EpochUDF.h

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// # EpochUDF.h: TaQL UDFs for Epoch conversions
// # Copyright (C) 2011
// # 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 MEAS_EPOCHUDF_H
#define MEAS_EPOCHUDF_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/meas/MeasUDF/EpochEngine.h>
#include <casacore/meas/MeasUDF/PositionEngine.h>
#include <casacore/tables/TaQL/UDFBase.h>
 
namespace casacore {
 
// <summary>
// TaQL UDFs for Epoch conversions.
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="" date="" tests="tMeas.cc">
// </reviewed>
 
// <prerequisite>
// # Classes you should understand before using this one.
//   <li> UDFBase
// </prerequisite>
 
// <synopsis>
// EpochUDF defines UDFs (user defined functions) that can be used in TaQL
// to convert Measures for epochs.
// Special functions exist to convert to local sidereal time.
// In this way such derived values appear to be ordinary TaQL functions.
//
// A function is called like:
// <srcblock>
//   meas.epoch (toref, epoch, fromref, pos, posref)
// For example,
//   meas.dir ('APP', 'MOON', POSITION, TIME)
// </srcblock>
// <ul>
//  <li>
//  <src>toref</src> is a single constant string.
//  <li>
// <src>dir</src> can have various value types. A single numeric array is
// a series of RA,DEC in J2000. If given as a set, the last argument of the
// set can be the reference types of the values in the set. The values can
// be strings (indicating planetary objects) or value pairs giving lon,lat.
// The default reference type is J2000.
// </ul>
// All functions have data type double and unit radian.
// </synopsis>
 
// <motivation>
// It makes it possible to handle measures in TaQL.
// </motivation>
 
class EpochUDF : public UDFBase {
 public:
  // Define the possible function types.
  enum FuncType { EPOCH, LAST };
 
  explicit EpochUDF(FuncType);
 
  // Function to create an object.
  static UDFBase* makeEPOCH(const String&);
  static UDFBase* makeLAST(const String&);
 
  // Setup the object.
  virtual void setup(const Table&, const TaQLStyle&);
 
  // Get the value.
  virtual Double getDouble(const TableExprId& id);
  virtual MArray<Double> getArrayDouble(const TableExprId& id);
 
 private:
  // # Data members.
  EpochEngine itsEngine;
  PositionEngine itsPositionEngine;
  FuncType itsType;
  MEpoch::Types itsRefType;
  Bool itsSidFrac;  // T = use fraction for sidereal times
};
 
}  // namespace casacore
 
#endif