NondeterministicSearchAgent improved.

Author: RuedigerLunde

aima-core/src/main/java/aima/core/search/agent/NondeterministicSearchAgent.java

@@ -12,8 +12,7 @@
 import java.util.function.Function;
 
 /**
- * This agent traverses the nondeterministic environment using a
- * contingency plan. See page 135, AIMA3e.
+ * This agent traverses the nondeterministic environment using a contingency plan. See page 135, AIMA3e.
  *
  * @param <P> The type used to represent percepts
  * @param <S> The type used to represent states
@@ -22,10 +21,9 @@
  * @author Andrew Brown
  */
 public class NondeterministicSearchAgent<P, S, A> extends SimpleAgent<P, A> {
-	/**
-	 * Maps percepts to states.
-	 */
+	/** Maps percepts to states. */
 	private Function<P, S> ptsFunction;
+	/** Is informed about every computed contingency plan. */
 	private Notifier notifier;
 
 	private NondeterministicProblem<S, A> problem;
@@ -37,18 +35,16 @@ public NondeterministicSearchAgent(Function<P, S> ptsFn) {
 	}
 
 	public NondeterministicSearchAgent(BiFunction<P, Agent<P, A>, S> ptsFn) {
-		this.ptsFunction = (percept) -> ptsFn.apply(percept, this);
+		this.ptsFunction = percept -> ptsFn.apply(percept, this);
 	}
 
-
 	public NondeterministicSearchAgent(BiFunction<P, Agent<P, A>, S> ptsFn, Notifier notifier) {
 		this(ptsFn);
 		this.notifier = notifier;
 	}
 
 	/**
 	 * Computes a contingency plan for the given problem and prepares plan execution.
-	 * 
 	 * @param problem
 	 *            The search problem for this agent to solve.
 	 */
@@ -63,51 +59,49 @@ public void makePlan(NondeterministicProblem<S, A> problem) {
 			notifier.notify("Contingency plan: " + contingencyPlan);
 	}
 
-	/**
-	 * Returns the search problem for this agent.
-	 *
-	 * @return The search problem for this agent.
-	 */
-	public NondeterministicProblem<S, A> getProblem() {
-		return problem;
-	}
-
-	/**
-	 * Returns the contingency plan of the agent.
-	 * 
-	 * @return The plan the agent uses to clean the vacuum world or null.
-	 */
-	public Plan<S, A> getPlan() {
-		return contingencyPlan;
-	}
-
 	/**
 	 * Selects next action from the contingency plan.
-	 * 
 	 * @param percept A percept.
 	 * @return An action from the contingency plan.
 	 */
 	@Override
-	public Optional<A> act(P percept) {
-		S state = (S) ptsFunction.apply(percept);
+	public final Optional<A> act(P percept) {
+		S state = ptsFunction.apply(percept);
 		// at goal or no plan?
 		if (problem.testGoal(state) || contingencyPlan == null)
 			return Optional.empty();
 
 		currStep++;
-		// end of plan reached?
-		if (currStep == contingencyPlan.size()) {
-			contingencyPlan = null;
-			return Optional.empty();
+		while (true) {
+			// end of plan reached?
+			if (currStep == contingencyPlan.size()) {
+				contingencyPlan = null;
+				return Optional.empty();
+			}
+
+			// next step is action step?
+			if (contingencyPlan.isActionStep(currStep))
+				return Optional.of(contingencyPlan.getAction(currStep));
+
+			// determine next sub-plan and execute it!
+			contingencyPlan = contingencyPlan.getPlan(currStep, state);
+			currStep = 0;
 		}
+	}
 
-		// next step is action step?
-		if (contingencyPlan.isActionStep(currStep))
-			return Optional.of(contingencyPlan.getAction(currStep));
+	/**
+	 * Returns the search problem for this agent.
+	 * @return The search problem for this agent.
+	 */
+	public NondeterministicProblem<S, A> getProblem() {
+		return problem;
+	}
 
-		// determine next sub-plan and act it!
-		contingencyPlan = contingencyPlan.getPlan(currStep, state);
-		currStep = -1;
-		return act(percept);
+	/**
+	 * Returns the contingency plan of the agent.
+	 * @return The plan the agent uses to clean the vacuum world or null.
+	 */
+	public Plan<S, A> getPlan() {
+		return contingencyPlan;
 	}
 }

aima-core/src/main/java/aima/core/search/agent/SimpleProblemSolvingAgent.java

@@ -79,7 +79,6 @@ public Optional<A> act(P percept) {
 		return Optional.ofNullable(!seq.isEmpty() ? seq.remove() : null);
 	}
 
-
 	protected abstract void updateState(P percept);
 
 	/**