org.pageseeder.flint.lucene.query.AnyTermParameter Maven / Gradle / Ivy
/*
* Copyright 2015 Allette Systems (Australia)
* http://www.allette.com.au
*
* Licensed 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.pageseeder.flint.lucene.query;
import java.io.IOException;
import java.util.Collections;
import java.util.List;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.BooleanClause.Occur;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.TermQuery;
import org.pageseeder.flint.lucene.search.Terms;
import org.pageseeder.xmlwriter.XMLWriter;
/**
* A basic search parameter wrapping a simple list of {@link Term}s.
*
* The final query must match at least one of the terms listed.
*
* @author Christophe Lauret
* @version 13 August 2010
*/
public final class AnyTermParameter implements SearchParameter {
/**
* An empty parameter.
*/
private static final AnyTermParameter EMPTY = new AnyTermParameter();
/**
* The wrapped list of Lucene Terms.
*/
private final List _terms;
/**
* The query (lazy initialised).
*/
private volatile Query _query;
/**
* Creates an empty instance of this class.
*/
private AnyTermParameter() {
this._terms = Collections.emptyList();
}
/**
* Creates a new term parameter from the specified field name and text.
*
* @param field The name of the field to search.
* @param text The text to match in the field value.
*
* @throws NullPointerException If either parameter is null.
*/
public AnyTermParameter(String field, String text) throws NullPointerException {
if (field == null) throw new NullPointerException("field");
if (text == null) throw new NullPointerException("text");
this._terms = Collections.singletonList(new Term(field, text));
}
/**
* Creates a new term parameter from the specified term.
*
* @param terms The term to match.
*
* @throws NullPointerException If either is null.
*/
public AnyTermParameter(List terms) throws NullPointerException {
if (terms == null) throw new NullPointerException("terms");
this._terms = terms;
}
/**
* {@inheritDoc}
*/
@Override
public boolean isEmpty() {
return this._terms.isEmpty();
}
/**
* Returns the wrapped term.
* @return the wrapped term.
*/
public List term() {
return this._terms;
}
/**
* {@inheritDoc}
*/
@Override
public Query toQuery() {
if (isEmpty()) return null;
if (this._query == null) {
this._query = buildQuery();
}
return this._query;
}
/**
* {@inheritDoc}
*/
@Override
public void toXML(XMLWriter xml) throws IOException {
xml.openElement("any-term-parameter", true);
// indicate whether this search term is empty
xml.attribute("is-empty", Boolean.toString(isEmpty()));
// not empty, give details
Terms.toXML(xml, this._terms);
xml.closeElement();
}
/**
* {@inheritDoc}
*/
@Override
public String toString() {
return this._terms.toString();
}
// Private helpers
// ----------------------------------------------------------------------------------------------
/**
* Returns an instance of this class which method {@link #isEmpty()} always return true.
* @return an instance of this class that does not need to match any term.
*/
public static AnyTermParameter empty() {
return EMPTY;
}
// Private helpers
// ----------------------------------------------------------------------------------------------
/**
* Returns the query that would match any one of the terms in the list.
*
* @return the corresponding query.
*/
private Query buildQuery() {
if (isEmpty()) return null;
if (this._terms.size() == 1) return new TermQuery(this._terms.get(0));
else {
BooleanQuery.Builder q = new BooleanQuery.Builder();
for (Term t : this._terms) {
q.add(new TermQuery(t), Occur.SHOULD);
}
return q.build();
}
}
}