FrequencyEngine.h

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// # FrequencyEngine.h: Engine for TaQL UDF Frequency conversions
// # Copyright (C) 2016
// # 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_FREQUENCYENGINE_H
#define MEAS_FREQUENCYENGINE_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/meas/MeasUDF/MeasEngine.h>
#include <casacore/measures/Measures/MFrequency.h>
#include <casacore/measures/Measures/MCFrequency.h>
#include <casacore/measures/Measures/MeasConvert.h>
 
namespace casacore {
 
// # Forward declarations
class DopplerEngine;
class RadialVelocityEngine;
class DirectionEngine;
class EpochEngine;
class PositionEngine;
 
// <summary>
// Engine for TaQL UDF Frequency conversions
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="" date="" tests="tMeas.cc">
// </reviewed>
 
// <prerequisite>
// # Classes you should understand before using this one.
//   <li> EngineBase
// </prerequisite>
 
// <synopsis>
// FrequencyEngine defines Engines (user defined functions) that can be used
// in TaQL to convert Measures for frequencies.
// In this way such derived values appear to be ordinary TaQL functions.
//
// Frequency conversions require a MeasFrame containing sky direction,
// epoch and position on earth.
// In TaQL these functions can be called like:
// <srcblock>
//   meas.freq ('TOPO', 1GHz, 'LSRK', 'CasA', date(),
//              [1e6m,1e6m,1e6m], 'WGS84')
// </srcblock>
// which converts the frequency from LSRK to TOPO.
// <ul>
//  <li>
//  <src>toref</src> is a single constant string.
//  <li>
// <src>pos</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 such functions return data with type double and unit Hz.
//
// Frequencies can be given like:
//    [f1,f2,...], fromRef
// where fromRef is the reference type.
//
// A frequency can also be a table column which usually knows its type.
// It can also be an expression (e.g. FREQUENCY[0,]) which also knows the type.
// </synopsis>
 
// <motivation>
// It makes it possible to handle measures in TaQL.
// </motivation>
 
class FrequencyEngine : public MeasEngine<MFrequency> {
 public:
  FrequencyEngine();
 
  virtual ~FrequencyEngine();
 
  // Get the values.
  Array<Double> getArrayDouble(const TableExprId& id, int type);
 
  // Get the frequencies.
  Array<MFrequency> getFrequencies(const TableExprId& id);
 
  // Handle the argument(s) giving the input frequencies and reference type.
  // The frequency can be a column in a table.
  void handleFrequency(std::vector<TENShPtr>& args, uInt& argnr);
 
  // Set the MeasConvert object.
  void setConverter(MFrequency::Types toType);
 
  // Set the possible doppler engine.
  // It can be done only once.
  void setDopplerEngine(DopplerEngine& engine);
 
  // Set the possible radial velocity engine.
  // It can be done only once.
  void setRadVelEngine(RadialVelocityEngine& engine);
 
  // Set the possible direction engine.
  // It can be done only once.
  void setDirectionEngine(DirectionEngine& engine);
 
  // Set the possible epoch engine.
  // It can be done only once.
  void setEpochEngine(EpochEngine& engine);
 
  // Set the possible position engine.
  // It can be done only once.
  void setPositionEngine(PositionEngine& engine);
 
 private:
  virtual void handleValues(TableExprNode& operand, const TableExprId& id,
                            Array<MFrequency>& frequencies);
 
  // # Data members.
  MeasFrame itsFrame;    // # frame used by converter
  MeasFrame itsRVFrame;  // # frame used for radial velocities
  MFrequency::Convert itsConverter;
  EpochEngine* itsEpochEngine;
  PositionEngine* itsPositionEngine;
  DirectionEngine* itsDirectionEngine;
  DopplerEngine* itsDopplerEngine;
  RadialVelocityEngine* itsRadVelEngine;
};
 
}  // namespace casacore
 
#endif