/***********************************************************************************************************************
 *
 * Copyright (C) 2010 by the Stratosphere project (http://stratosphere.eu)
 *
 * 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 eu.stratosphere.nephele.services.iomanager;

import java.io.DataInput;
import java.io.IOException;
import java.io.InputStream;

/**
 * <p>
 * Provides a facility for deserializing objects of type <T> from an {@link InputStream}.
 * </p>
 * <p>
 * Deserializers are stateful, but must not buffer the input since other producers may read from the input between calls
 * to {@link #deserialize(Object)}.
 * </p>
 * 
 * @author Erik Nijkamp
 * @param <T>
 */
public interface Deserializer<T> {
	/**
	 * <p>
	 * Prepare the deserializer for reading.
	 * </p>
	 */
	void open(DataInput in) throws IOException;

	/**
	 * <p>
	 * Deserialize the next object from the underlying input stream. If the object <code>t</code> is non-null then this
	 * deserializer <i>may</i> set its internal state to the next object read from the input stream. Otherwise, if the
	 * object <code>t</code> is null a new deserialized object will be created.
	 * </p>
	 * 
	 * @return the deserialized object
	 */
	T deserialize(T t) throws IOException;

	/**
	 * <p>
	 * Clear up any resources.
	 * </p>
	 */
	void close() throws IOException;
}
