/*
* 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.lucene.search;
import java.util.Objects;
/** A clause in a BooleanQuery. */
public final class BooleanClause {
/** Specifies how clauses are to occur in matching documents. */
public static enum Occur {
/** Use this operator for clauses that <i>must</i> appear in the matching documents. */
MUST { @Override public String toString() { return "+"; } },
/** Like {@link #MUST} except that these clauses do not participate in scoring. */
FILTER { @Override public String toString() { return "#"; } },
/** Use this operator for clauses that <i>should</i> appear in the
* matching documents. For a BooleanQuery with no <code>MUST</code>
* clauses one or more <code>SHOULD</code> clauses must match a document
* for the BooleanQuery to match.
* @see BooleanQuery.Builder#setMinimumNumberShouldMatch
*/
SHOULD { @Override public String toString() { return ""; } },
/** Use this operator for clauses that <i>must not</i> appear in the matching documents.
* Note that it is not possible to search for queries that only consist
* of a <code>MUST_NOT</code> clause. These clauses do not contribute to the
* score of documents. */
MUST_NOT { @Override public String toString() { return "-"; } };
}
/** The query whose matching documents are combined by the boolean query.
*/
private final Query query;
private final Occur occur;
/** Constructs a BooleanClause.
*/
public BooleanClause(Query query, Occur occur) {
this.query = Objects.requireNonNull(query, "Query must not be null");
this.occur = Objects.requireNonNull(occur, "Occur must not be null");
}
public Occur getOccur() {
return occur;
}
public Query getQuery() {
return query;
}
public boolean isProhibited() {
return Occur.MUST_NOT == occur;
}
public boolean isRequired() {
return occur == Occur.MUST || occur == Occur.FILTER;
}
public boolean isScoring() {
return occur == Occur.MUST || occur == Occur.SHOULD;
}
/** Returns true if <code>o</code> is equal to this. */
@Override
public boolean equals(Object o) {
if (o == null || !(o instanceof BooleanClause))
return false;
BooleanClause other = (BooleanClause)o;
return this.query.equals(other.query)
&& this.occur == other.occur;
}
/** Returns a hash code value for this object.*/
@Override
public int hashCode() {
return 31 * query.hashCode() + occur.hashCode();
}
@Override
public String toString() {
return occur.toString() + query.toString();
}
}