ceph/src/boost/boost/compute/algorithm/transform_reduce.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_TRANSFORM_REDUCE_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_TRANSFORM_REDUCE_HPP
  13
  14 #include <boost/compute/system.hpp>
  15 #include <boost/compute/algorithm/reduce.hpp>
  16 #include <boost/compute/iterator/transform_iterator.hpp>
  17 #include <boost/compute/iterator/zip_iterator.hpp>
  18 #include <boost/compute/functional/detail/unpack.hpp>
  19 #include <boost/compute/detail/iterator_range_size.hpp>
  20
  21 namespace boost {
  22 namespace compute {
  23
  24 /// Transforms each value in the range [\p first, \p last) with the unary
  25 /// \p transform_function and then reduces each transformed value with
  26 /// \p reduce_function.
  27 ///
  28 /// For example, to calculate the sum of the absolute values of a vector
  29 /// of integers:
  30 ///
  31 /// \snippet test/test_transform_reduce.cpp sum_abs_int
  32 ///
  33 /// Space complexity on GPUs: \Omega(n)<br>
  34 /// Space complexity on CPUs: \Omega(1)
  35 ///
  36 /// \see reduce(), inner_product()
  37 template<class InputIterator,
  38          class OutputIterator,
  39          class UnaryTransformFunction,
  40          class BinaryReduceFunction>
  41 inline void transform_reduce(InputIterator first,
  42                              InputIterator last,
  43                              OutputIterator result,
  44                              UnaryTransformFunction transform_function,
  45                              BinaryReduceFunction reduce_function,
  46                              command_queue &queue = system::default_queue())
  47 {
  48     ::boost::compute::reduce(
  49         ::boost::compute::make_transform_iterator(first, transform_function),
  50         ::boost::compute::make_transform_iterator(last, transform_function),
  51         result,
  52         reduce_function,
  53         queue
  54     );
  55 }
  56
  57 /// \overload
  58 template<class InputIterator1,
  59          class InputIterator2,
  60          class OutputIterator,
  61          class BinaryTransformFunction,
  62          class BinaryReduceFunction>
  63 inline void transform_reduce(InputIterator1 first1,
  64                              InputIterator1 last1,
  65                              InputIterator2 first2,
  66                              OutputIterator result,
  67                              BinaryTransformFunction transform_function,
  68                              BinaryReduceFunction reduce_function,
  69                              command_queue &queue = system::default_queue())
  70 {
  71     typedef typename std::iterator_traits<InputIterator1>::difference_type difference_type;
  72
  73     difference_type n = std::distance(first1, last1);
  74
  75     ::boost::compute::transform_reduce(
  76         ::boost::compute::make_zip_iterator(
  77             boost::make_tuple(first1, first2)
  78         ),
  79         ::boost::compute::make_zip_iterator(
  80             boost::make_tuple(last1, first2 + n)
  81         ),
  82         result,
  83         detail::unpack(transform_function),
  84         reduce_function,
  85         queue
  86     );
  87 }
  88
  89 } // end compute namespace
  90 } // end boost namespace
  91
  92 #endif // BOOST_COMPUTE_ALGORITHM_TRANSFORM_REDUCE_HPP