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 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> 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 * @since 3.0
35 */
36 public class WhileClosure<E> implements Closure<E> {
37
38 /**
39 * Factory method that performs validation.
40 *
41 * @param <E> the type that the closure acts on
42 * @param predicate the predicate used to evaluate when the loop terminates, not null
43 * @param closure the closure to execute, not null
44 * @param doLoop true to act as a do-while loop, always executing the closure once
45 * @return the {@code while} closure
46 * @throws NullPointerException if the predicate or closure is null
47 */
48 public static <E> Closure<E> whileClosure(final Predicate<? super E> predicate,
49 final Closure<? super E> closure, final boolean doLoop) {
50 return new WhileClosure<>(Objects.requireNonNull(predicate, "predicate"),
51 Objects.requireNonNull(closure, "closure"), doLoop);
52 }
53 /** The test condition */
54 private final Predicate<? super E> iPredicate;
55 /** The closure to call */
56 private final Closure<? super E> iClosure;
57
58 /** The flag, true is a do loop, false is a while */
59 private final boolean iDoLoop;
60
61 /**
62 * Constructor that performs no validation.
63 * Use {@code whileClosure} if you want that.
64 *
65 * @param predicate the predicate used to evaluate when the loop terminates, not null
66 * @param closure the closure to execute, not null
67 * @param doLoop true to act as a do-while loop, always executing the closure once
68 */
69 public WhileClosure(final Predicate<? super E> predicate, final Closure<? super E> closure, final boolean doLoop) {
70 iPredicate = predicate;
71 iClosure = closure;
72 iDoLoop = doLoop;
73 }
74
75 /**
76 * Executes the closure until the predicate is false.
77 *
78 * @param input the input object
79 */
80 @Override
81 public void execute(final E input) {
82 if (iDoLoop) {
83 iClosure.execute(input);
84 }
85 while (iPredicate.evaluate(input)) {
86 iClosure.execute(input);
87 }
88 }
89
90 /**
91 * Gets the closure.
92 *
93 * @return the closure
94 * @since 3.1
95 */
96 public Closure<? super E> getClosure() {
97 return iClosure;
98 }
99
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 }