1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.codec.binary;
18
19 /**
20 * <p>
21 * Operations on {@link CharSequence} that are {@code null} safe.
22 * </p>
23 * <p>
24 * Copied from Apache Commons Lang r1586295 on April 10, 2014 (day of 3.3.2 release).
25 * </p>
26 *
27 * @see CharSequence
28 * @since 1.10
29 */
30 public class CharSequenceUtils {
31
32 /**
33 * Green implementation of regionMatches.
34 *
35 * <p>
36 * Note: This function differs from the current implementation in Apache Commons Lang
37 * where the input indices are not valid. It is only used within this package.
38 * </p>
39 *
40 * @param cs
41 * the {@code CharSequence} to be processed
42 * @param ignoreCase
43 * whether or not to be case-insensitive
44 * @param thisStart
45 * the index to start on the {@code cs} CharSequence
46 * @param substring
47 * the {@code CharSequence} to be looked for
48 * @param start
49 * the index to start on the {@code substring} CharSequence
50 * @param length
51 * character length of the region
52 * @return whether the region matched
53 */
54 static boolean regionMatches(final CharSequence cs, final boolean ignoreCase, final int thisStart,
55 final CharSequence substring, final int start, final int length) {
56 if (cs instanceof String && substring instanceof String) {
57 return ((String) cs).regionMatches(ignoreCase, thisStart, (String) substring, start, length);
58 }
59 int index1 = thisStart;
60 int index2 = start;
61 int tmpLen = length;
62 while (tmpLen-- > 0) {
63 final char c1 = cs.charAt(index1++);
64 final char c2 = substring.charAt(index2++);
65 if (c1 == c2) {
66 continue;
67 }
68 if (!ignoreCase) {
69 return false;
70 }
71 // The same check as in String.regionMatches():
72 if (Character.toUpperCase(c1) != Character.toUpperCase(c2) &&
73 Character.toLowerCase(c1) != Character.toLowerCase(c2)) {
74 return false;
75 }
76 }
77 return true;
78 }
79 }