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Lucene example source code file (MultiPhraseQuery.java)

This example Lucene source code file (MultiPhraseQuery.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, booleanquery, complexexplanation, explanation, explanation, io, ioexception, multiphrasequery, multiphraseweight, override, override, query, term, term, util

The Lucene MultiPhraseQuery.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.*;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.MultipleTermPositions;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermPositions;
import org.apache.lucene.search.Explanation.IDFExplanation;
import org.apache.lucene.util.ArrayUtil;
import org.apache.lucene.util.ToStringUtils;

/**
 * MultiPhraseQuery is a generalized version of PhraseQuery, with an added
 * method {@link #add(Term[])}.
 * To use this class, to search for the phrase "Microsoft app*" first use
 * add(Term) on the term "Microsoft", then find all terms that have "app" as
 * prefix using IndexReader.terms(Term), and use MultiPhraseQuery.add(Term[]
 * terms) to add them to the query.
 *
 * @version 1.0
 */
public class MultiPhraseQuery extends Query {
  private String field;
  private ArrayList<Term[]> termArrays = new ArrayList();
  private ArrayList<Integer> positions = new ArrayList();

  private int slop = 0;

  /** Sets the phrase slop for this query.
   * @see PhraseQuery#setSlop(int)
   */
  public void setSlop(int s) { slop = s; }

  /** Sets the phrase slop for this query.
   * @see PhraseQuery#getSlop()
   */
  public int getSlop() { return slop; }

  /** Add a single term at the next position in the phrase.
   * @see PhraseQuery#add(Term)
   */
  public void add(Term term) { add(new Term[]{term}); }

  /** Add multiple terms at the next position in the phrase.  Any of the terms
   * may match.
   *
   * @see PhraseQuery#add(Term)
   */
  public void add(Term[] terms) {
    int position = 0;
    if (positions.size() > 0)
      position = positions.get(positions.size()-1).intValue() + 1;

    add(terms, position);
  }

  /**
   * Allows to specify the relative position of terms within the phrase.
   * 
   * @see PhraseQuery#add(Term, int)
   * @param terms
   * @param position
   */
  public void add(Term[] terms, int position) {
    if (termArrays.size() == 0)
      field = terms[0].field();

    for (int i = 0; i < terms.length; i++) {
      if (terms[i].field() != field) {
        throw new IllegalArgumentException(
            "All phrase terms must be in the same field (" + field + "): "
                + terms[i]);
      }
    }

    termArrays.add(terms);
    positions.add(Integer.valueOf(position));
  }

  /**
   * Returns a List of the terms in the multiphrase.
   * Do not modify the List or its contents.
   */
  public List<Term[]> getTermArrays() {
	  return Collections.unmodifiableList(termArrays);
  }

  /**
   * Returns the relative positions of terms in this phrase.
   */
  public int[] getPositions() {
    int[] result = new int[positions.size()];
    for (int i = 0; i < positions.size(); i++)
      result[i] = positions.get(i).intValue();
    return result;
  }

  // inherit javadoc
  @Override
  public void extractTerms(Set<Term> terms) {
    for (final Term[] arr : termArrays) {
      for (final Term term: arr) {
        terms.add(term);
      }
    }
  }


  private class MultiPhraseWeight extends Weight {
    private Similarity similarity;
    private float value;
    private final IDFExplanation idfExp;
    private float idf;
    private float queryNorm;
    private float queryWeight;

    public MultiPhraseWeight(Searcher searcher)
      throws IOException {
      this.similarity = getSimilarity(searcher);

      // compute idf
      ArrayList<Term> allTerms = new ArrayList();
      for(final Term[] terms: termArrays) {
        for (Term term: terms) {
          allTerms.add(term);
        }
      }
      idfExp = similarity.idfExplain(allTerms, searcher);
      idf = idfExp.getIdf();
    }

    @Override
    public Query getQuery() { return MultiPhraseQuery.this; }

    @Override
    public float getValue() { return value; }

    @Override
    public float sumOfSquaredWeights() {
      queryWeight = idf * getBoost();             // compute query weight
      return queryWeight * queryWeight;           // square it
    }

    @Override
    public void normalize(float queryNorm) {
      this.queryNorm = queryNorm;
      queryWeight *= queryNorm;                   // normalize query weight
      value = queryWeight * idf;                  // idf for document 
    }

    @Override
    public Scorer scorer(IndexReader reader, boolean scoreDocsInOrder, boolean topScorer) throws IOException {
      if (termArrays.size() == 0)                  // optimize zero-term case
        return null;

      PhraseQuery.PostingsAndFreq[] postingsFreqs = new PhraseQuery.PostingsAndFreq[termArrays.size()];

      for (int pos=0; pos<postingsFreqs.length; pos++) {
        Term[] terms = termArrays.get(pos);

        final TermPositions p;
        int docFreq;

        if (terms.length > 1) {
          p = new MultipleTermPositions(reader, terms);

          // coarse -- this overcounts since a given doc can
          // have more than one terms:
          docFreq = 0;
          for(int termIdx=0;termIdx<terms.length;termIdx++) {
            docFreq += reader.docFreq(terms[termIdx]);
          }
        } else {
          p = reader.termPositions(terms[0]);
          docFreq = reader.docFreq(terms[0]);

          if (p == null)
            return null;
        }

        postingsFreqs[pos] = new PhraseQuery.PostingsAndFreq(p, docFreq, positions.get(pos).intValue(), terms[0]);
      }

      // sort by increasing docFreq order
      if (slop == 0) {
        ArrayUtil.mergeSort(postingsFreqs);
      }

      if (slop == 0) {
        ExactPhraseScorer s = new ExactPhraseScorer(this, postingsFreqs, similarity,
                                                    reader.norms(field));
        if (s.noDocs) {
          return null;
        } else {
          return s;
        }
      } else {
        return new SloppyPhraseScorer(this, postingsFreqs, similarity,
                                      slop, reader.norms(field));
      }
    }

    @Override
    public Explanation explain(IndexReader reader, int doc)
      throws IOException {
      ComplexExplanation result = new ComplexExplanation();
      result.setDescription("weight("+getQuery()+" in "+doc+"), product of:");

      Explanation idfExpl = new Explanation(idf, "idf(" + field + ":" + idfExp.explain() +")");

      // explain query weight
      Explanation queryExpl = new Explanation();
      queryExpl.setDescription("queryWeight(" + getQuery() + "), product of:");

      Explanation boostExpl = new Explanation(getBoost(), "boost");
      if (getBoost() != 1.0f)
        queryExpl.addDetail(boostExpl);

      queryExpl.addDetail(idfExpl);

      Explanation queryNormExpl = new Explanation(queryNorm,"queryNorm");
      queryExpl.addDetail(queryNormExpl);

      queryExpl.setValue(boostExpl.getValue() *
                         idfExpl.getValue() *
                         queryNormExpl.getValue());

      result.addDetail(queryExpl);

      // explain field weight
      ComplexExplanation fieldExpl = new ComplexExplanation();
      fieldExpl.setDescription("fieldWeight("+getQuery()+" in "+doc+
                               "), product of:");

      Scorer scorer = scorer(reader, true, false);
      if (scorer == null) {
        return new Explanation(0.0f, "no matching docs");
      }

      Explanation tfExplanation = new Explanation();
      int d = scorer.advance(doc);
      float phraseFreq;
      if (d == doc) {
        phraseFreq = scorer.freq();
      } else {
        phraseFreq = 0.0f;
      }

      tfExplanation.setValue(similarity.tf(phraseFreq));
      tfExplanation.setDescription("tf(phraseFreq=" + phraseFreq + ")");
      fieldExpl.addDetail(tfExplanation);
      fieldExpl.addDetail(idfExpl);

      Explanation fieldNormExpl = new Explanation();
      byte[] fieldNorms = reader.norms(field);
      float fieldNorm =
        fieldNorms!=null ? similarity.decodeNormValue(fieldNorms[doc]) : 1.0f;
      fieldNormExpl.setValue(fieldNorm);
      fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
      fieldExpl.addDetail(fieldNormExpl);

      fieldExpl.setMatch(Boolean.valueOf(tfExplanation.isMatch()));
      fieldExpl.setValue(tfExplanation.getValue() *
                         idfExpl.getValue() *
                         fieldNormExpl.getValue());

      result.addDetail(fieldExpl);
      result.setMatch(fieldExpl.getMatch());

      // combine them
      result.setValue(queryExpl.getValue() * fieldExpl.getValue());

      if (queryExpl.getValue() == 1.0f)
        return fieldExpl;

      return result;
    }
  }

  @Override
  public Query rewrite(IndexReader reader) {
    if (termArrays.size() == 1) {                 // optimize one-term case
      Term[] terms = termArrays.get(0);
      BooleanQuery boq = new BooleanQuery(true);
      for (int i=0; i<terms.length; i++) {
        boq.add(new TermQuery(terms[i]), BooleanClause.Occur.SHOULD);
      }
      boq.setBoost(getBoost());
      return boq;
    } else {
      return this;
    }
  }

  @Override
  public Weight createWeight(Searcher searcher) throws IOException {
    return new MultiPhraseWeight(searcher);
  }

  /** Prints a user-readable version of this query. */
  @Override
  public final String toString(String f) {
    StringBuilder buffer = new StringBuilder();
    if (field == null || !field.equals(f)) {
      buffer.append(field);
      buffer.append(":");
    }

    buffer.append("\"");
    Iterator<Term[]> i = termArrays.iterator();
    while (i.hasNext()) {
      Term[] terms = i.next();
      if (terms.length > 1) {
        buffer.append("(");
        for (int j = 0; j < terms.length; j++) {
          buffer.append(terms[j].text());
          if (j < terms.length-1)
            buffer.append(" ");
        }
        buffer.append(")");
      } else {
        buffer.append(terms[0].text());
      }
      if (i.hasNext())
        buffer.append(" ");
    }
    buffer.append("\"");

    if (slop != 0) {
      buffer.append("~");
      buffer.append(slop);
    }

    buffer.append(ToStringUtils.boost(getBoost()));

    return buffer.toString();
  }


  /** Returns true if <code>o is equal to this. */
  @Override
  public boolean equals(Object o) {
    if (!(o instanceof MultiPhraseQuery)) return false;
    MultiPhraseQuery other = (MultiPhraseQuery)o;
    return this.getBoost() == other.getBoost()
      && this.slop == other.slop
      && termArraysEquals(this.termArrays, other.termArrays)
      && this.positions.equals(other.positions);
  }

  /** Returns a hash code value for this object.*/
  @Override
  public int hashCode() {
    return Float.floatToIntBits(getBoost())
      ^ slop
      ^ termArraysHashCode()
      ^ positions.hashCode()
      ^ 0x4AC65113;
  }
  
  // Breakout calculation of the termArrays hashcode
  private int termArraysHashCode() {
    int hashCode = 1;
    for (final Term[] termArray: termArrays) {
      hashCode = 31 * hashCode
          + (termArray == null ? 0 : Arrays.hashCode(termArray));
    }
    return hashCode;
  }

  // Breakout calculation of the termArrays equals
  private boolean termArraysEquals(List<Term[]> termArrays1, List termArrays2) {
    if (termArrays1.size() != termArrays2.size()) {
      return false;
    }
    ListIterator<Term[]> iterator1 = termArrays1.listIterator();
    ListIterator<Term[]> iterator2 = termArrays2.listIterator();
    while (iterator1.hasNext()) {
      Term[] termArray1 = iterator1.next();
      Term[] termArray2 = iterator2.next();
      if (!(termArray1 == null ? termArray2 == null : Arrays.equals(termArray1,
          termArray2))) {
        return false;
      }
    }
    return true;
  }
}

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