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() {}
@Override
public String getMessage() {
return "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<BooleanClause>();
private boolean disableCoord;
/** Constructs an empty boolean query. */
public BooleanQuery() {}
/** 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; }
// Implement coord disabling.
// Inherit javadoc.
@Override
public Similarity getSimilarity(Searcher searcher) {
Similarity result = super.getSimilarity(searcher);
if (disableCoord) { // disable coord as requested
result = new SimilarityDelegator(result) {
@Override
public float coord(int overlap, int maxOverlap) {
return 1.0f;
}
};
}
return result;
}
/**
* 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) {}</pre>
*/
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;
public BooleanWeight(Searcher searcher)
throws IOException {
this.similarity = getSimilarity(searcher);
weights = new ArrayList<Weight>(clauses.size());
for (int i = 0 ; i < clauses.size(); i++) {
weights.add(clauses.get(i).getQuery().createWeight(searcher));
}
}
@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;
int maxCoord = 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) {
continue;
}
Explanation e = w.explain(reader, doc);
if (!c.isProhibited()) maxCoord++;
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);
float coordFactor = similarity.coord(coord, maxCoord);
if (coordFactor == 1.0f) // coord is no-op
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<Scorer>();
List<Scorer> prohibited = new ArrayList<Scorer>();
List<Scorer> optional = new ArrayList<Scorer>();
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(similarity, minNrShouldMatch, optional, prohibited);
}
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(similarity, minNrShouldMatch, required, prohibited, optional);
}
@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);
}
@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</code> 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);
}
}