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 Testing Hasher that returns the array values % shape.getNumberOfBits().
24 *
25 * <p>To be used for testing only.</p>
26 */
27 public final class ArrayHasher implements Hasher {
28 private final class Producer implements IndexProducer {
29 Shape shape;
30
31 Producer(final Shape shape) {
32 this.shape = shape;
33 }
34
35 @Override
36 public boolean forEachIndex(final IntPredicate consumer) {
37 Objects.requireNonNull(consumer, "consumer");
38
39 int pos = 0;
40 for (int i = 0; i < shape.getNumberOfHashFunctions(); i++) {
41 final int result = values[pos++] % shape.getNumberOfBits();
42 pos %= values.length;
43 if (!consumer.test(result)) {
44 return false;
45 }
46 }
47 return true;
48 }
49 }
50
51 private final int[] values;
52
53 public ArrayHasher(final int... values) {
54 this.values = values;
55 }
56
57 @Override
58 public IndexProducer indices(final Shape shape) {
59 Objects.requireNonNull(shape, "shape");
60 return new Producer(shape);
61 }
62 }