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 * <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    /** The test condition */
055    private final Predicate<? super T> iPredicate;
056    /** The closure to call */
057    private final Closure<? super T> iClosure;
058
059    /** The flag, true is a do loop, false is a while */
060    private final boolean iDoLoop;
061
062    /**
063     * Constructor that performs no validation.
064     * Use {@code whileClosure} if you want that.
065     *
066     * @param predicate  the predicate used to evaluate when the loop terminates, not null
067     * @param closure  the closure to execute, not null
068     * @param doLoop  true to act as a do-while loop, always executing the closure once
069     */
070    public WhileClosure(final Predicate<? super T> predicate, final Closure<? super T> closure, final boolean doLoop) {
071        iPredicate = predicate;
072        iClosure = closure;
073        iDoLoop = doLoop;
074    }
075
076    /**
077     * Executes the closure until the predicate is false.
078     *
079     * @param input  the input object
080     */
081    @Override
082    public void execute(final T input) {
083        if (iDoLoop) {
084            iClosure.accept(input);
085        }
086        while (iPredicate.test(input)) {
087            iClosure.accept(input);
088        }
089    }
090
091    /**
092     * Gets the closure.
093     *
094     * @return the closure
095     * @since 3.1
096     */
097    public Closure<? super T> getClosure() {
098        return iClosure;
099    }
100
101    /**
102     * Gets the predicate in use.
103     *
104     * @return the predicate
105     * @since 3.1
106     */
107    public Predicate<? super T> getPredicate() {
108        return iPredicate;
109    }
110
111    /**
112     * Is the loop a do-while loop.
113     *
114     * @return true is do-while, false if while
115     * @since 3.1
116     */
117    public boolean isDoLoop() {
118        return iDoLoop;
119    }
120
121}