StdPartioningOps

PartitioningOperations

Header File: Kokkos_Core.hpp

All algorithms are currently in the Kokkos::Experimental namespace.

Kokkos::Experimental::is_partitioned

template <class ExecutionSpace, class InputIterator, class PredicateType>
InputIterator is_partitioned(const ExecutionSpace& exespace,                              (1)
                             InputIterator first, InputIterator last,
                             PredicateType pred);

template <class ExecutionSpace, class InputIterator, class PredicateType>
InputIterator is_partitioned(const std::string& label, const ExecutionSpace& exespace,    (2)
                             InputIterator first, InputIterator last,
                             PredicateType pred);

template <class ExecutionSpace, class DataType, class... Properties, class PredicateType>
auto is_partitioned(const ExecutionSpace& exespace,
                    const ::Kokkos::View<DataType, Properties...>& view,                  (3)
                    PredicateType pred);

template <class ExecutionSpace, class DataType, class... Properties, class PredicateType>
auto is_partitioned(const std::string& label, const ExecutionSpace& exespace,
                    const ::Kokkos::View<DataType, Properties...>& view,                  (4)
                    PredicateType pred);

Description

Returns true if all elements in [first, last) satisfying the predicate pred appear before all elements that don't, or if [first, last) is empty.

Overload set: (1,2) accept iterators; (3,4) accepting views

Parameters and Requirements

• exespace, label, first, last, view, pred: same requirements as find_if (TODO: link)
• label:
  • for 1, the default string is: Kokkos::is_partitioned_iterator_api_default
  • for 3, the default string is: Kokkos::is_partitioned_view_api_default

Return

• true: if range is partitioned according to pred or if range is empty
• false: otherwise

Example

namespace KE = Kokkos::Experimental;

template<class ValueType>
struct IsNegative
{
  KOKKOS_INLINE_FUNCTION
  bool operator()(const ValueType & operand) const {
    constexpr auto zero = static_cast<ValueType>(0);
    return (operand < zero);
  }
};

using view_type = Kokkos::View<int*>;
view_type a("a", 15);
// fill a somehow

auto exespace  = Kokkos::DefaultExecutionSpace;
const auto res = KE::is_partitioned(exespace, KE::cbegin(a), KE::cend(a), IsNegative<int>());
// note that we used {cbegin, cend} here, because checking if the view
// is partitioned does not need to have write access to the view's elements.
// We could have also used {begin, end}, but if we know that we only
// need read access, it is good practice to ensure const-correctness.

// ...