/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.flink.runtime.util;

import java.util.Iterator;

import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.util.MutableObjectIterator;

public class RegularToMutableObjectIterator<T> implements MutableObjectIterator<T> {

	private final Iterator<T> iterator;
	
	private final TypeSerializer<T> serializer;

	public RegularToMutableObjectIterator(Iterator<T> iterator, TypeSerializer<T> serializer) {
		this.iterator = iterator;
		this.serializer = serializer;
	}

	@Override
	public T next(T reuse) {
		// -----------------------------------------------------------------------------------------
		// IMPORTANT: WE NEED TO COPY INTO THE REUSE OBJECT TO SIMULATE THE MUTABLE OBJECT RUNTIME
		// -----------------------------------------------------------------------------------------
		if (this.iterator.hasNext()) {
			return this.serializer.copy(this.iterator.next(), reuse);
		} else {
			return null;
		}
	}

	@Override
	public T next() {
		if (this.iterator.hasNext()) {
			return this.iterator.next();
		} else {
			return null;
		}
	}
}