Lucene example source code file (DocIdBitSet.java)

This example Lucene source code file (DocIdBitSet.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

bitset, bitset, docidbitset, docidbitsetiterator, docidbitsetiterator, docidset, docidsetiterator, docidsetiterator, no_more_docs, override, override, util

The Lucene DocIdBitSet.java source code

package org.apache.lucene.util;

/**
 * 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.util.BitSet;

import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.DocIdSetIterator;


/** Simple DocIdSet and DocIdSetIterator backed by a BitSet */
public class DocIdBitSet extends DocIdSet {
  private BitSet bitSet;
    
  public DocIdBitSet(BitSet bitSet) {
    this.bitSet = bitSet;
  }

  @Override
  public DocIdSetIterator iterator() {
    return new DocIdBitSetIterator(bitSet);
  }

  /** This DocIdSet implementation is cacheable. */
  @Override
  public boolean isCacheable() {
    return true;
  }
  
  /**
   * Returns the underlying BitSet. 
   */
  public BitSet getBitSet() {
	return this.bitSet;
  }
  
  private static class DocIdBitSetIterator extends DocIdSetIterator {
    private int docId;
    private BitSet bitSet;
    
    DocIdBitSetIterator(BitSet bitSet) {
      this.bitSet = bitSet;
      this.docId = -1;
    }
    
    @Override
    public int docID() {
      return docId;
    }
    
    @Override
    public int nextDoc() {
      // (docId + 1) on next line requires -1 initial value for docNr:
      int d = bitSet.nextSetBit(docId + 1);
      // -1 returned by BitSet.nextSetBit() when exhausted
      docId = d == -1 ? NO_MORE_DOCS : d;
      return docId;
    }
  
    @Override
    public int advance(int target) {
      int d = bitSet.nextSetBit(target);
      // -1 returned by BitSet.nextSetBit() when exhausted
      docId = d == -1 ? NO_MORE_DOCS : d;
      return docId;
    }
  }
}