| /* |
| * 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. |
| * |
| * 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. |
| * |
| * 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}. |
| * |
| * 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 |
| * |
| * 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 |
| * |
| * 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 |
| * |
| * 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. |
| * |
| * 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 |
| * |
| * @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() + "]"; |
| } |
| |
| } |