001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.collections4.bloomfilter; 018 019/** 020 * A Hasher creates IndexExtractor based on the hash implementation and the 021 * provided Shape. 022 * 023 * @since 4.5 024 */ 025public interface Hasher { 026 027 /** 028 * Creates an IndexExtractor for this hasher based on the Shape. 029 * 030 * <p>The {@code IndexExtractor} will create indices within the range defined by the number of bits in 031 * the shape. The total number of indices will respect the number of hash functions per item 032 * defined by the shape. However the count of indices may not be a multiple of the number of 033 * hash functions if the implementation has removed duplicates.</p> 034 * 035 * <p>This IndexExtractor must be deterministic in that it must return the same indices for the 036 * same Shape.</p> 037 * 038 * <p>No guarantee is made as to order of indices.</p> 039 * <p>Duplicates indices for a single item may be produced.</p> 040 * 041 * @param shape the shape of the desired Bloom filter. 042 * @return the iterator of integers 043 */ 044 IndexExtractor indices(Shape shape); 045}