ceph/src/boost/libs/compute/include/boost/compute/experimental/sort_by_transform.hpp

   1 //---------------------------------------------------------------------------//
   2 // Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@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_EXPERIMENTAL_SORT_BY_TRANSFORM_HPP
  12 #define BOOST_COMPUTE_EXPERIMENTAL_SORT_BY_TRANSFORM_HPP
  13
  14 #include <iterator>
  15
  16 #include <boost/compute/algorithm/sort_by_key.hpp>
  17 #include <boost/compute/algorithm/transform.hpp>
  18 #include <boost/compute/container/vector.hpp>
  19 #include <boost/compute/detail/iterator_range_size.hpp>
  20 #include <boost/compute/type_traits/result_of.hpp>
  21
  22 namespace boost {
  23 namespace compute {
  24 namespace experimental {
  25
  26 template<class Iterator, class Transform, class Compare>
  27 inline void sort_by_transform(Iterator first,
  28                               Iterator last,
  29                               Transform transform,
  30                               Compare compare,
  31                               command_queue &queue = system::default_queue())
  32 {
  33     typedef typename std::iterator_traits<Iterator>::value_type value_type;
  34     typedef typename boost::compute::result_of<Transform(value_type)>::type key_type;
  35
  36     size_t n = detail::iterator_range_size(first, last);
  37     if(n < 2){
  38         return;
  39     }
  40
  41     const context &context = queue.get_context();
  42
  43     ::boost::compute::vector<key_type> keys(n, context);
  44
  45     ::boost::compute::transform(
  46         first,
  47         last,
  48         keys.begin(),
  49         transform,
  50         queue
  51     );
  52
  53     ::boost::compute::sort_by_key(
  54         keys.begin(),
  55         keys.end(),
  56         first,
  57         compare,
  58         queue
  59     );
  60 }
  61
  62 } // end experimental namespace
  63 } // end compute namespace
  64 } // end boost namespace
  65
  66 #endif // BOOST_COMPUTE_EXPERIMENTAL_SORT_BY_TRANSFORM_HPP