thrust/cub/iterator/discard_output_iterator.cuh

/******************************************************************************
 * Copyright (c) 2011, Duane Merrill.  All rights reserved.
 * Copyright (c) 2011-2018, NVIDIA CORPORATION.  All rights reserved.
 * 
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 *       names of its contributors may be used to endorse or promote products
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/**
 * \file
 * Random-access iterator types
 */

#pragma once

#include <iterator>
#include <iostream>

#include "../config.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


/// Optional outer namespace(s)
CUB_NS_PREFIX

/// CUB namespace
namespace cub {


/**
 * \addtogroup UtilIterator
 * @{
 */


/**
 * \brief A discard iterator
 */
template <typename OffsetT = ptrdiff_t>
class DiscardOutputIterator
{
public:

    // Required iterator traits
    typedef DiscardOutputIterator   self_type;              ///< My own type
    typedef OffsetT                 difference_type;        ///< Type to express the result of subtracting one iterator from another
    typedef void                    value_type;             ///< The type of the element the iterator can point to
    typedef void                    pointer;                ///< The type of a pointer to an element the iterator can point to
    typedef void                    reference;              ///< The type of a reference to an element the iterator can point to

#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;                                        ///< The iterator category
#else
    typedef std::random_access_iterator_tag     iterator_category;      ///< The iterator category
#endif  // THRUST_VERSION

private:

    OffsetT offset;

#if defined(_WIN32) || !defined(_WIN64)
    // Workaround for win32 parameter-passing bug (ulonglong2 argmin DeviceReduce)
    OffsetT pad[CUB_MAX(1, (16 / sizeof(OffsetT) - 1))];
#endif

public:

    /// Constructor
    __host__ __device__ __forceinline__ DiscardOutputIterator(
        OffsetT offset = 0)     ///< Base offset
    :
        offset(offset)
    {}

    /// Postfix increment
    __host__ __device__ __forceinline__ self_type operator++(int)
    {
        self_type retval = *this;
        offset++;
        return retval;
    }

    /// Prefix increment
    __host__ __device__ __forceinline__ self_type operator++()
    {
        offset++;
        return *this;
    }

    /// Indirection
    __host__ __device__ __forceinline__ self_type& operator*()
    {
        // return self reference, which can be assigned to anything
        return *this;
    }

    /// Addition
    template <typename Distance>
    __host__ __device__ __forceinline__ self_type operator+(Distance n) const
    {
        self_type retval(offset + n);
        return retval;
    }

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

    /// Subtraction
    template <typename Distance>
    __host__ __device__ __forceinline__ self_type operator-(Distance n) const
    {
        self_type retval(offset - n);
        return retval;
    }

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

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

    /// Array subscript
    template <typename Distance>
    __host__ __device__ __forceinline__ self_type& operator[](Distance n)
    {
        // return self reference, which can be assigned to anything
        return *this;
    }

    /// Structure dereference
    __host__ __device__ __forceinline__ pointer operator->()
    {
        return;
    }

    /// Assignment to self (no-op)
    __host__ __device__ __forceinline__ void operator=(self_type const& other)
    {
        offset = other.offset;
    }

    /// Assignment to anything else (no-op)
    template<typename T>
    __host__ __device__ __forceinline__ void operator=(T const&)
    {}

    /// Cast to void* operator
    __host__ __device__ __forceinline__ operator void*() const { return NULL; }

    /// Equal to
    __host__ __device__ __forceinline__ bool operator==(const self_type& rhs)
    {
        return (offset == rhs.offset);
    }

    /// Not equal to
    __host__ __device__ __forceinline__ bool operator!=(const self_type& rhs)
    {
        return (offset != rhs.offset);
    }

    /// ostream operator
    friend std::ostream& operator<<(std::ostream& os, const self_type& itr)
    {
        os << "[" << itr.offset << "]";
        return os;
    }

};


/** @} */       // end group UtilIterator

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