From 333cfdccfb14100b259b852271cab9e6175fb457 Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Mon, 28 Apr 2014 10:29:45 +0300
Subject: [PATCH 01/11] [turns] rename less functor from less_seg_dist_other_op
 to less_seg_fraction_other_op (to indicate that the fraction comparison is
 now used)

---
 .../geometry/algorithms/detail/overlay/linear_linear.hpp  | 2 +-
 .../geometry/algorithms/detail/turns/compare_turns.hpp    | 4 ++--
 test/algorithms/test_get_turns_ll_invariance.hpp          | 8 ++++----
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/boost/geometry/algorithms/detail/overlay/linear_linear.hpp b/include/boost/geometry/algorithms/detail/overlay/linear_linear.hpp
index d0a4d56f0..3db50f589 100644
--- a/include/boost/geometry/algorithms/detail/overlay/linear_linear.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/linear_linear.hpp
@@ -201,7 +201,7 @@ protected:
 
         // sort by seg_id, distance, and operation
         std::sort(boost::begin(turns), boost::end(turns),
-                  detail::turns::less_seg_dist_other_op<>());
+                  detail::turns::less_seg_fraction_other_op<>());
 
         // remove duplicate turns
         turns::remove_duplicate_turns
diff --git a/include/boost/geometry/algorithms/detail/turns/compare_turns.hpp b/include/boost/geometry/algorithms/detail/turns/compare_turns.hpp
index f06140b7b..7e21c654e 100644
--- a/include/boost/geometry/algorithms/detail/turns/compare_turns.hpp
+++ b/include/boost/geometry/algorithms/detail/turns/compare_turns.hpp
@@ -27,14 +27,14 @@ namespace detail { namespace turns
 // TURNS SORTING AND SEARCHING
 
 // sort turns by G1 - source_index == 0 by:
-// seg_id -> distance -> other_id -> operation
+// seg_id -> fraction -> other_id -> operation
 template
 <
     typename IdLess = std::less<int>,
     int N = 0, int U = 1, int I = 2, int B = 3, int C = 4, int O = 0,
     std::size_t OpId = 0
 >
-struct less_seg_dist_other_op
+struct less_seg_fraction_other_op
 {
     BOOST_STATIC_ASSERT(OpId < 2);
 
diff --git a/test/algorithms/test_get_turns_ll_invariance.hpp b/test/algorithms/test_get_turns_ll_invariance.hpp
index 460face4e..b0c981e64 100644
--- a/test/algorithms/test_get_turns_ll_invariance.hpp
+++ b/test/algorithms/test_get_turns_ll_invariance.hpp
@@ -122,16 +122,16 @@ public:
         filter_continue_turns::apply(rturns_wo_cont);
 
         std::sort(boost::begin(turns_all), boost::end(turns_all),
-                  bg_turns::less_seg_dist_other_op<>());
+                  bg_turns::less_seg_fraction_other_op<>());
 
         std::sort(boost::begin(turns_wo_cont), boost::end(turns_wo_cont),
-                  bg_turns::less_seg_dist_other_op<>());
+                  bg_turns::less_seg_fraction_other_op<>());
 
         std::sort(boost::begin(rturns_all), boost::end(rturns_all),
-                  bg_turns::less_seg_dist_other_op<std::greater<int> >());
+                  bg_turns::less_seg_fraction_other_op<std::greater<int> >());
 
         std::sort(boost::begin(rturns_wo_cont), boost::end(rturns_wo_cont),
-                  bg_turns::less_seg_dist_other_op<std::greater<int> >());
+                  bg_turns::less_seg_fraction_other_op<std::greater<int> >());
 
         remove_duplicate_turns::apply(turns_all);
         remove_duplicate_turns::apply(turns_wo_cont);

From f25e0c2d7ee9fa5639c9fece27af043842ced50b Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Mon, 28 Apr 2014 12:07:08 +0300
Subject: [PATCH 02/11] [test][set ops] separate tests with multiple points as
 different test cases

---
 .../algorithms/intersection_linear_linear.cpp | 47 ++++++++++++++++++-
 1 file changed, 45 insertions(+), 2 deletions(-)

diff --git a/test/algorithms/intersection_linear_linear.cpp b/test/algorithms/intersection_linear_linear.cpp
index 930cb0f41..5f5b9821b 100644
--- a/test/algorithms/intersection_linear_linear.cpp
+++ b/test/algorithms/intersection_linear_linear.cpp
@@ -667,6 +667,28 @@ BOOST_AUTO_TEST_CASE( test_intersection_linestring_multilinestring )
          from_wkt<ML>("MULTILINESTRING((1 0,18 0,19 0))"),
          "lmli18a"
          );
+}
+
+
+
+
+
+
+#ifndef BOOST_GEOMETRY_TEST_NO_DEGENERATE
+BOOST_AUTO_TEST_CASE( test_intersection_l_ml_degenerate )
+{
+#ifdef GEOMETRY_TEST_DEBUG
+    std::cout << std::endl << std::endl << std::endl;
+    std::cout << "*** LINESTRING / MULTILINESTRING INTERSECTION"
+              << " (DEGENERATE) ***"
+              << std::endl;
+    std::cout << std::endl;
+#endif
+
+    typedef linestring_type L;
+    typedef multi_linestring_type ML;
+
+    typedef test_intersection_of_geometries<L, ML, ML> tester;
 
     // the following test cases concern linestrings with duplicate
     // points and possibly linestrings with zero length.
@@ -719,7 +741,7 @@ BOOST_AUTO_TEST_CASE( test_intersection_linestring_multilinestring )
          "lmli20d"
          );
 }
-
+#endif // BOOST_GEOMETRY_TEST_NO_DEGENERATE
 
 
 
@@ -738,7 +760,7 @@ BOOST_AUTO_TEST_CASE( test_intersection_multilinestring_linestring )
 
     typedef test_intersection_of_geometries<ML, L, ML> tester;
 
-    // the inertsection code automatically reverses the order of the
+    // the intersection code automatically reverses the order of the
     // geometries according to the geometry IDs.
     // all calls below are actually reversed, and internally the
     // intersection of the linestring with the multi-linestring is
@@ -1071,8 +1093,28 @@ BOOST_AUTO_TEST_CASE( test_intersection_multilinestring_multilinestring )
 #endif
          "mlmli18a"
          );
+}
 
 
+
+
+
+
+#ifndef BOOST_GEOMETRY_TEST_NO_DEGENERATE
+BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
+{
+#ifdef GEOMETRY_TEST_DEBUG
+    std::cout << std::endl << std::endl << std::endl;
+    std::cout << "*** MULTILINESTRING / MULTILINESTRING INTERSECTION"
+              << " (DEGENERATE) ***"
+              << std::endl;
+    std::cout << std::endl;
+#endif
+
+    typedef multi_linestring_type ML;
+
+    typedef test_intersection_of_geometries<ML, ML, ML> tester;
+
     // the following test cases concern linestrings with duplicate
     // points and possibly linestrings with zero length.
 
@@ -1165,3 +1207,4 @@ BOOST_AUTO_TEST_CASE( test_intersection_multilinestring_multilinestring )
          "mlmli20e"
          );
 }
+#endif // BOOST_GEOMETRY_TEST_NO_DEGENERATE

From 82ce56765ddd187803144872661bc2565f5b8e1a Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Mon, 28 Apr 2014 12:07:56 +0300
Subject: [PATCH 03/11] [test][set ops] separate test with duplicate points as
 different test cases; add test cases with spikes;

---
 test/algorithms/difference_linear_linear.cpp | 148 +++++++++++++++++++
 1 file changed, 148 insertions(+)

diff --git a/test/algorithms/difference_linear_linear.cpp b/test/algorithms/difference_linear_linear.cpp
index ecbcb438f..4da8e4174 100644
--- a/test/algorithms/difference_linear_linear.cpp
+++ b/test/algorithms/difference_linear_linear.cpp
@@ -616,6 +616,13 @@ BOOST_AUTO_TEST_CASE( test_difference_linestring_multilinestring )
          from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10))"),
          "lmldf19"
          );
+
+    tester::apply
+        (from_wkt<L>("LINESTRING(0 0,10 0)"),
+         from_wkt<ML>("MULTILINESTRING((-1 0,0 0),(10 0,12 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         "lmldf20"
+         );
 }
 
 
@@ -907,6 +914,34 @@ BOOST_AUTO_TEST_CASE( test_difference_multilinestring_multilinestring )
          "mlmldf18a"
          );
 
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((-1 0,0 0),(10 0,12 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         "mlmldf19"
+         );
+}
+
+
+
+
+
+
+#ifndef BOOST_GEOMETRY_TEST_NO_DEGENERATE
+BOOST_AUTO_TEST_CASE( test_difference_ml_ml_degenerate )
+{
+#ifdef GEOMETRY_TEST_DEBUG
+    std::cout << std::endl << std::endl << std::endl;
+    std::cout << "*** MULTILINESTRING / MULTILINESTRING DIFFERENCE" 
+              << " (DEGENERATE) ***"
+              << std::endl;
+    std::cout << std::endl;
+#endif
+
+    typedef multi_linestring_type ML;
+
+    typedef test_difference_of_geometries<ML, ML, ML> tester;
+
     // the following test cases concern linestrings with duplicate
     // points and possibly linestrings with zero length.
 
@@ -975,3 +1010,116 @@ BOOST_AUTO_TEST_CASE( test_difference_multilinestring_multilinestring )
          "mlmldf23"
          );
 }
+#endif // BOOST_GEOMETRY_TEST_NO_DEGENERATE
+
+
+
+
+BOOST_AUTO_TEST_CASE( test_difference_ml_ml_spikes )
+{
+#ifdef GEOMETRY_TEST_DEBUG
+    std::cout << std::endl << std::endl << std::endl;
+    std::cout << "*** MULTILINESTRING / MULTILINESTRING DIFFERENCE" 
+              << " (WITH SPIKES) ***"
+              << std::endl;
+    std::cout << std::endl;
+#endif
+
+    typedef multi_linestring_type ML;
+
+    typedef test_difference_of_geometries<ML, ML, ML> tester;
+
+    // the following test cases concern linestrings with spikes
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10 0))"),
+         "mlmldf-spikes-01"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((9 0,1 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10 0))"),
+         "mlmldf-spikes-02"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0,2 0,8 0,3 0,7 0,4 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10 0))"),
+         "mlmldf-spikes-03"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,3 0,2 0,4 0,3 0,5 0,4 0,6 0,\
+                      5 0,7 0,6 0,8 0,7 0,9 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10 0))"),
+         "mlmldf-spikes-04"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,7 0),\
+                      (9 1,9 0,9 2))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(6 0,7 0),(8 0,10 0))"),
+         "mlmldf-spikes-05"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,7 0),\
+                      (9 0,9 2,9 1))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(6 0,7 0),(8 0,10 0))"),
+         "mlmldf-spikes-05a"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(9 0,6 0,8 0),\
+                      (11 0,8 0,12 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0))"),
+         "mlmldf-spikes-06"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((-1 0,0 0,-2 0),(11 0,10 0,12 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         "mlmldf-spikes-07"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((-1 -1,0 0,-2 -2),(11 1,10 0,12 2))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         "mlmldf-spikes-07a"
+         );
+
+#if 0
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(11 0,10 0,12 0),\
+                      (7 5,7 0,8 0,6.5 0,8.5 0,8.5 5))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(6 0,6.5 0),(8.5 0,10 0))"),
+         "mlmldf-spikes-08"
+         );
+#endif
+
+    // now the first geometry has a spike
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(8 0,10 0,8 0))"),
+         "mlmldf-spikes-10"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0,4 0),(2 0,9 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10 0,9 0))"),
+         "mlmldf-spikes-11"
+         );
+}

From d7c6c3918275e645f04140639ddc2c206bf204ac Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Wed, 30 Apr 2014 12:09:37 +0300
Subject: [PATCH 04/11] [test][difference L/L] add a couple more test cases of
 geometries with spikes

---
 test/algorithms/difference_linear_linear.cpp | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/test/algorithms/difference_linear_linear.cpp b/test/algorithms/difference_linear_linear.cpp
index 4da8e4174..9044b5f88 100644
--- a/test/algorithms/difference_linear_linear.cpp
+++ b/test/algorithms/difference_linear_linear.cpp
@@ -1098,7 +1098,7 @@ BOOST_AUTO_TEST_CASE( test_difference_ml_ml_spikes )
          "mlmldf-spikes-07a"
          );
 
-#if 0
+#if 0 // get_turns has a bug for this one
     tester::apply
         (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
          from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(11 0,10 0,12 0),\
@@ -1122,4 +1122,20 @@ BOOST_AUTO_TEST_CASE( test_difference_ml_ml_spikes )
          from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10 0,9 0))"),
          "mlmldf-spikes-11"
          );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((11 1,10 0,12 2))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         "mlmldf-spikes-12"
+         );
+
+#if 0 // get_turns has a bug for this one
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((11 0,10 0,12 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         "mlmldf-spikes-13"
+         );
+#endif
 }

From a5056728b7e275f68f5b4b75184f149b27b4b398 Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Wed, 30 Apr 2014 12:11:13 +0300
Subject: [PATCH 05/11] [copyright headers] unify the way they look

---
 .../algorithms/detail/overlay/intersection_insert.hpp         | 4 ++--
 include/boost/geometry/algorithms/union.hpp                   | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/boost/geometry/algorithms/detail/overlay/intersection_insert.hpp b/include/boost/geometry/algorithms/detail/overlay/intersection_insert.hpp
index b3d3e80d8..173639e9a 100644
--- a/include/boost/geometry/algorithms/detail/overlay/intersection_insert.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/intersection_insert.hpp
@@ -5,12 +5,12 @@
 // This file was modified by Oracle on 2014.
 // Modifications copyright (c) 2014 Oracle and/or its affiliates.
 
+// Contributed and/or modified by Menelaos Karavelas, 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)
 
-// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
-
 #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_INTERSECTION_INSERT_HPP
 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_INTERSECTION_INSERT_HPP
 
diff --git a/include/boost/geometry/algorithms/union.hpp b/include/boost/geometry/algorithms/union.hpp
index ca9b8ff11..bfd0ab3ba 100644
--- a/include/boost/geometry/algorithms/union.hpp
+++ b/include/boost/geometry/algorithms/union.hpp
@@ -5,12 +5,12 @@
 // This file was modified by Oracle on 2014.
 // Modifications copyright (c) 2014 Oracle and/or its affiliates.
 
+// Contributed and/or modified by Menelaos Karavelas, 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)
 
-// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
-
 #ifndef BOOST_GEOMETRY_ALGORITHMS_UNION_HPP
 #define BOOST_GEOMETRY_ALGORITHMS_UNION_HPP
 

From 65e111866945b8d7a3732f8b491d432143bd5a7c Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Wed, 30 Apr 2014 12:12:27 +0300
Subject: [PATCH 06/11] [algorithms][overlay] allow for spikes in output
 likestrings; this modifies the behavior of existing set ops and allows to
 support linear geometries with spikes; change copy_segments for linestrings
 to take a template parameter to control whether spikes are accepted or not;
 by default they are not accepted (but the follow code now explicitly allows
 for them in places where it wasn't;

---
 .../detail/overlay/copy_segments.hpp          | 54 ++++++++++++++-----
 .../algorithms/detail/overlay/follow.hpp      | 19 ++++---
 .../detail/overlay/follow_linear_linear.hpp   | 11 ++--
 3 files changed, 60 insertions(+), 24 deletions(-)

diff --git a/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp b/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp
index f2306d4d9..626224563 100644
--- a/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp
@@ -1,6 +1,11 @@
 // Boost.Geometry (aka GGL, Generic Geometry Library)
 
-// Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
+// Copyright (c) 2007-2014 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 Menelaos Karavelas, 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
@@ -12,6 +17,7 @@
 
 #include <boost/array.hpp>
 #include <boost/mpl/assert.hpp>
+#include <boost/type_traits.hpp>
 #include <vector>
 
 #include <boost/assert.hpp>
@@ -28,6 +34,7 @@
 #include <boost/geometry/views/closeable_view.hpp>
 #include <boost/geometry/views/reversible_view.hpp>
 
+#include <boost/geometry/algorithms/detail/overlay/append_no_duplicates.hpp>
 #include <boost/geometry/algorithms/detail/overlay/append_no_dups_or_spikes.hpp>
 
 namespace boost { namespace geometry
@@ -39,7 +46,7 @@ namespace detail { namespace copy_segments
 {
 
 
-template<bool Reverse>
+template <bool Reverse>
 struct copy_segments_ring
 {
     template
@@ -102,9 +109,32 @@ struct copy_segments_ring
     }
 };
 
-template<bool Reverse>
-struct copy_segments_linestring
+template <bool Reverse, bool RemoveSpikes = true>
+class copy_segments_linestring
 {
+private:
+    // remove spikes
+    template <typename RangeOut, typename Point, typename RobustPolicy>
+    static inline void append_to_output(RangeOut& current_output,
+                                        Point const& point,
+                                        RobustPolicy const& robust_policy,
+                                        boost::true_type const&)
+    {
+        detail::overlay::append_no_dups_or_spikes(current_output, point,
+                                                  robust_policy);
+    }
+
+    // keep spikes
+    template <typename RangeOut, typename Point, typename RobustPolicy>
+    static inline void append_to_output(RangeOut& current_output,
+                                        Point const& point,
+                                        RobustPolicy const&,
+                                        boost::false_type const&)
+    {
+        detail::overlay::append_no_duplicates(current_output, point);
+    }
+
+public:
     template
     <
         typename LineString,
@@ -133,13 +163,13 @@ struct copy_segments_linestring
 
         for (size_type i = 0; i < count; ++i, ++it)
         {
-            detail::overlay::append_no_dups_or_spikes(current_output, *it,
-                robust_policy);
+            append_to_output(current_output, *it, robust_policy,
+                             boost::integral_constant<bool, RemoveSpikes>());
         }
     }
 };
 
-template<bool Reverse>
+template <bool Reverse>
 struct copy_segments_polygon
 {
     template
@@ -168,7 +198,7 @@ struct copy_segments_polygon
 };
 
 
-template<bool Reverse>
+template <bool Reverse>
 struct copy_segments_box
 {
     template
@@ -224,24 +254,24 @@ struct copy_segments : not_implemented<Tag>
 {};
 
 
-template<bool Reverse>
+template <bool Reverse>
 struct copy_segments<ring_tag, Reverse>
     : detail::copy_segments::copy_segments_ring<Reverse>
 {};
 
 
-template<bool Reverse>
+template <bool Reverse>
 struct copy_segments<linestring_tag, Reverse>
     : detail::copy_segments::copy_segments_linestring<Reverse>
 {};
 
-template<bool Reverse>
+template <bool Reverse>
 struct copy_segments<polygon_tag, Reverse>
     : detail::copy_segments::copy_segments_polygon<Reverse>
 {};
 
 
-template<bool Reverse>
+template <bool Reverse>
 struct copy_segments<box_tag, Reverse>
     : detail::copy_segments::copy_segments_box<Reverse>
 {};
diff --git a/include/boost/geometry/algorithms/detail/overlay/follow.hpp b/include/boost/geometry/algorithms/detail/overlay/follow.hpp
index 38dc05119..ea0263c47 100644
--- a/include/boost/geometry/algorithms/detail/overlay/follow.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/follow.hpp
@@ -5,12 +5,12 @@
 // This file was modified by Oracle on 2014.
 // Modifications copyright (c) 2014 Oracle and/or its affiliates.
 
+// Contributed and/or modified by Menelaos Karavelas, 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)
 
-// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
-
 #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_FOLLOW_HPP
 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_FOLLOW_HPP
 
@@ -193,7 +193,10 @@ struct action_selector<overlay_intersection>
     {
         // On leave, copy all segments from starting point, append the intersection point
         // and add the output piece
-        geometry::copy_segments<false>(linestring, segment_id, index, robust_policy, current_piece);
+        detail::copy_segments::copy_segments_linestring
+            <
+                false, false // do not reverse; do not remove spikes
+            >::apply(linestring, segment_id, index, robust_policy, current_piece);
         detail::overlay::append_no_duplicates(current_piece, point);
         if (::boost::size(current_piece) > 1)
         {
@@ -484,10 +487,12 @@ public :
 
         if (action::is_entered(entered))
         {
-            geometry::copy_segments<false>(linestring, current_segment_id,
-                    boost::size(linestring) - 1,
-                    robust_policy,
-                    current_piece);
+            detail::copy_segments::copy_segments_linestring
+                <
+                    false, false // do not reverse; do not remove spikes
+                >::apply(linestring, current_segment_id,
+                         boost::size(linestring) - 1, robust_policy,
+                         current_piece);
         }
 
         // Output the last one, if applicable
diff --git a/include/boost/geometry/algorithms/detail/overlay/follow_linear_linear.hpp b/include/boost/geometry/algorithms/detail/overlay/follow_linear_linear.hpp
index c009df00d..beb8fa710 100644
--- a/include/boost/geometry/algorithms/detail/overlay/follow_linear_linear.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/follow_linear_linear.hpp
@@ -268,11 +268,12 @@ protected:
             // We don't rescale linear/linear
             detail::no_rescale_policy robust_policy;
 
-            geometry::copy_segments<false>(linestring,
-                                           current_segment_id,
-                                           boost::size(linestring) - 1,
-                                           robust_policy,
-                                           current_piece);
+            detail::copy_segments::copy_segments_linestring
+                <
+                    false, false // do not reverse; do not remove spikes
+                >::apply(linestring, current_segment_id,
+                         boost::size(linestring) - 1, robust_policy,
+                         current_piece);
         }
 
         // Output the last one, if applicable

From 98e6dd3783ebb3b7758335da5ab195788b891bd7 Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Wed, 30 Apr 2014 15:57:51 +0300
Subject: [PATCH 07/11] [overlay] add template parameter to follow and
 action_selector about removing spikes; the default behavior is to remove
 them; this is backward compatible with the code before the changes in
 copy_segments

---
 .../algorithms/detail/overlay/follow.hpp      | 28 +++++++++++--------
 .../detail/overlay/follow_linear_linear.hpp   |  3 +-
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/include/boost/geometry/algorithms/detail/overlay/follow.hpp b/include/boost/geometry/algorithms/detail/overlay/follow.hpp
index ea0263c47..632f79f40 100644
--- a/include/boost/geometry/algorithms/detail/overlay/follow.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/follow.hpp
@@ -140,7 +140,7 @@ static inline bool was_entered(Turn const& turn, Operation const& op, bool first
 
 
 // Template specialization structure to call the right actions for the right type
-template<overlay_type OverlayType>
+template <overlay_type OverlayType, bool RemoveSpikes = true>
 struct action_selector
 {
     // If you get here the overlay type is not intersection or difference
@@ -148,8 +148,8 @@ struct action_selector
 };
 
 // Specialization for intersection, containing the implementation
-template<>
-struct action_selector<overlay_intersection>
+template <bool RemoveSpikes>
+struct action_selector<overlay_intersection, RemoveSpikes>
 {
     template
     <
@@ -195,7 +195,7 @@ struct action_selector<overlay_intersection>
         // and add the output piece
         detail::copy_segments::copy_segments_linestring
             <
-                false, false // do not reverse; do not remove spikes
+                false, RemoveSpikes
             >::apply(linestring, segment_id, index, robust_policy, current_piece);
         detail::overlay::append_no_duplicates(current_piece, point);
         if (::boost::size(current_piece) > 1)
@@ -251,10 +251,10 @@ struct action_selector<overlay_intersection>
 };
 
 // Specialization for difference, which reverses these actions
-template<>
-struct action_selector<overlay_difference>
+template <bool RemoveSpikes>
+struct action_selector<overlay_difference, RemoveSpikes>
 {
-    typedef action_selector<overlay_intersection> normal_action;
+    typedef action_selector<overlay_intersection, RemoveSpikes> normal_action;
 
     template
     <
@@ -346,12 +346,13 @@ template
     typename LineStringOut,
     typename LineString,
     typename Polygon,
-    overlay_type OverlayType
+    overlay_type OverlayType,
+    bool RemoveSpikes = true
 >
 class follow
 {
 
-    template<typename Turn>
+    template <typename Turn>
     struct sort_on_segment
     {
         // In case of turn point at the same location, we want to have continue/blocked LAST
@@ -412,7 +413,10 @@ public :
             Geometry const& geometry,
             RobustPolicy const& robust_policy)
     {
-        return following::action_selector<OverlayType>::included(point, geometry, robust_policy);
+        return following::action_selector
+            <
+                OverlayType, RemoveSpikes
+            >::included(point, geometry, robust_policy);
     }
 
     template
@@ -434,7 +438,7 @@ public :
                 typename turn_type::container_type
             >::type turn_operation_iterator_type;
 
-        typedef following::action_selector<OverlayType> action;
+        typedef following::action_selector<OverlayType, RemoveSpikes> action;
 
         // Sort intersection points on segments-along-linestring, and distance
         // (like in enrich is done for poly/poly)
@@ -489,7 +493,7 @@ public :
         {
             detail::copy_segments::copy_segments_linestring
                 <
-                    false, false // do not reverse; do not remove spikes
+                    false, RemoveSpikes
                 >::apply(linestring, current_segment_id,
                          boost::size(linestring) - 1, robust_policy,
                          current_piece);
diff --git a/include/boost/geometry/algorithms/detail/overlay/follow_linear_linear.hpp b/include/boost/geometry/algorithms/detail/overlay/follow_linear_linear.hpp
index beb8fa710..131154f82 100644
--- a/include/boost/geometry/algorithms/detail/overlay/follow_linear_linear.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/follow_linear_linear.hpp
@@ -173,7 +173,8 @@ template
 class follow_linestring_linear_linestring
 {
 protected:
-    typedef following::action_selector<OverlayType> action;
+    // allow spikes (false indicates: do not remove spikes)
+    typedef following::action_selector<OverlayType, false> action;
 
     template
     <

From 606295db4af1b6b82b6ecf5321be862d45691302 Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Mon, 5 May 2014 12:08:36 +0300
Subject: [PATCH 08/11] [test][set ops L/L] add more test cases for difference
 and intersection of linear geometries; the geometries in these test cases
 have spikes

---
 test/algorithms/difference_linear_linear.cpp  |  83 ++++-
 .../algorithms/intersection_linear_linear.cpp | 313 ++++++++++++++++++
 2 files changed, 392 insertions(+), 4 deletions(-)

diff --git a/test/algorithms/difference_linear_linear.cpp b/test/algorithms/difference_linear_linear.cpp
index 9044b5f88..cbd0d3698 100644
--- a/test/algorithms/difference_linear_linear.cpp
+++ b/test/algorithms/difference_linear_linear.cpp
@@ -401,6 +401,21 @@ BOOST_AUTO_TEST_CASE( test_difference_linestring_linestring )
          from_wkt<ML>("MULTILINESTRING((0 0,1 0),(5 0,10 0))"),
          "lldf23"
          );
+
+    // the following two tests have been discussed with by Adam
+    tester::apply
+        (from_wkt<L>("LINESTRING(1 0,1 1,2 1)"),
+         from_wkt<L>("LINESTRING(2 1,1 1,1 0)"),
+         from_wkt<ML>("MULTILINESTRING()"),
+         "lldf24"
+         );
+
+    tester::apply
+        (from_wkt<L>("LINESTRING(1 0,1 1,2 1)"),
+         from_wkt<L>("LINESTRING(1 2,1 1,1 0)"),
+         from_wkt<ML>("MULTILINESTRING((1 1,2 1))"),
+         "lldf25"
+         );
 }
 
 
@@ -1098,7 +1113,6 @@ BOOST_AUTO_TEST_CASE( test_difference_ml_ml_spikes )
          "mlmldf-spikes-07a"
          );
 
-#if 0 // get_turns has a bug for this one
     tester::apply
         (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
          from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(11 0,10 0,12 0),\
@@ -1106,9 +1120,36 @@ BOOST_AUTO_TEST_CASE( test_difference_ml_ml_spikes )
          from_wkt<ML>("MULTILINESTRING((0 0,1 0),(6 0,6.5 0),(8.5 0,10 0))"),
          "mlmldf-spikes-08"
          );
-#endif
 
     // now the first geometry has a spike
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,7 0,4 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(8 0,10 0))"),
+         "mlmldf-spikes-09"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,7 0,4 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,7 0,4 0,9 0))"),
+         "mlmldf-spikes-09a"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,7 0,4 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,5 0),(9 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((5 0,7 0,5 0),(5 0,9 0))"),
+         "mlmldf-spikes-09b"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,7 0,4 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,5 0),(6 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((5 0,6 0),(6 0,5 0),(5 0,6 0))"),
+         "mlmldf-spikes-09c"
+         );
+
     tester::apply
         (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
          from_wkt<ML>("MULTILINESTRING((1 0,8 0))"),
@@ -1130,12 +1171,46 @@ BOOST_AUTO_TEST_CASE( test_difference_ml_ml_spikes )
          "mlmldf-spikes-12"
          );
 
-#if 0 // get_turns has a bug for this one
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((11 -1,10 0,12 -2))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         "mlmldf-spikes-12a"
+         );
+
     tester::apply
         (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
          from_wkt<ML>("MULTILINESTRING((11 0,10 0,12 0))"),
          from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
          "mlmldf-spikes-13"
          );
-#endif
+
+    // the following three tests have been discussed with Adam
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((1 0,1 1,2 1))"),
+         from_wkt<ML>("MULTILINESTRING((1 2,1 1,1 2))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,1 1,2 1))"),
+         "mlmldf-spikes-14"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,1 0,0 0))"),
+         from_wkt<ML>("MULTILINESTRING((2 0,1 0,2 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0,0 0))"),
+         "mlmldf-spikes-15"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((1 0,1 1,2 1))"),
+         from_wkt<ML>("MULTILINESTRING((2 0,1 1,2 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,1 1,2 1))"),
+         "mlmldf-spikes-16"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((1 0,1 1,2 1))"),
+         from_wkt<ML>("MULTILINESTRING((2 1,1 1,2 1))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,1 1))"),
+         "mlmldf-spikes-17"
+         );
 }
diff --git a/test/algorithms/intersection_linear_linear.cpp b/test/algorithms/intersection_linear_linear.cpp
index 5f5b9821b..f18a1e4b1 100644
--- a/test/algorithms/intersection_linear_linear.cpp
+++ b/test/algorithms/intersection_linear_linear.cpp
@@ -461,6 +461,21 @@ BOOST_AUTO_TEST_CASE( test_intersection_linestring_linestring )
          from_wkt<ML>("MULTILINESTRING((1 0,4 0),(4 0,5 0))"),
          "lli23"
          );
+
+    // the following two tests have been discussed with by Adam
+    tester::apply
+        (from_wkt<L>("LINESTRING(1 0,1 1,2 1)"),
+         from_wkt<L>("LINESTRING(2 1,1 1,1 0)"),
+         from_wkt<ML>("MULTILINESTRING((1 0,1 1,2 1))"),
+         "lli24"
+         );
+
+    tester::apply
+        (from_wkt<L>("LINESTRING(1 0,1 1,2 1)"),
+         from_wkt<L>("LINESTRING(1 2,1 1,1 0)"),
+         from_wkt<ML>("MULTILINESTRING((1 0,1 1))"),
+         "lli25"
+         );
 }
 
 
@@ -700,8 +715,12 @@ BOOST_AUTO_TEST_CASE( test_intersection_l_ml_degenerate )
                       (1 1,1 1,2 2,2 2),(1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0),(0 0,0 0,0 10,0 10),\
                       (4 0,4 10,4 10))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,20 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((0 0),(1 0),(2 0),(3 0),(4 0),\
                       (5 0,18 0,19 0,20 0))"),
+#endif
          "lmli20a"
          );
 
@@ -712,8 +731,12 @@ BOOST_AUTO_TEST_CASE( test_intersection_l_ml_degenerate )
                       (1 1,1 1,2 2,2 2),(1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0),(0 0,0 0,0 10,0 10),\
                       (4 0,4 0,4 10,4 10))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,20 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((0 0),(1 0),(2 0),(3 0),(4 0),\
                       (5 0,18 0,19 0,20 0))"),
+#endif
          "lmli20b"
          );
 
@@ -724,8 +747,12 @@ BOOST_AUTO_TEST_CASE( test_intersection_l_ml_degenerate )
                       (1 1,1 1,2 2,2 2),(1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0),(0 0,0 0,0 10,0 10),\
                       (30 0,30 0,30 0))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,20 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((0 0),(1 0),(2 0),(3 0),\
                       (5 0,18 0,19 0,20 0),(30 0))"),
+#endif
          "lmli20c"
          );
 
@@ -736,8 +763,12 @@ BOOST_AUTO_TEST_CASE( test_intersection_l_ml_degenerate )
                       (1 1,1 1,2 2,2 2),(1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0),(0 0,0 0,0 10,0 10),\
                       (30 0,30 0,31 0))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,20 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((0 0),(1 0),(2 0),(3 0),\
                       (5 0,18 0,19 0,20 0),(30 0))"),
+#endif
          "lmli20d"
          );
 }
@@ -1126,10 +1157,15 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
                       (1 1,2 2),(1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0),(0 0,0 10),\
                       (4 0,4 10),(5 5,5 5))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,20 0))"),
+         from_wkt<ML>("MULTILINESTRING((5 0,20 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((5 5),(0 0),(1 0),(2 0),(3 0),\
                       (4 0),(5 0,18 0,19 0,20 0),(2 0),(4 10))"),
          from_wkt<ML>("MULTILINESTRING((5 0,20 0),(1 0),(2 0),(2 0),(3 0),\
                       (0 0),(4 0),(4 10),(5 5))"),
+#endif
          "mlmli20a"
          );
 
@@ -1141,10 +1177,15 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
                       (1 1,1 1,2 2,2 2),(1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0,3 0),(0 0,0 0,0 10,0 10),\
                       (4 0,4 10,4 10),(5 5,5 5))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,20 0))"),
+         from_wkt<ML>("MULTILINESTRING((5 0,20 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((5 5),(0 0),(1 0),(2 0),(3 0),(4 0),\
                       (5 0,18 0,19 0,20 0),(2 0),(4 10))"),
          from_wkt<ML>("MULTILINESTRING((5 0,20 0),(1 0),(2 0),(2 0),\
                       (3 0),(0 0),(4 0),(4 10),(5 5))"),
+#endif
          "mlmli20aa"
          );
 
@@ -1156,10 +1197,15 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
                       (1 1,1 1,2 2,2 2),(1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0),(0 0,0 0,0 10,0 10),\
                       (4 0,4 0,4 10,4 10),(0 5,15 5))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,20 0))"),
+         from_wkt<ML>("MULTILINESTRING((5 0,20 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((5 5),(0 0),(1 0),(2 0),(3 0),(4 0),\
                       (5 0,18 0,19 0,20 0))"),
          from_wkt<ML>("MULTILINESTRING((5 0,20 0),(1 0),(2 0),(3 0),\
                       (0 0),(4 0),(5 5))"),
+#endif
          "mlmli20b"
          );
 
@@ -1171,10 +1217,15 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
                       (1 1,1 1,2 2,2 2),(1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0),(0 0,0 0,0 10,0 10),\
                       (30 0,30 0,30 0))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,20 0))"),
+         from_wkt<ML>("MULTILINESTRING((5 0,20 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((0 0),(1 0),(2 0),(3 0),\
                       (5 0,18 0,19 0,20 0),(30 0))"),
          from_wkt<ML>("MULTILINESTRING((5 0,20 0),(1 0),(2 0),(3 0),\
                       (0 0),(30 0))"),
+#endif
          "mlmli20c"
          );
 
@@ -1186,10 +1237,15 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
                       (1 1,1 1,2 2,2 2),(1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0),(0 0,0 0,0 10,0 10),\
                       (30 0,30 0,31 0))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,20 0))"),
+         from_wkt<ML>("MULTILINESTRING((5 0,20 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((0 0),(1 0),(2 0),(3 0),\
                       (5 0,18 0,19 0,20 0),(30 0))"),
          from_wkt<ML>("MULTILINESTRING((5 0,20 0),(1 0),(2 0),(3 0),\
                       (0 0),(30 0))"),
+#endif
          "mlmli20d"
          );
 
@@ -1200,11 +1256,268 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_degenerate )
                       (1 10,1 10,1 0,1 0,1 -10),\
                       (2 0,2 0),(3 0,3 0,3 0),(0 0,0 0,0 10,0 10),\
                       (30 0,30 0,31 0,31 0))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((5 0,18 0,19 0,30 0))"),
+         from_wkt<ML>("MULTILINESTRING((5 0,20 0,30 0))"),
+#else
          from_wkt<ML>("MULTILINESTRING((0 0),(1 0),(2 0),(3 0),\
                       (5 0,18 0,19 0,30 0),(30 0))"),
          from_wkt<ML>("MULTILINESTRING((5 0,20 0,30 0),(1 0),(2 0),(3 0),\
                       (0 0),(30 0))"),
+#endif
          "mlmli20e"
          );
 }
 #endif // BOOST_GEOMETRY_TEST_NO_DEGENERATE
+
+
+
+
+BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_spikes )
+{
+#ifdef GEOMETRY_TEST_DEBUG
+    std::cout << std::endl << std::endl << std::endl;
+    std::cout << "*** MULTILINESTRING / MULTILINESTRING INTERSECTION" 
+              << " (WITH SPIKES) ***"
+              << std::endl;
+    std::cout << std::endl;
+#endif
+
+    typedef multi_linestring_type ML;
+
+    typedef test_intersection_of_geometries<ML, ML, ML> tester;
+
+    // the following test cases concern linestrings with spikes
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0,5 0))"),
+         "mlmli-spikes-01"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((9 0,1 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0))"),
+         from_wkt<ML>("MULTILINESTRING((9 0,1 0,5 0))"),
+         "mlmli-spikes-02"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0,2 0,8 0,3 0,7 0,4 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0,2 0,8 0,3 0,7 0,4 0,5 0))"),
+         "mlmli-spikes-03"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,3 0,2 0,4 0,3 0,5 0,4 0,6 0,\
+                      5 0,7 0,6 0,8 0,7 0,9 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,3 0,2 0,4 0,3 0,5 0,4 0,6 0,\
+                      5 0,7 0,6 0,8 0,7 0,9 0))"),
+         "mlmli-spikes-04"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,7 0),\
+                      (9 1,9 0,9 2))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0),(7 0,8 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,7 0))"),
+#else
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0),(7 0,8 0),(9 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,7 0),(9 0))"),
+#endif
+         "mlmli-spikes-05"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,7 0),\
+                      (9 0,9 2,9 1))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0),(7 0,8 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,7 0))"),
+#else
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0),(7 0,8 0),(9 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,7 0),(9 0))"),
+#endif
+         "mlmli-spikes-05a"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(9 0,6 0,8 0),\
+                      (11 0,8 0,12 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0),(6 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(9 0,6 0,8 0),\
+                      (10 0,8 0,10 0))"),
+         "mlmli-spikes-06"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((-1 0,0 0,-2 0),(11 0,10 0,12 0))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING()"),
+#else
+         from_wkt<ML>("MULTILINESTRING((0 0),(10 0))"),
+#endif
+         "mlmli-spikes-07"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((-1 -1,0 0,-2 -2),(11 1,10 0,12 2))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING()"),
+#else
+         from_wkt<ML>("MULTILINESTRING((0 0),(10 0))"),
+#endif
+         "mlmli-spikes-07a"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(11 0,10 0,12 0),\
+                      (7 5,7 0,8 0,6.5 0,8.5 0,8.5 5))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0),(6.5 0,8.5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,6.5 0,8.5 0))"),
+#else
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0),(6.5 0,8.5 0),(10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,6 0,5 0),(7 0,8 0,6.5 0,8.5 0),(10 0))"),
+#endif
+         "mlmli-spikes-08"
+         );
+
+    // now the first geometry has a spike
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,7 0,4 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,7 0,4 0,8 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0))"),
+         "mlmli-spikes-09"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,7 0,4 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 0),(9 0,10 0))"),
+         "mlmli-spikes-09a"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,7 0,4 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,5 0),(9 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,5 0),(5 0,4 0,5 0),(9 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,5 0),(9 0,10 0))"),
+         "mlmli-spikes-09b"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,7 0,4 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,5 0),(6 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,5 0),(6 0,7 0,6 0),(5 0,4 0,5 0),\
+                      (6 0,10 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,5 0),(6 0,10 0))"),
+         "mlmli-spikes-09c"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0),(8 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0))"),
+         "mlmli-spikes-10"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0,4 0),(2 0,9 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,9 0),(9 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 0,8 0,4 0),(2 0,9 0,5 0))"),
+         "mlmli-spikes-11"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((11 1,10 0,12 2))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING()"),
+#else
+         from_wkt<ML>("MULTILINESTRING((10 0))"),
+#endif
+         "mlmli-spikes-12"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((11 -1,10 0,12 -2))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING()"),
+#else
+         from_wkt<ML>("MULTILINESTRING((10 0))"),
+#endif
+         "mlmli-spikes-12a"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,10 0,5 0))"),
+         from_wkt<ML>("MULTILINESTRING((11 0,10 0,12 0))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING()"),
+#else
+         from_wkt<ML>("MULTILINESTRING((10 0))"),
+#endif
+         "mlmli-spikes-13"
+         );
+
+    // the following three tests have been discussed with Adam
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((1 0,1 1,2 1))"),
+         from_wkt<ML>("MULTILINESTRING((1 2,1 1,1 2))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING()"),
+#else
+         from_wkt<ML>("MULTILINESTRING((1 1))"),
+#endif
+         "mlmli-spikes-14"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,1 0,0 0))"),
+         from_wkt<ML>("MULTILINESTRING((2 0,1 0,2 0))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING()"),
+#else
+         from_wkt<ML>("MULTILINESTRING((1 0))"),
+#endif
+         "mlmli-spikes-15"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((1 0,1 1,2 1))"),
+         from_wkt<ML>("MULTILINESTRING((2 0,1 1,2 0))"),
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+         from_wkt<ML>("MULTILINESTRING()"),
+#else
+         from_wkt<ML>("MULTILINESTRING((1 1))"),
+#endif
+         "mlmli-spikes-16"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((1 0,1 1,2 1))"),
+         from_wkt<ML>("MULTILINESTRING((2 1,1 1,2 1))"),
+         from_wkt<ML>("MULTILINESTRING((1 1,2 1))"),
+         from_wkt<ML>("MULTILINESTRING((2 1,1 1,2 1))"),
+         "mlmli-spikes-17"
+         );
+}

From 826045c3a11ef087f8821b5e0c070320b848376f Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Mon, 5 May 2014 12:10:20 +0300
Subject: [PATCH 09/11] [set ops L/L] remove commented code in assign_policy;
 add template parameter to control the behavior of intersection wrt whether
 isolated points are followed or not;

---
 .../detail/overlay/linear_linear.hpp          | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/include/boost/geometry/algorithms/detail/overlay/linear_linear.hpp b/include/boost/geometry/algorithms/detail/overlay/linear_linear.hpp
index 3db50f589..db9e91fb6 100644
--- a/include/boost/geometry/algorithms/detail/overlay/linear_linear.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/linear_linear.hpp
@@ -125,7 +125,12 @@ template
     overlay_type OverlayType,
     bool EnableFilterContinueTurns = false,
     bool EnableRemoveDuplicateTurns = false,
-    bool EnableDegenerateTurns = true
+    bool EnableDegenerateTurns = true,
+#ifdef BOOST_GEOMETRY_INTERSECTION_DO_NOT_INCLUDE_ISOLATED_POINTS
+    bool EnableFollowIsolatedPoints = false
+#else
+    bool EnableFollowIsolatedPoints = true
+#endif
 >
 class linear_linear_linestring
 {
@@ -147,7 +152,6 @@ protected:
         static inline void apply(Info& , Point1 const& , Point2 const& ,
                                  IntersectionInfo const& , DirInfo const& )
         {
-            //calculate_distance_policy::apply(info, p1, p2, ii, di);
         }
     };
 
@@ -256,7 +260,9 @@ public:
 
         return sort_and_follow_turns
             <
-                OverlayType, OverlayType == overlay_intersection
+                OverlayType,
+                EnableFollowIsolatedPoints
+                && OverlayType == overlay_intersection
             >(turns, linear1, linear2, oit);
     }
 };
@@ -271,13 +277,14 @@ template
     typename LinestringOut,
     bool EnableFilterContinueTurns,
     bool EnableRemoveDuplicateTurns,
-    bool EnableDegenerateTurns
+    bool EnableDegenerateTurns,
+    bool EnableFollowIsolatedPoints
 >
 struct linear_linear_linestring
     <
         Linear1, Linear2, LinestringOut, overlay_union,
         EnableFilterContinueTurns, EnableRemoveDuplicateTurns,
-        EnableDegenerateTurns
+        EnableDegenerateTurns, EnableFollowIsolatedPoints
     >
 {
     template
@@ -302,7 +309,7 @@ struct linear_linear_linestring
             <
                 Linear2, Linear1, LinestringOut, overlay_difference,
                 EnableFilterContinueTurns, EnableRemoveDuplicateTurns,
-                EnableDegenerateTurns
+                EnableDegenerateTurns, EnableFollowIsolatedPoints
             >::apply(linear2, linear1, robust_policy, oit, strategy);
     }
 };

From 321d12c56ac37c0c70a546cec9d64855b23a9ca3 Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Mon, 5 May 2014 14:45:26 +0300
Subject: [PATCH 10/11] [test][set ops L/L] add two more test cases with spikes
 (examples sent by Adam on the BG mailing list)

---
 test/algorithms/difference_linear_linear.cpp   | 15 +++++++++++++++
 test/algorithms/intersection_linear_linear.cpp | 16 ++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/test/algorithms/difference_linear_linear.cpp b/test/algorithms/difference_linear_linear.cpp
index cbd0d3698..f46bcddf3 100644
--- a/test/algorithms/difference_linear_linear.cpp
+++ b/test/algorithms/difference_linear_linear.cpp
@@ -1213,4 +1213,19 @@ BOOST_AUTO_TEST_CASE( test_difference_ml_ml_spikes )
          from_wkt<ML>("MULTILINESTRING((1 0,1 1))"),
          "mlmldf-spikes-17"
          );
+
+    // test cases sent by Adam on the mailing list (equal slikes)
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,1 1,0 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 1,0 0))"),
+         from_wkt<ML>("MULTILINESTRING()"),
+         "mlmldf-spikes-18"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,1 1,0 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 1,0 0,1 1))"),
+         from_wkt<ML>("MULTILINESTRING()"),
+         "mlmldf-spikes-19"
+         );
 }
diff --git a/test/algorithms/intersection_linear_linear.cpp b/test/algorithms/intersection_linear_linear.cpp
index f18a1e4b1..33891571d 100644
--- a/test/algorithms/intersection_linear_linear.cpp
+++ b/test/algorithms/intersection_linear_linear.cpp
@@ -1520,4 +1520,20 @@ BOOST_AUTO_TEST_CASE( test_intersection_ml_ml_spikes )
          from_wkt<ML>("MULTILINESTRING((2 1,1 1,2 1))"),
          "mlmli-spikes-17"
          );
+
+    // test cases sent by Adam on the mailing list (equal slikes)
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,1 1,0 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 1,0 0))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 1,0 0))"),
+         "mlmli-spikes-18"
+         );
+
+    tester::apply
+        (from_wkt<ML>("MULTILINESTRING((0 0,1 1,0 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 1,0 0,1 1))"),
+         from_wkt<ML>("MULTILINESTRING((0 0,1 1,0 0))"),
+         from_wkt<ML>("MULTILINESTRING((1 1,0 0,1 1))"),
+         "mlmli-spikes-19"
+         );
 }

From 793a6321c6f22c751d5fa89b0402da1f5abda104 Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Tue, 6 May 2014 21:51:15 +0300
Subject: [PATCH 11/11] [copy segments] replace generic #include of type traits
 by the specific one used (integral_constant)

---
 .../boost/geometry/algorithms/detail/overlay/copy_segments.hpp  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp b/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp
index 626224563..05b348a6d 100644
--- a/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp
@@ -17,7 +17,7 @@
 
 #include <boost/array.hpp>
 #include <boost/mpl/assert.hpp>
-#include <boost/type_traits.hpp>
+#include <boost/type_traits/integral_constant.hpp>
 #include <vector>
 
 #include <boost/assert.hpp>