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 com.google.errorprone.annotations.DoNotMock; 019import java.io.Serializable; 020import org.checkerframework.checker.nullness.qual.Nullable; 021 022/** 023 * An object which can send data from an object of type {@code T} into a {@code PrimitiveSink}. 024 * Implementations for common types can be found in {@link Funnels}. 025 * 026 * <p>Note that serialization of {@linkplain BloomFilter bloom filters} requires the proper 027 * serialization of funnels. When possible, it is recommended that funnels be implemented as a 028 * single-element enum to maintain serialization guarantees. See Effective Java (2nd Edition), Item 029 * 3: "Enforce the singleton property with a private constructor or an enum type". For example: 030 * 031 * <pre>{@code 032 * public enum PersonFunnel implements Funnel<Person> { 033 * INSTANCE; 034 * public void funnel(Person person, PrimitiveSink into) { 035 * into.putUnencodedChars(person.getFirstName()) 036 * .putUnencodedChars(person.getLastName()) 037 * .putInt(person.getAge()); 038 * } 039 * } 040 * }</pre> 041 * 042 * @author Dimitris Andreou 043 * @since 11.0 044 */ 045@Beta 046@DoNotMock("Implement with a lambda") 047@ElementTypesAreNonnullByDefault 048public interface Funnel<T extends @Nullable Object> extends Serializable { 049 050 /** 051 * Sends a stream of data from the {@code from} object into the sink {@code into}. There is no 052 * requirement that this data be complete enough to fully reconstitute the object later. 053 * 054 * @since 12.0 (in Guava 11.0, {@code PrimitiveSink} was named {@code Sink}) 055 */ 056 void funnel(@ParametricNullness T from, PrimitiveSink into); 057}