    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 *      https://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 java.util.Objects;
    020
    021import org.apache.commons.collections4.Closure;
    022import org.apache.commons.collections4.Predicate;
    023
    024/**
    025 * Closure implementation that executes a closure repeatedly until a condition is met,
    026 * like a do-while or while loop.
    027 * <p>
    028 * <strong>WARNING:</strong> from v4.1 onwards this class will <strong>not</strong> be serializable anymore
    029 * in order to prevent potential remote code execution exploits. Please refer to
    030 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
    031 * for more details.
    032 * </p>
    033 *
    034 * @param <T> The type of the input to the operation.
    035 * @since 3.0
    036 */
    037public class WhileClosure<T> implements Closure<T> {
    038
    039    /**
    040     * Factory method that performs validation.
    041     *
    042     * @param <E> The type that the closure acts on
    043     * @param predicate  The predicate used to evaluate when the loop terminates, not null
    044     * @param closure  The closure to execute, not null
    045     * @param doLoop  true to act as a do-while loop, always executing the closure once
    046     * @return The {@code while} closure
    047     * @throws NullPointerException if the predicate or closure is null
    048     */
    049    public static <E> Closure<E> whileClosure(final Predicate<? super E> predicate,
    050                                              final Closure<? super E> closure, final boolean doLoop) {
    051        return new WhileClosure<>(Objects.requireNonNull(predicate, "predicate"),
    052                Objects.requireNonNull(closure, "closure"), doLoop);
    053    }
    054
    055    /** The test condition */
    056    private final Predicate<? super T> iPredicate;
    057
    058    /** The closure to call */
    059    private final Closure<? super T> iClosure;
    060
    061    /** The flag, true is a do loop, false is a while */
    062    private final boolean iDoLoop;
    063
    064    /**
    065     * Constructor that performs no validation.
    066     * Use {@code whileClosure} if you want that.
    067     *
    068     * @param predicate  The predicate used to evaluate when the loop terminates, not null
    069     * @param closure  The closure to 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 T> predicate, final Closure<? super T> closure, final boolean doLoop) {
    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 T input) {
    085        if (iDoLoop) {
    086            iClosure.accept(input);
    087        }
    088        while (iPredicate.test(input)) {
    089            iClosure.accept(input);
    090        }
    091    }
    092
    093    /**
    094     * Gets the closure.
    095     *
    096     * @return The closure
    097     * @since 3.1
    098     */
    099    public Closure<? super T> getClosure() {
    100        return iClosure;
    101    }
    102
    103    /**
    104     * Gets the predicate in use.
    105     *
    106     * @return The predicate
    107     * @since 3.1
    108     */
    109    public Predicate<? super T> getPredicate() {
    110        return iPredicate;
    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}