transform_input_iterator.cuh

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 * Copyright (c) 2011, Duane Merrill.  All rights reserved.
 * Copyright (c) 2011-2018, NVIDIA CORPORATION.  All rights reserved.
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 * modification, are permitted provided that the following conditions are met:
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 *       names of its contributors may be used to endorse or promote products
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#pragma once

#include <iterator>
#include <iostream>

#include "../thread/thread_load.cuh"
#include "../thread/thread_store.cuh"
#include "../util_device.cuh"
#include "../util_namespace.cuh"

#if (THRUST_VERSION >= 100700)
    // This iterator is compatible with Thrust API 1.7 and newer
    #include <thrust/iterator/iterator_facade.h>
    #include <thrust/iterator/iterator_traits.h>
#endif // THRUST_VERSION


CUB_NS_PREFIX

namespace cub {

template <
    typename ValueType,
    typename ConversionOp,
    typename InputIteratorT,
    typename OffsetT = ptrdiff_t>
class TransformInputIterator
{
public:

    // Required iterator traits
    typedef TransformInputIterator              self_type;              
    typedef OffsetT                             difference_type;        
    typedef ValueType                           value_type;             
    typedef ValueType*                          pointer;                
    typedef ValueType                           reference;              

#if (THRUST_VERSION >= 100700)
    // Use Thrust's iterator categories so we can use these iterators in Thrust 1.7 (or newer) methods
    typedef typename thrust::detail::iterator_facade_category<
        thrust::any_system_tag,
        thrust::random_access_traversal_tag,
        value_type,
        reference
      >::type iterator_category;                                        
#else
    typedef std::random_access_iterator_tag     iterator_category;      
#endif  // THRUST_VERSION

private:

    ConversionOp    conversion_op;
    InputIteratorT  input_itr;

public:

    __host__ __device__ __forceinline__ TransformInputIterator(
        InputIteratorT      input_itr,          
        ConversionOp        conversion_op)      
    :
        conversion_op(conversion_op),
        input_itr(input_itr)
    {}

    __host__ __device__ __forceinline__ self_type operator++(int)
    {
        self_type retval = *this;
        input_itr++;
        return retval;
    }

    __host__ __device__ __forceinline__ self_type operator++()
    {
        input_itr++;
        return *this;
    }

    __host__ __device__ __forceinline__ reference operator*() const
    {
        return conversion_op(*input_itr);
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ self_type operator+(Distance n) const
    {
        self_type retval(input_itr + n, conversion_op);
        return retval;
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ self_type& operator+=(Distance n)
    {
        input_itr += n;
        return *this;
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ self_type operator-(Distance n) const
    {
        self_type retval(input_itr - n, conversion_op);
        return retval;
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ self_type& operator-=(Distance n)
    {
        input_itr -= n;
        return *this;
    }

    __host__ __device__ __forceinline__ difference_type operator-(self_type other) const
    {
        return input_itr - other.input_itr;
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ reference operator[](Distance n) const
    {
        return conversion_op(input_itr[n]);
    }

    __host__ __device__ __forceinline__ pointer operator->()
    {
        return &conversion_op(*input_itr);
    }

    __host__ __device__ __forceinline__ bool operator==(const self_type& rhs)
    {
        return (input_itr == rhs.input_itr);
    }

    __host__ __device__ __forceinline__ bool operator!=(const self_type& rhs)
    {
        return (input_itr != rhs.input_itr);
    }

    friend std::ostream& operator<<(std::ostream& os, const self_type& itr)
    {
        return os;
    }
};


       // end group UtilIterator

}               // CUB namespace
CUB_NS_POSTFIX  // Optional outer namespace(s)