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 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 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> 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 * @since 3.0
035 */
036public class WhileClosure<E> implements Closure<E> {
037
038    /**
039     * Factory method that performs validation.
040     *
041     * @param <E> the type that the closure acts on
042     * @param predicate  the predicate used to evaluate when the loop terminates, not null
043     * @param closure  the closure to execute, not null
044     * @param doLoop  true to act as a do-while loop, always executing the closure once
045     * @return the {@code while} closure
046     * @throws NullPointerException if the predicate or closure is null
047     */
048    public static <E> Closure<E> whileClosure(final Predicate<? super E> predicate,
049                                              final Closure<? super E> closure, final boolean doLoop) {
050        return new WhileClosure<>(Objects.requireNonNull(predicate, "predicate"),
051                Objects.requireNonNull(closure, "closure"), doLoop);
052    }
053    /** The test condition */
054    private final Predicate<? super E> iPredicate;
055    /** The closure to call */
056    private final Closure<? super E> iClosure;
057
058    /** The flag, true is a do loop, false is a while */
059    private final boolean iDoLoop;
060
061    /**
062     * Constructor that performs no validation.
063     * Use {@code whileClosure} if you want that.
064     *
065     * @param predicate  the predicate used to evaluate when the loop terminates, not null
066     * @param closure  the closure to execute, not null
067     * @param doLoop  true to act as a do-while loop, always executing the closure once
068     */
069    public WhileClosure(final Predicate<? super E> predicate, final Closure<? super E> closure, final boolean doLoop) {
070        iPredicate = predicate;
071        iClosure = closure;
072        iDoLoop = doLoop;
073    }
074
075    /**
076     * Executes the closure until the predicate is false.
077     *
078     * @param input  the input object
079     */
080    @Override
081    public void execute(final E input) {
082        if (iDoLoop) {
083            iClosure.execute(input);
084        }
085        while (iPredicate.evaluate(input)) {
086            iClosure.execute(input);
087        }
088    }
089
090    /**
091     * Gets the closure.
092     *
093     * @return the closure
094     * @since 3.1
095     */
096    public Closure<? super E> getClosure() {
097        return iClosure;
098    }
099
100    /**
101     * Gets the predicate in use.
102     *
103     * @return the predicate
104     * @since 3.1
105     */
106    public Predicate<? super E> getPredicate() {
107        return iPredicate;
108    }
109
110    /**
111     * Is the loop a do-while loop.
112     *
113     * @return true is do-while, false if while
114     * @since 3.1
115     */
116    public boolean isDoLoop() {
117        return iDoLoop;
118    }
119
120}