| package org.apache.lucene.search.spans; |
| |
| /* |
| * 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. |
| */ |
| |
| import java.io.IOException; |
| import java.util.Collection; |
| |
| /** Expert: an enumeration of span matches. Used to implement span searching. |
| * Each span represents a range of term positions within a document. Matches |
| * are enumerated in order, by increasing document number, within that by |
| * increasing start position and finally by increasing end position. */ |
| public abstract class Spans { |
| /** Move to the next match, returning true iff any such exists. */ |
| public abstract boolean next() throws IOException; |
| |
| /** Skips to the first match beyond the current, whose document number is |
| * greater than or equal to <i>target</i>. |
| * <p>The behavior of this method is <b>undefined</b> when called with |
| * <code> target ≤ current</code>, or after the iterator has exhausted. |
| * Both cases may result in unpredicted behavior. |
| * <p>Returns true iff there is such |
| * a match. <p>Behaves as if written: <pre class="prettyprint"> |
| * boolean skipTo(int target) { |
| * do { |
| * if (!next()) |
| * return false; |
| * } while (target > doc()); |
| * return true; |
| * } |
| * </pre> |
| * Most implementations are considerably more efficient than that. |
| */ |
| public abstract boolean skipTo(int target) throws IOException; |
| |
| /** Returns the document number of the current match. Initially invalid. */ |
| public abstract int doc(); |
| |
| /** Returns the start position of the current match. Initially invalid. */ |
| public abstract int start(); |
| |
| /** Returns the end position of the current match. Initially invalid. */ |
| public abstract int end(); |
| |
| /** |
| * Returns the payload data for the current span. |
| * This is invalid until {@link #next()} is called for |
| * the first time. |
| * This method must not be called more than once after each call |
| * of {@link #next()}. However, most payloads are loaded lazily, |
| * so if the payload data for the current position is not needed, |
| * this method may not be called at all for performance reasons. An ordered |
| * SpanQuery does not lazy load, so if you have payloads in your index and |
| * you do not want ordered SpanNearQuerys to collect payloads, you can |
| * disable collection with a constructor option.<br> |
| * <br> |
| * Note that the return type is a collection, thus the ordering should not be relied upon. |
| * <br/> |
| * @lucene.experimental |
| * |
| * @return a List of byte arrays containing the data of this payload, otherwise null if isPayloadAvailable is false |
| * @throws IOException if there is a low-level I/O error |
| */ |
| // TODO: Remove warning after API has been finalized |
| public abstract Collection<byte[]> getPayload() throws IOException; |
| |
| /** |
| * Checks if a payload can be loaded at this position. |
| * <p/> |
| * Payloads can only be loaded once per call to |
| * {@link #next()}. |
| * |
| * @return true if there is a payload available at this position that can be loaded |
| */ |
| public abstract boolean isPayloadAvailable() throws IOException; |
| |
| /** |
| * Returns the estimated cost of this spans. |
| * <p> |
| * This is generally an upper bound of the number of documents this iterator |
| * might match, but may be a rough heuristic, hardcoded value, or otherwise |
| * completely inaccurate. |
| */ |
| public abstract long cost(); |
| } |