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.bloomfilter;
18
19 import java.util.Objects;
20 import java.util.function.IntPredicate;
21
22 /**
23 * A Hasher that returns no values.
24 *
25 * <p>To be used for testing only.</p>
26 */
27 final class NullHasher implements Hasher {
28
29 /**
30 * The instance of the Null Hasher.
31 */
32 static final NullHasher INSTANCE = new NullHasher();
33
34 private static final IndexProducer PRODUCER = new IndexProducer() {
35 @Override
36 public int[] asIndexArray() {
37 return new int[0];
38 }
39
40 @Override
41 public boolean forEachIndex(final IntPredicate consumer) {
42 Objects.requireNonNull(consumer, "consumer");
43 return true;
44 }
45 };
46
47 private NullHasher() {
48 // No instances
49 }
50
51 @Override
52 public IndexProducer indices(final Shape shape) {
53 Objects.requireNonNull(shape, "shape");
54 return PRODUCER;
55 }
56 }