LELConvert.h

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// # LELConvert.h:  Class to convert a LEL node from one numerical type to another
// # Copyright (C) 1997,1998,1999,2000
// # 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 LATTICES_LELCONVERT_H
#define LATTICES_LELCONVERT_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/lattices/LEL/LELInterface.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// <summary>
// Class to convert a LEL node from one numerical type to another
// </summary>
 
// <use visibility=local>
 
// <reviewed reviewer="" date="yyyy/mm/dd" tests="" demos="">
// </reviewed>
 
// <prerequisite>
//   <li> <linkto class="Lattice"> Lattice</linkto>
//   <li> <linkto class="LatticeExpr"> LatticeExpr</linkto>
//   <li> <linkto class="LatticeExprNode"> LatticeExprNode</linkto>
//   <li> <linkto class="LELInterface"> LELInterface</linkto>
// </prerequisite>
 
// <etymology>
//  This derived LEL letter class handles numerical type conversions
// </etymology>
 
// <synopsis>
// This LEL letter class is derived from LELInterface.  It
// is used to construct LEL objects that know how to convert
// between numerical types, such as Double to Float.  They
// operate on numerical Lattices and return a numerical Lattice.
// The LELConvert object is embedded in the tree, and the conversion
// actually happens at tree evaluation time.
// <p>
// A description of the implementation details of the LEL classes can
// be found in
// <a href="../notes/216.html">Note 216</a>
// </synopsis>
 
// <example>
// Examples are not very useful as the user would never use
// these classes directly.  Look in LatticeExprNode.cc to see
// how it invokes these classes.  An example of how the user
// would indirectly use this class (through the envelope) is:
// <srcblock>
// IPosition shape(2,5,10);
// ArrayLattice<Float> x(shape); x.set(1.0);
// ArrayLattice<Double> y(shape);
// y.copyData(x);                 // y = x;
// </srcblock>
// The LELConvert class is embedded in the tree at construction time
// so as to handle the conversion from Float to Double at evaluation time
// </example>
 
// <motivation>
//  We needed to be able to handle mixed types in the LEL classes
// </motivation>
 
// # <todo asof="1998/01/21">
// # </todo>
 
template <class T, class F>
class LELConvert : public LELInterface<T> {
 public:
  // Constructor.  <src><F></src> is the type we are coinverting from.
  // <src><T></src> is the type we are converting to.
  LELConvert(const std::shared_ptr<LELInterface<F>>& expr);
 
  // Destructor does nothing
  ~LELConvert();
 
  // Recursively evaluate the expression.
  virtual void eval(LELArray<T>& result, const Slicer& section) const;
 
  // Recursively evaluate the scalar
  virtual LELScalar<T> getScalar() const;
 
  // Do further preparations (e.g. optimization) on the expression.
  virtual Bool prepareScalarExpr();
 
  // Get class name
  virtual String className() const;
 
  // Handle locking/syncing of a lattice in a lattice expression.
  // <group>
  virtual Bool lock(FileLocker::LockType, uInt nattempts);
  virtual void unlock();
  virtual Bool hasLock(FileLocker::LockType) const;
  virtual void resync();
  // </group>
 
 private:
  std::shared_ptr<LELInterface<F>> pExpr_p;
};
 
}  // namespace casacore
 
#ifndef CASACORE_NO_AUTO_TEMPLATES
#include <casacore/lattices/LEL/LELConvert.tcc>
#endif  // # CASACORE_NO_AUTO_TEMPLATES
#endif