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/***********************************************************************************************************************
 *
 * Copyright (C) 2010-2013 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.api.java.functions;

import java.util.Iterator;

import eu.stratosphere.util.Collector;

/**
 * A variant of the {@link FlatMapFunction} that returns elements through an iterator, rather then
 * through a collector. In all other respects, it behaves exactly like the FlatMapFunction.
 * 

* The function needs to be serializable, as defined in {@link java.io.Serializable}. * * @param Type of the input elements. * @param Type of the returned elements. */ public abstract class FlatMapIterator extends FlatMapFunction { private static final long serialVersionUID = 1L; /** * The core method of the function. Takes an element from the input data set and transforms * it into zero, one, or more elements. * * @param value The input value. * @return An iterator over the returned elements. * * @throws Exception This method may throw exceptions. Throwing an exception will cause the operation * to fail and may trigger recovery. */ public abstract Iterator flatMap(IN value) throws Exception; // -------------------------------------------------------------------------------------------- /** * Delegates calls to the {@link #flatMap(Object)} method. */ @Override public final void flatMap(IN value, Collector out) throws Exception { for (Iterator iter = flatMap(value); iter.hasNext(); ) { out.collect(iter.next()); } } }





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