ceph/src/boost/boost/compute/algorithm/inplace_merge.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_ALGORITHM_INPLACE_MERGE_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_INPLACE_MERGE_HPP
  13
  14 #include <iterator>
  15
  16 #include <boost/static_assert.hpp>
  17
  18 #include <boost/compute/system.hpp>
  19 #include <boost/compute/command_queue.hpp>
  20 #include <boost/compute/algorithm/merge.hpp>
  21 #include <boost/compute/container/vector.hpp>
  22 #include <boost/compute/type_traits/is_device_iterator.hpp>
  23
  24 namespace boost {
  25 namespace compute {
  26
  27 /// Merges the sorted values in the range [\p first, \p middle) with
  28 /// the sorted values in the range [\p middle, \p last) in-place.
  29 ///
  30 /// Space complexity: \Omega(n)
  31 template<class Iterator>
  32 inline void inplace_merge(Iterator first,
  33                           Iterator middle,
  34                           Iterator last,
  35                           command_queue &queue = system::default_queue())
  36 {
  37     BOOST_STATIC_ASSERT(is_device_iterator<Iterator>::value);
  38     BOOST_ASSERT(first < middle && middle < last);
  39
  40     typedef typename std::iterator_traits<Iterator>::value_type T;
  41
  42     const context &context = queue.get_context();
  43
  44     ptrdiff_t left_size = std::distance(first, middle);
  45     ptrdiff_t right_size = std::distance(middle, last);
  46
  47     vector<T> left(left_size, context);
  48     vector<T> right(right_size, context);
  49
  50     copy(first, middle, left.begin(), queue);
  51     copy(middle, last, right.begin(), queue);
  52
  53     ::boost::compute::merge(
  54         left.begin(),
  55         left.end(),
  56         right.begin(),
  57         right.end(),
  58         first,
  59         queue
  60     );
  61 }
  62
  63 } // end compute namespace
  64 } // end boost namespace
  65
  66 #endif // BOOST_COMPUTE_ALGORITHM_INPLACE_MERGE_HPP