| /* |
| * 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.queries.intervals; |
| |
| import java.io.IOException; |
| import org.apache.lucene.search.DocIdSetIterator; |
| import org.apache.lucene.search.TwoPhaseIterator; |
| |
| /** |
| * A {@link DocIdSetIterator} that also allows iteration over matching intervals in a document. |
| * |
| * <p>Once the iterator is positioned on a document by calling {@link #advance(int)} or {@link |
| * #nextDoc()}, intervals may be retrieved by calling {@link #nextInterval()} until {@link |
| * #NO_MORE_INTERVALS} is returned. |
| * |
| * <p>The limits of the current interval are returned by {@link #start()} and {@link #end()}. When |
| * the iterator has been moved to a new document, but before {@link #nextInterval()} has been |
| * called, both these methods return {@code -1}. |
| * |
| * <p>Note that it is possible for a document to return {@link #NO_MORE_INTERVALS} on the first call |
| * to {@link #nextInterval()} |
| */ |
| public abstract class IntervalIterator extends DocIdSetIterator { |
| |
| /** |
| * When returned from {@link #nextInterval()}, indicates that there are no more matching intervals |
| * on the current document |
| */ |
| public static final int NO_MORE_INTERVALS = Integer.MAX_VALUE; |
| |
| /** |
| * The start of the current interval |
| * |
| * <p>Returns -1 if {@link #nextInterval()} has not yet been called and {@link #NO_MORE_INTERVALS} |
| * once the iterator is exhausted. |
| */ |
| public abstract int start(); |
| |
| /** |
| * The end of the current interval |
| * |
| * <p>Returns -1 if {@link #nextInterval()} has not yet been called and {@link #NO_MORE_INTERVALS} |
| * once the iterator is exhausted. |
| */ |
| public abstract int end(); |
| |
| /** |
| * The number of gaps within the current interval |
| * |
| * <p>Note that this returns the number of gaps between the immediate sub-intervals of this |
| * interval, and does not include the gaps inside those sub-intervals. |
| * |
| * <p>Should not be called before {@link #nextInterval()}, or after it has returned {@link |
| * #NO_MORE_INTERVALS} |
| */ |
| public abstract int gaps(); |
| |
| /** The width of the current interval */ |
| public int width() { |
| return end() - start() + 1; |
| } |
| |
| /** |
| * Advance the iterator to the next interval |
| * |
| * <p>Should not be called after {@link DocIdSetIterator#NO_MORE_DOCS} is returned by {@link |
| * DocIdSetIterator#nextDoc()} or {@link DocIdSetIterator#advance(int)}. If that's the case in |
| * some existing code, please consider opening an issue. However, after {@link |
| * IntervalIterator#NO_MORE_INTERVALS} is returned by this method, it might be called again. |
| * |
| * @return the start of the next interval, or {@link IntervalIterator#NO_MORE_INTERVALS} if there |
| * are no more intervals on the current document |
| */ |
| public abstract int nextInterval() throws IOException; |
| |
| /** |
| * An indication of the average cost of iterating over all intervals in a document |
| * |
| * @see TwoPhaseIterator#matchCost() |
| */ |
| public abstract float matchCost(); |
| |
| @Override |
| public String toString() { |
| return docID() + ":[" + start() + "->" + end() + "]"; |
| } |
| } |