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.logging.log4j.util;
18
19 /**
20 * <em>Consider this class private.</em>
21 */
22 public final class Chars {
23
24 /** Carriage Return. */
25 public static final char CR = '\r';
26
27 /** Double Quote. */
28 public static final char DQUOTE = '\"';
29
30 /** Equals '='. */
31 public static final char EQ = '=';
32
33 /** Line Feed. */
34 public static final char LF = '\n';
35
36 /** NUL. */
37 public static final char NUL = 0;
38
39 /** Single Quote [']. */
40 public static final char QUOTE = '\'';
41
42 /** Space. */
43 public static final char SPACE = ' ';
44
45 /** Tab. */
46 public static final char TAB = '\t';
47
48 /**
49 * Converts a digit into an upper-case hexadecimal character or the null character if invalid.
50 *
51 * @param digit a number 0 - 15
52 * @return the hex character for that digit or '\0' if invalid
53 */
54 public static char getUpperCaseHex(final int digit) {
55 if (digit < 0 || digit >= 16) {
56 return '\0';
57 }
58 return digit < 10 ? getNumericalDigit(digit) : getUpperCaseAlphaDigit(digit);
59 }
60
61 /**
62 * Converts a digit into an lower-case hexadecimal character or the null character if invalid.
63 *
64 * @param digit a number 0 - 15
65 * @return the hex character for that digit or '\0' if invalid
66 */
67 public static char getLowerCaseHex(final int digit) {
68 if (digit < 0 || digit >= 16) {
69 return '\0';
70 }
71 return digit < 10 ? getNumericalDigit(digit) : getLowerCaseAlphaDigit(digit);
72 }
73
74 private static char getNumericalDigit(final int digit) {
75 return (char) ('0' + digit);
76 }
77
78 private static char getUpperCaseAlphaDigit(final int digit) {
79 return (char) ('A' + digit - 10);
80 }
81
82 private static char getLowerCaseAlphaDigit(final int digit) {
83 return (char) ('a' + digit - 10);
84 }
85
86 private Chars() {
87 }
88 }