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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.math3.util;
+
+import org.apache.commons.math3.exception.MaxCountExceededException;
+
+import java.util.Collection;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+/**
+ * This abstract class provides a general framework for managing iterative algorithms. The maximum
+ * number of iterations can be set, and methods are provided to monitor the current iteration count.
+ * A lightweight event framework is also provided.
+ */
+public class IterationManager {
+
+ /** Keeps a count of the number of iterations. */
+ private IntegerSequence.Incrementor iterations;
+
+ /** The collection of all listeners attached to this iterative algorithm. */
+ private final Collection<IterationListener> listeners;
+
+ /**
+ * Creates a new instance of this class.
+ *
+ * @param maxIterations the maximum number of iterations
+ */
+ public IterationManager(final int maxIterations) {
+ this.iterations = IntegerSequence.Incrementor.create().withMaximalCount(maxIterations);
+ this.listeners = new CopyOnWriteArrayList<IterationListener>();
+ }
+
+ /**
+ * Creates a new instance of this class.
+ *
+ * @param maxIterations the maximum number of iterations
+ * @param callBack the function to be called when the maximum number of iterations has been
+ * reached
+ * @throws org.apache.commons.math3.exception.NullArgumentException if {@code callBack} is
+ * {@code null}
+ * @since 3.1
+ * @deprecated as of 3.6, replaced with {@link #IterationManager(int,
+ * org.apache.commons.math3.util.IntegerSequence.Incrementor.MaxCountExceededCallback)}
+ */
+ @Deprecated
+ public IterationManager(
+ final int maxIterations, final Incrementor.MaxCountExceededCallback callBack) {
+ this(
+ maxIterations,
+ new IntegerSequence.Incrementor.MaxCountExceededCallback() {
+ /** {@inheritDoc} */
+ public void trigger(final int maximalCount) throws MaxCountExceededException {
+ callBack.trigger(maximalCount);
+ }
+ });
+ }
+
+ /**
+ * Creates a new instance of this class.
+ *
+ * @param maxIterations the maximum number of iterations
+ * @param callBack the function to be called when the maximum number of iterations has been
+ * reached
+ * @throws org.apache.commons.math3.exception.NullArgumentException if {@code callBack} is
+ * {@code null}
+ * @since 3.6
+ */
+ public IterationManager(
+ final int maxIterations,
+ final IntegerSequence.Incrementor.MaxCountExceededCallback callBack) {
+ this.iterations =
+ IntegerSequence.Incrementor.create()
+ .withMaximalCount(maxIterations)
+ .withCallback(callBack);
+ this.listeners = new CopyOnWriteArrayList<IterationListener>();
+ }
+
+ /**
+ * Attaches a listener to this manager.
+ *
+ * @param listener A {@code IterationListener} object.
+ */
+ public void addIterationListener(final IterationListener listener) {
+ listeners.add(listener);
+ }
+
+ /**
+ * Informs all registered listeners that the initial phase (prior to the main iteration loop)
+ * has been completed.
+ *
+ * @param e The {@link IterationEvent} object.
+ */
+ public void fireInitializationEvent(final IterationEvent e) {
+ for (IterationListener l : listeners) {
+ l.initializationPerformed(e);
+ }
+ }
+
+ /**
+ * Informs all registered listeners that a new iteration (in the main iteration loop) has been
+ * performed.
+ *
+ * @param e The {@link IterationEvent} object.
+ */
+ public void fireIterationPerformedEvent(final IterationEvent e) {
+ for (IterationListener l : listeners) {
+ l.iterationPerformed(e);
+ }
+ }
+
+ /**
+ * Informs all registered listeners that a new iteration (in the main iteration loop) has been
+ * started.
+ *
+ * @param e The {@link IterationEvent} object.
+ */
+ public void fireIterationStartedEvent(final IterationEvent e) {
+ for (IterationListener l : listeners) {
+ l.iterationStarted(e);
+ }
+ }
+
+ /**
+ * Informs all registered listeners that the final phase (post-iterations) has been completed.
+ *
+ * @param e The {@link IterationEvent} object.
+ */
+ public void fireTerminationEvent(final IterationEvent e) {
+ for (IterationListener l : listeners) {
+ l.terminationPerformed(e);
+ }
+ }
+
+ /**
+ * Returns the number of iterations of this solver, 0 if no iterations has been performed yet.
+ *
+ * @return the number of iterations.
+ */
+ public int getIterations() {
+ return iterations.getCount();
+ }
+
+ /**
+ * Returns the maximum number of iterations.
+ *
+ * @return the maximum number of iterations.
+ */
+ public int getMaxIterations() {
+ return iterations.getMaximalCount();
+ }
+
+ /**
+ * Increments the iteration count by one, and throws an exception if the maximum number of
+ * iterations is reached. This method should be called at the beginning of a new iteration.
+ *
+ * @throws MaxCountExceededException if the maximum number of iterations is reached.
+ */
+ public void incrementIterationCount() throws MaxCountExceededException {
+ iterations.increment();
+ }
+
+ /**
+ * Removes the specified iteration listener from the list of listeners currently attached to
+ * {@code this} object. Attempting to remove a listener which was <em>not</em> previously
+ * registered does not cause any error.
+ *
+ * @param listener The {@link IterationListener} to be removed.
+ */
+ public void removeIterationListener(final IterationListener listener) {
+ listeners.remove(listener);
+ }
+
+ /** Sets the iteration count to 0. This method must be called during the initial phase. */
+ public void resetIterationCount() {
+ iterations = iterations.withStart(0);
+ }
+}