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