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/*
 * Original Guava code is copyright (C) 2015 The Guava Authors.
 * Modifications from Guava are copyright (C) 2016 DiffPlug.
 *
 * 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.diffplug.common.hash;

import java.io.Serializable;

import com.diffplug.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}.
 *
 * 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:
 * 
   {@code
 *   public enum PersonFunnel implements Funnel {
 *     INSTANCE;
 *     public void funnel(Person person, PrimitiveSink into) {
 *       into.putUnencodedChars(person.getFirstName())
 *           .putUnencodedChars(person.getLastName())
 *           .putInt(person.getAge());
 *     }
 *   }}
 *
 * @author Dimitris Andreou
 * @since 11.0
 */
@Beta
public interface Funnel 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);
}