1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections4.functors;
18
19 import java.util.Objects;
20
21 import org.apache.commons.collections4.Closure;
22 import org.apache.commons.collections4.Predicate;
23
24 /**
25 * Closure implementation that executes a closure repeatedly until a condition is met,
26 * like a do-while or while loop.
27 * <p>
28 * <strong>WARNING:</strong> from v4.1 onwards this class will <strong>not</strong> be serializable anymore
29 * in order to prevent potential remote code execution exploits. Please refer to
30 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
31 * for more details.
32 * </p>
33 *
34 * @param <T> the type of the input to the operation.
35 * @since 3.0
36 */
37 public class WhileClosure<T> implements Closure<T> {
38
39 /**
40 * Factory method that performs validation.
41 *
42 * @param <E> the type that the closure acts on
43 * @param predicate the predicate used to evaluate when the loop terminates, not null
44 * @param closure the closure to execute, not null
45 * @param doLoop true to act as a do-while loop, always executing the closure once
46 * @return the {@code while} closure
47 * @throws NullPointerException if the predicate or closure is null
48 */
49 public static <E> Closure<E> whileClosure(final Predicate<? super E> predicate,
50 final Closure<? super E> closure, final boolean doLoop) {
51 return new WhileClosure<>(Objects.requireNonNull(predicate, "predicate"),
52 Objects.requireNonNull(closure, "closure"), doLoop);
53 }
54 /** The test condition */
55 private final Predicate<? super T> iPredicate;
56 /** The closure to call */
57 private final Closure<? super T> iClosure;
58
59 /** The flag, true is a do loop, false is a while */
60 private final boolean iDoLoop;
61
62 /**
63 * Constructor that performs no validation.
64 * Use {@code whileClosure} if you want that.
65 *
66 * @param predicate the predicate used to evaluate when the loop terminates, not null
67 * @param closure the closure to execute, not null
68 * @param doLoop true to act as a do-while loop, always executing the closure once
69 */
70 public WhileClosure(final Predicate<? super T> predicate, final Closure<? super T> closure, final boolean doLoop) {
71 iPredicate = predicate;
72 iClosure = closure;
73 iDoLoop = doLoop;
74 }
75
76 /**
77 * Executes the closure until the predicate is false.
78 *
79 * @param input the input object
80 */
81 @Override
82 public void execute(final T input) {
83 if (iDoLoop) {
84 iClosure.accept(input);
85 }
86 while (iPredicate.test(input)) {
87 iClosure.accept(input);
88 }
89 }
90
91 /**
92 * Gets the closure.
93 *
94 * @return the closure
95 * @since 3.1
96 */
97 public Closure<? super T> getClosure() {
98 return iClosure;
99 }
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 }