From fa6d0ce2ee1e4d63ba99e2f7965701b0ec73eee0 Mon Sep 17 00:00:00 2001
From: Barend Gehrels <barend@xs4all.nl>
Date: Wed, 6 Dec 2017 11:23:27 +0100
Subject: [PATCH] [traverse] replace switch_source by inspecting region ids
 locally

---
 .../algorithms/detail/overlay/traversal.hpp   | 28 +++++++++++--------
 .../overlay/traversal_switch_detector.hpp     | 23 ---------------
 .../algorithms/detail/overlay/turn_info.hpp   |  2 --
 .../extensions/algorithms/dissolve.hpp        |  1 -
 4 files changed, 17 insertions(+), 37 deletions(-)

diff --git a/include/boost/geometry/algorithms/detail/overlay/traversal.hpp b/include/boost/geometry/algorithms/detail/overlay/traversal.hpp
index fe1a7adee..2d8f46e24 100644
--- a/include/boost/geometry/algorithms/detail/overlay/traversal.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/traversal.hpp
@@ -236,7 +236,23 @@ struct traversal
             segment_identifier const& current,
             segment_identifier const& previous) const
     {
-        return turn.switch_source
+        turn_operation_type const& op0 = turn.operations[0];
+        turn_operation_type const& op1 = turn.operations[1];
+
+        bool const switch_source = op0.enriched.region_id != -1
+                && op0.enriched.region_id == op1.enriched.region_id;
+
+#if defined(BOOST_GEOMETRY_DEBUG_TRAVERSAL_SWITCH_DETECTOR)
+        if (switch_source)
+        {
+            std::cout << "Switch source at " << &turn << std::endl;
+        }
+        else
+        {
+            std::cout << "DON'T SWITCH SOURCES at " << &turn << std::endl;
+        }
+#endif
+        return switch_source
                 ? current.*Member != previous.*Member
                 : current.*Member == previous.*Member;
     }
@@ -247,16 +263,6 @@ struct traversal
     {
         // For uu/ii, only switch sources if indicated
 
-#if defined(BOOST_GEOMETRY_DEBUG_TRAVERSAL_SWITCH_DETECTOR)
-        if (turn.switch_source)
-        {
-            std::cout << "Switch source at " << turn_index << std::endl;
-        }
-        else
-        {
-            std::cout << "DON'T SWITCH SOURCES at " << turn_index << std::endl;
-        }
-#endif
         if (OverlayType == overlay_buffer
                 || OverlayType == overlay_dissolve_union)
         {
diff --git a/include/boost/geometry/algorithms/detail/overlay/traversal_switch_detector.hpp b/include/boost/geometry/algorithms/detail/overlay/traversal_switch_detector.hpp
index 13edb4b90..b4a3edee4 100644
--- a/include/boost/geometry/algorithms/detail/overlay/traversal_switch_detector.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/traversal_switch_detector.hpp
@@ -611,29 +611,6 @@ struct traversal_switch_detector
             }
         }
 
-        // Iterate through all uu/ii turns (non-clustered)
-        for (std::size_t turn_index = 0; turn_index < m_turns.size(); ++turn_index)
-        {
-            turn_type& turn = m_turns[turn_index];
-
-            if (turn.discarded
-                    || turn.blocked()
-                    || turn.is_clustered()
-                    || ! (turn.both(operation_union) || turn.both(operation_intersection)))
-            {
-                // Skip discarded, blocked, non-uu/ii and clustered turns
-                continue;
-            }
-
-
-            signed_size_type const region0 = get_region_id(turn.operations[0]);
-            signed_size_type const region1 = get_region_id(turn.operations[1]);
-
-            // Switch sources for same region
-            turn.switch_source = region0 == region1;
-        }
-
-
 #if defined(BOOST_GEOMETRY_DEBUG_TRAVERSAL_SWITCH_DETECTOR)
         std::cout << "SWITCH END ITERATION" << std::endl;
 
diff --git a/include/boost/geometry/algorithms/detail/overlay/turn_info.hpp b/include/boost/geometry/algorithms/detail/overlay/turn_info.hpp
index 3ed75cf09..545b5e902 100644
--- a/include/boost/geometry/algorithms/detail/overlay/turn_info.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/turn_info.hpp
@@ -94,7 +94,6 @@ struct turn_info
     bool discarded;
 
     bool has_colocated_both; // Colocated with a uu turn (for union) or ii (other)
-    bool switch_source; // For u/u turns which can either switch or not
 
     Container operations;
 
@@ -104,7 +103,6 @@ struct turn_info
         , cluster_id(-1)
         , discarded(false)
         , has_colocated_both(false)
-        , switch_source(false)
     {}
 
     inline bool both(operation_type type) const
diff --git a/include/boost/geometry/extensions/algorithms/dissolve.hpp b/include/boost/geometry/extensions/algorithms/dissolve.hpp
index c9d4a8aaa..0c7ecee0c 100644
--- a/include/boost/geometry/extensions/algorithms/dissolve.hpp
+++ b/include/boost/geometry/extensions/algorithms/dissolve.hpp
@@ -127,7 +127,6 @@ struct dissolve_ring_or_polygon
             turn.discarded = false;
             turn.cluster_id = -1;
             turn.has_colocated_both = false;
-            turn.switch_source = false;
             turn.touch_only = false;
         }