moved code to separate files;

added template parameter for enabling/disabling functionality wrt filtering turns, removing turns, and the parameters of the assign policy;

include/boost/geometry/algorithms/detail/overlay/linear_linear.hpp

@@ -20,7 +20,14 @@
 #include <boost/geometry/algorithms/detail/turns/print_turns.hpp>
 #include <boost/geometry/algorithms/detail/overlay/follow_linear_linear.hpp>
 
-#include <boost/geometry/multi/geometries/multi_linestring.hpp>
+#ifndef BOOST_GEOMETRY_DIFFERENCE_DO_NOT_FILTER_CONTINUE_TURNS
+#include <boost/geometry/algorithms/detail/turns/filter_continue_turns.hpp>
+#endif
+
+#ifndef BOOST_GEOMETRY_DIFFERENCE_DO_NOT_REMOVE_DUPLICATE_TURNS
+#include <boost/geometry/algorithms/detail/turns/remove_duplicate_turns.hpp>
+#endif
+
 
 namespace boost { namespace geometry
 {
@@ -118,7 +125,10 @@ template
     typename Linear1,
     typename Linear2,
     typename LinestringOut,
-    overlay_type OverlayType
+    overlay_type OverlayType,
+    bool EnableFilterContinueTurns = true,
+    bool EnableRemoveDuplicateTurns = true,
+    bool EnableDegenerateTurns = true
 >
 class linear_linear_linestring
 {
@@ -126,7 +136,11 @@ protected:
     struct AssignPolicy
     {
         static bool const include_no_turn = false;
-        static bool const include_degenerate = false;
+#ifdef BOOST_GEOMETRY_DIFFERENCE_INCLUDE_DEGENERATE_TURNS
+        static bool const include_degenerate = true;
+#else
+        static bool const include_degenerate = EnableDegenerateTurns;
+#endif
         static bool const include_opposite = false;
 
         template
@@ -145,68 +159,6 @@ protected:
     };
 
 
-    class IsContinueTurn
-    {
-    private:
-        template <typename Operation>
-        inline bool is_continue_or_opposite(Operation const& operation) const
-        {
-            return operation == operation_continue
-                || operation == operation_opposite;
-        }
-
-    public:
-        template <typename Turn>
-        bool operator()(Turn const& turn) const
-        {
-            if ( turn.method != method_collinear
-                 && turn.method != method_equal )
-            {
-                return false;
-            }
-
-            return is_continue_or_opposite(turn.operations[0].operation)
-                && is_continue_or_opposite(turn.operations[1].operation);
-        }
-    };
-
-
-#ifndef BOOST_GEOMETRY_DIFFERENCE_DO_NOT_REMOVE_DUPLICATE_TURNS
-    struct TurnEqualsTo
-    {
-        template <typename Turn>
-        bool operator()(Turn const& t1, Turn const& t2) const
-        {
-            return geometry::equals(t1.point, t2.point)
-                && t1.operations[0].seg_id == t2.operations[0].seg_id
-                && t1.operations[0].other_id == t2.operations[0].other_id;
-        }
-    };
-#endif
-
-
-    template <typename Turns>
-    static inline void filter_turns(Turns& turns)
-    {
-        turns.erase( std::remove_if(turns.begin(), turns.end(),
-                                    IsContinueTurn()),
-                     turns.end()
-                     );
-    }
-
-
-#ifndef BOOST_GEOMETRY_DIFFERENCE_DO_NOT_REMOVE_DUPLICATE_TURNS
-    template <typename Turns>
-    static inline void remove_duplicates(Turns& turns)
-    {
-        turns.erase( std::unique(turns.begin(), turns.end(),
-                                 TurnEqualsTo()),
-                     turns.end()
-                     );
-    }
-#endif
-
-
     template
     <
         typename Turns,
@@ -274,9 +226,17 @@ protected:
                           LinearGeometry2 const& linear2,
                           OutputIterator oit)
     {
+#ifndef BOOST_GEOMETRY_DIFFERENCE_DO_NOT_FILTER_CONTINUE_TURNS
         // remove turns that have no added value
-        filter_turns(turns);
-        filter_turns(reverse_turns);
+        turns::filter_continue_turns
+            <
+                Turns, EnableFilterContinueTurns
+            >::apply(turns);
+        turns::filter_continue_turns
+            <
+                Turns, EnableFilterContinueTurns
+            >::apply(reverse_turns);
+#endif
 
         // sort by seg_id, distance, and operation
         std::sort(boost::begin(turns), boost::end(turns),
@@ -287,8 +247,14 @@ protected:
 
 #ifndef BOOST_GEOMETRY_DIFFERENCE_DO_NOT_REMOVE_DUPLICATE_TURNS
         // remove duplicate turns
-        remove_duplicates(turns);
-        remove_duplicates(reverse_turns);
+        turns::remove_duplicate_turns
+            <
+                Turns, EnableRemoveDuplicateTurns
+            >::apply(turns);
+        turns::remove_duplicate_turns
+            <
+                Turns, EnableRemoveDuplicateTurns
+            >::apply(reverse_turns);
 #endif
 
 #ifdef GEOMETRY_TEST_DEBUG

include/boost/geometry/algorithms/detail/turns/filter_continue_turns.hpp

@@ -0,0 +1,78 @@
+// Boost.Geometry (aka GGL, Generic Geometry Library)
+
+// Copyright (c) 2014, Oracle and/or its affiliates.
+
+// Licensed under the Boost Software License version 1.0.
+// http://www.boost.org/users/license.html
+
+// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
+
+
+#ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_FILTER_CONTINUE_TURNS_HPP
+#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_FILTER_CONTINUE_TURNS_HPP
+
+#include <algorithm>
+#include <boost/geometry/algorithms/detail/overlay/turn_info.hpp>
+
+namespace boost { namespace geometry
+{
+
+namespace detail { namespace turns
+{
+
+
+template <typename Turns, bool Enable>
+struct filter_continue_turns
+{
+    static inline void apply(Turns& turns) {}
+};
+
+
+template <typename Turns>
+class filter_continue_turns<Turns, true>
+{
+private:
+    class IsContinueTurn
+    {
+    private:
+        template <typename Operation>
+        inline bool is_continue_or_opposite(Operation const& operation) const
+        {
+            return operation == detail::overlay::operation_continue
+                || operation == detail::overlay::operation_opposite;
+        }
+
+    public:
+        template <typename Turn>
+        bool operator()(Turn const& turn) const
+        {
+            if ( turn.method != detail::overlay::method_collinear
+                 && turn.method != detail::overlay::method_equal )
+            {
+                return false;
+            }
+
+            return is_continue_or_opposite(turn.operations[0].operation)
+                && is_continue_or_opposite(turn.operations[1].operation);
+        }
+    };
+
+
+public:
+    static inline void apply(Turns& turns)
+    {
+        turns.erase( std::remove_if(turns.begin(), turns.end(),
+                                    IsContinueTurn()),
+                     turns.end()
+                     );
+    }
+};
+
+
+}} // namespace detail::turns
+
+}} // namespect boost::geometry
+
+
+
+#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_FILTER_CONTINUE_TURNS_HPP

include/boost/geometry/algorithms/detail/turns/remove_duplicate_turns.hpp

@@ -0,0 +1,62 @@
+// Boost.Geometry (aka GGL, Generic Geometry Library)
+
+// Copyright (c) 2014, Oracle and/or its affiliates.
+
+// Licensed under the Boost Software License version 1.0.
+// http://www.boost.org/users/license.html
+
+// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
+
+
+#ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_REMOVE_DUPLICATE_TURNS_HPP
+#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_REMOVE_DUPLICATE_TURNS_HPP
+
+#include <algorithm>
+#include <boost/geometry/algorithms/equals.hpp>
+
+namespace boost { namespace geometry
+{
+
+namespace detail { namespace turns
+{
+
+template <typename Turns, bool Enable>
+struct remove_duplicate_turns
+{
+    static inline void apply(Turns& turns) {}
+};
+
+
+
+template <typename Turns>
+class remove_duplicate_turns<Turns, true>
+{
+private:
+    struct TurnEqualsTo
+    {
+        template <typename Turn>
+        bool operator()(Turn const& t1, Turn const& t2) const
+        {
+            return geometry::equals(t1.point, t2.point)
+                && t1.operations[0].seg_id == t2.operations[0].seg_id
+                && t1.operations[0].other_id == t2.operations[0].other_id;
+        }
+    };
+
+public:
+    static inline void apply(Turns& turns)
+    {
+        turns.erase( std::unique(turns.begin(), turns.end(),
+                                 TurnEqualsTo()),
+                     turns.end()
+                     );
+    }
+};
+
+
+
+}} // namespace detail::turns
+
+}} // namespect boost::geometry
+
+#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_TURNS_REMOVE_DUPLICATE_TURNS_HPP