192 lines
5.6 KiB
C
192 lines
5.6 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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//
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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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#ifndef vtk_m_Algorithms_h
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#define vtk_m_Algorithms_h
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#include <vtkm/cont/ArrayPortalToIterators.h>
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#include <vtkm/BinaryPredicates.h>
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#include <vtkm/internal/Configure.h>
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#include <algorithm>
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#include <iterator>
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namespace vtkm
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{
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/// Similar to std::lower_bound and std::upper_bound, but returns an iterator
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/// to any matching item (rather than a specific one). Returns @a last when
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/// @a val is not found.
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/// @{
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template <typename IterT, typename T, typename Comp>
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VTKM_EXEC_CONT IterT BinarySearch(IterT first, IterT last, const T& val, Comp comp)
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{
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auto len = last - first;
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while (len != 0)
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{
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const auto halfLen = len / 2;
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IterT mid = first + halfLen;
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if (comp(*mid, val))
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{
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first = mid + 1;
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len -= halfLen + 1;
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}
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else if (comp(val, *mid))
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{
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len = halfLen;
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}
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else
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{
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return mid; // found element
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}
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}
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return last; // did not find element
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}
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template <typename IterT, typename T>
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VTKM_EXEC_CONT IterT BinarySearch(IterT first, IterT last, const T& val)
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{
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return vtkm::BinarySearch(first, last, val, vtkm::SortLess{});
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}
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/// @}
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/// Similar to std::lower_bound and std::upper_bound, but returns the index of
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/// any matching item (rather than a specific one). Returns -1 when @a val is not
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/// found.
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/// @{
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template <typename PortalT, typename T, typename Comp>
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VTKM_EXEC_CONT vtkm::Id BinarySearch(const PortalT& portal, const T& val, Comp comp)
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{
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auto first = vtkm::cont::ArrayPortalToIteratorBegin(portal);
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auto last = vtkm::cont::ArrayPortalToIteratorEnd(portal);
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auto result = vtkm::BinarySearch(first, last, val, comp);
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return result == last ? static_cast<vtkm::Id>(-1) : static_cast<vtkm::Id>(result - first);
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}
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// Return -1 if not found
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template <typename PortalT, typename T>
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VTKM_EXEC_CONT vtkm::Id BinarySearch(const PortalT& portal, const T& val)
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{
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auto first = vtkm::cont::ArrayPortalToIteratorBegin(portal);
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auto last = vtkm::cont::ArrayPortalToIteratorEnd(portal);
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auto result = vtkm::BinarySearch(first, last, val, vtkm::SortLess{});
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return result == last ? static_cast<vtkm::Id>(-1) : static_cast<vtkm::Id>(result - first);
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}
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/// @}
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/// Implementation of std::lower_bound or std::upper_bound that is appropriate
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/// for both control and execution environments.
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/// The overloads that take portals return indices instead of iterators.
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/// @{
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template <typename IterT, typename T, typename Comp>
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VTKM_EXEC_CONT IterT LowerBound(IterT first, IterT last, const T& val, Comp comp)
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{
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#ifdef VTKM_CUDA
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auto len = last - first;
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while (len != 0)
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{
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const auto halfLen = len / 2;
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IterT mid = first + halfLen;
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if (comp(*mid, val))
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{
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first = mid + 1;
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len -= halfLen + 1;
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}
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else
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{
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len = halfLen;
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}
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}
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return first;
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#else // VTKM_CUDA
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return std::lower_bound(first, last, val, std::move(comp));
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#endif // VTKM_CUDA
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}
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template <typename IterT, typename T>
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VTKM_EXEC_CONT IterT LowerBound(IterT first, IterT last, const T& val)
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{
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return vtkm::LowerBound(first, last, val, vtkm::SortLess{});
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}
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template <typename PortalT, typename T, typename Comp>
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VTKM_EXEC_CONT vtkm::Id LowerBound(const PortalT& portal, const T& val, Comp comp)
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{
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auto first = vtkm::cont::ArrayPortalToIteratorBegin(portal);
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auto last = vtkm::cont::ArrayPortalToIteratorEnd(portal);
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auto result = vtkm::LowerBound(first, last, val, comp);
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return static_cast<vtkm::Id>(result - first);
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}
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template <typename PortalT, typename T>
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VTKM_EXEC_CONT vtkm::Id LowerBound(const PortalT& portal, const T& val)
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{
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auto first = vtkm::cont::ArrayPortalToIteratorBegin(portal);
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auto last = vtkm::cont::ArrayPortalToIteratorEnd(portal);
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auto result = vtkm::LowerBound(first, last, val, vtkm::SortLess{});
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return static_cast<vtkm::Id>(result - first);
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}
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template <typename IterT, typename T, typename Comp>
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VTKM_EXEC_CONT IterT UpperBound(IterT first, IterT last, const T& val, Comp comp)
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{
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#ifdef VTKM_CUDA
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auto len = last - first;
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while (len != 0)
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{
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const auto halfLen = len / 2;
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IterT mid = first + halfLen;
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if (!comp(val, *mid))
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{
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first = mid + 1;
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len -= halfLen + 1;
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}
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else
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{
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len = halfLen;
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}
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}
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return first;
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#else // VTKM_CUDA
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return std::upper_bound(first, last, val, std::move(comp));
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#endif // VTKM_CUDA
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}
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template <typename IterT, typename T>
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VTKM_EXEC_CONT IterT UpperBound(IterT first, IterT last, const T& val)
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{
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return vtkm::UpperBound(first, last, val, vtkm::SortLess{});
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}
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template <typename PortalT, typename T, typename Comp>
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VTKM_EXEC_CONT vtkm::Id UpperBound(const PortalT& portal, const T& val, Comp comp)
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{
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auto first = vtkm::cont::ArrayPortalToIteratorBegin(portal);
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auto last = vtkm::cont::ArrayPortalToIteratorEnd(portal);
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auto result = vtkm::UpperBound(first, last, val, comp);
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return static_cast<vtkm::Id>(result - first);
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}
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template <typename PortalT, typename T>
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VTKM_EXEC_CONT vtkm::Id UpperBound(const PortalT& portal, const T& val)
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{
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auto first = vtkm::cont::ArrayPortalToIteratorBegin(portal);
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auto last = vtkm::cont::ArrayPortalToIteratorEnd(portal);
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auto result = vtkm::UpperBound(first, last, val, vtkm::SortLess{});
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return static_cast<vtkm::Id>(result - first);
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}
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/// @}
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} // end namespace vtkm
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#endif // vtk_m_Algorithms_h
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