Tempus_StepperForwardEulerObserverBase.hpp

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// @HEADER
// ****************************************************************************
//                Tempus: Copyright (2017) Sandia Corporation
//
// Distributed under BSD 3-clause license (See accompanying file Copyright.txt)
// ****************************************************************************
// @HEADER

#ifndef Tempus_StepperForwardEulerObserverBase_hpp
#define Tempus_StepperForwardEulerObserverBase_hpp

#include "Tempus_config.hpp"
#include "Tempus_SolutionHistory.hpp"
#include "Tempus_StepperForwardEulerAppAction.hpp"


namespace Tempus {

/** \brief Base observer for StepperForwardEuler.
 *
 *  This class provides a means to observe values (e.g., solution variables
 *  through SolutionHistory, and stepper member data through the Stepper),
 *  and cannot modify them.
 *
 *  Users deriving from this class can observer a lot of data, and it is
 *  expected that users will NOT modify any of that data.  If the user
 *  wishes to modify the solution and/or stepper data during the
 *  Stepper::takeStep, they should use the Modifier class (with care!).
 *
 *  Below is the ForwardEuler algorithm with the locations of the observe calls
 *  italicized.
 *
 *  \f{algorithm}{                                                                               
 *  \renewcommand{\thealgorithm}{}                                                               
 *  \caption{Forward Euler with the locations of the application actions indicated.}             
 *  \begin{algorithmic}[1]                                                                       
 *    \State Start with $x_n$, $\Delta t_n$                                                             
 *    \State {\it appAction.execute(solutionHistory, stepper, BEGIN\_STEP)}                             
 *    \State Form $f(x_{n},t_{n})$                                                                      
 *    \State {\it appAction.execute(solutionHistory, stepper, BEFORE\_EXPLICIT\_EVAL)}                  
 *    \State Form $x_n \leftarrow x_{n} + \Delta t_n f(x_{n},t_n)$                                      
 *    \State {\it appAction.execute(solutionHistory, stepper, END\_STEP)}    
 *  \end{algorithmic}                                                                            
 *  \f}                                                                                          
 */
template<class Scalar>
class StepperForwardEulerObserverBase
  : virtual public Tempus::StepperForwardEulerAppAction<Scalar>
{
private:

  /* \brief Adaptor execute function
   *
   *  This is an adaptor function to bridge between the AppAction
   *  interface and this derived interface.  It is meant to be private
   *  and non-virtual as deriving from this class should only need to
   *  implement the observe function.
   *
   *  For the Observer interface, this adaptor simply "applies" constantness
   *  to the arguments.
   */
  void execute(
    Teuchos::RCP<SolutionHistory<Scalar> > sh,
    Teuchos::RCP<StepperForwardEuler<Scalar> > stepper,
    const typename StepperForwardEulerAppAction<Scalar>::ACTION_LOCATION actLoc)
  { this->observe(sh, stepper, actLoc); }

public:

  /// Observe ForwardEuler Stepper.
  virtual void observe(
    Teuchos::RCP<const SolutionHistory<Scalar> > /* sh */,
    Teuchos::RCP<const StepperForwardEuler<Scalar> > /* stepper */,
    const typename StepperForwardEulerAppAction<Scalar>::ACTION_LOCATION actLoc) = 0;

};

} // namespace Tempus

#endif // Tempus_StepperForwardEulerObserverBase_hpp