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1//---------------------------------------------------------------------------//
2// Copyright (c) 2014 Roshan <thisisroshansmail@gmail.com>
3//
4// Distributed under the Boost Software License, Version 1.0
5// See accompanying file LICENSE_1_0.txt or copy at
6// http://www.boost.org/LICENSE_1_0.txt
7//
8// See http://boostorg.github.com/compute for more information.
9//---------------------------------------------------------------------------//
10
11#ifndef BOOST_COMPUTE_ALGORITHM_STABLE_PARTITION_HPP
12#define BOOST_COMPUTE_ALGORITHM_STABLE_PARTITION_HPP
13
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14#include <boost/static_assert.hpp>
15
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16#include <boost/compute/system.hpp>
17#include <boost/compute/context.hpp>
18#include <boost/compute/functional.hpp>
19#include <boost/compute/command_queue.hpp>
20#include <boost/compute/algorithm/copy_if.hpp>
21#include <boost/compute/container/vector.hpp>
92f5a8d4 22#include <boost/compute/type_traits/is_device_iterator.hpp>
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23
24namespace boost {
25namespace compute {
26
27///
28/// \brief Partitioning algorithm
29///
30/// Partitions the elements in the range [\p first, \p last) according to
31/// \p predicate. The order of the elements is preserved.
32/// \return Iterator pointing to end of true values
33///
34/// \param first Iterator pointing to start of range
35/// \param last Iterator pointing to end of range
36/// \param predicate Unary predicate to be applied on each element
37/// \param queue Queue on which to execute
38///
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39/// Space complexity: \Omega(3n)
40///
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41/// \see is_partitioned() and partition()
42///
43template<class Iterator, class UnaryPredicate>
44inline Iterator stable_partition(Iterator first,
45 Iterator last,
46 UnaryPredicate predicate,
47 command_queue &queue = system::default_queue())
48{
92f5a8d4 49 BOOST_STATIC_ASSERT(is_device_iterator<Iterator>::value);
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50 typedef typename std::iterator_traits<Iterator>::value_type value_type;
51
52 // make temporary copy of the input
53 ::boost::compute::vector<value_type> tmp(first, last, queue);
54
55 // copy true values
56 Iterator last_true =
57 ::boost::compute::copy_if(tmp.begin(),
58 tmp.end(),
59 first,
60 predicate,
61 queue);
62
63 // copy false values
64 Iterator last_false =
65 ::boost::compute::copy_if(tmp.begin(),
66 tmp.end(),
67 last_true,
68 not1(predicate),
69 queue);
70
71 // return iterator pointing to the last true value
72 return last_true;
73}
74
75} // end compute namespace
76} // end boost namespace
77
78#endif // BOOST_COMPUTE_ALGORITHM_STABLE_PARTITION_HPP