package org.apache.blur.manager.results;
import org.apache.blur.utils.BlurIterator;
/**
* 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.
*/
/**
*
*/
public class PeekableIterator<T, E extends Exception> implements BlurIterator<T, E> {
private final BlurIterator<T, E> _iterator;
private T _current;
private PeekableIterator(BlurIterator<T, E> iterator, T current) {
_iterator = iterator;
_current = current;
}
public static <T, E extends Exception> PeekableIterator<T, E> wrap(BlurIterator<T, E> iterator) throws E {
if (iterator.hasNext()) {
return new PeekableIterator<T, E>(iterator, iterator.next());
}
return new PeekableIterator<T, E>(iterator, null);
}
/**
* Only valid is hasNext is true. If hasNext if false, peek will return null;
*
* @return <T>
*/
public T peek() {
return _current;
}
@Override
public boolean hasNext() throws E {
if (_current != null) {
return true;
}
return _iterator.hasNext();
}
@Override
public T next() throws E {
T next = null;
if (_iterator.hasNext()) {
next = _iterator.next();
}
T result = _current;
_current = next;
return result;
}
@Override
public long getPosition() throws E {
return _iterator.getPosition() - 1;
}
}