1 package cz.cuni.amis.pathfinding.alg.astar;
2
3 import java.util.Comparator;
4 import java.util.Map;
5
6 /**
7 * This comparator is a tricky object - it serves for the {@link AStarHeap} to compare nodes inside the heap.
8 * <p><p>
9 * The trick is, that it is initialized {@link AStarHeapComparator#AStarHeapComparator(Map)} with a map
10 * that contains node's costs that are used during the comparation inside {@link AStarHeapComparator#compare(Object, Object)}.
11 * No magic yet, ha? Well, the magic is that this map is not cloned... simply a pointer to this very instance passed
12 * inside the constructor is saved to you may alter the cost as you wish to! Which is truly needed by the {@link AStar} class
13 * that is obtaining nodes' costs from the {@link AStarMap} implementor.
14 *
15 * @author Jimmy
16 *
17 * @param <NODE>
18 */
19 public class AStarHeapComparator<NODE> implements Comparator {
20
21 private Map<NODE, Integer> values;
22
23 public AStarHeapComparator(Map<NODE, Integer> estimatedCosts){
24 values = estimatedCosts;
25 }
26
27 public int compare(Object arg0, Object arg1) {
28 return values.get(arg0).intValue() - values.get(arg1).intValue();
29 }
30
31 }