Special AIMA Queue interface replaced by standard Java Queue interface.

aima-core/src/main/java/aima/core/environment/vacuum/NondeterministicVacuumAgent.java

@@ -107,24 +107,24 @@ public Action execute(Percept percept) {
 		Object currentStep = this.stack.peek();
 		// push...
 		if (currentStep instanceof Action) {
-			return (Action) this.stack.pop();
+			return (Action) this.stack.remove();
 		} // case: next step is a plan
 		else if (currentStep instanceof Plan) {
 			Plan newPlan = (Plan) currentStep;
 			if (newPlan.size() > 0) {
 				this.stack.push(newPlan.removeFirst());
 			} else {
-				this.stack.pop();
+				this.stack.remove();
 			}
 			return this.execute(percept);
 		} // case: next step is an if-then
 		else if (currentStep instanceof IfStateThenPlan) {
-			IfStateThenPlan conditional = (IfStateThenPlan) this.stack.pop();
+			IfStateThenPlan conditional = (IfStateThenPlan) this.stack.remove();
 			this.stack.push(conditional.ifStateMatches(percept));
 			return this.execute(percept);
 		} // case: ignore next step if null
 		else if (currentStep == null) {
-			this.stack.pop();
+			this.stack.remove();
 			return this.execute(percept);
 		} else {
 			throw new RuntimeException("Unrecognized contingency plan step.");

aima-core/src/main/java/aima/core/environment/wumpusworld/HybridWumpusAgent.java

@@ -4,6 +4,7 @@
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Queue;
 import java.util.Set;
 
 import aima.core.agent.Action;
@@ -23,7 +24,6 @@
 import aima.core.search.informed.AStarSearch;
 import aima.core.util.SetOps;
 import aima.core.util.datastructure.FIFOQueue;
-import aima.core.util.datastructure.Queue;
 
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): page 270.<br>
@@ -154,7 +154,7 @@ public Action execute(Percept percept) {
 			plan.add(new Climb());
 		}
 		// action <- POP(plan)
-		Action action = plan.pop();
+		Action action = plan.remove();
 		// TELL(KB, MAKE-ACTION-SENTENCE(action, t))
 		kb.makeActionSentence(action, t);
 		// t <- t+1

aima-core/src/main/java/aima/core/logic/propositional/inference/PLFCEntails.java

@@ -3,6 +3,7 @@
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
+import java.util.Queue;
 import java.util.Set;
 
 import aima.core.logic.propositional.kb.KnowledgeBase;
@@ -11,7 +12,6 @@
 import aima.core.logic.propositional.visitors.ConvertToConjunctionOfClauses;
 import aima.core.logic.propositional.visitors.SymbolCollector;
 import aima.core.util.datastructure.FIFOQueue;
-import aima.core.util.datastructure.Queue;
 
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): page 258.<br>
@@ -86,7 +86,7 @@ public boolean plfcEntails(KnowledgeBase kb, PropositionSymbol q) {
 		// while agenda is not empty do
 		while (!agenda.isEmpty()) {
 			// p <- Pop(agenda)
-			PropositionSymbol p = agenda.pop();
+			PropositionSymbol p = agenda.remove();
 			// if p = q then return true
 			if (p.equals(q)) {
 				return true;

aima-core/src/main/java/aima/core/search/csp/AC3Strategy.java

@@ -83,7 +83,7 @@ public DomainRestoreInfo reduceDomains(Variable var, Object value, CSP csp) {
 	private void reduceDomains(FIFOQueue<Variable> queue, CSP csp,
 			DomainRestoreInfo info) {
 		while (!queue.isEmpty()) {
-			Variable var = queue.pop();
+			Variable var = queue.remove();
 			for (Constraint constraint : csp.getConstraints(var)) {
 				if (constraint.getScope().size() == 2) {
 					Variable neighbor = csp.getNeighbor(var, constraint);

aima-core/src/main/java/aima/core/search/framework/PrioritySearch.java

@@ -2,10 +2,10 @@
 
 import java.util.Comparator;
 import java.util.List;
+import java.util.PriorityQueue;
 
 import aima.core.agent.Action;
 import aima.core.search.framework.qsearch.QueueSearch;
-import aima.core.util.datastructure.PriorityQueue;
 
 /**
  * Maintains a {@link QueueSearch} implementation and a node comparator. Search

aima-core/src/main/java/aima/core/search/framework/qsearch/BidirectionalSearch.java

@@ -4,14 +4,14 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Queue;
 
 import aima.core.agent.Action;
 import aima.core.search.framework.BidirectionalProblem;
 import aima.core.search.framework.Node;
 import aima.core.search.framework.Problem;
 import aima.core.search.framework.SearchUtils;
 import aima.core.util.CancelableThread;
-import aima.core.util.datastructure.Queue;
 
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): page 90.<br>
@@ -136,7 +136,7 @@ public void setReverseActionTestEnabled(boolean state) {
 	@Override
 	protected void insertIntoFrontier(Node node) {
 		if (!isExplored(node)) {
-			frontier.insert(node);
+			frontier.add(node);
 			updateMetrics(frontier.size());
 		}
 	}
@@ -149,7 +149,7 @@ protected void insertIntoFrontier(Node node) {
 	 */
 	@Override
 	protected Node popNodeFromFrontier() {
-		Node result = frontier.pop();
+		Node result = frontier.remove();
 		// add the node to the explored set of the corresponding problem
 		setExplored(result);
 		updateMetrics(frontier.size());
@@ -163,7 +163,7 @@ protected Node popNodeFromFrontier() {
 	@Override
 	protected boolean isFrontierEmpty() {
 		while (!frontier.isEmpty() && isExplored(frontier.peek())) {
-			frontier.pop();
+			frontier.remove();
 			updateMetrics(frontier.size());
 		}
 		return frontier.isEmpty();

aima-core/src/main/java/aima/core/search/framework/qsearch/GraphSearch.java

@@ -2,12 +2,12 @@
 
 import java.util.HashSet;
 import java.util.List;
+import java.util.Queue;
 import java.util.Set;
 
 import aima.core.agent.Action;
 import aima.core.search.framework.Node;
 import aima.core.search.framework.Problem;
-import aima.core.util.datastructure.Queue;
 
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): Figure 3.7, page 77.
@@ -63,7 +63,7 @@ public List<Action> search(Problem problem, Queue<Node> frontier) {
 	@Override
 	protected void insertIntoFrontier(Node node) {
 		if (!explored.contains(node.getState())) {
-			frontier.insert(node);
+			frontier.add(node);
 			updateMetrics(frontier.size());
 		}
 	}
@@ -78,7 +78,7 @@ protected void insertIntoFrontier(Node node) {
 	 */
 	@Override
 	protected Node popNodeFromFrontier() {
-		Node result = frontier.pop();
+		Node result = frontier.remove();
 		// add the node to the explored set
 		explored.add(result.getState());
 		updateMetrics(frontier.size());
@@ -92,7 +92,7 @@ protected Node popNodeFromFrontier() {
 	@Override
 	protected boolean isFrontierEmpty() {
 		while (!frontier.isEmpty() && explored.contains(frontier.peek().getState()))
-			frontier.pop();
+			frontier.remove();
 		updateMetrics(frontier.size());
 		return frontier.isEmpty();
 	}

aima-core/src/main/java/aima/core/search/framework/qsearch/GraphSearchBFS.java

@@ -2,12 +2,12 @@
 
 import java.util.HashSet;
 import java.util.List;
+import java.util.Queue;
 import java.util.Set;
 
 import aima.core.agent.Action;
 import aima.core.search.framework.Node;
 import aima.core.search.framework.Problem;
-import aima.core.util.datastructure.Queue;
 
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): Figure 3.7, page 77.
@@ -62,7 +62,7 @@ public List<Action> search(Problem problem, Queue<Node> frontier) {
 	@Override
 	protected void insertIntoFrontier(Node node) {
 		if (!explored.contains(node.getState()) && !frontierStates.contains(node.getState())) {
-			frontier.insert(node);
+			frontier.add(node);
 			frontierStates.add(node.getState());
 			updateMetrics(frontier.size());
 		}
@@ -76,7 +76,7 @@ protected void insertIntoFrontier(Node node) {
 	 */
 	@Override
 	protected Node popNodeFromFrontier() {
-		Node result = frontier.pop();
+		Node result = frontier.remove();
 		explored.add(result.getState());
 		frontierStates.remove(result.getState());
 		updateMetrics(frontier.size());

aima-core/src/main/java/aima/core/search/framework/qsearch/GraphSearchReducedFrontier.java

@@ -5,13 +5,13 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.PriorityQueue;
+import java.util.Queue;
 import java.util.Set;
 
 import aima.core.agent.Action;
 import aima.core.search.framework.Node;
 import aima.core.search.framework.Problem;
-import aima.core.util.datastructure.PriorityQueue;
-import aima.core.util.datastructure.Queue;
 
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): Figure 3.7, page 77.
@@ -82,7 +82,7 @@ protected void insertIntoFrontier(Node node) {
 		if (null == frontierNode) {
 			if (!explored.contains(node.getState())) {
 				// child.STATE is not in frontier and not yet explored
-				frontier.insert(node);
+				frontier.add(node);
 				frontierState.put(node.getState(), node);
 				updateMetrics(frontier.size());
 			}
@@ -91,7 +91,7 @@ protected void insertIntoFrontier(Node node) {
 			// replace that frontier node with child
 			if (frontier.remove(frontierNode))
 				frontierState.remove(frontierNode.getState());
-			frontier.insert(node);
+			frontier.add(node);
 			frontierState.put(node.getState(), node);
 			updateMetrics(frontier.size());
 		}
@@ -105,7 +105,7 @@ protected void insertIntoFrontier(Node node) {
 	 */
 	@Override
 	protected Node popNodeFromFrontier() {
-		Node result = frontier.pop();
+		Node result = frontier.remove();
 		// add the node to the explored set
 		explored.add(result.getState());
 		frontierState.remove(result.getState());

aima-core/src/main/java/aima/core/search/framework/qsearch/QueueSearch.java

@@ -1,14 +1,14 @@
 package aima.core.search.framework.qsearch;
 
 import java.util.List;
+import java.util.Queue;
 
 import aima.core.agent.Action;
 import aima.core.search.framework.Metrics;
 import aima.core.search.framework.Node;
 import aima.core.search.framework.Problem;
 import aima.core.search.framework.SearchUtils;
 import aima.core.util.CancelableThread;
-import aima.core.util.datastructure.Queue;
 
 /**
  * Base class for queue-based search implementations, especially for {@link TreeSearch},

aima-core/src/main/java/aima/core/search/framework/qsearch/TreeSearch.java

@@ -1,8 +1,9 @@
 package aima.core.search.framework.qsearch;
 
+import java.util.Queue;
+
 import aima.core.search.framework.Node;
 import aima.core.search.framework.Problem;
-import aima.core.util.datastructure.Queue;
 
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): Figure 3.7, page 77.
@@ -36,7 +37,7 @@ public class TreeSearch extends QueueSearch {
 	 */
 	@Override
 	protected void insertIntoFrontier(Node node) {
-		frontier.insert(node);
+		frontier.add(node);
 		updateMetrics(frontier.size());
 	}
 
@@ -47,7 +48,7 @@ protected void insertIntoFrontier(Node node) {
 	 */
 	@Override
 	protected Node popNodeFromFrontier() {
-		Node result = frontier.pop();
+		Node result = frontier.remove();
 		updateMetrics(frontier.size());
 		return result;
 	}

aima-core/src/main/java/aima/core/search/uninformed/BidirectionalSearch.java

@@ -88,8 +88,8 @@ List<Action> searchOutOfOrder(Problem p) throws Exception {
 
 		Node opNode = new Node(op.getInitialState());
 		Node rpNode = new Node(rp.getInitialState());
-		opFrontier.insert(opNode);
-		rpFrontier.insert(rpNode);
+		opFrontier.add(opNode);
+		rpFrontier.add(rpNode);
 
 		setQueueSize(opFrontier.size() + rpFrontier.size());
 		//setNodesExpanded(ogs.getNodesExpanded() + rgs.getNodesExpanded()); // TODO
@@ -99,15 +99,15 @@ List<Action> searchOutOfOrder(Problem p) throws Exception {
 			// in preparation for testing whether or not the two
 			// searches meet or one or other is at the GOAL.
 			if (!opFrontier.isEmpty()) {
-				opNode = opFrontier.pop();
+				opNode = opFrontier.remove();
 				// opFrontier.addAll(ogs.getResultingNodesToAddToFrontier(opNode,
 				// // TODO
 				// op));
 			} else {
 				opNode = null;
 			}
 			if (!rpFrontier.isEmpty()) {
-				rpNode = rpFrontier.pop();
+				rpNode = rpFrontier.remove();
 				// rpFrontier.addAll(rgs.getResultingNodesToAddToFrontier(rpNode,
 				// // TODO
 				// rp));
@@ -417,8 +417,8 @@ public Node getNodeBasedOn(Object state) {
 
 	//
 	// START-Queue
-	public E pop() {
-		E popped = super.pop();
+	public E remove() {
+		E popped = super.remove();
 		cachedState.remove(((Node) popped).getState());
 		return popped;
 	}

aima-core/src/main/java/aima/core/util/datastructure/FIFOQueue.java

@@ -2,15 +2,17 @@
 
 import java.util.Collection;
 import java.util.LinkedList;
+import java.util.Queue;
 
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): pg 80.<br>
  * <br>
  * First-in, first-out or FIFO queue, which pops the oldest element of the
- * queue;
+ * queue. This implementation is in fact a renamed LinkedList.
  * 
  * @author Ravi Mohan
  * @author Ciaran O'Reilly
+ * @author Ruediger Lunde
  */
 public class FIFOQueue<E> extends LinkedList<E> implements Queue<E> {
 	private static final long serialVersionUID = 1;
@@ -22,27 +24,4 @@ public FIFOQueue() {
 	public FIFOQueue(Collection<? extends E> c) {
 		super(c);
 	}
-
-	//
-	// START-Queue
-	public boolean isEmpty() {
-		return 0 == size();
-	}
-
-	public E pop() {
-		return poll();
-	}
-
-	public void push(E element) {
-		this.addLast(element);
-	}
-
-	public Queue<E> insert(E element) {
-		if (offer(element)) {
-			return this;
-		}
-		return null;
-	}
-	// END-Queue
-	//
 }