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/*
* Copyright 2008-2012 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 gather.h
* \brief Irregular copying from a source range
*/
#pragma once
#include <thrust/detail/config.h>
#include <thrust/detail/dispatchable.h>
namespace thrust
{
template<typename System,
typename InputIterator,
typename RandomAccessIterator,
typename OutputIterator>
OutputIterator gather(thrust::detail::dispatchable_base<System> &system,
InputIterator map_first,
InputIterator map_last,
RandomAccessIterator input_first,
OutputIterator result);
template<typename System,
typename InputIterator1,
typename InputIterator2,
typename RandomAccessIterator,
typename OutputIterator>
OutputIterator gather_if(thrust::detail::dispatchable_base<System> &system,
InputIterator1 map_first,
InputIterator1 map_last,
InputIterator2 stencil,
RandomAccessIterator input_first,
OutputIterator result);
template<typename System,
typename InputIterator1,
typename InputIterator2,
typename RandomAccessIterator,
typename OutputIterator,
typename Predicate>
OutputIterator gather_if(thrust::detail::dispatchable_base<System> &system,
InputIterator1 map_first,
InputIterator1 map_last,
InputIterator2 stencil,
RandomAccessIterator input_first,
OutputIterator result,
Predicate pred);
/*! \addtogroup gathering
* \ingroup copying
* \{
*/
/*! \p gather copies elements from a source array into a destination range according
* to a map. For each input iterator \c i in the range <tt>[map_first, map_last)</tt>, the
* value <tt>input_first[*i]</tt> is assigned to <tt>*(result + (i - map_first))</tt>.
* \p RandomAccessIterator must permit random access.
*
* \param map_first Beginning of the range of gather locations.
* \param map_last End of the range of gather locations.
* \param input_first Beginning of the source range.
* \param result Beginning of the destination range.
*
* \tparam InputIterator must be a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a> and \c InputIterator's \c value_type must be convertible to \c RandomAccessIterator's \c difference_type.
* \tparam RandomAccessIterator must be a model of <a href="http://www.sgi.com/tech/stl/RandomAccessIterator.html">Random Access Iterator</a> and \c RandomAccessIterator's \c value_type must be convertible to \c OutputIterator's \c value_type.
* \tparam OutputIterator must be a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a>.
*
* The following code snippet demonstrates how to use \p gather to reorder
* a range.
*
* \code
* #include <thrust/gather.h>
* #include <thrust/device_vector.h>
* ...
* // mark even indices with a 1; odd indices with a 0
* int values[10] = {1, 0, 1, 0, 1, 0, 1, 0, 1, 0};
* thrust::device_vector<int> d_values(values, values + 10);
*
* // gather all even indices into the first half of the range
* // and odd indices to the last half of the range
* int map[10] = {0, 2, 4, 6, 8, 1, 3, 5, 7, 9};
* thrust::device_vector<int> d_map(map, map + 10);
*
* thrust::device_vector<int> d_output(10);
* thrust::gather(d_map.begin(), d_map.end(),
* d_values.begin(),
* d_output.begin());
* // d_output is now {1, 1, 1, 1, 1, 0, 0, 0, 0, 0}
* \endcode
*
* \note \p gather is the inverse of thrust::scatter.
*/
template<typename InputIterator,
typename RandomAccessIterator,
typename OutputIterator>
OutputIterator gather(InputIterator map_first,
InputIterator map_last,
RandomAccessIterator input_first,
OutputIterator result);
/*! \p gather_if conditionally copies elements from a source array into a destination
* range according to a map. For each input iterator \c i in the range <tt>[map_first, map_last)</tt>,
* such that the value of <tt>*(stencil + (i - map_first))</tt> is \c true, the value
* <tt>input_first[*i]</tt> is assigned to <tt>*(result + (i - map_first))</tt>.
* \p RandomAccessIterator must permit random access.
*
* \param map_first Beginning of the range of gather locations.
* \param map_last End of the range of gather locations.
* \param stencil Beginning of the range of predicate values.
* \param input_first Beginning of the source range.
* \param result Beginning of the destination range.
*
* \tparam InputIterator1 must be a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a> and \c InputIterator1's \c value_type must be convertible to \c RandomAccessIterator's \c difference_type.
* \tparam InputIterator2 must be a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a> and \c InputIterator2's \c value_type must be convertible to \c bool.
* \tparam RandomAccessIterator must be a model of <a href="http://www.sgi.com/tech/stl/RandomAccessIterator.html">Random Access iterator</a> and \c RandomAccessIterator's \c value_type must be convertible to \c OutputIterator's \c value_type.
* \tparam OutputIterator must be a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a>.
*
* The following code snippet demonstrates how to use \p gather_if to gather selected values from
* an input range.
*
* \code
* #include <thrust/gather.h>
* #include <thrust/device_vector.h>
* ...
*
* int values[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
* thrust::device_vector<int> d_values(values, values + 10);
*
* // select elements at even-indexed locations
* int stencil[10] = {1, 0, 1, 0, 1, 0, 1, 0, 1, 0};
* thrust::device_vector<int> d_stencil(stencil, stencil + 10);
*
* // map all even indices into the first half of the range
* // and odd indices to the last half of the range
* int map[10] = {0, 2, 4, 6, 8, 1, 3, 5, 7, 9};
* thrust::device_vector<int> d_map(map, map + 10);
*
* thrust::device_vector<int> d_output(10, 7);
* thrust::gather_if(d_map.begin(), d_map.end(),
* d_stencil.begin(),
* d_values.begin(),
* d_output.begin());
* // d_output is now {0, 2, 4, 6, 8, 7, 7, 7, 7, 7}
* \endcode
*
* \note \p gather_if is the inverse of \p scatter_if.
*/
template<typename InputIterator1,
typename InputIterator2,
typename RandomAccessIterator,
typename OutputIterator>
OutputIterator gather_if(InputIterator1 map_first,
InputIterator1 map_last,
InputIterator2 stencil,
RandomAccessIterator input_first,
OutputIterator result);
/*! \p gather_if conditionally copies elements from a source array into a destination
* range according to a map. For each input iterator \c i in the range <tt>[map_first, map_last)</tt>
* such that the value of <tt>pred(*(stencil + (i - map_first)))</tt> is \c true,
* the value <tt>input_first[*i]</tt> is assigned to <tt>*(result + (i - map_first))</tt>.
* \p RandomAccessIterator must permit random access.
*
* \param map_first Beginning of the range of gather locations.
* \param map_last End of the range of gather locations.
* \param stencil Beginning of the range of predicate values.
* \param input_first Beginning of the source range.
* \param result Beginning of the destination range.
* \param pred Predicate to apply to the stencil values.
*
* \tparam InputIterator1 must be a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a> and \c InputIterator1's \c value_type must be convertible to \c RandomAccessIterator's \c difference_type.
* \tparam InputIterator2 must be a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a> and \c InputIterator2's \c value_type must be convertible to \c Predicate's \c argument_type.
* \tparam RandomAccessIterator must be a model of <a href="http://www.sgi.com/tech/stl/RandomAccessIterator.html">Random Access iterator</a> and \c RandomAccessIterator's \c value_type must be convertible to \c OutputIterator's \c value_type.
* \tparam OutputIterator must be a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a>.
* \tparam Predicate must be a model of <a href="http://www.sgi.com/tech/stl/Predicate.html">Predicate</a>.
*
* The following code snippet demonstrates how to use \p gather_if to gather selected values from
* an input range based on an arbitrary selection function.
*
* \code
* #include <thrust/gather.h>
* #include <thrust/device_vector.h>
*
* struct is_even
* {
* __host__ __device__
* bool operator()(const int x)
* {
* return (x % 2) == 0;
* }
* };
* ...
*
* int values[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
* thrust::device_vector<int> d_values(values, values + 10);
*
* // we will select an element when our stencil is even
* int stencil[10] = {0, 3, 4, 1, 4, 1, 2, 7, 8, 9};
* thrust::device_vector<int> d_stencil(stencil, stencil + 10);
*
* // map all even indices into the first half of the range
* // and odd indices to the last half of the range
* int map[10] = {0, 2, 4, 6, 8, 1, 3, 5, 7, 9};
* thrust::device_vector<int> d_map(map, map + 10);
*
* thrust::device_vector<int> d_output(10, 7);
* thrust::gather_if(d_map.begin(), d_map.end(),
* d_stencil.begin(),
* d_values.begin(),
* d_output.begin(),
* is_even());
* // d_output is now {0, 7, 4, 7, 8, 7, 3, 7, 7, 7}
* \endcode
*
* \note \p gather_if is the inverse of \p scatter_if.
*/
template<typename InputIterator1,
typename InputIterator2,
typename RandomAccessIterator,
typename OutputIterator,
typename Predicate>
OutputIterator gather_if(InputIterator1 map_first,
InputIterator1 map_last,
InputIterator2 stencil,
RandomAccessIterator input_first,
OutputIterator result,
Predicate pred);
/*! \} // gathering
*/
} // end namespace thrust
#include <thrust/detail/gather.inl>