package org.apache.lucene.search;
import org.apache.lucene.util.Parameter;
/**
* Copyright 2004 The Apache Software Foundation
*
* 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.
*/
/** A clause in a BooleanQuery. */
public class BooleanClause implements java.io.Serializable {
/** Specifies how terms may occur in matching documents. */
public static final class Occur extends Parameter implements java.io.Serializable {
private Occur(String name) {
// typesafe enum pattern, no public constructor
super(name);
}
public String toString() {
if (this == MUST) return "+";
if (this == MUST_NOT) return "-";
return "";
}
/** Use this operator for terms that <i>must</i> appear in the matching documents. */
public static final Occur MUST = new Occur("MUST");
/** Use this operator for terms that <i>should</i> appear in the
* matching documents. For a BooleanQuery with two <code>SHOULD</code>
* subqueries, at least one of the queries must appear in the matching documents. */
public static final Occur SHOULD = new Occur("SHOULD");
/** Use this operator for terms 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> query. */
public static final Occur MUST_NOT = new Occur("MUST_NOT");
}
/** The query whose matching documents are combined by the boolean query.
* @deprecated use {@link #setQuery(Query)} instead */
public Query query; // TODO: decrease visibility for Lucene 2.0
/** If true, documents documents which <i>do not</i>
match this sub-query will <i>not</i> match the boolean query.
@deprecated use {@link #setOccur(BooleanClause.Occur)} instead */
public boolean required = false; // TODO: decrease visibility for Lucene 2.0
/** If true, documents documents which <i>do</i>
match this sub-query will <i>not</i> match the boolean query.
@deprecated use {@link #setOccur(BooleanClause.Occur)} instead */
public boolean prohibited = false; // TODO: decrease visibility for Lucene 2.0
private Occur occur = Occur.SHOULD;
/** Constructs a BooleanClause with query <code>q</code>, required
* <code>r</code> and prohibited <code>p</code>.
* @deprecated use BooleanClause(Query, Occur) instead
* <ul>
* <li>For BooleanClause(query, true, false) use BooleanClause(query, BooleanClause.Occur.MUST)
* <li>For BooleanClause(query, false, false) use BooleanClause(query, BooleanClause.Occur.SHOULD)
* <li>For BooleanClause(query, false, true) use BooleanClause(query, BooleanClause.Occur.MUST_NOT)
* </ul>
*/
public BooleanClause(Query q, boolean r, boolean p) {
// TODO: remove for Lucene 2.0
query = q;
required = r;
prohibited = p;
if (required) {
if (prohibited) {
// prohibited && required doesn't make sense, but we want the old behaviour:
occur = Occur.MUST_NOT;
} else {
occur = Occur.MUST;
}
} else {
if (prohibited) {
occur = Occur.MUST_NOT;
} else {
occur = Occur.SHOULD;
}
}
}
/** Constructs a BooleanClause.
*/
public BooleanClause(Query query, Occur occur) {
this.query = query;
this.occur = occur;
setFields(occur);
}
public Occur getOccur() {
return occur;
}
public void setOccur(Occur occur) {
this.occur = occur;
setFields(occur);
}
public Query getQuery() {
return query;
}
public void setQuery(Query query) {
this.query = query;
}
public boolean isProhibited() {
return prohibited;
}
public boolean isRequired() {
return required;
}
private void setFields(Occur occur) {
if (occur == Occur.MUST) {
required = true;
prohibited = false;
} else if (occur == Occur.SHOULD) {
required = false;
prohibited = false;
} else if (occur == Occur.MUST_NOT) {
required = false;
prohibited = true;
} else {
throw new IllegalArgumentException("Unknown operator " + occur);
}
}
/** Returns true iff <code>o</code> is equal to this. */
public boolean equals(Object o) {
if (!(o instanceof BooleanClause))
return false;
BooleanClause other = (BooleanClause)o;
return this.query.equals(other.query)
&& (this.required == other.required)
&& (this.prohibited == other.prohibited);
}
/** Returns a hash code value for this object.*/
public int hashCode() {
return query.hashCode() ^ (this.required?1:0) ^ (this.prohibited?2:0);
}
public String toString() {
return occur.toString() + query.toString();
}
}
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