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bernhardmgruberbernhardmgruber
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Refactor Thrust iterators 2/n (NVIDIA#3840)
* Refactor discard_iterator * Refactor permutation_iterator
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-340
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4 files changed

+229
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‎thrust/thrust/iterator/detail/discard_iterator_base.h

-65
This file was deleted.

‎thrust/thrust/iterator/detail/permutation_iterator_base.h

-59
This file was deleted.

‎thrust/thrust/iterator/discard_iterator.h

+110-98
Original file line numberDiff line numberDiff line change
@@ -29,104 +29,123 @@
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#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
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# pragma system_header
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#endif // no system header
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#include <thrust/iterator/detail/discard_iterator_base.h>
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#include <thrust/iterator/iterator_facade.h>
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_CCCL_DIAG_PUSH
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_CCCL_DIAG_SUPPRESS_MSVC(4244 4267) // possible loss of data
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#include <thrust/iterator/counting_iterator.h>
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#include <thrust/iterator/detail/any_assign.h>
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#include <thrust/iterator/iterator_adaptor.h>
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#include <cuda/std/cstddef>
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THRUST_NAMESPACE_BEGIN
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/*! \addtogroup iterators
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* \{
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*/
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template <typename>
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class discard_iterator;
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/*! \addtogroup fancyiterator Fancy Iterators
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* \ingroup iterators
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* \{
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*/
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namespace detail
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{
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template <typename System>
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struct make_discard_iterator_base
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{
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// XXX value_type should actually be void but this interferes with zip_iterator<discard_iterator>
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using value_type = any_assign;
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using reference = any_assign&;
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using incrementable = ::cuda::std::ptrdiff_t;
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using base_iterator = counting_iterator<incrementable, System, random_access_traversal_tag>;
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using type =
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iterator_adaptor<discard_iterator<System>,
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base_iterator,
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value_type,
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iterator_system_t<base_iterator>,
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iterator_traversal_t<base_iterator>,
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reference>;
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};
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} // namespace detail
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/*! \p discard_iterator is an iterator which represents a special kind of pointer that
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* ignores values written to it upon dereference. This iterator is useful for ignoring
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* the output of certain algorithms without wasting memory capacity or bandwidth.
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* \p discard_iterator may also be used to count the size of an algorithm's output which
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* may not be known a priori.
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*
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* The following code snippet demonstrates how to use \p discard_iterator to
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* ignore one of the output ranges of reduce_by_key
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*
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* \code
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* #include <thrust/iterator/discard_iterator.h>
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* #include <thrust/reduce.h>
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* #include <thrust/device_vector.h>
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*
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* int main()
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* {
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* thrust::device_vector<int> keys(7), values(7);
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*
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* keys[0] = 1;
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* keys[1] = 3;
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* keys[2] = 3;
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* keys[3] = 3;
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* keys[4] = 2;
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* keys[5] = 2;
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* keys[6] = 1;
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*
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* values[0] = 9;
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* values[1] = 8;
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* values[2] = 7;
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* values[3] = 6;
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* values[4] = 5;
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* values[5] = 4;
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* values[6] = 3;
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*
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* thrust::device_vector<int> result(4);
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*
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* // we are only interested in the reduced values
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* // use discard_iterator to ignore the output keys
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* thrust::reduce_by_key(keys.begin(), keys.end(),
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* values.begin(),
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* thrust::make_discard_iterator(),
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* result.begin());
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*
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* // result is now [9, 21, 9, 3]
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*
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* return 0;
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* }
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* \endcode
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*
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* \see make_discard_iterator
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*/
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_CCCL_DIAG_PUSH
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_CCCL_DIAG_SUPPRESS_MSVC(4244 4267) // possible loss of data
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//! \addtogroup iterators
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//! \{
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//! \addtogroup fancyiterator Fancy Iterators
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//! \ingroup iterators
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//! \{
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//! \p discard_iterator is an iterator which represents a special kind of pointer that ignores values written to it upon
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//! dereference. This iterator is useful for ignoring the output of certain algorithms without wasting memory capacity
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//! or bandwidth. \p discard_iterator may also be used to count the size of an algorithm's output which may not be known
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//! a priori.
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//!
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//! The following code snippet demonstrates how to use \p discard_iterator to ignore one of the output ranges of
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//! reduce_by_key
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//!
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//! \code
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//! #include <thrust/iterator/discard_iterator.h>
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//! #include <thrust/reduce.h>
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//! #include <thrust/device_vector.h>
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//!
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//! int main()
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//! {
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//! thrust::device_vector<int> keys(7), values(7);
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//!
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//! keys[0] = 1;
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//! keys[1] = 3;
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//! keys[2] = 3;
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//! keys[3] = 3;
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//! keys[4] = 2;
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//! keys[5] = 2;
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//! keys[6] = 1;
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//!
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//! values[0] = 9;
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//! values[1] = 8;
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//! values[2] = 7;
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//! values[3] = 6;
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//! values[4] = 5;
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//! values[5] = 4;
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//! values[6] = 3;
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//!
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//! thrust::device_vector<int> result(4);
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//!
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//! // we are only interested in the reduced values
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//! // use discard_iterator to ignore the output keys
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//! thrust::reduce_by_key(keys.begin(), keys.end(),
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//! values.begin(),
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//! thrust::make_discard_iterator(),
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//! result.begin());
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//!
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//! // result is now [9, 21, 9, 3]
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//!
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//! return 0;
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//! }
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//! \endcode
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//!
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//! \see make_discard_iterator
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template <typename System = use_default>
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class discard_iterator : public detail::discard_iterator_base<System>::type
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class discard_iterator : public detail::make_discard_iterator_base<System>::type
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{
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/*! \cond
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*/
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//! \cond
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friend class iterator_core_access;
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using super_t = typename detail::discard_iterator_base<System>::type;
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using incrementable = typename detail::discard_iterator_base<System>::incrementable;
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using base_iterator = typename detail::discard_iterator_base<System>::base_iterator;
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using super_t = typename detail::make_discard_iterator_base<System>::type;
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using incrementable = typename detail::make_discard_iterator_base<System>::incrementable;
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using base_iterator = typename detail::make_discard_iterator_base<System>::base_iterator;
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110134
public:
111135
using reference = typename super_t::reference;
112136
using value_type = typename super_t::value_type;
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/*! \endcond
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*/
138+
//! \endcond
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/*! This constructor receives an optional index specifying the position of this
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* \p discard_iterator in a range.
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*
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* \p i The index of this \p discard_iterator in a range. Defaults to the
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* value returned by \c Incrementable's null constructor. For example,
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* when <tt>Incrementable == int</tt>, \c 0.
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*/
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//! This constructor receives an optional index specifying the position of this \p discard_iterator in a range.
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//!
142+
//! \p i The index of this \p discard_iterator in a range. Defaults to the value returned by \c Incrementable's null
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//! constructor. For example, when <tt>Incrementable == int</tt>, \c 0.
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_CCCL_HOST_DEVICE discard_iterator(incrementable const& i = incrementable())
125145
: super_t(base_iterator(i))
126146
{}
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128-
/*! \cond
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*/
148+
//! \cond
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131150
private: // Core iterator interface
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_CCCL_HOST_DEVICE reference dereference() const
@@ -136,31 +155,24 @@ class discard_iterator : public detail::discard_iterator_base<System>::type
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137156
mutable value_type m_element;
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139-
/*! \endcond
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*/
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}; // end constant_iterator
158+
//! \endcond
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};
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/*! \p make_discard_iterator creates a \p discard_iterator from an optional index parameter.
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*
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* \param i The index of the returned \p discard_iterator within a range.
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* In the default case, the value of this parameter is \c 0.
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*
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* \return A new \p discard_iterator with index as given by \p i.
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*
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* \see constant_iterator
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*/
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//! \p make_discard_iterator creates a \p discard_iterator from an optional index parameter.
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//!
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//! \param i The index of the returned \p discard_iterator within a range. In the default case, the value of this
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//! parameter is \c 0.
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//! \return A new \p discard_iterator with index as given by \p i.
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//! \see constant_iterator
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inline _CCCL_HOST_DEVICE discard_iterator<>
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make_discard_iterator(discard_iterator<>::difference_type i = discard_iterator<>::difference_type(0))
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{
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return discard_iterator<>(i);
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} // end make_discard_iterator()
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}
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/*! \} // end fancyiterators
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*/
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//! \} // end fancyiterators
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//! \} // end iterators
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/*! \} // end iterators
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*/
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_CCCL_DIAG_POP
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THRUST_NAMESPACE_END
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_CCCL_DIAG_POP

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