001/*
002 * Copyright (C) 2011 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.hash;
016
017import com.google.common.annotations.Beta;
018import java.io.Serializable;
019
020/**
021 * An object which can send data from an object of type {@code T} into a {@code PrimitiveSink}.
022 * Implementations for common types can be found in {@link Funnels}.
023 *
024 * <p>Note that serialization of {@linkplain BloomFilter bloom filters} requires the proper
025 * serialization of funnels. When possible, it is recommended that funnels be implemented as a
026 * single-element enum to maintain serialization guarantees. See Effective Java (2nd Edition), Item
027 * 3: "Enforce the singleton property with a private constructor or an enum type". For example:
028 *
029 * <pre>{@code
030 * public enum PersonFunnel implements Funnel<Person> {
031 *   INSTANCE;
032 *   public void funnel(Person person, PrimitiveSink into) {
033 *     into.putUnencodedChars(person.getFirstName())
034 *         .putUnencodedChars(person.getLastName())
035 *         .putInt(person.getAge());
036 *   }
037 * }
038 * }</pre>
039 *
040 * @author Dimitris Andreou
041 * @since 11.0
042 */
043@Beta
044public interface Funnel<T> extends Serializable {
045
046  /**
047   * Sends a stream of data from the {@code from} object into the sink {@code into}. There is no
048   * requirement that this data be complete enough to fully reconstitute the object later.
049   *
050   * @since 12.0 (in Guava 11.0, {@code PrimitiveSink} was named {@code Sink})
051   */
052  void funnel(T from, PrimitiveSink into);
053}