/**
* 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.
*/
package org.apache.nutch.searcher;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.index.Term;
import org.apache.nutch.searcher.Query.Clause;
/** Translate raw query fields to search the same-named field, as indexed by an
* IndexingFilter. */
public abstract class RawFieldQueryFilter implements QueryFilter {
private String field;
private boolean lowerCase;
private float boost;
/** Construct for the named field, lowercasing query values.*/
protected RawFieldQueryFilter(String field) {
this(field, true);
}
/** Construct for the named field, lowercasing query values.*/
protected RawFieldQueryFilter(String field, float boost) {
this(field, true, boost);
}
/** Construct for the named field, potentially lowercasing query values.*/
protected RawFieldQueryFilter(String field, boolean lowerCase) {
this(field, lowerCase, 0.0f);
}
/** Construct for the named field, potentially lowercasing query values.*/
protected RawFieldQueryFilter(String field, boolean lowerCase, float boost) {
this.field = field;
this.lowerCase = lowerCase;
this.boost = boost;
}
protected void setBoost(float boost) {
this.boost = boost;
}
public BooleanQuery filter(Query input, BooleanQuery output)
throws QueryException {
// examine each clause in the Nutch query
Clause[] clauses = input.getClauses();
for (int i = 0; i < clauses.length; i++) {
Clause c = clauses[i];
// skip non-matching clauses
if (!c.getField().equals(field))
continue;
// get the field value from the clause
// raw fields are guaranteed to be Terms, not Phrases
String value = c.getTerm().toString();
if (lowerCase)
value = value.toLowerCase();
// add a Lucene TermQuery for this clause
TermQuery clause = new TermQuery(new Term(field, value));
// set boost
clause.setBoost(boost);
// add it as specified in query
output.add(clause,
(c.isProhibited()
? BooleanClause.Occur.MUST_NOT
: (c.isRequired()
? BooleanClause.Occur.MUST
: BooleanClause.Occur.SHOULD
)
));
}
// return the modified Lucene query
return output;
}
}