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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.http.multipart;
17  
18  import java.io.Serializable;
19  import java.util.Comparator;
20  
21  final class CaseIgnoringComparator implements Comparator<CharSequence>, Serializable {
22  
23      private static final long serialVersionUID = 4582133183775373862L;
24  
25      static final CaseIgnoringComparator INSTANCE = new CaseIgnoringComparator();
26  
27      private CaseIgnoringComparator() {
28      }
29  
30      @Override
31      public int compare(CharSequence o1, CharSequence o2) {
32          int o1Length = o1.length();
33          int o2Length = o2.length();
34          int min = Math.min(o1Length, o2Length);
35          for (int i = 0; i < min; i++) {
36              char c1 = o1.charAt(i);
37              char c2 = o2.charAt(i);
38              if (c1 != c2) {
39                  c1 = Character.toUpperCase(c1);
40                  c2 = Character.toUpperCase(c2);
41                  if (c1 != c2) {
42                      c1 = Character.toLowerCase(c1);
43                      c2 = Character.toLowerCase(c2);
44                      if (c1 != c2) {
45                          return c1 - c2;
46                      }
47                  }
48              }
49          }
50          return o1Length - o2Length;
51      }
52  
53      private Object readResolve() {
54          return INSTANCE;
55      }
56  }