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/*
* Copyright 2008-2013 NVIDIA Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*! \file thrust/iterator/counting_iterator.h
* \brief An iterator which returns an increasing incrementable value
* when dereferenced
*/
/*
* Copyright David Abrahams 2003.
*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying NOTICE file for the complete license)
*
* For more information, see http://www.boost.org
*/
#pragma once
#include <thrust/detail/config.h>
#include <thrust/iterator/iterator_adaptor.h>
#include <thrust/iterator/iterator_facade.h>
#include <thrust/iterator/iterator_categories.h>
// #include the details first
#include <thrust/iterator/detail/counting_iterator.inl>
THRUST_NAMESPACE_BEGIN
/*! \addtogroup iterators
* \{
*/
/*! \addtogroup fancyiterator Fancy Iterators
* \ingroup iterators
* \{
*/
/*! \p counting_iterator is an iterator which represents a pointer into a range
* of sequentially changing values. This iterator is useful for creating a range
* filled with a sequence without explicitly storing it in memory. Using
* \p counting_iterator saves memory capacity and bandwidth.
*
* The following code snippet demonstrates how to create a \p counting_iterator whose
* \c value_type is \c int and which sequentially increments by \c 1.
*
* \code
* #include <thrust/iterator/counting_iterator.h>
* ...
* // create iterators
* thrust::counting_iterator<int> first(10);
* thrust::counting_iterator<int> last = first + 3;
*
* first[0] // returns 10
* first[1] // returns 11
* first[100] // returns 110
*
* // sum of [first, last)
* thrust::reduce(first, last); // returns 33 (i.e. 10 + 11 + 12)
*
* // initialize vector to [0,1,2,..]
* thrust::counting_iterator<int> iter(0);
* thrust::device_vector<int> vec(500);
* thrust::copy(iter, iter + vec.size(), vec.begin());
* \endcode
*
* This next example demonstrates how to use a \p counting_iterator with the
* \p thrust::copy_if function to compute the indices of the non-zero elements
* of a \p device_vector. In this example, we use the \p make_counting_iterator
* function to avoid specifying the type of the \p counting_iterator.
*
* \code
* #include <thrust/iterator/counting_iterator.h>
* #include <thrust/copy.h>
* #include <thrust/functional.h>
* #include <thrust/device_vector.h>
*
* int main()
* {
* // this example computes indices for all the nonzero values in a sequence
*
* // sequence of zero and nonzero values
* thrust::device_vector<int> stencil(8);
* stencil[0] = 0;
* stencil[1] = 1;
* stencil[2] = 1;
* stencil[3] = 0;
* stencil[4] = 0;
* stencil[5] = 1;
* stencil[6] = 0;
* stencil[7] = 1;
*
* // storage for the nonzero indices
* thrust::device_vector<int> indices(8);
*
* // compute indices of nonzero elements
* typedef thrust::device_vector<int>::iterator IndexIterator;
*
* // use make_counting_iterator to define the sequence [0, 8)
* IndexIterator indices_end = thrust::copy_if(thrust::make_counting_iterator(0),
* thrust::make_counting_iterator(8),
* stencil.begin(),
* indices.begin(),
* thrust::identity<int>());
* // indices now contains [1,2,5,7]
*
* return 0;
* }
* \endcode
*
* \see make_counting_iterator
*/
template<typename Incrementable,
typename System = use_default,
typename Traversal = use_default,
typename Difference = use_default>
class counting_iterator
: public detail::counting_iterator_base<Incrementable, System, Traversal, Difference>::type
{
/*! \cond
*/
typedef typename detail::counting_iterator_base<Incrementable, System, Traversal, Difference>::type super_t;
friend class thrust::iterator_core_access;
public:
typedef typename super_t::reference reference;
typedef typename super_t::difference_type difference_type;
/*! \endcond
*/
/*! Default constructor initializes this \p counting_iterator's counter to
* `Incrementable{}`.
*/
__host__ __device__
counting_iterator() : super_t(Incrementable{}) {}
/*! Copy constructor copies the value of another \p counting_iterator into a
* new \p counting_iterator.
*
* \p rhs The \p counting_iterator to copy.
*/
__host__ __device__
counting_iterator(counting_iterator const &rhs):super_t(rhs.base()){}
/*! Copy constructor copies the value of another counting_iterator
* with related System type.
*
* \param rhs The \p counting_iterator to copy.
*/
template<typename OtherSystem>
__host__ __device__
counting_iterator(counting_iterator<Incrementable, OtherSystem, Traversal, Difference> const &rhs,
typename thrust::detail::enable_if_convertible<
typename thrust::iterator_system<counting_iterator<Incrementable,OtherSystem,Traversal,Difference> >::type,
typename thrust::iterator_system<super_t>::type
>::type * = 0)
: super_t(rhs.base()){}
/*! This \c explicit constructor copies the value of an \c Incrementable
* into a new \p counting_iterator's \c Incrementable counter.
*
* \param x The initial value of the new \p counting_iterator's \c Incrementable
* counter.
*/
__host__ __device__
explicit counting_iterator(Incrementable x):super_t(x){}
#if THRUST_CPP_DIALECT >= 2011
counting_iterator & operator=(const counting_iterator &) = default;
#endif
/*! \cond
*/
private:
__host__ __device__
reference dereference() const
{
return this->base_reference();
}
// note that we implement equal specially for floating point counting_iterator
template <typename OtherIncrementable, typename OtherSystem, typename OtherTraversal, typename OtherDifference>
__host__ __device__
bool equal(counting_iterator<OtherIncrementable, OtherSystem, OtherTraversal, OtherDifference> const& y) const
{
typedef thrust::detail::counting_iterator_equal<difference_type,Incrementable,OtherIncrementable> e;
return e::equal(this->base(), y.base());
}
template <class OtherIncrementable>
__host__ __device__
difference_type
distance_to(counting_iterator<OtherIncrementable, System, Traversal, Difference> const& y) const
{
typedef typename
thrust::detail::eval_if<
thrust::detail::is_numeric<Incrementable>::value,
thrust::detail::identity_<thrust::detail::number_distance<difference_type, Incrementable, OtherIncrementable> >,
thrust::detail::identity_<thrust::detail::iterator_distance<difference_type, Incrementable, OtherIncrementable> >
>::type d;
return d::distance(this->base(), y.base());
}
/*! \endcond
*/
}; // end counting_iterator
/*! \p make_counting_iterator creates a \p counting_iterator
* using an initial value for its \c Incrementable counter.
*
* \param x The initial value of the new \p counting_iterator's counter.
* \return A new \p counting_iterator whose counter has been initialized to \p x.
*/
template <typename Incrementable>
inline __host__ __device__
counting_iterator<Incrementable> make_counting_iterator(Incrementable x)
{
return counting_iterator<Incrementable>(x);
}
/*! \} // end fancyiterators
*/
/*! \} // end iterators
*/
THRUST_NAMESPACE_END
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