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//---------------------------------------------------------------------------//
// Copyright (c) 2015 Jakub Szuppe <j.szuppe@gmail.com>
//
// Distributed under the Boost Software License, Version 1.0
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt
//
// See http://boostorg.github.com/compute for more information.
//---------------------------------------------------------------------------//
#ifndef BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_REDUCE_BY_KEY_HPP
#define BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_REDUCE_BY_KEY_HPP
#include <iterator>
#include <boost/compute/command_queue.hpp>
#include <boost/compute/functional.hpp>
#include <boost/compute/container/vector.hpp>
#include <boost/compute/container/detail/scalar.hpp>
#include <boost/compute/detail/meta_kernel.hpp>
#include <boost/compute/detail/iterator_range_size.hpp>
#include <boost/compute/type_traits/result_of.hpp>
namespace boost {
namespace compute {
namespace detail {
template<class InputKeyIterator, class InputValueIterator,
class OutputKeyIterator, class OutputValueIterator,
class BinaryFunction, class BinaryPredicate>
inline size_t serial_reduce_by_key(InputKeyIterator keys_first,
InputKeyIterator keys_last,
InputValueIterator values_first,
OutputKeyIterator keys_result,
OutputValueIterator values_result,
BinaryFunction function,
BinaryPredicate predicate,
command_queue &queue)
{
typedef typename
std::iterator_traits<InputValueIterator>::value_type value_type;
typedef typename
std::iterator_traits<InputKeyIterator>::value_type key_type;
typedef typename
::boost::compute::result_of<BinaryFunction(value_type, value_type)>::type result_type;
const context &context = queue.get_context();
size_t count = detail::iterator_range_size(keys_first, keys_last);
if(count < 1){
return count;
}
meta_kernel k("serial_reduce_by_key");
size_t count_arg = k.add_arg<uint_>("count");
size_t result_size_arg = k.add_arg<uint_ *>(memory_object::global_memory,
"result_size");
convert<result_type> to_result_type;
k <<
k.decl<result_type>("result") <<
" = " << to_result_type(values_first[0]) << ";\n" <<
k.decl<key_type>("previous_key") << " = " << keys_first[0] << ";\n" <<
k.decl<result_type>("value") << ";\n" <<
k.decl<key_type>("key") << ";\n" <<
k.decl<uint_>("size") << " = 1;\n" <<
keys_result[0] << " = previous_key;\n" <<
values_result[0] << " = result;\n" <<
"for(ulong i = 1; i < count; i++) {\n" <<
" value = " << to_result_type(values_first[k.var<uint_>("i")]) << ";\n" <<
" key = " << keys_first[k.var<uint_>("i")] << ";\n" <<
" if (" << predicate(k.var<key_type>("previous_key"),
k.var<key_type>("key")) << ") {\n" <<
" result = " << function(k.var<result_type>("result"),
k.var<result_type>("value")) << ";\n" <<
" }\n " <<
" else { \n" <<
keys_result[k.var<uint_>("size - 1")] << " = previous_key;\n" <<
values_result[k.var<uint_>("size - 1")] << " = result;\n" <<
" result = value;\n" <<
" size++;\n" <<
" } \n" <<
" previous_key = key;\n" <<
"}\n" <<
keys_result[k.var<uint_>("size - 1")] << " = previous_key;\n" <<
values_result[k.var<uint_>("size - 1")] << " = result;\n" <<
"*result_size = size;";
kernel kernel = k.compile(context);
scalar<uint_> result_size(context);
kernel.set_arg(result_size_arg, result_size.get_buffer());
kernel.set_arg(count_arg, static_cast<uint_>(count));
queue.enqueue_task(kernel);
return static_cast<size_t>(result_size.read(queue));
}
} // end detail namespace
} // end compute namespace
} // end boost namespace
#endif // BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_REDUCE_BY_KEY_HPP
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