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 /**
20 * A Hasher creates IndexProducer based on the hash implementation and the
21 * provided Shape.
22 *
23 * @since 4.5
24 */
25 public interface Hasher {
26
27 /**
28 * Creates an IndexProducer for this hasher based on the Shape.
29 *
30 * <p>The {@code IndexProducer} will create indices within the range defined by the number of bits in
31 * the shape. The total number of indices will respect the number of hash functions per item
32 * defined by the shape. However the count of indices may not be a multiple of the number of
33 * hash functions if the implementation has removed duplicates.</p>
34 *
35 * <p>This IndexProducer must be deterministic in that it must return the same indices for the
36 * same Shape.</p>
37 *
38 * <p>No guarantee is made as to order of indices.</p>
39 * <p>Duplicates indices for a single item may be produced.</p>
40 *
41 * @param shape the shape of the desired Bloom filter.
42 * @return the iterator of integers
43 */
44 IndexProducer indices(Shape shape);
45 }