parameter_accessor.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2026 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 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
// Lesser General Public License for more details.
 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 
 
#ifndef LIBMESH_PARAMETER_ACCESSOR_H
#define LIBMESH_PARAMETER_ACCESSOR_H
 
 
// Local Includes
#include "libmesh/libmesh_common.h"
#include "libmesh/compare_types.h" // remove_const
 
// C++ includes
#include <memory>
 
namespace libMesh
{
 
// Forward declarations
template <typename T>
class ParameterProxy;
 
template <typename T>
class ConstParameterProxy;
 
 
template <typename T=Number>
class ParameterAccessor
{
public:
  virtual ~ParameterAccessor() = default;
 
  virtual void set (const T & new_value) = 0;
 
  virtual const T & get () const = 0;
 
  ParameterProxy<T> operator* () { return ParameterProxy<T>(*this); }
 
  ConstParameterProxy<T> operator* () const { return ConstParameterProxy<T>(*this); }
 
  virtual std::unique_ptr<ParameterAccessor<T>> clone() const = 0;
};
 
template <typename T=Number>
class ParameterProxy
{
public:
  ParameterProxy (ParameterAccessor<T> & accessor)
    : _accessor(accessor) {}
 
  ParameterProxy (const ParameterProxy<T> & accessor) = default;
 
  ParameterProxy & operator = (const T & new_value) { _accessor.set(new_value); return *this; }
 
  ParameterProxy & operator = (const ParameterProxy<T> & new_value) { _accessor.set(new_value._accessor.get()); return *this; }
 
  ParameterProxy & operator = (const ConstParameterProxy<T> & new_value) { _accessor.set(new_value.get()); return *this; }
 
  ParameterProxy & operator += (const T & value_increment) { _accessor.set(_accessor.get() + value_increment); return *this; }
 
  ParameterProxy & operator -= (const T & value_decrement) { _accessor.set(_accessor.get() - value_decrement); return *this; }
 
  ParameterProxy & operator *= (const T & value_multiplier) { _accessor.set(_accessor.get() * value_multiplier); return *this; }
 
  ParameterProxy & operator /= (const T & value_divisor) { _accessor.set(_accessor.get() / value_divisor); return *this; }
 
  operator T () const { return _accessor.get(); }
 
  T get() const { return _accessor.get(); }
 
#ifdef LIBMESH_DEFAULT_QUADRUPLE_PRECISION
  operator boost::multiprecision::backends::float128_backend () const { return _accessor.get().backend(); }
#endif
 
private:
  ParameterAccessor<T> & _accessor;
};
 
 
template <typename T=Number>
class ConstParameterProxy
{
public:
  ConstParameterProxy (const ParameterAccessor<T> & accessor)
    : _accessor(accessor) {}
 
  operator T () const { return _accessor.get(); }
 
  T get() const { return _accessor.get(); }
 
#ifdef LIBMESH_DEFAULT_QUADRUPLE_PRECISION
  operator boost::multiprecision::backends::float128_backend () const { return _accessor.get().backend(); }
#endif
 
private:
  const ParameterAccessor<T> & _accessor;
};
 
 
} // namespace libMesh
 
#endif // LIBMESH_PARAMETER_ACCESSOR_H