//---------------------------------------------------------------------------//
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// Copyright (c) 2014 Roshan <thisisroshansmail@gmail.com>
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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// See http://boostorg.github.com/compute for more information.
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//---------------------------------------------------------------------------//
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#ifndef BOOST_COMPUTE_ALGORITHM_STABLE_PARTITION_HPP
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#define BOOST_COMPUTE_ALGORITHM_STABLE_PARTITION_HPP
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#include <boost/static_assert.hpp>
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#include <boost/compute/system.hpp>
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#include <boost/compute/context.hpp>
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#include <boost/compute/functional.hpp>
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#include <boost/compute/command_queue.hpp>
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#include <boost/compute/algorithm/copy_if.hpp>
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#include <boost/compute/container/vector.hpp>
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#include <boost/compute/type_traits/is_device_iterator.hpp>
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namespace boost {
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namespace compute {
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///
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/// \brief Partitioning algorithm
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///
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/// Partitions the elements in the range [\p first, \p last) according to
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/// \p predicate. The order of the elements is preserved.
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/// \return Iterator pointing to end of true values
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///
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/// \param first Iterator pointing to start of range
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/// \param last Iterator pointing to end of range
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/// \param predicate Unary predicate to be applied on each element
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/// \param queue Queue on which to execute
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///
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/// Space complexity: \Omega(3n)
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///
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/// \see is_partitioned() and partition()
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///
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template<class Iterator, class UnaryPredicate>
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inline Iterator stable_partition(Iterator first,
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Iterator last,
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UnaryPredicate predicate,
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command_queue &queue = system::default_queue())
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{
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BOOST_STATIC_ASSERT(is_device_iterator<Iterator>::value);
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typedef typename std::iterator_traits<Iterator>::value_type value_type;
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// make temporary copy of the input
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::boost::compute::vector<value_type> tmp(first, last, queue);
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// copy true values
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Iterator last_true =
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::boost::compute::copy_if(tmp.begin(),
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tmp.end(),
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first,
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predicate,
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queue);
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// copy false values
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Iterator last_false =
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::boost::compute::copy_if(tmp.begin(),
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tmp.end(),
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last_true,
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not1(predicate),
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queue);
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// return iterator pointing to the last true value
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return last_true;
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}
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} // end compute namespace
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} // end boost namespace
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#endif // BOOST_COMPUTE_ALGORITHM_STABLE_PARTITION_HPP
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