syncronize geometry and steps after post-processing

include/engine/guidance/assemble_geometry.hpp

@@ -51,7 +51,7 @@ LegGeometry assembleGeometry(const DataFacadeT &facade,
         current_distance +=
             util::coordinate_calculation::haversineDistance(prev_coordinate, coordinate);
 
-        //all changes to this check have to be matched with assemble_steps
+        // all changes to this check have to be matched with assemble_steps
         if (path_point.turn_instruction.type != extractor::guidance::TurnType::NoTurn)
         {
             geometry.segment_distances.push_back(current_distance);

include/engine/guidance/post_processing.hpp

@@ -2,6 +2,7 @@
 #define ENGINE_GUIDANCE_POST_PROCESSING_HPP
 
 #include "engine/guidance/route_step.hpp"
+#include "engine/guidance/leg_geometry.hpp"
 
 #include <vector>
 
@@ -12,9 +13,16 @@ namespace engine
 namespace guidance
 {
 
-//passed as none-reference to modify in-place and move out again
+// passed as none-reference to modify in-place and move out again
 std::vector<RouteStep> postProcess(std::vector<RouteStep> steps);
 
+// postProcess will break the connection between the leg geometry
+// for which a segment is supposed to represent exactly the coordinates
+// between routing maneuvers and the route steps itself.
+// If required, we can get both in sync again using this function.
+// Move in LegGeometry for modification in place.
+LegGeometry resyncGeometry(LegGeometry leg_geometry, const std::vector<RouteStep> &steps);
+
 } // namespace guidance
 } // namespace engine
 } // namespace osrm