170 lines
5.9 KiB
C
170 lines
5.9 KiB
C
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//============================================================================
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//
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// Copyright 2017 National Technology & Engineering Solutions of Sandia, LLC (NTESS).
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// Copyright 2017 UT-Battelle, LLC.
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// Copyright 2017 Los Alamos National Security.
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//
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// Under the terms of Contract DE-NA0003525 with NTESS,
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// the U.S. Government retains certain rights in this software.
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//
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// Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
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// Laboratory (LANL), the U.S. Government retains certain rights in
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// this software.
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//============================================================================
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#ifndef vtk_m_worklet_SortAndUniqueIndices_h
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#define vtk_m_worklet_SortAndUniqueIndices_h
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#include <vtkm/cont/ArrayHandle.h>
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#include <vtkm/cont/ArrayHandleIndex.h>
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#include <vtkm/cont/DeviceAdapterAlgorithm.h>
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namespace vtkm
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{
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namespace worklet
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{
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/// Produces an ArrayHandle<vtkm::Id> index array that stable-sorts and
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/// optionally uniquifies an input array.
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template <typename DeviceAdapter>
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struct StableSortIndices
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{
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using IndexArrayType = vtkm::cont::ArrayHandle<vtkm::Id>;
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// Allows Sort to be called on an array that indexes into KeyPortal.
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// If the values compare equal, the indices are compared to stabilize the
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// result.
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template <typename KeyPortalType>
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struct IndirectSortPredicate
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{
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using KeyType = typename KeyPortalType::ValueType;
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const KeyPortalType KeyPortal;
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VTKM_CONT
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IndirectSortPredicate(const KeyPortalType& keyPortal)
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: KeyPortal(keyPortal)
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{
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}
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template <typename IndexType>
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VTKM_EXEC bool operator()(const IndexType& a, const IndexType& b) const
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{
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// If the values compare equal, compare the indices as well so we get
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// consistent outputs.
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const KeyType valueA = this->KeyPortal.Get(a);
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const KeyType valueB = this->KeyPortal.Get(b);
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if (valueA < valueB)
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{
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return true;
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}
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else if (valueB < valueA)
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{
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return false;
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}
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else
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{
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return a < b;
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}
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}
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};
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// Allows Unique to be called on an array that indexes into KeyPortal.
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template <typename KeyPortalType>
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struct IndirectUniquePredicate
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{
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const KeyPortalType KeyPortal;
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VTKM_CONT
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IndirectUniquePredicate(const KeyPortalType& keyPortal)
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: KeyPortal(keyPortal)
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{
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}
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template <typename IndexType>
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VTKM_EXEC bool operator()(const IndexType& a, const IndexType& b) const
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{
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return this->KeyPortal.Get(a) == this->KeyPortal.Get(b);
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}
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};
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/// Permutes the @a indices array so that it will map @a keys into a stable
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/// sorted order. The @a keys array is not modified.
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///
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/// @param keys The ArrayHandle containing data to be sorted.
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/// @param indices The ArrayHandle<vtkm::Id> containing the permutation indices.
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///
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/// @note @a indices is expected to contain the values (0, numKeys] in
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/// increasing order. If the values in @a indices are not sequential, the sort
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/// will succeed and be consistently reproducible, but the result is not
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/// guaranteed to be stable with respect to the original ordering of @a keys.
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template <typename KeyType, typename Storage>
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VTKM_CONT static void Sort(const vtkm::cont::ArrayHandle<KeyType, Storage>& keys,
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IndexArrayType& indices)
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{
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using Algo = vtkm::cont::DeviceAdapterAlgorithm<DeviceAdapter>;
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using KeyArrayType = vtkm::cont::ArrayHandle<KeyType, Storage>;
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using KeyPortalType =
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typename KeyArrayType::template ExecutionTypes<DeviceAdapter>::PortalConst;
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using SortPredicate = IndirectSortPredicate<KeyPortalType>;
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VTKM_ASSERT(keys.GetNumberOfValues() == indices.GetNumberOfValues());
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KeyPortalType keyPortal = keys.PrepareForInput(DeviceAdapter());
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Algo::Sort(indices, SortPredicate(keyPortal));
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}
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/// Returns an index array that maps the @a keys array into a stable sorted
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/// ordering. The @a keys array is not modified.
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///
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/// This is a convenience overload that generates the index array.
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template <typename KeyType, typename Storage>
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VTKM_CONT static IndexArrayType Sort(const vtkm::cont::ArrayHandle<KeyType, Storage>& keys)
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{
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using Algo = vtkm::cont::DeviceAdapterAlgorithm<DeviceAdapter>;
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using KeyArrayType = vtkm::cont::ArrayHandle<KeyType, Storage>;
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using KeyPortalType =
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typename KeyArrayType::template ExecutionTypes<DeviceAdapter>::PortalConst;
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using SortPredicate = IndirectSortPredicate<KeyPortalType>;
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// Generate the initial index array
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IndexArrayType indices;
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{
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vtkm::cont::ArrayHandleIndex indicesSrc(keys.GetNumberOfValues());
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Algo::Copy(indicesSrc, indices);
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}
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KeyPortalType keyPortal = keys.PrepareForInput(DeviceAdapter());
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Algo::Sort(indices, SortPredicate(keyPortal));
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return indices;
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}
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/// Reduces the array returned by @a Sort so that the mapped @a keys are
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/// unique. The @a indices array will be modified in-place and the @a keys
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/// array is not modified.
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///
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template <typename KeyType, typename Storage>
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VTKM_CONT static void Unique(const vtkm::cont::ArrayHandle<KeyType, Storage>& keys,
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IndexArrayType& indices)
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{
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using Algo = vtkm::cont::DeviceAdapterAlgorithm<DeviceAdapter>;
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using KeyArrayType = vtkm::cont::ArrayHandle<KeyType, Storage>;
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using KeyPortalType =
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typename KeyArrayType::template ExecutionTypes<DeviceAdapter>::PortalConst;
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using UniquePredicate = IndirectUniquePredicate<KeyPortalType>;
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KeyPortalType keyPortal = keys.PrepareForInput(DeviceAdapter());
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Algo::Unique(indices, UniquePredicate(keyPortal));
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}
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};
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}
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} // end namespace vtkm::worklet
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#endif // vtk_m_worklet_SortAndUniqueIndices_h
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