function_parser.h

// ---------------------------------------------------------------------
//
// Copyright (C) 2005 - 2017 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_function_parser_h
#define dealii_function_parser_h


#include <deal.II/base/config.h>
#include <deal.II/base/exceptions.h>
#include <deal.II/base/auto_derivative_function.h>
#include <deal.II/base/tensor.h>
#include <deal.II/base/point.h>
#include <deal.II/base/thread_local_storage.h>
#include <vector>
#include <map>
#include <memory>

namespace mu
{
  class Parser;
}

DEAL_II_NAMESPACE_OPEN


template <typename> class Vector;


template <int dim>
class FunctionParser : public AutoDerivativeFunction<dim>
{
public:
  FunctionParser (const unsigned int n_components = 1,
                  const double       initial_time = 0.0,
                  const double       h = 1e-8);

  ~FunctionParser();

  typedef std::map<std::string, double> ConstMap;

  typedef ConstMap::iterator ConstMapIterator;

  void initialize (const std::string              &vars,
                   const std::vector<std::string> &expressions,
                   const ConstMap                 &constants,
                   const bool time_dependent = false);

  void initialize (const std::string &vars,
                   const std::string &expression,
                   const ConstMap    &constants,
                   const bool time_dependent = false);

  static
  std::string
  default_variable_names ();

  virtual double value (const Point<dim>   &p,
                        const unsigned int  component = 0) const;

  virtual void vector_value (const Point<dim>   &p,
                             Vector<double>     &values) const;

  DeclException2 (ExcParseError,
                  int, char *,
                  << "Parsing Error at Column " << arg1
                  << ". The parser said: " << arg2);

  DeclException2 (ExcInvalidExpressionSize,
                  int, int,
                  << "The number of components (" << arg1
                  << ") is not equal to the number of expressions ("
                  << arg2 << ").");


private:
#ifdef DEAL_II_WITH_MUPARSER

  mutable Threads::ThreadLocalStorage<std::vector<double> > vars;

#if TBB_VERSION_MAJOR >= 4
  mutable Threads::ThreadLocalStorage<std::vector<std::unique_ptr<mu::Parser> > > fp;
#else
  // older TBBs have a bug in which they want to return thread-local
  // objects by value. this doesn't work for std::unique_ptr, so use a
  // std::shared_ptr
  mutable Threads::ThreadLocalStorage<std::vector<std::shared_ptr<mu::Parser> > > fp;
#endif

  std::map<std::string, double> constants;

  std::vector<std::string> var_names;

  std::vector<std::string> expressions;

  void init_muparser() const;
#endif

  bool initialized;

  unsigned int n_vars;
};


template <int dim>
std::string
FunctionParser<dim>::default_variable_names ()
{
  switch (dim)
    {
    case 1:
      return "x";
    case 2:
      return "x,y";
    case 3:
      return "x,y,z";
    default:
      Assert (false, ExcNotImplemented());
    }
  return "";
}



DEAL_II_NAMESPACE_CLOSE

#endif