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Lucene example source code file (DocIdSetIterator.java)

This example Lucene source code file (DocIdSetIterator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

docidsetiterator, docidsetiterator, io, ioexception, ioexception, no_more_docs, no_more_docs

The Lucene DocIdSetIterator.java source code

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 {
  
  /**
   * 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: 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 (see NOTE below) the current whose document
   * number is greater than or equal to <i>target. 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: when  target ≤ current implementations may opt
   * not to advance beyond their current {@link #docID()}.
   * <p>
   * <b>NOTE: this method may be called with {@link #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: 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;

}

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