depth first search heuristic (H1)

analysis/Heuristics/DepthFirstHeuristic.java

+package Heuristics;
+
+import FaultTree.BasicEvent;
+import FaultTree.FaultTree;
+import FaultTree.*;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+
+public class DepthFirstHeuristic extends AbstractFaultTreeVisitor implements Heuristic {
+
+    private Map<BasicEvent, Integer> order;
+    private HashSet<FaultTree> visited;
+    private int counter;
+
+    @Override
+    public Map<BasicEvent, Integer> getOrder(FaultTree tree) {
+        //flush old values of order, visited and counter in case the same instance of DFS heuristic is used for multiple trees
+        order = new HashMap<>();
+        visited = new HashSet<>();
+        counter = 0;
+        visit(tree);
+        return this.order;
+    }
+
+    @Override
+    public void visitIntermediateEvent(IntermediateEvent event) {
+        if(visited.contains(event)){
+            return;
+        }
+        visited.add(event);
+        visit(event.left);
+        visit(event.right);
+    }
+
+    @Override
+    public void visitBasicEvent(BasicEvent event) {
+        if (!order.containsKey(event)) {
+            order.put(event, counter++);
+        }
+    }
+
+}