (e.g. class
// <linkto class=ROIncrementalStManAccessor:description>
// ROIncrementalStManAccessor</linkto>.
// This base class provides the functionality to get the
// <src>DataManager</src> object for a given column.
// </synopsis>
 
// <motivation>
// This base class makes it possible that every derived class can get the
// data manager, because RODataManAccessor is a friend of class Table.
// Otherwise all accessor classes needed to be friend of Table.
// </motivation>
 
// # <todo asof="$DATE:$">
// # </todo>
 
class RODataManAccessor {
 public:
  // Construct an empty object.
  RODataManAccessor() : itsDataManager(0) {}
 
  // Construct the accessor object for a data manager in the table.
  // An exception is thrown if the name of the data manager or column is
  // unknown.
  RODataManAccessor(const Table& table, const String& name, Bool byColumn);
 
  virtual ~RODataManAccessor();
 
  // Set data manager properties using the fields in the record.
  // Each data manager has its specific set of properties.
  void setProperties(const Record&) const;
 
  // Get data manager properties as a record.
  Record getProperties() const;
 
  // Get the data manager type.
  String dataManagerType() const { return itsDataManager->dataManagerType(); }
 
  // Get the data manager name.
  String dataManagerName() const { return itsDataManager->dataManagerName(); }
 
  // Get the data manager sequence nr.
  uInt dataManagerSeqNr() const { return itsDataManager->sequenceNr(); }
 
  // Show IO statistics.
  void showCacheStatistics(std::ostream& os) const { itsDataManager->showCacheStatistics(os); }
 
 protected:
  // Get the data manager for the given data manager or column name.
  DataManager* baseDataManager() const { return itsDataManager; }
 
 private:
  DataManager* itsDataManager;
};
 
}  // namespace casacore
 
#endif