FunctionWrapper.h

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// # FunctionWrapper.h: Construct function objects from C++ functions
// # Copyright (C) 2001,2002,2005
// # 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 SCIMATH_FUNCTIONWRAPPER_H
#define SCIMATH_FUNCTIONWRAPPER_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/scimath/Functionals/WrapperParam.h>
#include <casacore/casa/Arrays/ArrayFwd.h>
#include <memory>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward declarations
template <class T>
class WrapperBase;
 
// <summary> Construct nD function objects from C++ functions
// </summary>
//
// <use visibility=export>
//
// <reviewed reviewer="" date="1996/02/22" tests="" demos="">
// </reviewed>
//
// <prerequisite>
//   <li> <linkto class="Function">Function</linkto> class
//   <li> <linkto class="FunctionParam">FunctionParam</linkto>
// </prerequisite>
//
// <synopsis>
// This class is provided so that user can quickly construct a function
// object from a C++ function pointer without having to write a function
// class. The constructor constructs a function object from a function
// pointer, and an optional parameter list.
// Parameters are necessary if
// the function has to be used in a functional fitting process (see
// <linkto class=GenericL2Fit>GenericL2Fit</linkto>).
//
// The general function signature is <src>f(x;p)</src>, where <src>x</src>
// represents the <em>arguments</em>, and <src>p</src> the parameters.
// The allowed signatures of the function include all combinations of
// arguments and parameters, and are:
// <ul>
//  <li> <src>f()</src>  no arguments e.g. random number or constant
//  <li> <src>f(x)</src>  1-dimensional, e.g. <src>sin(x)</src>
//  <li> <src>f(Vectorx)</src>  n-dimensional, e.g. <src>sin(x+2y)</src>
// </ul>
//
// </synopsis>
//
// <example>
// <srcblock>
// Float func(const Vector<Float>& x) {return x(0)*x(1);}        // x*y
// // Convert C++ functions to Functionals
// FunctionWrapper<Float> Func(func,2);
// </srcblock>
//
 
template <class T>
class FunctionWrapper : public WrapperParam<T> {
 public:
  // # Constructors
  //  Default constructor, to enable arrays
  FunctionWrapper();
  // A function with no parameters and no arguments.
  FunctionWrapper(T (*f)());
  // A function with parameter and no arguments
  // (Note value of isPar irrelevant)
  FunctionWrapper(T (*f)(const T &), const Bool isPar);
  // A function with parameters and no arguments.
  // (Note value of isPar irrelevant)
  FunctionWrapper(T (*f)(const Vector<T> &), const Bool isPar);
  // Construct a  1-dimensional function with no parameters.
  FunctionWrapper(T (*f)(const T &));
  // Construct a  1-dimensional function with parameter.
  FunctionWrapper(T (*f)(const T &, const T &), const T &par);
  // Construct a  1-dimensional function with parameters.
  FunctionWrapper(T (*f)(const T &, const Vector<T> &), const Vector<T> &par);
  // Construct an n-dimensional  function with no parameters.
  FunctionWrapper(T (*f)(const Vector<T> &), const Int dim = 1);
  // Construct an n-dimensional  function with parameter.
  FunctionWrapper(T (*f)(const Vector<T> &, const T &), const T &par, const uInt dim = 1);
  // Construct an n-dimensional  function with parameters.
  FunctionWrapper(T (*f)(const Vector<T> &, const Vector<T> &), const Vector<T> &par,
                  const uInt dim = 1);
  // Copy constructor (reference semantics)
  // <group>
  FunctionWrapper(const FunctionWrapper<T> &other);
  // </group>
  // Copy assignment (reference semantics)
  FunctionWrapper<T> &operator=(const FunctionWrapper<T> &other);
 
  // Destructor
  virtual ~FunctionWrapper() {}
 
  // # Operators
  //  Evaluate the function at <src>x</src>.
  //  <group>
  virtual T eval(typename Function<T>::FunctionArg x) const;
  // </group>
 
  // # Member functions
  //  Get the dimensionality
  virtual uInt ndim() const;
  // Return a copy of this object from the heap. The caller is responsible
  // for deleting this pointer.
  // <group>
  virtual Function<T> *clone() const { return new FunctionWrapper<T>(*this); }
  // </group>
 
 protected:
  // # Data
  //  The function aid object
  std::shared_ptr<WrapperBase<T>> doit_p;
 
  // # Make members of parent classes known.
 protected:
  using WrapperParam<T>::param_p;
};
 
}  // namespace casacore
 
#ifndef CASACORE_NO_AUTO_TEMPLATES
#include <casacore/scimath/Functionals/FunctionWrapper.tcc>
#endif  // # CASACORE_NO_AUTO_TEMPLATES
#endif