fix looping in sliproad handler for lanes

src/engine/api/json_factory.cpp

@@ -235,7 +235,8 @@ util::json::Object makeRouteStep(guidance::RouteStep step, util::json::Value geo
     route_step.values["distance"] = std::round(step.distance * 10) / 10.;
     route_step.values["duration"] = std::round(step.duration * 10) / 10.;
     route_step.values["name"] = std::move(step.name);
-    if (!step.ref.empty()) route_step.values["ref"] = std::move(step.ref);
+    if (!step.ref.empty())
+        route_step.values["ref"] = std::move(step.ref);
     if (!step.pronunciation.empty())
         route_step.values["pronunciation"] = std::move(step.pronunciation);
     if (!step.destinations.empty())

src/extractor/guidance/sliproad_handler.cpp

@@ -37,9 +37,9 @@ SliproadHandler::SliproadHandler(const IntersectionGenerator &intersection_gener
 // included for interface reasons only
 bool SliproadHandler::canProcess(const NodeID /*nid*/,
                                  const EdgeID /*via_eid*/,
-                                 const Intersection & /*intersection*/) const
+                                 const Intersection &intersection) const
 {
-    return true;
+    return intersection.size() > 2;
 }
 
 Intersection SliproadHandler::
@@ -59,6 +59,13 @@ operator()(const NodeID, const EdgeID source_edge_id, Intersection intersection)
             while (intersection.size() == 2)
             {
                 const auto node = node_based_graph.GetTarget(in_edge);
+                if (node == at_node)
+                {
+                    // we ended up in a loop without exit
+                    output_node = SPECIAL_NODEID;
+                    intersection.clear();
+                    return intersection;
+                }
                 in_edge = intersection[1].turn.eid;
                 output_node = node_based_graph.GetTarget(in_edge);
                 intersection = intersection_generator(node, in_edge);
@@ -82,6 +89,10 @@ operator()(const NodeID, const EdgeID source_edge_id, Intersection intersection)
                 intersection_node_id, intersection[1], intersection_node_one);
             const auto intersection_following_index_two = findNextIntersectionForRoad(
                 intersection_node_id, intersection[2], intersection_node_two);
+            // in case of broken roads, we return
+            if (intersection_following_index_one.empty() ||
+                intersection_following_index_two.empty())
+                return 0;
 
             // In case of loops at the end of the road, we will arrive back at the intersection
             // itself. If that is the case, the road is obviously not a sliproad.

src/extractor/guidance/turn_analysis.cpp

@@ -94,6 +94,7 @@ Intersection TurnAnalysis::assignTurnTypes(const NodeID from_nid,
         }
     }
     // Handle sliproads
+    if (sliproad_handler.canProcess(from_nid, via_eid, intersection))
         intersection = sliproad_handler(from_nid, via_eid, std::move(intersection));
 
     // Turn On Ramps Into Off Ramps, if we come from a motorway-like road