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#pragma once

#if THRUST_DEVICE_COMPILER == THRUST_DEVICE_COMPILER_HCC
#include <iterator>
// This include is not required
// #include <thrust/system/hip/detail/transform.h>
#include <thrust/distance.h>
#include <thrust/swap.h>
#include <thrust/system/hip/detail/par_to_seq.h>
#include <thrust/system/hip/detail/parallel_for.h>

BEGIN_NS_THRUST

namespace hip_rocprim
{
namespace __swap_ranges
{
    template <class ItemsIt1, class ItemsIt2>
    struct swap_f
    {
        ItemsIt1 items1;
        ItemsIt2 items2;

        typedef typename iterator_traits<ItemsIt1>::value_type value1_type;
        typedef typename iterator_traits<ItemsIt2>::value_type value2_type;

        THRUST_HIP_FUNCTION
        swap_f(ItemsIt1 items1_, ItemsIt2 items2_)
            : items1(items1_)
            , items2(items2_)
        {
        }

        template <class Size>
        void THRUST_HIP_DEVICE_FUNCTION operator()(Size idx)
        {
            value1_type item1 = items1[idx];
            value2_type item2 = items2[idx];
            // XXX thrust::swap is buggy
            // if reference_type of ItemIt1/ItemsIt2
            // is a proxy reference, then KABOOM!
            // to avoid this, just copy the value first before swap
            // *todo* specialize on real & proxy references
            using thrust::swap;
            swap(item1, item2);
            items1[idx] = item1;
            items2[idx] = item2;
        }
    };
} // namespace __swap_ranges

template <class Derived, class ItemsIt1, class ItemsIt2>
ItemsIt2 THRUST_HIP_FUNCTION
swap_ranges(execution_policy<Derived>& policy,
            ItemsIt1                   first1,
            ItemsIt1                   last1,
            ItemsIt2                   first2)
{
    typedef typename iterator_traits<ItemsIt1>::difference_type size_type;

    size_type num_items = static_cast<size_type>(thrust::distance(first1, last1));

    hip_rocprim::parallel_for(
        policy, __swap_ranges::swap_f<ItemsIt1, ItemsIt2>(first1, first2), num_items
    );
    return first2 + num_items;
}

} // namespace hip_rocprim

END_NS_THRUST
#endif