/*
 * Copyright (C) 2011 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.hash;

import java.io.Serializable;

import com.google.common.annotations.Beta;

/**
 * An object which can send data from an object of type {@code T} into a
 * {@code PrimitiveSink}. Implementations for common types can be found in
 * {@link Funnels}.
 *
 * <p>
 * Note that serialization of {@linkplain BloomFilter bloom filters} requires
 * the proper serialization of funnels. When possible, it is recommended that
 * funnels be implemented as a single-element enum to maintain serialization
 * guarantees. See Effective Java (2nd Edition), Item 3: "Enforce the singleton
 * property with a private constructor or an enum type". For example:
 * 
 * <pre>
 *    {@code
 *   public enum PersonFunnel implements Funnel<Person> {
 *     INSTANCE;
 *     public void funnel(Person person, PrimitiveSink into) {
 *       into.putUnencodedChars(person.getFirstName())
 *           .putUnencodedChars(person.getLastName())
 *           .putInt(person.getAge());
 *     }
 *   }}
 * </pre>
 *
 * @author Dimitris Andreou
 * @since 11.0
 */
@Beta
public interface Funnel<T> extends Serializable {

	/**
	 * Sends a stream of data from the {@code from} object into the sink
	 * {@code into}. There is no requirement that this data be complete enough to
	 * fully reconstitute the object later.
	 *
	 * @since 12.0 (in Guava 11.0, {@code PrimitiveSink} was named {@code Sink})
	 */
	void funnel(T from, PrimitiveSink into);
}