Street search: traverse edges which may return multiple states

application/src/ext/java/org/opentripplanner/ext/flex/template/AbstractFlexTemplate.java

@@ -199,7 +199,7 @@ private FlexAccessEgress createFlexAccessEgress(
       return null;
     }
 
-    final var finalStateOpt = EdgeTraverser.traverseEdges(afterFlexState[0], transferEdges);
+    final var finalStateOpt = EdgeTraverser.traverseEdges(afterFlexState, transferEdges);
 
     return finalStateOpt
       .map(finalState -> {

application/src/ext/java/org/opentripplanner/ext/flex/template/FlexDirectPathFactory.java

@@ -113,7 +113,7 @@ private Optional<DirectFlexPath> createDirectGraphPath(
 
     final State[] afterFlexState = flexEdge.traverse(accessNearbyStop.state);
 
-    var finalStateOpt = EdgeTraverser.traverseEdges(afterFlexState[0], egress.edges);
+    var finalStateOpt = EdgeTraverser.traverseEdges(afterFlexState, egress.edges);
 
     if (finalStateOpt.isEmpty()) {
       return Optional.empty();

application/src/main/java/org/opentripplanner/routing/algorithm/mapping/RaptorPathToItineraryMapper.java

@@ -6,6 +6,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import java.util.Set;
 import org.opentripplanner.astar.model.GraphPath;
 import org.opentripplanner.framework.application.OTPFeature;
 import org.opentripplanner.framework.geometry.GeometryUtils;
@@ -38,8 +39,8 @@
 import org.opentripplanner.street.search.TraverseMode;
 import org.opentripplanner.street.search.request.StreetSearchRequest;
 import org.opentripplanner.street.search.request.StreetSearchRequestMapper;
+import org.opentripplanner.street.search.state.EdgeTraverser;
 import org.opentripplanner.street.search.state.State;
-import org.opentripplanner.street.search.state.StateEditor;
 import org.opentripplanner.transit.model.timetable.TripIdAndServiceDate;
 import org.opentripplanner.transit.model.timetable.TripOnServiceDate;
 import org.opentripplanner.transit.service.TransitService;
@@ -360,24 +361,15 @@ private List<Leg> mapNonTransitLeg(
           .build()
       );
     } else {
-      StateEditor se = new StateEditor(edges.get(0).getFromVertex(), transferStreetRequest);
-      se.setTimeSeconds(createZonedDateTime(pathLeg.fromTime()).toEpochSecond());
-
-      State s = se.makeState();
-      ArrayList<State> transferStates = new ArrayList<>();
-      transferStates.add(s);
-      for (Edge e : edges) {
-        var states = e.traverse(s);
-        if (State.isEmpty(states)) {
-          s = null;
-        } else {
-          transferStates.add(states[0]);
-          s = states[0];
-        }
-      }
-
-      State[] states = transferStates.toArray(new State[0]);
-      var graphPath = new GraphPath<>(states[states.length - 1]);
+      var legTransferSearchRequest = transferStreetRequest
+        .copyOf(createZonedDateTime(pathLeg.fromTime()).toInstant())
+        .build();
+      var initialStates = State.getInitialStates(
+        Set.of(edges.getFirst().getFromVertex()),
+        legTransferSearchRequest
+      );
+      var state = EdgeTraverser.traverseEdges(initialStates, edges);
+      var graphPath = new GraphPath<>(state.get());
 
       Itinerary subItinerary = graphPathToItineraryMapper.generateItinerary(graphPath);
 

application/src/main/java/org/opentripplanner/routing/algorithm/raptoradapter/transit/Transfer.java

@@ -4,14 +4,15 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
+import java.util.Set;
 import org.locationtech.jts.geom.Coordinate;
 import org.opentripplanner.raptor.api.model.RaptorTransfer;
 import org.opentripplanner.routing.algorithm.raptoradapter.transit.cost.RaptorCostConverter;
 import org.opentripplanner.routing.api.request.preference.WalkPreferences;
 import org.opentripplanner.street.model.edge.Edge;
 import org.opentripplanner.street.search.request.StreetSearchRequest;
 import org.opentripplanner.street.search.state.EdgeTraverser;
-import org.opentripplanner.street.search.state.StateEditor;
+import org.opentripplanner.street.search.state.State;
 import org.opentripplanner.utils.logging.Throttle;
 import org.opentripplanner.utils.tostring.ToStringBuilder;
 import org.slf4j.Logger;
@@ -84,10 +85,8 @@ public Optional<RaptorTransfer> asRaptorTransfer(StreetSearchRequest request) {
       );
     }
 
-    StateEditor se = new StateEditor(edges.get(0).getFromVertex(), request);
-    se.setTimeSeconds(0);
-
-    var state = EdgeTraverser.traverseEdges(se.makeState(), edges);
+    var initialStates = State.getInitialStates(Set.of(edges.getFirst().getFromVertex()), request);
+    var state = EdgeTraverser.traverseEdges(initialStates, edges);
 
     return state.map(s ->
       new DefaultRaptorTransfer(

application/src/main/java/org/opentripplanner/street/search/request/StreetSearchRequest.java

@@ -124,6 +124,10 @@ public DataOverlayContext dataOverlayContext() {
     return dataOverlayContext;
   }
 
+  public StreetSearchRequestBuilder copyOf(Instant time) {
+    return copyOf(this).withStartTime(time);
+  }
+
   public StreetSearchRequestBuilder copyOfReversed(Instant time) {
     return copyOf(this).withStartTime(time).withArriveBy(!arriveBy);
   }

application/src/main/java/org/opentripplanner/street/search/state/EdgeTraverser.java

@@ -2,7 +2,10 @@
 
 import java.util.Collection;
 import java.util.Optional;
+import org.opentripplanner.astar.model.ShortestPathTree;
 import org.opentripplanner.street.model.edge.Edge;
+import org.opentripplanner.street.model.vertex.Vertex;
+import org.opentripplanner.street.search.strategy.DominanceFunctions;
 
 /**
  * This is a very reduced version of the A* algorithm: from an initial state a number of edges are
@@ -14,24 +17,49 @@
  */
 public class EdgeTraverser {
 
-  public static Optional<State> traverseEdges(final State s, final Collection<Edge> edges) {
-    var state = s;
+  public static Optional<State> traverseEdges(
+    final Collection<State> initialStates,
+    final Collection<Edge> edges
+  ) {
+    return traverseEdges(initialStates.toArray(new State[0]), edges);
+  }
+
+  public static Optional<State> traverseEdges(
+    final State[] initialStates,
+    final Collection<Edge> edges
+  ) {
+    if (edges.isEmpty()) {
+      return Optional.of(initialStates[0]);
+    }
+
+    // The shortest path tree is used to prune dominated parallel states. For example,
+    // CAR_PICKUP can return both a CAR/WALK state after each traversal of which only
+    // the optimal states need to be continued.
+    var dominanceFunction = new DominanceFunctions.MinimumWeight();
+    var spt = new ShortestPathTree<>(dominanceFunction);
+    for (State initialState : initialStates) {
+      spt.add(initialState);
+    }
+
+    Vertex lastVertex = null;
+    var isArriveBy = initialStates[0].getRequest().arriveBy();
     for (Edge e : edges) {
-      var afterTraversal = e.traverse(state);
-      if (afterTraversal.length > 1) {
-        throw new IllegalStateException(
-          "Expected only a single state returned from edge %s but received %s".formatted(
-              e,
-              afterTraversal.length
-            )
-        );
-      }
-      if (State.isEmpty(afterTraversal)) {
+      var vertex = isArriveBy ? e.getToVertex() : e.getFromVertex();
+      var fromStates = spt.getStates(vertex);
+      if (fromStates == null || fromStates.isEmpty()) {
         return Optional.empty();
-      } else {
-        state = afterTraversal[0];
       }
+
+      for (State fromState : fromStates) {
+        var newToStates = e.traverse(fromState);
+        for (State newToState : newToStates) {
+          spt.add(newToState);
+        }
+      }
+
+      lastVertex = isArriveBy ? e.getFromVertex() : e.getToVertex();
     }
-    return Optional.ofNullable(state);
+
+    return Optional.ofNullable(lastVertex).map(spt::getState);
   }
 }

application/src/test/java/org/opentripplanner/_support/geometry/Coordinates.java

@@ -6,6 +6,8 @@ public class Coordinates {
 
   public static final Coordinate BERLIN = of(52.5212, 13.4105);
   public static final Coordinate BERLIN_BRANDENBURG_GATE = of(52.51627, 13.37770);
+  public static final Coordinate BERLIN_FERNSEHTURM = of(52.52084, 13.40934);
+  public static final Coordinate BERLIN_ADMIRALBRUCKE = of(52.49526, 13.415093);
   public static final Coordinate HAMBURG = of(53.5566, 10.0003);
   public static final Coordinate KONGSBERG_PLATFORM_1 = of(59.67216, 9.65107);
   public static final Coordinate BOSTON = of(42.36541, -71.06129);