org.apache.commons.collections.functors.WhileClosure Maven / Gradle / Ivy
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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.collections.functors;
import java.io.Serializable;
import org.apache.commons.collections.Closure;
import org.apache.commons.collections.Predicate;
/**
* Closure implementation that executes a closure repeatedly until a condition is met,
* like a do-while or while loop.
*
* @since Commons Collections 3.0
* @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
*
* @author Stephen Colebourne
*/
public class WhileClosure implements Closure, Serializable {
/** Serial version UID */
private static final long serialVersionUID = -3110538116913760108L;
/** The test condition */
private final Predicate iPredicate;
/** The closure to call */
private final Closure iClosure;
/** The flag, true is a do loop, false is a while */
private final boolean iDoLoop;
/**
* Factory method that performs validation.
*
* @param predicate the predicate used to evaluate when the loop terminates, not null
* @param closure the closure the execute, not null
* @param doLoop true to act as a do-while loop, always executing the closure once
* @return the while closure
* @throws IllegalArgumentException if the predicate or closure is null
*/
public static Closure getInstance(Predicate predicate, Closure closure, boolean doLoop) {
if (predicate == null) {
throw new IllegalArgumentException("Predicate must not be null");
}
if (closure == null) {
throw new IllegalArgumentException("Closure must not be null");
}
return new WhileClosure(predicate, closure, doLoop);
}
/**
* Constructor that performs no validation.
* Use getInstance if you want that.
*
* @param predicate the predicate used to evaluate when the loop terminates, not null
* @param closure the closure the execute, not null
* @param doLoop true to act as a do-while loop, always executing the closure once
*/
public WhileClosure(Predicate predicate, Closure closure, boolean doLoop) {
super();
iPredicate = predicate;
iClosure = closure;
iDoLoop = doLoop;
}
/**
* Executes the closure until the predicate is false.
*
* @param input the input object
*/
public void execute(Object input) {
if (iDoLoop) {
iClosure.execute(input);
}
while (iPredicate.evaluate(input)) {
iClosure.execute(input);
}
}
/**
* Gets the predicate in use.
*
* @return the predicate
* @since Commons Collections 3.1
*/
public Predicate getPredicate() {
return iPredicate;
}
/**
* Gets the closure.
*
* @return the closure
* @since Commons Collections 3.1
*/
public Closure getClosure() {
return iClosure;
}
/**
* Is the loop a do-while loop.
*
* @return true is do-while, false if while
* @since Commons Collections 3.1
*/
public boolean isDoLoop() {
return iDoLoop;
}
}