/*
* 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 org.apache.commons.math3.exception.NullArgumentException;
/**
* Utility that increments a counter until a maximum is reached, at
* which point, the instance will by default throw a
* {@link MaxCountExceededException}.
* However, the user is able to override this behaviour by defining a
* custom {@link MaxCountExceededCallback callback}, in order to e.g.
* select which exception must be thrown.
*
* @since 3.0
*/
public class Incrementor {
/**
* Upper limit for the counter.
*/
private int maximalCount;
/**
* Current count.
*/
private int count = 0;
/**
* Function called at counter exhaustion.
*/
private final MaxCountExceededCallback maxCountCallback;
/**
* Default constructor.
* For the new instance to be useful, the maximal count must be set
* by calling {@link #setMaximalCount(int) setMaximalCount}.
*/
public Incrementor() {
this(0);
}
/**
* Defines a maximal count.
*
* @param max Maximal count.
*/
public Incrementor(int max) {
this(max,
new MaxCountExceededCallback() {
/** {@inheritDoc} */
public void trigger(int max) throws MaxCountExceededException {
throw new MaxCountExceededException(max);
}
});
}
/**
* Defines a maximal count and a callback method to be triggered at
* counter exhaustion.
*
* @param max Maximal count.
* @param cb Function to be called when the maximal count has been reached.
* @throws NullArgumentException if {@code cb} is {@code null}
*/
public Incrementor(int max, MaxCountExceededCallback cb)
throws NullArgumentException {
if (cb == null){
throw new NullArgumentException();
}
maximalCount = max;
maxCountCallback = cb;
}
/**
* Sets the upper limit for the counter.
* This does not automatically reset the current count to zero (see
* {@link #resetCount()}).
*
* @param max Upper limit of the counter.
*/
public void setMaximalCount(int max) {
maximalCount = max;
}
/**
* Gets the upper limit of the counter.
*
* @return the counter upper limit.
*/
public int getMaximalCount() {
return maximalCount;
}
/**
* Gets the current count.
*
* @return the current count.
*/
public int getCount() {
return count;
}
/**
* Checks whether a single increment is allowed.
*
* @return {@code false} if the next call to {@link #incrementCount(int)
* incrementCount} will trigger a {@code MaxCountExceededException},
* {@code true} otherwise.
*/
public boolean canIncrement() {
return count < maximalCount;
}
/**
* Performs multiple increments.
* See the other {@link #incrementCount() incrementCount} method).
*
* @param value Number of increments.
* @throws MaxCountExceededException at counter exhaustion.
*/
public void incrementCount(int value) throws MaxCountExceededException {
for (int i = 0; i < value; i++) {
incrementCount();
}
}
/**
* Adds one to the current iteration count.
* At counter exhaustion, this method will call the
* {@link MaxCountExceededCallback#trigger(int) trigger} method of the
* callback object passed to the
* {@link #Incrementor(int,MaxCountExceededCallback) constructor}.
* If not explictly set, a default callback is used that will throw
* a {@code MaxCountExceededException}.
*
* @throws MaxCountExceededException at counter exhaustion, unless a
* custom {@link MaxCountExceededCallback callback} has been set at
* construction.
*/
public void incrementCount() throws MaxCountExceededException {
if (++count > maximalCount) {
maxCountCallback.trigger(maximalCount);
}
}
/**
* Resets the counter to 0.
*/
public void resetCount() {
count = 0;
}
/**
* Defines a method to be called at counter exhaustion.
* The {@link #trigger(int) trigger} method should usually throw an exception.
*/
public interface MaxCountExceededCallback {
/**
* Function called when the maximal count has been reached.
*
* @param maximalCount Maximal count.
* @throws MaxCountExceededException at counter exhaustion
*/
void trigger(int maximalCount) throws MaxCountExceededException;
}
}