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+/*
+ Copyright (c) Marshall Clow 2011-2012.
+
+ 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)
+*/
+
+/// \file partition_point.hpp
+/// \brief Find the partition point in a sequence
+/// \author Marshall Clow
+
+#ifndef BOOST_ALGORITHM_PARTITION_POINT_HPP
+#define BOOST_ALGORITHM_PARTITION_POINT_HPP
+
+#include <algorithm> // for std::partition_point, if available
+
+#include <boost/range/begin.hpp>
+#include <boost/range/end.hpp>
+
+namespace boost { namespace algorithm {
+
+#if __cplusplus >= 201103L
+// Use the C++11 versions of partition_point if it is available
+using std::partition_point; // Section 25.3.13
+#else
+/// \fn partition_point ( ForwardIterator first, ForwardIterator last, Predicate p )
+/// \brief Given a partitioned range, returns the partition point, i.e, the first element
+/// that does not satisfy p
+///
+/// \param first The start of the input sequence
+/// \param last One past the end of the input sequence
+/// \param p The predicate to test the values with
+/// \note This function is part of the C++2011 standard library.
+/// We will use the standard one if it is available,
+/// otherwise we have our own implementation.
+template <typename ForwardIterator, typename Predicate>
+ForwardIterator partition_point ( ForwardIterator first, ForwardIterator last, Predicate p )
+{
+ std::size_t dist = std::distance ( first, last );
+ while ( first != last ) {
+ std::size_t d2 = dist / 2;
+ ForwardIterator ret_val = first;
+ std::advance (ret_val, d2);
+ if (p (*ret_val)) {
+ first = ++ret_val;
+ dist -= d2 + 1;
+ }
+ else {
+ last = ret_val;
+ dist = d2;
+ }
+ }
+ return first;
+}
+#endif
+
+/// \fn partition_point ( Range &r, Predicate p )
+/// \brief Given a partitioned range, returns the partition point
+///
+/// \param r The input range
+/// \param p The predicate to test the values with
+///
+template <typename Range, typename Predicate>
+typename boost::range_iterator<Range> partition_point ( Range &r, Predicate p )
+{
+ return boost::algorithm::partition_point (boost::begin(r), boost::end(r), p);
+}
+
+
+}}
+
+#endif // BOOST_ALGORITHM_PARTITION_POINT_HPP