package org.apache.lucene.search.spans;
/**
* 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.Set;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Weight;
import org.apache.lucene.search.Searcher;
import org.apache.lucene.search.Similarity;
import org.apache.lucene.util.ToStringUtils;
/**
* <p>Wrapper to allow {@link SpanQuery} objects participate in composite
* single-field SpanQueries by 'lying' about their search field. That is,
* the masked SpanQuery will function as normal,
* but {@link SpanQuery#getField()} simply hands back the value supplied
* in this class's constructor.</p>
*
* <p>This can be used to support Queries like {@link SpanNearQuery} or
* {@link SpanOrQuery} across different fields, which is not ordinarily
* permitted.</p>
*
* <p>This can be useful for denormalized relational data: for example, when
* indexing a document with conceptually many 'children': </p>
*
* <pre>
* teacherid: 1
* studentfirstname: james
* studentsurname: jones
*
* teacherid: 2
* studenfirstname: james
* studentsurname: smith
* studentfirstname: sally
* studentsurname: jones
* </pre>
*
* <p>a SpanNearQuery with a slop of 0 can be applied across two
* {@link SpanTermQuery} objects as follows:
* <pre>
* SpanQuery q1 = new SpanTermQuery(new Term("studentfirstname", "james"));
* SpanQuery q2 = new SpanTermQuery(new Term("studentsurname", "jones"));
* SpanQuery q2m = new FieldMaskingSpanQuery(q2, "studentfirstname");
* Query q = new SpanNearQuery(new SpanQuery[]{q1, q2m}, -1, false);
* </pre>
* to search for 'studentfirstname:james studentsurname:jones' and find
* teacherid 1 without matching teacherid 2 (which has a 'james' in position 0
* and 'jones' in position 1). </p>
*
* <p>Note: as {@link #getField()} returns the masked field, scoring will be
* done using the norms of the field name supplied. This may lead to unexpected
* scoring behaviour.</p>
*/
public class FieldMaskingSpanQuery extends SpanQuery {
private SpanQuery maskedQuery;
private String field;
public FieldMaskingSpanQuery(SpanQuery maskedQuery, String maskedField) {
this.maskedQuery = maskedQuery;
this.field = maskedField;
}
@Override
public String getField() {
return field;
}
public SpanQuery getMaskedQuery() {
return maskedQuery;
}
// :NOTE: getBoost and setBoost are not proxied to the maskedQuery
// ...this is done to be more consistent with things like SpanFirstQuery
@Override
public Spans getSpans(IndexReader reader) throws IOException {
return maskedQuery.getSpans(reader);
}
@Override
public void extractTerms(Set<Term> terms) {
maskedQuery.extractTerms(terms);
}
@Override
public Weight createWeight(Searcher searcher) throws IOException {
return maskedQuery.createWeight(searcher);
}
@Override
public Query rewrite(IndexReader reader) throws IOException {
FieldMaskingSpanQuery clone = null;
SpanQuery rewritten = (SpanQuery) maskedQuery.rewrite(reader);
if (rewritten != maskedQuery) {
clone = (FieldMaskingSpanQuery) this.clone();
clone.maskedQuery = rewritten;
}
if (clone != null) {
return clone;
} else {
return this;
}
}
@Override
public String toString(String field) {
StringBuilder buffer = new StringBuilder();
buffer.append("mask(");
buffer.append(maskedQuery.toString(field));
buffer.append(")");
buffer.append(ToStringUtils.boost(getBoost()));
buffer.append(" as ");
buffer.append(this.field);
return buffer.toString();
}
@Override
public boolean equals(Object o) {
if (!(o instanceof FieldMaskingSpanQuery))
return false;
FieldMaskingSpanQuery other = (FieldMaskingSpanQuery) o;
return (this.getField().equals(other.getField())
&& (this.getBoost() == other.getBoost())
&& this.getMaskedQuery().equals(other.getMaskedQuery()));
}
@Override
public int hashCode() {
return getMaskedQuery().hashCode()
^ getField().hashCode()
^ Float.floatToRawIntBits(getBoost());
}
}