1 /**
2 * Copyright 2010-2014 The Kuali Foundation
3 *
4 * Licensed under the Educational Community License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.opensource.org/licenses/ecl2.php
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,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.kuali.common.util;
17
18 public final class Ascii {
19
20 private Ascii() {
21 }
22
23 private static final int LETTER_OFFSET = 13;
24 private static final int NUMBER_OFFSET = 5;
25 private static final char NUMBER_MIDPOINT = '4';
26 private static final char LCASE_MIDPOINT = 'm';
27 private static final char UCASE_MIDPOINT = 'M';
28
29 /**
30 * Return true if the character is in the range A-Z or a-z
31 */
32 public static boolean isLetter(char c) {
33 return isLowerCase(c) || isUpperCase(c);
34 }
35
36 /**
37 * Return true if the character is in the range 0-9
38 */
39 public static boolean isDigit(char c) {
40 return c >= '0' && c <= '9';
41 }
42
43 /**
44 * Return true if the character is in the range a-z
45 */
46 public static boolean isLowerCase(char c) {
47 return c >= 'a' && c <= 'z';
48 }
49
50 /**
51 * Return true if the character is in the range A-Z
52 */
53 public static boolean isUpperCase(char c) {
54 return c >= 'A' && c <= 'Z';
55 }
56
57 /**
58 * <p>
59 * If the character is a letter or digit, apply the flip algorithm to it, otherwise leave it alone.
60 * </p>
61 *
62 * The flip algorithm makes the character in the top row become the character in the bottom row, and vice versa.
63 *
64 * <pre>
65 * 01234 abcdefghijklm ABCDEFGHIJKLM
66 * 56789 nopqrstuvwxyz NOPQRSTUVWXYZ
67 * </pre>
68 */
69 public static char flip(char c) {
70 if (isLowerCase(c)) {
71 if (c > LCASE_MIDPOINT) {
72 return (char) ((int) c - LETTER_OFFSET);
73 } else {
74 return (char) ((int) c + LETTER_OFFSET);
75 }
76 } else if (isUpperCase(c)) {
77 if (c > UCASE_MIDPOINT) {
78 return (char) ((int) c - LETTER_OFFSET);
79 } else {
80 return (char) ((int) c + LETTER_OFFSET);
81 }
82 } else if (isDigit(c)) {
83 if (c > NUMBER_MIDPOINT) {
84 return (char) ((int) c - NUMBER_OFFSET);
85 } else {
86 return (char) ((int) c + NUMBER_OFFSET);
87 }
88 } else {
89 return c;
90 }
91 }
92
93 }