copy method
Implementation
@override
GraphState copy() {
GraphDijkstraState state = GraphDijkstraState(
startId: startId,
targetId: targetId,
status: status,
parents: HashMap.from(parents),
edges: HashMap.from(edges),
coords: HashMap.from(coords),
nodes: HashMap.from(nodes),
open: PriorityQueue((a, b) => gCost[a]!.compareTo(gCost[b]!)),
gCost: HashMap.from(gCost),
);
state.open.addAll(open.toList());
return state;
}