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diff --git a/boost/geometry/algorithms/detail/overlay/append_no_dups_or_spikes.hpp b/boost/geometry/algorithms/detail/overlay/append_no_dups_or_spikes.hpp
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+++ b/boost/geometry/algorithms/detail/overlay/append_no_dups_or_spikes.hpp
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+// Boost.Geometry (aka GGL, Generic Geometry Library)
+
+// Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
+
+// This file was modified by Oracle on 2014.
+// Modifications copyright (c) 2014 Oracle and/or its affiliates.
+
+// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
+
+// Use, modification and distribution is subject to 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)
+
+#ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_APPEND_NO_DUPS_OR_SPIKES_HPP
+#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_APPEND_NO_DUPS_OR_SPIKES_HPP
+
+#include <boost/range.hpp>
+
+#include <boost/geometry/algorithms/append.hpp>
+#include <boost/geometry/algorithms/detail/point_is_spike_or_equal.hpp>
+#include <boost/geometry/algorithms/detail/equals/point_point.hpp>
+
+#include <boost/geometry/util/range.hpp>
+
+
+namespace boost { namespace geometry
+{
+
+
+#ifndef DOXYGEN_NO_DETAIL
+namespace detail { namespace overlay
+{
+
+// TODO: move this / rename this
+template <typename Point1, typename Point2, typename RobustPolicy>
+inline bool points_equal_or_close(Point1 const& point1,
+        Point2 const& point2,
+        RobustPolicy const& robust_policy)
+{
+    if (detail::equals::equals_point_point(point1, point2))
+    {
+        return true;
+    }
+
+    if (! RobustPolicy::enabled)
+    {
+        return false;
+    }
+
+    // Try using specified robust policy
+    typedef typename geometry::robust_point_type
+    <
+        Point1,
+        RobustPolicy
+    >::type robust_point_type;
+
+    robust_point_type point1_rob, point2_rob;
+    geometry::recalculate(point1_rob, point1, robust_policy);
+    geometry::recalculate(point2_rob, point2, robust_policy);
+
+    return detail::equals::equals_point_point(point1_rob, point2_rob);
+}
+
+
+template <typename Range, typename Point, typename RobustPolicy>
+inline void append_no_dups_or_spikes(Range& range, Point const& point,
+        RobustPolicy const& robust_policy)
+{
+#ifdef BOOST_GEOMETRY_DEBUG_INTERSECTION
+    std::cout << "  add: ("
+        << geometry::get<0>(point) << ", " << geometry::get<1>(point) << ")"
+        << std::endl;
+#endif
+    // The code below thies condition checks all spikes/dups
+    // for geometries >= 3 points.
+    // So we have to check the first potential duplicate differently
+    if (boost::size(range) == 1
+        && points_equal_or_close(*(boost::begin(range)), point, robust_policy))
+    {
+        return;
+    }
+
+    traits::push_back<Range>::apply(range, point);
+
+    // If a point is equal, or forming a spike, remove the pen-ultimate point
+    // because this one caused the spike.
+    // If so, the now-new-pen-ultimate point can again cause a spike
+    // (possibly at a corner). So keep doing this.
+    // Besides spikes it will also avoid adding duplicates.
+    while(boost::size(range) >= 3
+            && point_is_spike_or_equal(point,
+                *(boost::end(range) - 3),
+                *(boost::end(range) - 2),
+                robust_policy))
+    {
+        // Use the Concept/traits, so resize and append again
+        traits::resize<Range>::apply(range, boost::size(range) - 2);
+        traits::push_back<Range>::apply(range, point);
+    }
+}
+
+template <typename Range, typename RobustPolicy>
+inline void clean_closing_dups_and_spikes(Range& range,
+                RobustPolicy const& robust_policy)
+{
+    std::size_t const minsize
+        = core_detail::closure::minimum_ring_size
+            <
+                geometry::closure<Range>::value
+            >::value;
+
+    if (boost::size(range) <= minsize)
+    {
+        return;
+    }
+
+    typedef typename boost::range_iterator<Range>::type iterator_type;
+    static bool const closed = geometry::closure<Range>::value == geometry::closed;
+
+// TODO: the following algorithm could be rewritten to first look for spikes
+// and then erase some number of points from the beginning of the Range
+
+    bool found = false;
+    do
+    {
+        found = false;
+        iterator_type first = boost::begin(range);
+        iterator_type second = first + 1;
+        iterator_type ultimate = boost::end(range) - 1;
+        if (closed)
+        {
+            ultimate--;
+        }
+
+        // Check if closing point is a spike (this is so if the second point is
+        // considered as a spike w.r.t. the last segment)
+        if (point_is_spike_or_equal(*second, *ultimate, *first, robust_policy))
+        {
+            range::erase(range, first);
+            if (closed)
+            {
+                // Remove closing last point
+                range::resize(range, boost::size(range) - 1);
+                // Add new closing point
+                range::push_back(range, range::front(range));
+            }
+            found = true;
+        }
+    } while(found && boost::size(range) > minsize);
+}
+
+
+}} // namespace detail::overlay
+#endif // DOXYGEN_NO_DETAIL
+
+
+}} // namespace boost::geometry
+
+
+#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_APPEND_NO_DUPS_OR_SPIKES_HPP