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Lucene example source code file (FilteredDocIdSetIterator.java)

This example Lucene source code file (FilteredDocIdSetIterator.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, filtereddocidsetiterator, illegalargumentexception, io, ioexception, ioexception, no_more_docs, no_more_docs, override, override

The Lucene FilteredDocIdSetIterator.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;

/**
 * Abstract decorator class of a DocIdSetIterator
 * implementation that provides on-demand filter/validation
 * mechanism on an underlying DocIdSetIterator.  See {@link
 * FilteredDocIdSet}.
 */
public abstract class FilteredDocIdSetIterator extends DocIdSetIterator {
  protected DocIdSetIterator _innerIter;
  private int doc;
	
  /**
   * Constructor.
   * @param innerIter Underlying DocIdSetIterator.
   */
  public FilteredDocIdSetIterator(DocIdSetIterator innerIter) {
    if (innerIter == null) {
      throw new IllegalArgumentException("null iterator");
    }
    _innerIter = innerIter;
    doc = -1;
  }
	
  /**
   * Validation method to determine whether a docid should be in the result set.
   * @param doc docid to be tested
   * @return true if input docid should be in the result set, false otherwise.
   * @see #FilteredDocIdSetIterator(DocIdSetIterator)
   */
  abstract protected boolean match(int doc) throws IOException;
	
  @Override
  public int docID() {
    return doc;
  }
  
  @Override
  public int nextDoc() throws IOException {
    while ((doc = _innerIter.nextDoc()) != NO_MORE_DOCS) {
      if (match(doc)) {
        return doc;
      }
    }
    return doc;
  }
  
  @Override
  public int advance(int target) throws IOException {
    doc = _innerIter.advance(target);
    if (doc != NO_MORE_DOCS) {
      if (match(doc)) {
        return doc;
      } else {
        while ((doc = _innerIter.nextDoc()) != NO_MORE_DOCS) {
          if (match(doc)) {
            return doc;
          }
        }
        return doc;
      }
    }
    return doc;
  }
  
}

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