solver.h

// ---------------------------------------------------------------------
//
// Copyright (C) 1998 - 2018 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, 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.
// The full text of the license can be found in the file LICENSE at
// the top level of the deal.II distribution.
//
// ---------------------------------------------------------------------

#ifndef dealii_solver_h
#define dealii_solver_h

#include <deal.II/base/config.h>
#include <deal.II/base/subscriptor.h>
#include <deal.II/lac/vector_memory.h>
#include <deal.II/lac/solver_control.h>

// Ignore deprecation warnings for auto_ptr.
#include <boost/signals2.hpp>

DEAL_II_NAMESPACE_OPEN

template <typename number> class Vector;

template <class VectorType = Vector<double> >
class Solver : public Subscriptor
{
public:
  typedef VectorType vector_type;

  Solver (SolverControl            &solver_control,
          VectorMemory<VectorType> &vector_memory);

  Solver (SolverControl &solver_control);

  boost::signals2::connection
  connect (const std::function<SolverControl::State (const unsigned int iteration,
                                                     const double       check_value,
                                                     const VectorType   &current_iterate)> &slot);



protected:
  mutable GrowingVectorMemory<VectorType> static_vector_memory;

  VectorMemory<VectorType> &memory;

private:
  struct StateCombiner
  {
    typedef SolverControl::State result_type;

    SolverControl::State operator() (const SolverControl::State state1,
                                     const SolverControl::State state2) const;

    template <typename Iterator>
    SolverControl::State operator() (const Iterator begin,
                                     const Iterator end) const;
  };

protected:
  boost::signals2::signal<SolverControl::State (const unsigned int iteration,
                                                const double       check_value,
                                                const VectorType   &current_iterate),
                                                      StateCombiner> iteration_status;
};


/*-------------------------------- Inline functions ------------------------*/


template <class VectorType>
inline
SolverControl::State
Solver<VectorType>::StateCombiner::operator ()(const SolverControl::State state1,
                                               const SolverControl::State state2) const
{
  if ((state1 == SolverControl::failure)
      ||
      (state2 == SolverControl::failure))
    return SolverControl::failure;
  else if ((state1 == SolverControl::iterate)
           ||
           (state2 == SolverControl::iterate))
    return SolverControl::iterate;
  else
    return SolverControl::success;
}


template <class VectorType>
template <typename Iterator>
inline
SolverControl::State
Solver<VectorType>::StateCombiner::operator ()(const Iterator begin,
                                               const Iterator end) const
{
  Assert (begin != end, ExcMessage ("You can't combine iterator states if no state is given."));

  // combine the first with all of the following states
  SolverControl::State state = *begin;
  Iterator p = begin;
  ++p;
  for (; p != end; ++p)
    state = this->operator()(state, *p);

  return state;
}


template <class VectorType>
inline
Solver<VectorType>::Solver (SolverControl        &solver_control,
                            VectorMemory<VectorType> &vector_memory)
  :
  memory(vector_memory)
{
  // connect the solver control object to the signal. SolverControl::check
  // only takes two arguments, the iteration and the check_value, and so
  // we simply ignore the third argument that is passed in whenever the
  // signal is executed
  connect (std::bind(&SolverControl::check,
                     std::ref(solver_control),
                     std::placeholders::_1,
                     std::placeholders::_2));
}



template <class VectorType>
inline
Solver<VectorType>::Solver (SolverControl &solver_control)
  :
  // use the static memory object this class owns
  memory(static_vector_memory)
{
  // connect the solver control object to the signal. SolverControl::check
  // only takes two arguments, the iteration and the check_value, and so
  // we simply ignore the third argument that is passed in whenever the
  // signal is executed
  connect (std::bind(&SolverControl::check,
                     std::ref(solver_control),
                     std::placeholders::_1,
                     std::placeholders::_2));
}



template <class VectorType>
inline
boost::signals2::connection
Solver<VectorType>::
connect (const std::function<SolverControl::State (const unsigned int iteration,
                                                   const double       check_value,
                                                   const VectorType   &current_iterate)> &slot)
{
  return iteration_status.connect (slot);
}



DEAL_II_NAMESPACE_CLOSE

#endif