package org.apache.lucene.search;
/**
* 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.
*/
import java.io.IOException;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.index.IndexReader;
/**
* A Query that matches documents within an exclusive range.
*
* @version $Id: RangeQuery.java,v 1.12 2004/03/29 22:48:03 cutting Exp $
*/
public class RangeQuery extends Query
{
private Term lowerTerm;
private Term upperTerm;
private boolean inclusive;
/** Constructs a query selecting all terms greater than
* <code>lowerTerm</code> but less than <code>upperTerm</code>.
* There must be at least one term and either term may be null,
* in which case there is no bound on that side, but if there are
* two terms, both terms <b>must</b> be for the same field.
*/
public RangeQuery(Term lowerTerm, Term upperTerm, boolean inclusive)
{
if (lowerTerm == null && upperTerm == null)
{
throw new IllegalArgumentException("At least one term must be non-null");
}
if (lowerTerm != null && upperTerm != null && lowerTerm.field() != upperTerm.field())
{
throw new IllegalArgumentException("Both terms must be for the same field");
}
// if we have a lowerTerm, start there. otherwise, start at beginning
if (lowerTerm != null) {
this.lowerTerm = lowerTerm;
}
else {
this.lowerTerm = new Term(upperTerm.field(), "");
}
this.upperTerm = upperTerm;
this.inclusive = inclusive;
}
/**
* FIXME: Describe <code>rewrite</code> method here.
*
* @param reader an <code>IndexReader</code> value
* @return a <code>Query</code> value
* @exception IOException if an error occurs
*/
public Query rewrite(IndexReader reader) throws IOException {
BooleanQuery query = new BooleanQuery();
TermEnum enumerator = reader.terms(lowerTerm);
try {
boolean checkLower = false;
if (!inclusive) // make adjustments to set to exclusive
checkLower = true;
String testField = getField();
do {
Term term = enumerator.term();
if (term != null && term.field() == testField) {
if (!checkLower || term.text().compareTo(lowerTerm.text()) > 0) {
checkLower = false;
if (upperTerm != null) {
int compare = upperTerm.text().compareTo(term.text());
/* if beyond the upper term, or is exclusive and
* this is equal to the upper term, break out */
if ((compare < 0) || (!inclusive && compare == 0))
break;
}
TermQuery tq = new TermQuery(term); // found a match
tq.setBoost(getBoost()); // set the boost
query.add(tq, false, false); // add to query
}
}
else {
break;
}
}
while (enumerator.next());
}
finally {
enumerator.close();
}
return query;
}
public Query combine(Query[] queries) {
return Query.mergeBooleanQueries(queries);
}
/** Returns the field name for this query */
public String getField() {
return (lowerTerm != null ? lowerTerm.field() : upperTerm.field());
}
/** Returns the lower term of this range query */
public Term getLowerTerm() { return lowerTerm; }
/** Returns the upper term of this range query */
public Term getUpperTerm() { return upperTerm; }
/** Returns <code>true</code> if the range query is inclusive */
public boolean isInclusive() { return inclusive; }
/** Prints a user-readable version of this query. */
public String toString(String field)
{
StringBuffer buffer = new StringBuffer();
if (!getField().equals(field))
{
buffer.append(getField());
buffer.append(":");
}
buffer.append(inclusive ? "[" : "{");
buffer.append(lowerTerm != null ? lowerTerm.text() : "null");
buffer.append(" TO ");
buffer.append(upperTerm != null ? upperTerm.text() : "null");
buffer.append(inclusive ? "]" : "}");
if (getBoost() != 1.0f)
{
buffer.append("^");
buffer.append(Float.toString(getBoost()));
}
return buffer.toString();
}
}
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