Lucene example source code file (BooleanQuery.java)

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Java - Lucene tags/keywords

arraylist, arraylist, booleanclause, booleanclause, booleanquery, booleanquery, explanation, io, ioexception, iterator, list, override, override, query, util, weight

The Lucene BooleanQuery.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 org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.util.ToStringUtils;
import org.apache.lucene.search.BooleanClause.Occur;

import java.io.IOException;
import java.util.*;

/** A Query that matches documents matching boolean combinations of other
  * queries, e.g. {@link TermQuery}s, {@link PhraseQuery}s or other
  * BooleanQuerys.
  */
public class BooleanQuery extends Query implements Iterable<BooleanClause> {

  private static int maxClauseCount = 1024;

  /** Thrown when an attempt is made to add more than {@link
   * #getMaxClauseCount()} clauses. This typically happens if
   * a PrefixQuery, FuzzyQuery, WildcardQuery, or TermRangeQuery 
   * is expanded to many terms during search. 
   */
  public static class TooManyClauses extends RuntimeException {
    public TooManyClauses() {
      super("maxClauseCount is set to " + maxClauseCount);
    }
  }

  /** Return the maximum number of clauses permitted, 1024 by default.
   * Attempts to add more than the permitted number of clauses cause {@link
   * TooManyClauses} to be thrown.
   * @see #setMaxClauseCount(int)
   */
  public static int getMaxClauseCount() { return maxClauseCount; }

  /** 
   * Set the maximum number of clauses permitted per BooleanQuery.
   * Default value is 1024.
   */
  public static void setMaxClauseCount(int maxClauseCount) {
    if (maxClauseCount < 1)
      throw new IllegalArgumentException("maxClauseCount must be >= 1");
    BooleanQuery.maxClauseCount = maxClauseCount;
  }

  private ArrayList<BooleanClause> clauses = new ArrayList();
  private final boolean disableCoord;

  /** Constructs an empty boolean query. */
  public BooleanQuery() {
    disableCoord = false;
  }

  /** Constructs an empty boolean query.
   *
   * {@link Similarity#coord(int,int)} may be disabled in scoring, as
   * appropriate. For example, this score factor does not make sense for most
   * automatically generated queries, like {@link WildcardQuery} and {@link
   * FuzzyQuery}.
   *
   * @param disableCoord disables {@link Similarity#coord(int,int)} in scoring.
   */
  public BooleanQuery(boolean disableCoord) {
    this.disableCoord = disableCoord;
  }

  /** Returns true iff {@link Similarity#coord(int,int)} is disabled in
   * scoring for this query instance.
   * @see #BooleanQuery(boolean)
   */
  public boolean isCoordDisabled() { return disableCoord; }

  /**
   * Specifies a minimum number of the optional BooleanClauses
   * which must be satisfied.
   *
   * <p>
   * By default no optional clauses are necessary for a match
   * (unless there are no required clauses).  If this method is used,
   * then the specified number of clauses is required.
   * </p>
   * <p>
   * Use of this method is totally independent of specifying that
   * any specific clauses are required (or prohibited).  This number will
   * only be compared against the number of matching optional clauses.
   * </p>
   *
   * @param min the number of optional clauses that must match
   */
  public void setMinimumNumberShouldMatch(int min) {
    this.minNrShouldMatch = min;
  }
  protected int minNrShouldMatch = 0;

  /**
   * Gets the minimum number of the optional BooleanClauses
   * which must be satisfied.
   */
  public int getMinimumNumberShouldMatch() {
    return minNrShouldMatch;
  }

  /** Adds a clause to a boolean query.
   *
   * @throws TooManyClauses if the new number of clauses exceeds the maximum clause number
   * @see #getMaxClauseCount()
   */
  public void add(Query query, BooleanClause.Occur occur) {
    add(new BooleanClause(query, occur));
  }

  /** Adds a clause to a boolean query.
   * @throws TooManyClauses if the new number of clauses exceeds the maximum clause number
   * @see #getMaxClauseCount()
   */
  public void add(BooleanClause clause) {
    if (clauses.size() >= maxClauseCount)
      throw new TooManyClauses();

    clauses.add(clause);
  }

  /** Returns the set of clauses in this query. */
  public BooleanClause[] getClauses() {
    return clauses.toArray(new BooleanClause[clauses.size()]);
  }

  /** Returns the list of clauses in this query. */
  public List<BooleanClause> clauses() { return clauses; }

  /** Returns an iterator on the clauses in this query. It implements the {@link Iterable} interface to
   * make it possible to do:
   * <pre>for (BooleanClause clause : booleanQuery) {}

*/ public final Iterator<BooleanClause> iterator() { return clauses().iterator(); } /** * Expert: the Weight for BooleanQuery, used to * normalize, score and explain these queries. * * <p>NOTE: this API and implementation is subject to * change suddenly in the next release.</p> */ protected class BooleanWeight extends Weight { /** The Similarity implementation. */ protected Similarity similarity; protected ArrayList<Weight> weights; protected int maxCoord; // num optional + num required private final boolean disableCoord; public BooleanWeight(Searcher searcher, boolean disableCoord) throws IOException { this.similarity = getSimilarity(searcher); this.disableCoord = disableCoord; weights = new ArrayList<Weight>(clauses.size()); for (int i = 0 ; i < clauses.size(); i++) { BooleanClause c = clauses.get(i); weights.add(c.getQuery().createWeight(searcher)); if (!c.isProhibited()) maxCoord++; } } @Override public Query getQuery() { return BooleanQuery.this; } @Override public float getValue() { return getBoost(); } @Override public float sumOfSquaredWeights() throws IOException { float sum = 0.0f; for (int i = 0 ; i < weights.size(); i++) { // call sumOfSquaredWeights for all clauses in case of side effects float s = weights.get(i).sumOfSquaredWeights(); // sum sub weights if (!clauses.get(i).isProhibited()) // only add to sum for non-prohibited clauses sum += s; } sum *= getBoost() * getBoost(); // boost each sub-weight return sum ; } @Override public void normalize(float norm) { norm *= getBoost(); // incorporate boost for (Weight w : weights) { // normalize all clauses, (even if prohibited in case of side affects) w.normalize(norm); } } @Override public Explanation explain(IndexReader reader, int doc) throws IOException { final int minShouldMatch = BooleanQuery.this.getMinimumNumberShouldMatch(); ComplexExplanation sumExpl = new ComplexExplanation(); sumExpl.setDescription("sum of:"); int coord = 0; float sum = 0.0f; boolean fail = false; int shouldMatchCount = 0; Iterator<BooleanClause> cIter = clauses.iterator(); for (Iterator<Weight> wIter = weights.iterator(); wIter.hasNext();) { Weight w = wIter.next(); BooleanClause c = cIter.next(); if (w.scorer(reader, true, true) == null) { if (c.isRequired()) { fail = true; Explanation r = new Explanation(0.0f, "no match on required clause (" + c.getQuery().toString() + ")"); sumExpl.addDetail(r); } continue; } Explanation e = w.explain(reader, doc); if (e.isMatch()) { if (!c.isProhibited()) { sumExpl.addDetail(e); sum += e.getValue(); coord++; } else { Explanation r = new Explanation(0.0f, "match on prohibited clause (" + c.getQuery().toString() + ")"); r.addDetail(e); sumExpl.addDetail(r); fail = true; } if (c.getOccur() == Occur.SHOULD) shouldMatchCount++; } else if (c.isRequired()) { Explanation r = new Explanation(0.0f, "no match on required clause (" + c.getQuery().toString() + ")"); r.addDetail(e); sumExpl.addDetail(r); fail = true; } } if (fail) { sumExpl.setMatch(Boolean.FALSE); sumExpl.setValue(0.0f); sumExpl.setDescription ("Failure to meet condition(s) of required/prohibited clause(s)"); return sumExpl; } else if (shouldMatchCount < minShouldMatch) { sumExpl.setMatch(Boolean.FALSE); sumExpl.setValue(0.0f); sumExpl.setDescription("Failure to match minimum number "+ "of optional clauses: " + minShouldMatch); return sumExpl; } sumExpl.setMatch(0 < coord ? Boolean.TRUE : Boolean.FALSE); sumExpl.setValue(sum); final float coordFactor = disableCoord ? 1.0f : similarity.coord(coord, maxCoord); if (coordFactor == 1.0f) { return sumExpl; // eliminate wrapper } else { ComplexExplanation result = new ComplexExplanation(sumExpl.isMatch(), sum*coordFactor, "product of:"); result.addDetail(sumExpl); result.addDetail(new Explanation(coordFactor, "coord("+coord+"/"+maxCoord+")")); return result; } } @Override public Scorer scorer(IndexReader reader, boolean scoreDocsInOrder, boolean topScorer) throws IOException { List<Scorer> required = new ArrayList(); List<Scorer> prohibited = new ArrayList(); List<Scorer> optional = new ArrayList(); Iterator<BooleanClause> cIter = clauses.iterator(); for (Weight w : weights) { BooleanClause c = cIter.next(); Scorer subScorer = w.scorer(reader, true, false); if (subScorer == null) { if (c.isRequired()) { return null; } } else if (c.isRequired()) { required.add(subScorer); } else if (c.isProhibited()) { prohibited.add(subScorer); } else { optional.add(subScorer); } } // Check if we can return a BooleanScorer if (!scoreDocsInOrder && topScorer && required.size() == 0 && prohibited.size() < 32) { return new BooleanScorer(this, disableCoord, similarity, minNrShouldMatch, optional, prohibited, maxCoord); } if (required.size() == 0 && optional.size() == 0) { // no required and optional clauses. return null; } else if (optional.size() < minNrShouldMatch) { // either >1 req scorer, or there are 0 req scorers and at least 1 // optional scorer. Therefore if there are not enough optional scorers // no documents will be matched by the query return null; } // Return a BooleanScorer2 return new BooleanScorer2(this, disableCoord, similarity, minNrShouldMatch, required, prohibited, optional, maxCoord); } @Override public boolean scoresDocsOutOfOrder() { int numProhibited = 0; for (BooleanClause c : clauses) { if (c.isRequired()) { return false; // BS2 (in-order) will be used by scorer() } else if (c.isProhibited()) { ++numProhibited; } } if (numProhibited > 32) { // cannot use BS return false; } // scorer() will return an out-of-order scorer if requested. return true; } } @Override public Weight createWeight(Searcher searcher) throws IOException { return new BooleanWeight(searcher, disableCoord); } @Override public Query rewrite(IndexReader reader) throws IOException { if (minNrShouldMatch == 0 && clauses.size() == 1) { // optimize 1-clause queries BooleanClause c = clauses.get(0); if (!c.isProhibited()) { // just return clause Query query = c.getQuery().rewrite(reader); // rewrite first if (getBoost() != 1.0f) { // incorporate boost if (query == c.getQuery()) // if rewrite was no-op query = (Query)query.clone(); // then clone before boost query.setBoost(getBoost() * query.getBoost()); } return query; } } BooleanQuery clone = null; // recursively rewrite for (int i = 0 ; i < clauses.size(); i++) { BooleanClause c = clauses.get(i); Query query = c.getQuery().rewrite(reader); if (query != c.getQuery()) { // clause rewrote: must clone if (clone == null) clone = (BooleanQuery)this.clone(); clone.clauses.set(i, new BooleanClause(query, c.getOccur())); } } if (clone != null) { return clone; // some clauses rewrote } else return this; // no clauses rewrote } // inherit javadoc @Override public void extractTerms(Set<Term> terms) { for (BooleanClause clause : clauses) { clause.getQuery().extractTerms(terms); } } @Override @SuppressWarnings("unchecked") public Object clone() { BooleanQuery clone = (BooleanQuery)super.clone(); clone.clauses = (ArrayList<BooleanClause>) this.clauses.clone(); return clone; } /** Prints a user-readable version of this query. */ @Override public String toString(String field) { StringBuilder buffer = new StringBuilder(); boolean needParens=(getBoost() != 1.0) || (getMinimumNumberShouldMatch()>0) ; if (needParens) { buffer.append("("); } for (int i = 0 ; i < clauses.size(); i++) { BooleanClause c = clauses.get(i); if (c.isProhibited()) buffer.append("-"); else if (c.isRequired()) buffer.append("+"); Query subQuery = c.getQuery(); if (subQuery != null) { if (subQuery instanceof BooleanQuery) { // wrap sub-bools in parens buffer.append("("); buffer.append(subQuery.toString(field)); buffer.append(")"); } else { buffer.append(subQuery.toString(field)); } } else { buffer.append("null"); } if (i != clauses.size()-1) buffer.append(" "); } if (needParens) { buffer.append(")"); } if (getMinimumNumberShouldMatch()>0) { buffer.append('~'); buffer.append(getMinimumNumberShouldMatch()); } if (getBoost() != 1.0f) { buffer.append(ToStringUtils.boost(getBoost())); } return buffer.toString(); } /** Returns true iff <code>o is equal to this. */ @Override public boolean equals(Object o) { if (!(o instanceof BooleanQuery)) return false; BooleanQuery other = (BooleanQuery)o; return (this.getBoost() == other.getBoost()) && this.clauses.equals(other.clauses) && this.getMinimumNumberShouldMatch() == other.getMinimumNumberShouldMatch() && this.disableCoord == other.disableCoord; } /** Returns a hash code value for this object.*/ @Override public int hashCode() { return Float.floatToIntBits(getBoost()) ^ clauses.hashCode() + getMinimumNumberShouldMatch() + (disableCoord ? 17:0); } }

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