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.collections.buffer;
18
19 import org.apache.commons.collections.Buffer;
20 import org.apache.commons.collections.Predicate;
21 import org.apache.commons.collections.collection.PredicatedCollection;
22
23 /**
24 * Decorates another {@link Buffer} to validate that additions
25 * match a specified predicate.
26 * <p>
27 * This buffer exists to provide validation for the decorated buffer.
28 * It is normally created to decorate an empty buffer.
29 * If an object cannot be added to the buffer, an IllegalArgumentException is thrown.
30 * <p>
31 * One usage would be to ensure that no null entries are added to the buffer.
32 * <pre>Buffer buffer = PredicatedBuffer.decorate(new UnboundedFifoBuffer(), NotNullPredicate.INSTANCE);</pre>
33 * <p>
34 * This class is Serializable from Commons Collections 3.1.
35 *
36 * @since 3.0
37 * @version $Id: PredicatedBuffer.java 1436835 2013-01-22 11:03:31Z tn $
38 */
39 public class PredicatedBuffer<E> extends PredicatedCollection<E> implements Buffer<E> {
40
41 /** Serialization version */
42 private static final long serialVersionUID = 2307609000539943581L;
43
44 /**
45 * Factory method to create a predicated (validating) buffer.
46 * <p>
47 * If there are any elements already in the buffer being decorated, they
48 * are validated.
49 *
50 * @param <E> the type of the elements in the buffer
51 * @param buffer the buffer to decorate, must not be null
52 * @param predicate the predicate to use for validation, must not be null
53 * @return a new predicated Buffer
54 * @throws IllegalArgumentException if buffer or predicate is null
55 * @throws IllegalArgumentException if the buffer contains invalid elements
56 */
57 public static <E> PredicatedBuffer<E> predicatedBuffer(final Buffer<E> buffer,
58 final Predicate<? super E> predicate) {
59 return new PredicatedBuffer<E>(buffer, predicate);
60 }
61
62 //-----------------------------------------------------------------------
63 /**
64 * Constructor that wraps (not copies).
65 * <p>
66 * If there are any elements already in the collection being decorated, they
67 * are validated.
68 *
69 * @param buffer the buffer to decorate, must not be null
70 * @param predicate the predicate to use for validation, must not be null
71 * @throws IllegalArgumentException if buffer or predicate is null
72 * @throws IllegalArgumentException if the buffer contains invalid elements
73 */
74 protected PredicatedBuffer(final Buffer<E> buffer, final Predicate<? super E> predicate) {
75 super(buffer, predicate);
76 }
77
78 /**
79 * Gets the buffer being decorated.
80 *
81 * @return the decorated buffer
82 */
83 @Override
84 protected Buffer<E> decorated() {
85 return (Buffer<E>) super.decorated();
86 }
87
88 //-----------------------------------------------------------------------
89
90 public E get() {
91 return decorated().get();
92 }
93
94 public E remove() {
95 return decorated().remove();
96 }
97
98 }