    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 *
    031 * @since 3.0
    032 */
    033public class WhileClosure<E> implements Closure<E> {
    034
    035    /** The test condition */
    036    private final Predicate<? super E> iPredicate;
    037    /** The closure to call */
    038    private final Closure<? super E> iClosure;
    039    /** The flag, true is a do loop, false is a while */
    040    private final boolean iDoLoop;
    041
    042    /**
    043     * Factory method that performs validation.
    044     *
    045     * @param <E> the type that the closure acts on
    046     * @param predicate  the predicate used to evaluate when the loop terminates, not null
    047     * @param closure  the closure the execute, not null
    048     * @param doLoop  true to act as a do-while loop, always executing the closure once
    049     * @return the <code>while</code> closure
    050     * @throws NullPointerException if the predicate or closure is null
    051     */
    052    public static <E> Closure<E> whileClosure(final Predicate<? super E> predicate,
    053                                              final Closure<? super E> closure, final boolean doLoop) {
    054        if (predicate == null) {
    055            throw new NullPointerException("Predicate must not be null");
    056        }
    057        if (closure == null) {
    058            throw new NullPointerException("Closure must not be null");
    059        }
    060        return new WhileClosure<>(predicate, closure, doLoop);
    061    }
    062
    063    /**
    064     * Constructor that performs no validation.
    065     * Use <code>whileClosure</code> if you want that.
    066     *
    067     * @param predicate  the predicate used to evaluate when the loop terminates, not null
    068     * @param closure  the closure the execute, not null
    069     * @param doLoop  true to act as a do-while loop, always executing the closure once
    070     */
    071    public WhileClosure(final Predicate<? super E> predicate, final Closure<? super E> closure, final boolean doLoop) {
    072        super();
    073        iPredicate = predicate;
    074        iClosure = closure;
    075        iDoLoop = doLoop;
    076    }
    077
    078    /**
    079     * Executes the closure until the predicate is false.
    080     *
    081     * @param input  the input object
    082     */
    083    @Override
    084    public void execute(final E input) {
    085        if (iDoLoop) {
    086            iClosure.execute(input);
    087        }
    088        while (iPredicate.evaluate(input)) {
    089            iClosure.execute(input);
    090        }
    091    }
    092
    093    /**
    094     * Gets the predicate in use.
    095     *
    096     * @return the predicate
    097     * @since 3.1
    098     */
    099    public Predicate<? super E> getPredicate() {
    100        return iPredicate;
    101    }
    102
    103    /**
    104     * Gets the closure.
    105     *
    106     * @return the closure
    107     * @since 3.1
    108     */
    109    public Closure<? super E> getClosure() {
    110        return iClosure;
    111    }
    112
    113    /**
    114     * Is the loop a do-while loop.
    115     *
    116     * @return true is do-while, false if while
    117     * @since 3.1
    118     */
    119    public boolean isDoLoop() {
    120        return iDoLoop;
    121    }
    122
    123}