ceph/src/boost/boost/compute/algorithm/rotate.hpp

   1 //---------------------------------------------------------------------------//
   2 // Copyright (c) 2014 Roshan <thisisroshansmail@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_ROTATE_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_ROTATE_HPP
  13
  14 #include <boost/compute/system.hpp>
  15 #include <boost/compute/algorithm/copy.hpp>
  16 #include <boost/compute/container/vector.hpp>
  17
  18 namespace boost {
  19 namespace compute {
  20
  21 /// Performs left rotation such that element at \p n_first comes to the
  22 /// beginning.
  23 ///
  24 /// Space complexity: \Omega(distance(\p first, \p last))
  25 ///
  26 /// \see rotate_copy()
  27 template<class InputIterator>
  28 inline void rotate(InputIterator first,
  29                    InputIterator n_first,
  30                    InputIterator last,
  31                    command_queue &queue = system::default_queue())
  32 {
  33     //Handle trivial cases
  34     if (n_first==first || n_first==last)
  35     {
  36         return;
  37     }
  38
  39     //Handle others
  40     typedef typename std::iterator_traits<InputIterator>::value_type T;
  41
  42     size_t count = detail::iterator_range_size(first, n_first);
  43     size_t count2 = detail::iterator_range_size(first, last);
  44
  45     const context &context = queue.get_context();
  46     vector<T> temp(count2, context);
  47     ::boost::compute::copy(first, last, temp.begin(), queue);
  48
  49     ::boost::compute::copy(temp.begin()+count, temp.end(), first, queue);
  50     ::boost::compute::copy(temp.begin(), temp.begin()+count, last-count, queue);
  51 }
  52
  53 } //end compute namespace
  54 } //end boost namespace
  55
  56 #endif // BOOST_COMPUTE_ALGORITHM_ROTATE_HPP