Lucene example source code file (BooleanFilter.java)

This example Lucene source code file (BooleanFilter.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

arraylist, arraylist, booleanfilter, booleanfilter, docidset, docidset, docidsetiterator, io, ioexception, openbitset, openbitsetdisi, openbitsetdisi, override, string, stringbuilder, util

The Lucene BooleanFilter.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;
import java.util.ArrayList;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.BooleanClause.Occur;
import org.apache.lucene.util.OpenBitSet;
import org.apache.lucene.util.OpenBitSetDISI;

/**
 * A container Filter that allows Boolean composition of Filters.
 * Filters are allocated into one of three logical constructs;
 * SHOULD, MUST NOT, MUST
 * The results Filter BitSet is constructed as follows:
 * SHOULD Filters are OR'd together
 * The resulting Filter is NOT'd with the NOT Filters
 * The resulting Filter is AND'd with the MUST Filters
 */

public class BooleanFilter extends Filter
{
  ArrayList<Filter> shouldFilters = null;
  ArrayList<Filter> notFilters = null;
  ArrayList<Filter> mustFilters = null;
  
  private DocIdSetIterator getDISI(ArrayList<Filter> filters, int index, IndexReader reader)
  throws IOException
  {
    return filters.get(index).getDocIdSet(reader).iterator();
  }

  /**
   * Returns the a DocIdSetIterator representing the Boolean composition
   * of the filters that have been added.
   */
  @Override
  public DocIdSet getDocIdSet(IndexReader reader) throws IOException
  {
    OpenBitSetDISI res = null;
  
    if (shouldFilters != null) {
      for (int i = 0; i < shouldFilters.size(); i++) {
        if (res == null) {
          res = new OpenBitSetDISI(getDISI(shouldFilters, i, reader), reader.maxDoc());
        } else { 
          DocIdSet dis = shouldFilters.get(i).getDocIdSet(reader);
          if(dis instanceof OpenBitSet) {
            // optimized case for OpenBitSets
            res.or((OpenBitSet) dis);
          } else {
            res.inPlaceOr(getDISI(shouldFilters, i, reader));
          }
        }
      }
    }
    
    if (notFilters!=null) {
      for (int i = 0; i < notFilters.size(); i++) {
        if (res == null) {
          res = new OpenBitSetDISI(getDISI(notFilters, i, reader), reader.maxDoc());
          res.flip(0, reader.maxDoc()); // NOTE: may set bits on deleted docs
        } else {
          DocIdSet dis = notFilters.get(i).getDocIdSet(reader);
          if(dis instanceof OpenBitSet) {
            // optimized case for OpenBitSets
            res.andNot((OpenBitSet) dis);
          } else {
            res.inPlaceNot(getDISI(notFilters, i, reader));
          }
        }
      }
    }
    
    if (mustFilters!=null) {
      for (int i = 0; i < mustFilters.size(); i++) {
        if (res == null) {
          res = new OpenBitSetDISI(getDISI(mustFilters, i, reader), reader.maxDoc());
        } else {
          DocIdSet dis = mustFilters.get(i).getDocIdSet(reader);
          if(dis instanceof OpenBitSet) {
            // optimized case for OpenBitSets
            res.and((OpenBitSet) dis);
          } else {
            res.inPlaceAnd(getDISI(mustFilters, i, reader));
          }
        }
      }
    }
    
    if (res !=null)
      return finalResult(res, reader.maxDoc());

    return DocIdSet.EMPTY_DOCIDSET;
  }

  /** Provide a SortedVIntList when it is definitely smaller
   * than an OpenBitSet.
   * @deprecated Either use CachingWrapperFilter, or
   * switch to a different DocIdSet implementation yourself.
   * This method will be removed in Lucene 4.0 
   */
  @Deprecated
  protected final DocIdSet finalResult(OpenBitSetDISI result, int maxDocs) {
    return result;
  }

  /**
  * Adds a new FilterClause to the Boolean Filter container
  * @param filterClause A FilterClause object containing a Filter and an Occur parameter
  */
  
  public void add(FilterClause filterClause)
  {
    if (filterClause.getOccur().equals(Occur.MUST)) {
      if (mustFilters==null) {
        mustFilters=new ArrayList<Filter>();
      }
      mustFilters.add(filterClause.getFilter());
    }
    if (filterClause.getOccur().equals(Occur.SHOULD)) {
      if (shouldFilters==null) {
        shouldFilters=new ArrayList<Filter>();
      }
      shouldFilters.add(filterClause.getFilter());
    }
    if (filterClause.getOccur().equals(Occur.MUST_NOT)) {
      if (notFilters==null) {
        notFilters=new ArrayList<Filter>();
      }
      notFilters.add(filterClause.getFilter());
    }
  }

  private boolean equalFilters(ArrayList<Filter> filters1, ArrayList filters2)
  {
     return (filters1 == filters2) ||
              ((filters1 != null) && filters1.equals(filters2));
  }
  
  @Override
  public boolean equals(Object obj)
  {
    if (this == obj)
      return true;

    if ((obj == null) || (obj.getClass() != this.getClass()))
      return false;

    BooleanFilter other = (BooleanFilter)obj;
    return equalFilters(notFilters, other.notFilters)
        && equalFilters(mustFilters, other.mustFilters)
        && equalFilters(shouldFilters, other.shouldFilters);
  }

  @Override
  public int hashCode()
  {
    int hash=7;
    hash = 31 * hash + (null == mustFilters ? 0 : mustFilters.hashCode());
    hash = 31 * hash + (null == notFilters ? 0 : notFilters.hashCode());
    hash = 31 * hash + (null == shouldFilters ? 0 : shouldFilters.hashCode());
    return hash;
  }
  
  /** Prints a user-readable version of this query. */
  @Override
  public String toString()
  {
    StringBuilder buffer = new StringBuilder();
    buffer.append("BooleanFilter(");
    appendFilters(shouldFilters, "", buffer);
    appendFilters(mustFilters, "+", buffer);
    appendFilters(notFilters, "-", buffer);
    buffer.append(")");
    return buffer.toString();
  }
  
  private void appendFilters(ArrayList<Filter> filters, String occurString, StringBuilder buffer)
  {
    if (filters != null) {
      for (int i = 0; i < filters.size(); i++) {
        buffer.append(' ');
        buffer.append(occurString);
        buffer.append(filters.get(i).toString());
      }
    }
  }    
}