| /* |
| * 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.lucene.spatial.prefix.tree; |
| |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| |
| /** |
| * An Iterator of SpatialPrefixTree Cells. The order is always sorted without duplicates. |
| * |
| * @lucene.experimental |
| */ |
| public abstract class CellIterator implements Iterator<Cell> { |
| |
| //note: nextCell or thisCell can be non-null but neither at the same time. That's |
| // because they might return the same instance when re-used! |
| |
| protected Cell nextCell;//to be returned by next(), and null'ed after |
| protected Cell thisCell;//see next() & thisCell(). Should be cleared in hasNext(). |
| |
| /** Returns the cell last returned from {@link #next()}. It's cleared by hasNext(). */ |
| public Cell thisCell() { |
| assert thisCell != null : "Only call thisCell() after next(), not hasNext()"; |
| return thisCell; |
| } |
| |
| // Arguably this belongs here and not on Cell |
| //public SpatialRelation getShapeRel() |
| |
| /** |
| * Gets the next cell that is >= {@code fromCell}, compared using non-leaf bytes. If it returns null then |
| * the iterator is exhausted. |
| */ |
| public Cell nextFrom(Cell fromCell) { |
| while (true) { |
| if (!hasNext()) |
| return null; |
| Cell c = next();//will update thisCell |
| if (c.compareToNoLeaf(fromCell) >= 0) { |
| return c; |
| } |
| } |
| } |
| |
| /** This prevents sub-cells (those underneath the current cell) from being iterated to, |
| * if applicable, otherwise a NO-OP. */ |
| @Override |
| public void remove() { |
| assert thisCell != null; |
| } |
| |
| @Override |
| public Cell next() { |
| if (nextCell == null) { |
| if (!hasNext()) |
| throw new NoSuchElementException(); |
| } |
| thisCell = nextCell; |
| nextCell = null; |
| return thisCell; |
| } |
| } |