add boost on mac

macx64/include/boost/compute/algorithm/nth_element.hpp

@@ -0,0 +1,94 @@
+//---------------------------------------------------------------------------//
+// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
+//
+// Distributed under the Boost Software License, Version 1.0
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+//
+// See http://boostorg.github.com/compute for more information.
+//---------------------------------------------------------------------------//
+
+#ifndef BOOST_COMPUTE_ALGORITHM_NTH_ELEMENT_HPP
+#define BOOST_COMPUTE_ALGORITHM_NTH_ELEMENT_HPP
+
+#include <boost/static_assert.hpp>
+
+#include <boost/compute/command_queue.hpp>
+#include <boost/compute/algorithm/fill_n.hpp>
+#include <boost/compute/algorithm/find.hpp>
+#include <boost/compute/algorithm/partition.hpp>
+#include <boost/compute/algorithm/sort.hpp>
+#include <boost/compute/functional/bind.hpp>
+#include <boost/compute/type_traits/is_device_iterator.hpp>
+
+namespace boost {
+namespace compute {
+
+/// Rearranges the elements in the range [\p first, \p last) such that
+/// the \p nth element would be in that position in a sorted sequence.
+///
+/// Space complexity: \Omega(3n)
+template<class Iterator, class Compare>
+inline void nth_element(Iterator first,
+                        Iterator nth,
+                        Iterator last,
+                        Compare compare,
+                        command_queue &queue = system::default_queue())
+{
+    BOOST_STATIC_ASSERT(is_device_iterator<Iterator>::value);
+    if(nth == last) return;
+
+    typedef typename std::iterator_traits<Iterator>::value_type value_type;
+
+    while(1)
+    {
+        value_type value = nth.read(queue);
+
+        using boost::compute::placeholders::_1;
+        Iterator new_nth = partition(
+            first, last, ::boost::compute::bind(compare, _1, value), queue
+        );
+
+        Iterator old_nth = find(new_nth, last, value, queue);
+
+        value_type new_value = new_nth.read(queue);
+
+        fill_n(new_nth, 1, value, queue);
+        fill_n(old_nth, 1, new_value, queue);
+
+        new_value = nth.read(queue);
+
+        if(value == new_value) break;
+
+        if(std::distance(first, nth) < std::distance(first, new_nth))
+        {
+            last = new_nth;
+        }
+        else
+        {
+            first = new_nth;
+        }
+    }
+}
+
+/// \overload
+template<class Iterator>
+inline void nth_element(Iterator first,
+                        Iterator nth,
+                        Iterator last,
+                        command_queue &queue = system::default_queue())
+{
+    BOOST_STATIC_ASSERT(is_device_iterator<Iterator>::value);
+    if(nth == last) return;
+
+    typedef typename std::iterator_traits<Iterator>::value_type value_type;
+
+    less<value_type> less_than;
+
+    return nth_element(first, nth, last, less_than, queue);
+}
+
+} // end compute namespace
+} // end boost namespace
+
+#endif // BOOST_COMPUTE_ALGORITHM_NTH_ELEMENT_HPP