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1   /**
2    * Logback: the reliable, generic, fast and flexible logging framework.
3    * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
4    *
5    * This program and the accompanying materials are dual-licensed under
6    * either the terms of the Eclipse Public License v1.0 as published by
7    * the Eclipse Foundation
8    *
9    *   or (per the licensee's choosing)
10   *
11   * under the terms of the GNU Lesser General Public License version 2.1
12   * as published by the Free Software Foundation.
13   */
14  package ch.qos.logback.core.pattern;
15  
16  public class SpacePadder {
17  
18    final static String[] SPACES = { " ", "  ", "    ", "        ", // 1,2,4,8
19        // spaces
20        "                ", // 16 spaces
21        "                                " }; // 32 spaces
22  
23    final static public void leftPad(StringBuilder buf, String s, int desiredLength) {
24      int actualLen = 0;
25      if (s != null) {
26        actualLen = s.length();
27      }
28      if (actualLen < desiredLength) {
29        spacePad(buf, desiredLength - actualLen);
30      }
31      if (s != null) {
32        buf.append(s);
33      }
34    }
35  
36    final static public void rightPad(StringBuilder buf, String s, int desiredLength) {
37      int actualLen = 0;
38      if (s != null) {
39        actualLen = s.length();
40      }
41      if (s != null) {
42        buf.append(s);
43      }
44      if (actualLen < desiredLength) {
45        spacePad(buf, desiredLength - actualLen);
46      }
47    }
48    
49    /**
50     * Fast space padding method.
51     */
52    final static public void spacePad(StringBuilder sbuf, int length) {
53      while (length >= 32) {
54        sbuf.append(SPACES[5]);
55        length -= 32;
56      }
57  
58      for (int i = 4; i >= 0; i--) {
59        if ((length & (1 << i)) != 0) {
60          sbuf.append(SPACES[i]);
61        }
62      }
63    }
64  }