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ZippingIterator.java
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ZippingIterator.java
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/**
* Copyright 2014 DuraSpace, Inc.
*
* 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 org.fcrepo.kernel.impl.rdf.impl.mappings;
import static org.slf4j.LoggerFactory.getLogger;
import java.util.Iterator;
import org.slf4j.Logger;
import com.google.common.collect.AbstractIterator;
import com.google.common.base.Function;
/**
* An {@link Iterator} that zips an Iterator of functions with an iterator of
* values on which the functions must act.
*
* @author ajs6f
* @since Oct 10, 2013
* @param <FromType>
* @param <ToType>
*/
public class ZippingIterator<FromType, ToType> extends AbstractIterator<ToType> {
private Iterator<FromType> from;
private Iterator<Function<FromType, ToType>> through;
private static final Logger LOGGER = getLogger(ZippingIterator.class);
/**
* Default constructor.
*
* @param from
* @param through
*/
public ZippingIterator(final Iterator<FromType> from,
final Iterator<Function<FromType, ToType>> through) {
super();
this.from = from;
this.through = through;
}
@Override
protected ToType computeNext() {
final boolean hasNext = (from.hasNext() && through.hasNext());
if (hasNext) {
LOGGER.trace("Found next element.");
final FromType f = from.next();
final Function<FromType, ToType> t = through.next();
LOGGER.trace("Supplying from next element {} through function {}",
f, t);
return t.apply(f);
}
return endOfData();
}
}