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Lucene example source code file (BooleanScorer2.java)

This example Lucene source code file (BooleanScorer2.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, conjunctionscorer, coordinator, io, ioexception, ioexception, list, list, no_more_docs, override, override, scorer, scorer, similarity, singlematchscorer, util

The Lucene BooleanScorer2.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 java.util.List;

import org.apache.lucene.search.BooleanClause.Occur;

/* See the description in BooleanScorer.java, comparing
 * BooleanScorer & BooleanScorer2 */

/** An alternative to BooleanScorer that also allows a minimum number
 * of optional scorers that should match.
 * <br>Implements skipTo(), and has no limitations on the numbers of added scorers.
 * <br>Uses ConjunctionScorer, DisjunctionScorer, ReqOptScorer and ReqExclScorer.
 */
class BooleanScorer2 extends Scorer {
  
  private final List<Scorer> requiredScorers;
  private final List<Scorer> optionalScorers;
  private final List<Scorer> prohibitedScorers;

  private class Coordinator {
    float[] coordFactors = null;
    int maxCoord = 0; // to be increased for each non prohibited scorer
    int nrMatchers; // to be increased by score() of match counting scorers.
    
    void init(Similarity sim, boolean disableCoord) { // use after all scorers have been added.
      coordFactors = new float[optionalScorers.size() + requiredScorers.size() + 1];
      for (int i = 0; i < coordFactors.length; i++) {
        coordFactors[i] = disableCoord ? 1.0f : sim.coord(i, maxCoord);
      }
    }
  }

  private final Coordinator coordinator;

  /** The scorer to which all scoring will be delegated,
   * except for computing and using the coordination factor.
   */
  private final Scorer countingSumScorer;

  /** The number of optionalScorers that need to match (if there are any) */
  private final int minNrShouldMatch;

  private int doc = -1;

  /**
   * Creates a {@link Scorer} with the given similarity and lists of required,
   * prohibited and optional scorers. In no required scorers are added, at least
   * one of the optional scorers will have to match during the search.
   * 
   * @param weight
   *          The BooleanWeight to be used.
   * @param disableCoord
   *          If this parameter is true, coordination level matching 
   *          ({@link Similarity#coord(int, int)}) is not used.
   * @param minNrShouldMatch
   *          The minimum number of optional added scorers that should match
   *          during the search. In case no required scorers are added, at least
   *          one of the optional scorers will have to match during the search.
   * @param required
   *          the list of required scorers.
   * @param prohibited
   *          the list of prohibited scorers.
   * @param optional
   *          the list of optional scorers.
   */
  public BooleanScorer2(Weight weight, boolean disableCoord, Similarity similarity, int minNrShouldMatch,
      List<Scorer> required, List prohibited, List optional, int maxCoord) throws IOException {
    super(weight);
    if (minNrShouldMatch < 0) {
      throw new IllegalArgumentException("Minimum number of optional scorers should not be negative");
    }
    coordinator = new Coordinator();
    this.minNrShouldMatch = minNrShouldMatch;
    coordinator.maxCoord = maxCoord;

    optionalScorers = optional;
    requiredScorers = required;    
    prohibitedScorers = prohibited;
    
    coordinator.init(similarity, disableCoord);
    countingSumScorer = makeCountingSumScorer(disableCoord, similarity);
  }
  
  /** Count a scorer as a single match. */
  private class SingleMatchScorer extends Scorer {
    private Scorer scorer;
    private int lastScoredDoc = -1;
    // Save the score of lastScoredDoc, so that we don't compute it more than
    // once in score().
    private float lastDocScore = Float.NaN;

    SingleMatchScorer(Scorer scorer) {
      super(scorer.weight);
      this.scorer = scorer;
    }

    @Override
    public float score() throws IOException {
      int doc = docID();
      if (doc >= lastScoredDoc) {
        if (doc > lastScoredDoc) {
          lastDocScore = scorer.score();
          lastScoredDoc = doc;
        }
        coordinator.nrMatchers++;
      }
      return lastDocScore;
    }

    @Override
    public int docID() {
      return scorer.docID();
    }

    @Override
    public int nextDoc() throws IOException {
      return scorer.nextDoc();
    }

    @Override
    public int advance(int target) throws IOException {
      return scorer.advance(target);
    }
  }

  private Scorer countingDisjunctionSumScorer(final List<Scorer> scorers,
      int minNrShouldMatch) throws IOException {
    // each scorer from the list counted as a single matcher
    return new DisjunctionSumScorer(weight, scorers, minNrShouldMatch) {
      private int lastScoredDoc = -1;
      // Save the score of lastScoredDoc, so that we don't compute it more than
      // once in score().
      private float lastDocScore = Float.NaN;
      @Override public float score() throws IOException {
        int doc = docID();
        if (doc >= lastScoredDoc) {
          if (doc > lastScoredDoc) {
            lastDocScore = super.score();
            lastScoredDoc = doc;
          }
          coordinator.nrMatchers += super.nrMatchers;
        }
        return lastDocScore;
      }
    };
  }

  private Scorer countingConjunctionSumScorer(boolean disableCoord,
                                              Similarity similarity,
                                              List<Scorer> requiredScorers) throws IOException {
    // each scorer from the list counted as a single matcher
    final int requiredNrMatchers = requiredScorers.size();
    return new ConjunctionScorer(weight, disableCoord ? 1.0f : similarity.coord(requiredScorers.size(), requiredScorers.size()), requiredScorers) {
      private int lastScoredDoc = -1;
      // Save the score of lastScoredDoc, so that we don't compute it more than
      // once in score().
      private float lastDocScore = Float.NaN;
      @Override public float score() throws IOException {
        int doc = docID();
        if (doc >= lastScoredDoc) {
          if (doc > lastScoredDoc) {
            lastDocScore = super.score();
            lastScoredDoc = doc;
          }
          coordinator.nrMatchers += requiredNrMatchers;
        }
        // All scorers match, so defaultSimilarity super.score() always has 1 as
        // the coordination factor.
        // Therefore the sum of the scores of the requiredScorers
        // is used as score.
        return lastDocScore;
      }
    };
  }

  private Scorer dualConjunctionSumScorer(boolean disableCoord,
                                          Similarity similarity,
                                          Scorer req1, Scorer req2) throws IOException { // non counting.
    return new ConjunctionScorer(weight, disableCoord ? 1.0f : similarity.coord(2, 2), new Scorer[]{req1, req2});
    // All scorers match, so defaultSimilarity always has 1 as
    // the coordination factor.
    // Therefore the sum of the scores of two scorers
    // is used as score.
  }

  /** Returns the scorer to be used for match counting and score summing.
   * Uses requiredScorers, optionalScorers and prohibitedScorers.
   */
  private Scorer makeCountingSumScorer(boolean disableCoord,
                                       Similarity similarity) throws IOException { // each scorer counted as a single matcher
    return (requiredScorers.size() == 0)
      ? makeCountingSumScorerNoReq(disableCoord, similarity)
      : makeCountingSumScorerSomeReq(disableCoord, similarity);
  }

  private Scorer makeCountingSumScorerNoReq(boolean disableCoord, Similarity similarity) throws IOException { // No required scorers
    // minNrShouldMatch optional scorers are required, but at least 1
    int nrOptRequired = (minNrShouldMatch < 1) ? 1 : minNrShouldMatch;
    Scorer requiredCountingSumScorer;
    if (optionalScorers.size() > nrOptRequired)
      requiredCountingSumScorer = countingDisjunctionSumScorer(optionalScorers, nrOptRequired);
    else if (optionalScorers.size() == 1)
      requiredCountingSumScorer = new SingleMatchScorer(optionalScorers.get(0));
    else {
      requiredCountingSumScorer = countingConjunctionSumScorer(disableCoord, similarity, optionalScorers);
    }
    return addProhibitedScorers(requiredCountingSumScorer);
  }

  private Scorer makeCountingSumScorerSomeReq(boolean disableCoord, Similarity similarity) throws IOException { // At least one required scorer.
    if (optionalScorers.size() == minNrShouldMatch) { // all optional scorers also required.
      ArrayList<Scorer> allReq = new ArrayList(requiredScorers);
      allReq.addAll(optionalScorers);
      return addProhibitedScorers(countingConjunctionSumScorer(disableCoord, similarity, allReq));
    } else { // optionalScorers.size() > minNrShouldMatch, and at least one required scorer
      Scorer requiredCountingSumScorer =
            requiredScorers.size() == 1
            ? new SingleMatchScorer(requiredScorers.get(0))
            : countingConjunctionSumScorer(disableCoord, similarity, requiredScorers);
      if (minNrShouldMatch > 0) { // use a required disjunction scorer over the optional scorers
        return addProhibitedScorers( 
                      dualConjunctionSumScorer( // non counting
                              disableCoord,
                              similarity,
                              requiredCountingSumScorer,
                              countingDisjunctionSumScorer(
                                      optionalScorers,
                                      minNrShouldMatch)));
      } else { // minNrShouldMatch == 0
        return new ReqOptSumScorer(
                      addProhibitedScorers(requiredCountingSumScorer),
                      optionalScorers.size() == 1
                        ? new SingleMatchScorer(optionalScorers.get(0))
                        // require 1 in combined, optional scorer.
                        : countingDisjunctionSumScorer(optionalScorers, 1));
      }
    }
  }
  
  /** Returns the scorer to be used for match counting and score summing.
   * Uses the given required scorer and the prohibitedScorers.
   * @param requiredCountingSumScorer A required scorer already built.
   */
  private Scorer addProhibitedScorers(Scorer requiredCountingSumScorer) throws IOException
  {
    return (prohibitedScorers.size() == 0)
          ? requiredCountingSumScorer // no prohibited
          : new ReqExclScorer(requiredCountingSumScorer,
                              ((prohibitedScorers.size() == 1)
                                ? prohibitedScorers.get(0)
                                : new DisjunctionSumScorer(weight, prohibitedScorers)));
  }

  /** Scores and collects all matching documents.
   * @param collector The collector to which all matching documents are passed through.
   */
  @Override
  public void score(Collector collector) throws IOException {
    collector.setScorer(this);
    while ((doc = countingSumScorer.nextDoc()) != NO_MORE_DOCS) {
      collector.collect(doc);
    }
  }
  
  @Override
  protected boolean score(Collector collector, int max, int firstDocID) throws IOException {
    doc = firstDocID;
    collector.setScorer(this);
    while (doc < max) {
      collector.collect(doc);
      doc = countingSumScorer.nextDoc();
    }
    return doc != NO_MORE_DOCS;
  }

  @Override
  public int docID() {
    return doc;
  }
  
  @Override
  public int nextDoc() throws IOException {
    return doc = countingSumScorer.nextDoc();
  }
  
  @Override
  public float score() throws IOException {
    coordinator.nrMatchers = 0;
    float sum = countingSumScorer.score();
    return sum * coordinator.coordFactors[coordinator.nrMatchers];
  }

  @Override
  public float freq() {
    return coordinator.nrMatchers;
  }

  @Override
  public int advance(int target) throws IOException {
    return doc = countingSumScorer.advance(target);
  }

  @Override
  protected void visitSubScorers(Query parent, Occur relationship, ScorerVisitor<Query, Query, Scorer> visitor) {
    super.visitSubScorers(parent, relationship, visitor);
    final Query q = weight.getQuery();
    for (Scorer s : optionalScorers) {
      s.visitSubScorers(q, Occur.SHOULD, visitor);
    }
    for (Scorer s : prohibitedScorers) {
      s.visitSubScorers(q, Occur.MUST_NOT, visitor);
    }
    for (Scorer s : requiredScorers) {
      s.visitSubScorers(q, Occur.MUST, visitor);
    }
  }
}

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