vtk-m/vtkm/VecFromPortal.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.
//============================================================================
#ifndef vtk_m_VecFromPortal_h
#define vtk_m_VecFromPortal_h

#include <vtkm/Math.h>
#include <vtkm/TypeTraits.h>
#include <vtkm/Types.h>
#include <vtkm/VecTraits.h>

#include <vtkm/internal/ArrayPortalValueReference.h>

namespace vtkm
{

/// \brief A short variable-length array from a window in an ArrayPortal.
///
/// The \c VecFromPortal class is a Vec-like class that holds an array portal
/// and exposes a small window of that portal as if it were a \c Vec.
///
template <typename PortalType>
class VecFromPortal
{
public:
  using ComponentType = typename std::remove_const<typename PortalType::ValueType>::type;

  VTKM_SUPPRESS_EXEC_WARNINGS
  VTKM_EXEC_CONT
  VecFromPortal(const PortalType& portal, vtkm::IdComponent numComponents = 0, vtkm::Id offset = 0)
    : Portal(portal)
    , NumComponents(numComponents)
    , Offset(offset)
  {
  }

  VTKM_EXEC_CONT
  vtkm::IdComponent GetNumberOfComponents() const { return this->NumComponents; }

  template <typename T, vtkm::IdComponent DestSize>
  VTKM_EXEC_CONT void CopyInto(vtkm::Vec<T, DestSize>& dest) const
  {
    vtkm::IdComponent numComponents = vtkm::Min(DestSize, this->NumComponents);
    for (vtkm::IdComponent index = 0; index < numComponents; index++)
    {
      dest[index] = this->Portal.Get(index + this->Offset);
    }
  }

  template <vtkm::IdComponent N>
  VTKM_EXEC_CONT operator vtkm::Vec<ComponentType, N>() const
  {
    vtkm::Vec<ComponentType, N> result;
    this->CopyInto(result);
    for (vtkm::IdComponent index = this->NumComponents; index < N; ++index)
    {
      result[index] = vtkm::TypeTraits<ComponentType>::ZeroInitialization();
    }
    return result;
  }

  VTKM_SUPPRESS_EXEC_WARNINGS
  VTKM_EXEC_CONT
  vtkm::internal::ArrayPortalValueReference<PortalType> operator[](vtkm::IdComponent index) const
  {
    return vtkm::internal::ArrayPortalValueReference<PortalType>(this->Portal,
                                                                 index + this->Offset);
  }

  template <typename T, vtkm::IdComponent N>
  VTKM_EXEC_CONT VecFromPortal& operator=(const vtkm::Vec<T, N>& src)
  {
    vtkm::IdComponent numComponents = vtkm::Min(N, this->NumComponents);
    for (vtkm::IdComponent index = 0; index < numComponents; ++index)
    {
      this->Portal.Set(index + this->Offset, src[index]);
    }
    return *this;
  }

  VTKM_EXEC_CONT const PortalType& GetPortal() const { return this->Portal; }
  VTKM_EXEC_CONT vtkm::Id GetOffset() const { return this->Offset; }

private:
  PortalType Portal;
  vtkm::IdComponent NumComponents;
  vtkm::Id Offset;
};

template <typename PortalType>
struct TypeTraits<vtkm::VecFromPortal<PortalType>>
{
private:
  using ComponentType = typename PortalType::ValueType;

public:
  using NumericTag = typename vtkm::TypeTraits<ComponentType>::NumericTag;
  using DimensionalityTag = TypeTraitsVectorTag;

  VTKM_SUPPRESS_EXEC_WARNINGS
  VTKM_EXEC_CONT
  static vtkm::VecFromPortal<PortalType> ZeroInitialization()
  {
    return vtkm::VecFromPortal<PortalType>();
  }
};

template <typename PortalType>
struct VecTraits<vtkm::VecFromPortal<PortalType>>
{
  using VecType = vtkm::VecFromPortal<PortalType>;

  using ComponentType = typename VecType::ComponentType;
  using BaseComponentType = typename vtkm::VecTraits<ComponentType>::BaseComponentType;
  using HasMultipleComponents = vtkm::VecTraitsTagMultipleComponents;
  using IsSizeStatic = vtkm::VecTraitsTagSizeVariable;

  VTKM_SUPPRESS_EXEC_WARNINGS
  VTKM_EXEC_CONT
  static vtkm::IdComponent GetNumberOfComponents(const VecType& vector)
  {
    return vector.GetNumberOfComponents();
  }

  VTKM_SUPPRESS_EXEC_WARNINGS
  VTKM_EXEC_CONT
  static ComponentType GetComponent(const VecType& vector, vtkm::IdComponent componentIndex)
  {
    return vector[componentIndex];
  }

  VTKM_SUPPRESS_EXEC_WARNINGS
  VTKM_EXEC_CONT
  static void SetComponent(const VecType& vector,
                           vtkm::IdComponent componentIndex,
                           const ComponentType& value)
  {
    vector[componentIndex] = value;
  }

  VTKM_SUPPRESS_EXEC_WARNINGS
  template <vtkm::IdComponent destSize>
  VTKM_EXEC_CONT static void CopyInto(const VecType& src, vtkm::Vec<ComponentType, destSize>& dest)
  {
    src.CopyInto(dest);
  }
};

} // namespace vtkm

#endif //vtk_m_VecFromPortal_h