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diff --git a/boost/compute/algorithm/detail/count_if_with_reduce.hpp b/boost/compute/algorithm/detail/count_if_with_reduce.hpp
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+++ b/boost/compute/algorithm/detail/count_if_with_reduce.hpp
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+//---------------------------------------------------------------------------//
+// 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_DETAIL_COUNT_IF_WITH_REDUCE_HPP
+#define BOOST_COMPUTE_ALGORITHM_DETAIL_COUNT_IF_WITH_REDUCE_HPP
+
+#include <boost/compute/algorithm/reduce.hpp>
+#include <boost/compute/iterator/transform_iterator.hpp>
+#include <boost/compute/types/fundamental.hpp>
+
+namespace boost {
+namespace compute {
+namespace detail {
+
+template<class Predicate, class Arg>
+struct invoked_countable_predicate
+{
+    invoked_countable_predicate(Predicate p, Arg a)
+        : predicate(p), arg(a)
+    {
+    }
+
+    Predicate predicate;
+    Arg arg;
+};
+
+template<class Predicate, class Arg>
+inline meta_kernel& operator<<(meta_kernel &kernel,
+                               const invoked_countable_predicate<Predicate, Arg> &expr)
+{
+    return kernel << "(" << expr.predicate(expr.arg) << " ? 1 : 0)";
+}
+
+// the countable_predicate wraps Predicate and converts its result from
+// bool to ulong so that it can be used with reduce()
+template<class Predicate>
+struct countable_predicate
+{
+    typedef ulong_ result_type;
+
+    countable_predicate(Predicate predicate)
+        : m_predicate(predicate)
+    {
+    }
+
+    template<class Arg>
+    invoked_countable_predicate<Predicate, Arg> operator()(const Arg &arg) const
+    {
+        return invoked_countable_predicate<Predicate, Arg>(m_predicate, arg);
+    }
+
+    Predicate m_predicate;
+};
+
+// counts the number of elements matching predicate using reduce()
+template<class InputIterator, class Predicate>
+inline size_t count_if_with_reduce(InputIterator first,
+                                   InputIterator last,
+                                   Predicate predicate,
+                                   command_queue &queue)
+{
+    countable_predicate<Predicate> reduce_predicate(predicate);
+
+    ulong_ count = 0;
+    ::boost::compute::reduce(
+        ::boost::compute::make_transform_iterator(first, reduce_predicate),
+        ::boost::compute::make_transform_iterator(last, reduce_predicate),
+        &count,
+        ::boost::compute::plus<ulong_>(),
+        queue
+    );
+
+    return static_cast<size_t>(count);
+}
+
+} // end detail namespace
+} // end compute namespace
+} // end boost namespace
+
+#endif // BOOST_COMPUTE_ALGORITHM_DETAIL_COUNT_IF_WITH_REDUCE_HPP