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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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package org.apache.solr.search;
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import org.apache.lucene.search.*;
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* Extra lucene sorting utilities & convenience methods
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* @version $Id: Sorting.java 778893 2009-05-26 21:34:53Z yonik $
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public class Sorting {
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/** Returns a {@link SortField} for a string field.
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* If nullLast and nullFirst are both false, then default lucene string sorting is used where
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* null strings sort first in an ascending sort, and last in a descending sort.
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* @param fieldName the name of the field to sort on
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* @param reverse true for a reverse (desc) sort
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* @param nullLast true if null should come last, regardless of sort order
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* @param nullFirst true if null should come first, regardless of sort order
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public static SortField getStringSortField(String fieldName, boolean reverse, boolean nullLast, boolean nullFirst) {
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if (!reverse) return new SortField(fieldName, nullStringLastComparatorSource);
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else return new SortField(fieldName, SortField.STRING, true);
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} else if (nullFirst) {
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if (reverse) return new SortField(fieldName, nullStringLastComparatorSource, true);
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else return new SortField(fieldName, SortField.STRING, false);
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return new SortField(fieldName, SortField.STRING, reverse);
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static final FieldComparatorSource nullStringLastComparatorSource = new MissingStringLastComparatorSource(null);