| /*- |
| * 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.sling.query.iterator; |
| |
| import java.util.Iterator; |
| import java.util.ListIterator; |
| |
| import org.apache.sling.query.api.internal.Option; |
| import org.apache.sling.query.util.LazyList; |
| |
| public class LastIterator<T> extends AbstractIterator<Option<T>> { |
| |
| private final LazyList<Option<T>> lazyList; |
| |
| private final ListIterator<Option<T>> iterator; |
| |
| private boolean finished; |
| |
| private boolean initialized; |
| |
| private int lastIndex = -1; |
| |
| public LastIterator(Iterator<Option<T>> iterator) { |
| this.lazyList = new LazyList<Option<T>>(iterator); |
| this.iterator = lazyList.listIterator(); |
| } |
| |
| @Override |
| protected Option<T> getElement() { |
| if (finished) { |
| return null; |
| } |
| |
| initializeLastIndex(); |
| |
| Option<T> candidate; |
| if (iterator.hasNext()) { |
| candidate = iterator.next(); |
| } else { |
| finished = true; |
| return null; |
| } |
| if (iterator.previousIndex() == lastIndex) { |
| finished = true; |
| return candidate; |
| } else { |
| return Option.empty(candidate.getArgumentId()); |
| } |
| } |
| |
| private void initializeLastIndex() { |
| ListIterator<Option<T>> i = lazyList.listIterator(); |
| if (!initialized) { |
| while (i.hasNext()) { |
| if (!i.next().isEmpty()) { |
| lastIndex = i.previousIndex(); |
| } |
| } |
| } |
| initialized = true; |
| } |
| } |