001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4.functors;
018
019import org.apache.commons.collections4.Closure;
020import org.apache.commons.collections4.Predicate;
021
022/**
023 * Closure implementation that executes a closure repeatedly until a condition is met,
024 * like a do-while or while loop.
025 * <p>
026 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> be serializable anymore
027 * in order to prevent potential remote code execution exploits. Please refer to
028 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
029 * for more details.
030 * </p>
031 *
032 * @since 3.0
033 */
034public class WhileClosure<E> implements Closure<E> {
035
036    /** The test condition */
037    private final Predicate<? super E> iPredicate;
038    /** The closure to call */
039    private final Closure<? super E> iClosure;
040    /** The flag, true is a do loop, false is a while */
041    private final boolean iDoLoop;
042
043    /**
044     * Factory method that performs validation.
045     *
046     * @param <E> the type that the closure acts on
047     * @param predicate  the predicate used to evaluate when the loop terminates, not null
048     * @param closure  the closure the execute, not null
049     * @param doLoop  true to act as a do-while loop, always executing the closure once
050     * @return the <code>while</code> closure
051     * @throws NullPointerException if the predicate or closure is null
052     */
053    public static <E> Closure<E> whileClosure(final Predicate<? super E> predicate,
054                                              final Closure<? super E> closure, final boolean doLoop) {
055        if (predicate == null) {
056            throw new NullPointerException("Predicate must not be null");
057        }
058        if (closure == null) {
059            throw new NullPointerException("Closure must not be null");
060        }
061        return new WhileClosure<>(predicate, closure, doLoop);
062    }
063
064    /**
065     * Constructor that performs no validation.
066     * Use <code>whileClosure</code> if you want that.
067     *
068     * @param predicate  the predicate used to evaluate when the loop terminates, not null
069     * @param closure  the closure the execute, not null
070     * @param doLoop  true to act as a do-while loop, always executing the closure once
071     */
072    public WhileClosure(final Predicate<? super E> predicate, final Closure<? super E> closure, final boolean doLoop) {
073        super();
074        iPredicate = predicate;
075        iClosure = closure;
076        iDoLoop = doLoop;
077    }
078
079    /**
080     * Executes the closure until the predicate is false.
081     *
082     * @param input  the input object
083     */
084    @Override
085    public void execute(final E input) {
086        if (iDoLoop) {
087            iClosure.execute(input);
088        }
089        while (iPredicate.evaluate(input)) {
090            iClosure.execute(input);
091        }
092    }
093
094    /**
095     * Gets the predicate in use.
096     *
097     * @return the predicate
098     * @since 3.1
099     */
100    public Predicate<? super E> getPredicate() {
101        return iPredicate;
102    }
103
104    /**
105     * Gets the closure.
106     *
107     * @return the closure
108     * @since 3.1
109     */
110    public Closure<? super E> getClosure() {
111        return iClosure;
112    }
113
114    /**
115     * Is the loop a do-while loop.
116     *
117     * @return true is do-while, false if while
118     * @since 3.1
119     */
120    public boolean isDoLoop() {
121        return iDoLoop;
122    }
123
124}