package org.apache.lucene.search;
/**
* 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;
/**
* This abstract class defines methods to iterate over a set of non-decreasing
* doc ids. Note that this class assumes it iterates on doc Ids, and therefore
* {@link #NO_MORE_DOCS} is set to {@value #NO_MORE_DOCS} in order to be used as
* a sentinel object. Implementations of this class are expected to consider
* {@link Integer#MAX_VALUE} as an invalid value.
*/
public abstract class DocIdSetIterator {
private int doc = -1;
/**
* When returned by {@link #nextDoc()}, {@link #advance(int)} and
* {@link #docID()} it means there are no more docs in the iterator.
*/
public static final int NO_MORE_DOCS = Integer.MAX_VALUE;
/**
* Returns the following:
* <ul>
* <li>-1 or {@link #NO_MORE_DOCS} if {@link #nextDoc()} or
* {@link #advance(int)} were not called yet.
* <li>{@link #NO_MORE_DOCS} if the iterator has exhausted.
* <li>Otherwise it should return the doc ID it is currently on.
* </ul>
* <p>
*
* @since 2.9
*/
public abstract int docID();
/**
* Advances to the next document in the set and returns the doc it is
* currently on, or {@link #NO_MORE_DOCS} if there are no more docs in the
* set.<br>
*
* <b>NOTE:</b> after the iterator has exhausted you should not call this
* method, as it may result in unpredicted behavior.
*
* @since 2.9
*/
public abstract int nextDoc() throws IOException;
/**
* Advances to the first beyond the current whose document number is greater
* than or equal to <i>target</i>. Returns the current document number or
* {@link #NO_MORE_DOCS} if there are no more docs in the set.
* <p>
* Behaves as if written:
*
* <pre>
* int advance(int target) {
* int doc;
* while ((doc = nextDoc()) < target) {
* }
* return doc;
* }
* </pre>
*
* Some implementations are considerably more efficient than that.
* <p>
* <b>NOTE:</b> certain implementations may return a different value (each
* time) if called several times in a row with the same target.
* <p>
* <b>NOTE:</b> this method may be called with {@value #NO_MORE_DOCS} for
* efficiency by some Scorers. If your implementation cannot efficiently
* determine that it should exhaust, it is recommended that you check for that
* value in each call to this method.
* <p>
* <b>NOTE:</b> after the iterator has exhausted you should not call this
* method, as it may result in unpredicted behavior.
* <p>
*
* @since 2.9
*/
public abstract int advance(int target) throws IOException;
}