org.opentripplanner.street.search.state.EdgeTraverser Maven / Gradle / Ivy
package org.opentripplanner.street.search.state;
import java.util.Collection;
import java.util.Optional;
import org.opentripplanner.street.model.edge.Edge;
/**
* This is a very reduced version of the A* algorithm: from an initial state a number of edges are
* traversed in sequential order. It doesn't take into account the potential other paths that are
* possible.
*
* This is not a general search algorithm! It's only useful for calculating cost and time of
* traversing a predetermined set of edges.
*/
public class EdgeTraverser {
public static Optional traverseEdges(final State s, final Collection edges) {
var state = s;
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)) {
return Optional.empty();
} else {
state = afterTraversal[0];
}
}
return Optional.ofNullable(state);
}
}