ArrayHandleOffsetsToNumComponents.h

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//============================================================================
//  The contents of this file are covered by the Viskores license. See
//  LICENSE.txt for details.
//
//  By contributing to this file, all contributors agree to the Developer
//  Certificate of Origin Version 1.1 (DCO 1.1) as stated in DCO.txt.
//============================================================================
 
//============================================================================
//  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 viskores_cont_ArrayHandleOffsetsToNumComponents_h
#define viskores_cont_ArrayHandleOffsetsToNumComponents_h
 
#include <viskores/cont/ArrayHandle.h>
 
namespace viskores
{
namespace internal
{
 
// Note that `ArrayPortalOffsetsToNumComponents` requires a source portal with +1 entry
// to avoid branching. See `ArrayHandleOffsetsToNumComponents` for details.
template <typename OffsetsPortal>
class VISKORES_ALWAYS_EXPORT ArrayPortalOffsetsToNumComponents
{
  OffsetsPortal Portal;
 
public:
  ArrayPortalOffsetsToNumComponents() = default;
 
  ArrayPortalOffsetsToNumComponents(const OffsetsPortal& portal)
    : Portal(portal)
  {
  }
 
  using ValueType = viskores::IdComponent;
 
  VISKORES_EXEC_CONT viskores::Id GetNumberOfValues() const
  {
    return this->Portal.GetNumberOfValues() - 1;
  }
 
  VISKORES_EXEC_CONT viskores::IdComponent Get(viskores::Id index) const
  {
    return static_cast<viskores::IdComponent>(this->Portal.Get(index + 1) -
                                              this->Portal.Get(index));
  }
};
 
}
} // namespace viskores::internal
 
namespace viskores
{
namespace cont
{
 
template <typename OffsetsStorageTag>
struct VISKORES_ALWAYS_EXPORT StorageTagOffsetsToNumComponents
{
};
 
namespace internal
{
 
template <typename OffsetsStorageTag>
class VISKORES_ALWAYS_EXPORT
  Storage<viskores::IdComponent,
          viskores::cont::StorageTagOffsetsToNumComponents<OffsetsStorageTag>>
{
  using OffsetsStorage = viskores::cont::internal::Storage<viskores::Id, OffsetsStorageTag>;
 
public:
  VISKORES_STORAGE_NO_RESIZE;
  VISKORES_STORAGE_NO_WRITE_PORTAL;
 
  using ReadPortalType =
    viskores::internal::ArrayPortalOffsetsToNumComponents<typename OffsetsStorage::ReadPortalType>;
 
  VISKORES_CONT static std::vector<viskores::cont::internal::Buffer> CreateBuffers()
  {
    return OffsetsStorage::CreateBuffers();
  }
 
  VISKORES_CONT static viskores::IdComponent GetNumberOfComponentsFlat(
    const std::vector<viskores::cont::internal::Buffer>&)
  {
    return 1;
  }
 
  VISKORES_CONT static viskores::Id GetNumberOfValues(
    const std::vector<viskores::cont::internal::Buffer>& buffers)
  {
    viskores::Id numOffsets = OffsetsStorage::GetNumberOfValues(buffers);
    if (numOffsets < 1)
    {
      throw viskores::cont::ErrorBadValue(
        "ArrayHandleOffsetsToNumComponents requires an offsets array with at least one value.");
    }
    return numOffsets - 1;
  }
 
  VISKORES_CONT static ReadPortalType CreateReadPortal(
    const std::vector<viskores::cont::internal::Buffer>& buffers,
    viskores::cont::DeviceAdapterId device,
    viskores::cont::Token& token)
  {
    VISKORES_ASSERT(OffsetsStorage::GetNumberOfValues(buffers) > 0);
    return ReadPortalType(OffsetsStorage::CreateReadPortal(buffers, device, token));
  }
};
 
} // namespace internal
 
template <class OffsetsArray>
class VISKORES_ALWAYS_EXPORT ArrayHandleOffsetsToNumComponents
  : public viskores::cont::ArrayHandle<
      viskores::IdComponent,
      viskores::cont::StorageTagOffsetsToNumComponents<typename OffsetsArray::StorageTag>>
{
  VISKORES_IS_ARRAY_HANDLE(OffsetsArray);
  VISKORES_STATIC_ASSERT_MSG((std::is_same<typename OffsetsArray::ValueType, viskores::Id>::value),
                             "Offsets array must have a value type of viskores::Id.");
 
public:
  VISKORES_ARRAY_HANDLE_SUBCLASS(
    ArrayHandleOffsetsToNumComponents,
    (ArrayHandleOffsetsToNumComponents<OffsetsArray>),
    (viskores::cont::ArrayHandle<
      viskores::IdComponent,
      viskores::cont::StorageTagOffsetsToNumComponents<typename OffsetsArray::StorageTag>>));
 
  VISKORES_CONT ArrayHandleOffsetsToNumComponents(const OffsetsArray& array)
    : Superclass(array.GetBuffers())
  {
  }
};
 
template <typename OffsetsStorageTag>
VISKORES_CONT viskores::cont::ArrayHandleOffsetsToNumComponents<
  viskores::cont::ArrayHandle<viskores::Id, OffsetsStorageTag>>
make_ArrayHandleOffsetsToNumComponents(
  const viskores::cont::ArrayHandle<viskores::Id, OffsetsStorageTag>& array)
{
  // Converts to correct type.
  return array;
}
 
}
} // namespace viskores::cont
 
#endif //viskores_cont_ArrayHandleOffsetsToNumComponents_h