vtk-m/vtkm/filter/FilterTraits.h

//============================================================================
//  Copyright (c) Kitware, Inc.
//  All rights reserved.
//  See LICENSE.txt for details.
//  This software is distributed WITHOUT ANY WARRANTY; without even
//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
//  PURPOSE.  See the above copyright notice for more information.
//
//  Copyright 2014 Sandia Corporation.
//  Copyright 2014 UT-Battelle, LLC.
//  Copyright 2014 Los Alamos National Security.
//
//  Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
//  the U.S. Government retains certain rights in this software.
//
//  Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
//  Laboratory (LANL), the U.S. Government retains certain rights in
//  this software.
//============================================================================

#ifndef vtk_m_filter_FilterTraits_h
#define vtk_m_filter_FilterTraits_h

#include <vtkm/TypeListTag.h>

namespace vtkm {
namespace filter {
template<typename Filter>
class FilterTraits
{
public:
  // A filter is able to state what subset of types it supports
  // by default. By default we use the empty tag to represent that the
  // filter accepts all types specified by the users provided policy
  typedef vtkm::ListTagEmpty InputFieldTypeList;
};

template<typename DerivedPolicy, typename FilterType>
struct DeduceFilterFieldTypes
{
  using FList = typename vtkm::filter::FilterTraits<FilterType>::InputFieldTypeList;
  using PList = typename DerivedPolicy::FieldTypeList;

  using FListIsEmpty = std::is_same<vtkm::ListTagEmpty,FList>;
  using TypeList = typename std::conditional<FListIsEmpty::value,
                                PList, //filter list is empty
                                vtkm::ListTagIntersect<FList, PList>
                                >::type;
};

}
}

#endif //vtk_m_filter_FilterTraits_h