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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.hadoop.hbase.codec.prefixtree.encode.tokenize;
20  
21  import java.util.Comparator;
22  
23  import org.apache.hadoop.classification.InterfaceAudience;
24  
25  /**
26   * Determines order of nodes in the output array.  Maybe possible to optimize further.
27   */
28  @InterfaceAudience.Private
29  public class TokenDepthComparator implements Comparator<TokenizerNode> {
30  
31    @Override
32    public int compare(TokenizerNode a, TokenizerNode b) {
33      if(a==null){
34        throw new IllegalArgumentException("a cannot be null");
35      }
36      if(b==null){
37        throw new IllegalArgumentException("b cannot be null");
38      }
39  
40      // put leaves at the end
41      if (!a.isLeaf() && b.isLeaf()) {
42        return -1;
43      }
44      if (a.isLeaf() && !b.isLeaf()) {
45        return 1;
46      }
47  
48      if (a.isLeaf() && b.isLeaf()) {// keep leaves in sorted order (for debugability)
49        return a.getId() < b.getId() ? -1 : 1;
50      }
51  
52      // compare depth
53      if (a.getTokenOffset() < b.getTokenOffset()) {
54        return -1;
55      }
56      if (a.getTokenOffset() > b.getTokenOffset()) {
57        return 1;
58      }
59  
60      // if same depth, return lower id first. ids are unique
61      return a.getId() < b.getId() ? -1 : 1;
62    }
63  
64  }