componentmapper.hh

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#pragma once
 
#include <cassert>
#include <type_traits>
 
#include <dune/common/exceptions.hh>
#include <dune/common/fmatrix.hh>
#include <dune/common/fvector.hh>
#include <dune/common/typetraits.hh>
 
namespace Dune::Vtk {
 
struct DefaultComponentMapper
{
  // Evaluate a component of a vector valued data
  template <class T, int N, int M>
  static double map (int comp, FieldMatrix<T,N,M> const& mat)
  {
    int r = comp / 3;
    int c = comp % 3;
    return r < N && c < M ? double(mat[r][c]) : 0.0;
  }
 
  // Evaluate a component of a vector valued data
  template <class T, int N>
  static double map (int comp, FieldVector<T,N> const& vec)
  {
    return comp < N ? double(vec[comp]) : 0.0;
  }
 
  // Evaluate a component of a vector valued data
  template <class T,
    std::enable_if_t<IsIndexable<T,int>::value, int> = 0>
  static double map (int comp, T const& value)
  {
    return value[comp];
  }
 
  // Return the scalar values
  template <class T,
    std::enable_if_t<not IsIndexable<T,int>::value, int> = 0>
  static double map (int comp, T const& value)
  {
    assert(comp == 0);
    return value;
  }
 
 
  template <class D, class F>
  static auto mapImpl (int comp, D const& x, F const& f, Dune::PriorityTag<2>)
    -> decltype(f.evaluate(comp,x))
  {
    return f.evaluate(comp,x);
  }
 
  template <class D, class F>
  static auto mapImpl (int comp, D const& x, F const& f, Dune::PriorityTag<1>)
    -> decltype(map(comp, f(x)))
  {
    return map(comp, f(x));
  }
 
  template <class D, class F>
  static double mapImpl (int comp, D const& x, F const& f, Dune::PriorityTag<0>)
  {
    DUNE_THROW(Dune::NotImplemented, "Evaluation of the grid function is not implemented");
    return 0.0;
  }
 
  template <class D, class F>
  static double map (int comp, D const& x, F const& f)
  {
    return mapImpl(comp,x,f,Dune::PriorityTag<3>{});
  }
};
 
} // end namespace Dune::Vtk