Add support for opposite approach request parameter (#6842)

* Added approach on the opposite side of the road.

* Additional test and docs coverage for opposite approach

---------

Co-authored-by: Aleksandrs Saveljevs <Aleksandrs.Saveljevs@gmail.com>

include/engine/api/base_parameters.hpp

@@ -52,7 +52,8 @@ namespace osrm::engine::api
  *              optional per coordinate
  *  - bearings: limits the search for segments in the road network to given bearing(s) in degree
  *              towards true north in clockwise direction, optional per coordinate
- *  - approaches: force the phantom node to start towards the node with the road country side.
+ *  - approaches: force the phantom node to start towards the node with the road country side or
+ *                its opposite
  *
  * \see OSRM, Coordinate, Hint, Bearing, RouteParameters, TableParameters,
  *      NearestParameters, TripParameters, MatchParameters and TileParameters

include/engine/approach.hpp

@@ -36,7 +36,8 @@ namespace osrm::engine
 enum class Approach : std::uint8_t
 {
     CURB = 0,
-    UNRESTRICTED = 1
+    UNRESTRICTED = 1,
+    OPPOSITE = 2
 
 };
 } // namespace osrm::engine

include/engine/geospatial_query.hpp

@@ -558,7 +558,7 @@ template <typename RTreeT, typename DataFacadeT> class GeospatialQuery
     {
         bool isOnewaySegment =
             !(segment.data.forward_segment_id.enabled && segment.data.reverse_segment_id.enabled);
-        if (!isOnewaySegment && approach == Approach::CURB)
+        if (!isOnewaySegment && (approach == Approach::CURB || approach == Approach::OPPOSITE))
         {
             // Check the counter clockwise
             //
@@ -573,6 +573,9 @@ template <typename RTreeT, typename DataFacadeT> class GeospatialQuery
             if (datafacade.IsLeftHandDriving(segment.data.forward_segment_id.id))
                 input_coordinate_is_at_right = !input_coordinate_is_at_right;
 
+            if (approach == Approach::OPPOSITE)
+                input_coordinate_is_at_right = !input_coordinate_is_at_right;
+
             return std::make_pair(input_coordinate_is_at_right, (!input_coordinate_is_at_right));
         }
         return std::make_pair(true, true);