ceph/src/boost/boost/compute/algorithm/max_element.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_MAX_ELEMENT_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_MAX_ELEMENT_HPP
  13
  14 #include <boost/compute/system.hpp>
  15 #include <boost/compute/command_queue.hpp>
  16 #include <boost/compute/functional.hpp>
  17 #include <boost/compute/algorithm/detail/find_extrema.hpp>
  18
  19 namespace boost {
  20 namespace compute {
  21
  22 /// Returns an iterator pointing to the element in the range
  23 /// [\p first, \p last) with the maximum value.
  24 ///
  25 /// \param first first element in the input range
  26 /// \param last last element in the input range
  27 /// \param compare comparison function object which returns true if the first
  28 ///        argument is less than (i.e. is ordered before) the second.
  29 /// \param queue command queue to perform the operation
  30 ///
  31 /// For example, to find \c int2 value with maximum first component in given vector:
  32 /// \code
  33 /// // comparison function object
  34 /// BOOST_COMPUTE_FUNCTION(bool, compare_first, (const int2_ &a, const int2_ &b),
  35 /// {
  36 ///     return a.x < b.x;
  37 /// });
  38 ///
  39 /// // create vector
  40 /// boost::compute::vector<uint2_> data = ...
  41 ///
  42 /// boost::compute::vector<uint2_>::iterator max =
  43 ///     boost::compute::max_element(data.begin(), data.end(), compare_first, queue);
  44 /// \endcode
  45 ///
  46 /// Space complexity on CPUs: \Omega(1)<br>
  47 /// Space complexity on GPUs: \Omega(N)
  48 ///
  49 /// \see min_element()
  50 template<class InputIterator, class Compare>
  51 inline InputIterator
  52 max_element(InputIterator first,
  53             InputIterator last,
  54             Compare compare,
  55             command_queue &queue = system::default_queue())
  56 {
  57     return detail::find_extrema(first, last, compare, false, queue);
  58 }
  59
  60 ///\overload
  61 template<class InputIterator>
  62 inline InputIterator
  63 max_element(InputIterator first,
  64             InputIterator last,
  65             command_queue &queue = system::default_queue())
  66 {
  67     typedef typename std::iterator_traits<InputIterator>::value_type value_type;
  68
  69     return ::boost::compute::max_element(
  70         first, last, ::boost::compute::less<value_type>(), queue
  71     );
  72 }
  73
  74 } // end compute namespace
  75 } // end boost namespace
  76
  77 #endif // BOOST_COMPUTE_ALGORITHM_MAX_ELEMENT_HPP