TableMeasDescBase.h

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// # TableMeasDescBase.h: Definition of a Measure in a Table.
// # Copyright (C) 1997,1999,2000,2001
// # 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
// #                        520 Edgemont Road
// #                        Charlottesville, VA 22903-2475 USA
 
#ifndef MEASURES_TABLEMEASDESCBASE_H
#define MEASURES_TABLEMEASDESCBASE_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/measures/TableMeasures/TableMeasValueDesc.h>
#include <casacore/measures/TableMeasures/TableMeasRefDesc.h>
#include <casacore/measures/TableMeasures/TableMeasType.h>
#include <casacore/casa/Quanta/Unit.h>
#include <casacore/casa/Arrays/Vector.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward Declarations
class String;
class Table;
class TableDesc;
class TableRecord;
class TableColumn;
class Measure;
template <class T>
class Quantum;
 
// <summary>
// Definition of a Measure in a Table.
// </summary>
 
// <use visibility=local>
 
// <reviewed reviewer="Bob Garwood" date="1999/12/23" tests="tTableMeasures.cc">
// </reviewed>
 
// <prerequisite>
// # Classes you should understand before using this one.
//   <li> <linkto module=Measures>Measures</linkto>
//   <li> <linkto module=Tables>Tables</linkto>
//   <li> <linkto class=TableMeasDesc>TableMeasDesc</linkto>
// </prerequisite>
 
// <synopsis>
// Abstract base class for TableMeasDesc.
// </synopsis>
 
// <example>
// See class <linkto class="TableMeasDesc">TableMeasDesc</linkto>.
// </example>
 
// <motivation>
// Creating the required keyword for the definition of a Measure
// in a Table is somewhat complicated. This class assists in that
// process.
// </motivation>
//
// <thrown>
//    <li>AipsError during reconstruction if the column doesn't contain
//        a MEASINFO record.
//    <li>AipsError during reconstruction if the column has a MEASINFO
//        but it Measure type is invalid.
// </thrown>
//
 
// # <todo asof="$DATE:$">
// # A List of bugs, limitations, extensions or planned refinements.
// # </todo>
 
class TableMeasDescBase {
 public:
  // Null constructor.
  TableMeasDescBase();
 
  // Constructor with value and reference descriptors.
  // Note that setMeasType is always called by the derived class.
  TableMeasDescBase(const TableMeasValueDesc&, const TableMeasRefDesc&);
 
  // Copy constructor.
  TableMeasDescBase(const TableMeasDescBase& that);
 
  virtual ~TableMeasDescBase();
 
  // Clone the object.
  virtual TableMeasDescBase* clone() const;
 
  // Assignment operator.
  TableMeasDescBase& operator=(const TableMeasDescBase& that);
 
  // Makes the descriptor persistent.
  // <group>
  void write(TableDesc&);
  void write(Table&);
  // </group>
 
  // Make the descriptor persistent if there was no refcode vector.
  // This is only needed for old tables without such vectors.
  void writeIfOld(const Table&);
 
  // Get the name of the underlying column.
  const String& columnName() const { return itsValue.columnName(); }
 
  // Return the reference code.
  uInt getRefCode() const { return itsRef.getRefCode(); }
 
  // Returns True if the reference varies per row.
  Bool isRefCodeVariable() const { return itsRef.isRefCodeVariable(); }
 
  // Returns the name of the ref code column when the ref code is variable.
  // The null string is returned if the ref code is not variable.
  const String& refColumnName() const { return itsRef.columnName(); }
 
  // Returns a reference to its measure reference descriptor.
  const TableMeasRefDesc& getRefDesc() const { return itsRef; }
 
  // Get the name of the offset column. Empty string is returned if no
  // offset.
  const String& offsetColumnName() const { return itsRef.offsetColumnName(); }
 
  // Returns True if an offset has been defined.
  Bool hasOffset() const { return itsRef.hasOffset(); }
 
  // Returns True if the offset is variable.
  Bool isOffsetVariable() const { return itsRef.isOffsetVariable(); }
 
  // Returns True if the offset is variable and is stored in an
  // ArrayMeasColumn, i.e., offsets are stored per element.
  Bool isOffsetArray() const { return itsRef.isOffsetArray(); }
 
  // Returns a reference to the offset.
  const Measure& getOffset() const { return itsRef.getOffset(); }
 
  // Returns the descriptors measure type as a String.
  const String& type() const { return itsMeasType.type(); }
 
  // Returns the reference code for this object given a string.  Throws
  // an exception if the refString is invalid for this object.
  uInt refCode(const String& refString) const { return itsMeasType.refCode(refString); }
 
  // Translates the refCode for the descriptors measure type.
  const String& refType(uInt refCode) const { return itsMeasType.refType(refCode); }
 
  // Return the Units of the Measure values
  const Vector<Unit>& getUnits() const { return itsUnits; }
 
  // Reset the refCode, offset, or units.
  // It overwrites the value used when defining the TableMeasDesc.
  // It is only possible if it was defined as fixed for the entire column.
  // <group>
  void resetRefCode(uInt refCode) { itsRef.resetRefCode(refCode); }
  void resetOffset(const Measure& offset) { itsRef.resetOffset(offset); }
  void resetUnits(const Vector<Unit>& units);
  // </group>
 
  // Reconstructs the object for the given table and column name.
  static TableMeasDescBase* reconstruct(const Table& tab, const String& columnName);
 
  // Does this column contain table measures?
  static Bool hasMeasures(const TableColumn& column);
 
 protected:
  // Set the initial reference codes and types in the table.
  void initTabRef(const MeasureHolder& measHolder);
 
  // Set the measure and possible units.
  void setMeasUnits(const Measure& meas, const Vector<Quantum<Double>>& val,
                    const Vector<Unit>& units);
 
 private:
  TableMeasValueDesc itsValue;  // # The measure value column.
  TableMeasRefDesc itsRef;      // # The reference.
  // # this gives access to the columns Measure type etc
  TableMeasType itsMeasType;
  Vector<Unit> itsUnits;
};
 
}  // namespace casacore
 
#endif