package org.apache.lucene.index.sorter;
/*
* 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.
*/
import java.io.IOException;
import org.apache.lucene.index.AtomicReader;
import org.apache.lucene.index.NumericDocValues;
/**
* A {@link Sorter} which sorts documents according to their
* {@link NumericDocValues}. One can specify ascending or descending sort order.
*
* @lucene.experimental
*/
public class NumericDocValuesSorter extends Sorter {
private final String fieldName;
private final boolean ascending;
/** Constructor over the given field name, and ascending sort order. */
public NumericDocValuesSorter(final String fieldName) {
this(fieldName, true);
}
/**
* Constructor over the given field name, and whether sorting should be
* ascending ({@code true}) or descending ({@code false}).
*/
public NumericDocValuesSorter(final String fieldName, boolean ascending) {
this.fieldName = fieldName;
this.ascending = ascending;
}
@Override
public Sorter.DocMap sort(final AtomicReader reader) throws IOException {
final NumericDocValues ndv = reader.getNumericDocValues(fieldName);
final DocComparator comparator;
if (ascending) {
comparator = new DocComparator() {
@Override
public int compare(int docID1, int docID2) {
final long v1 = ndv.get(docID1);
final long v2 = ndv.get(docID2);
return v1 < v2 ? -1 : v1 == v2 ? 0 : 1;
}
};
} else {
comparator = new DocComparator() {
@Override
public int compare(int docID1, int docID2) {
final long v1 = ndv.get(docID1);
final long v2 = ndv.get(docID2);
return v1 > v2 ? -1 : v1 == v2 ? 0 : 1;
}
};
}
return sort(reader.maxDoc(), comparator);
}
@Override
public String getID() {
return "DocValues(" + fieldName + "," + (ascending ? "ascending" : "descending") + ")";
}
}