compute/experimental/sort_by_transform.hpp

0001 //---------------------------------------------------------------------------//
0002 // Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
0003 //
0004 // Distributed under the Boost Software License, Version 1.0
0005 // See accompanying file LICENSE_1_0.txt or copy at
0006 // http://www.boost.org/LICENSE_1_0.txt
0007 //
0008 // See http://boostorg.github.com/compute for more information.
0009 //---------------------------------------------------------------------------//
0010
0011 #ifndef BOOST_COMPUTE_EXPERIMENTAL_SORT_BY_TRANSFORM_HPP
0012 #define BOOST_COMPUTE_EXPERIMENTAL_SORT_BY_TRANSFORM_HPP
0013
0014 #include <iterator>
0015
0016 #include <boost/compute/algorithm/sort_by_key.hpp>
0017 #include <boost/compute/algorithm/transform.hpp>
0018 #include <boost/compute/container/vector.hpp>
0019 #include <boost/compute/detail/iterator_range_size.hpp>
0020 #include <boost/compute/type_traits/result_of.hpp>
0021
0022 namespace boost {
0023 namespace compute {
0024 namespace experimental {
0025
0026 template<class Iterator, class Transform, class Compare>
0027 inline void sort_by_transform(Iterator first,
0028                               Iterator last,
0029                               Transform transform,
0030                               Compare compare,
0031                               command_queue &queue = system::default_queue())
0032 {
0033     typedef typename std::iterator_traits<Iterator>::value_type value_type;
0034     typedef typename boost::compute::result_of<Transform(value_type)>::type key_type;
0035
0036     size_t n = detail::iterator_range_size(first, last);
0037     if(n < 2){
0038         return;
0039     }
0040
0041     const context &context = queue.get_context();
0042
0043     ::boost::compute::vector<key_type> keys(n, context);
0044
0045     ::boost::compute::transform(
0046         first,
0047         last,
0048         keys.begin(),
0049         transform,
0050         queue
0051     );
0052
0053     ::boost::compute::sort_by_key(
0054         keys.begin(),
0055         keys.end(),
0056         first,
0057         compare,
0058         queue
0059     );
0060 }
0061
0062 } // end experimental namespace
0063 } // end compute namespace
0064 } // end boost namespace
0065
0066 #endif // BOOST_COMPUTE_EXPERIMENTAL_SORT_BY_TRANSFORM_HPP