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1   /*
2    * Copyright (c) 2009 QOS.ch All rights reserved.
3    *
4    * Permission is hereby granted, free of charge, to any person obtaining a copy
5    * of this software and associated documentation files (the "Software"), to deal
6    * in the Software without restriction, including without limitation the rights
7    * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8    * copies of the Software, and to permit persons to whom the Software is
9    * furnished to do so, subject to the following conditions:
10   *
11   * The above copyright notice and this permission notice shall be included in
12   * all copies or substantial portions of the Software.
13   *
14   * THE SOFTWARE IS PROVIDED "AS  IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
20   * SOFTWARE.
21   */
22  package ch.qos.cal10n.util;
23  
24  /**
25   * @author Ceki Gücü
26   */
27  public class LexicalUtil {
28  
29  
30    public static StringBuilder convertSpecialCharacters(StringBuilder inBuf) {
31  
32      int i = inBuf.indexOf("\\");
33  
34      if (i == -1) {
35        return inBuf;
36      }
37  
38      StringBuilder outBuf = new StringBuilder(inBuf.length());
39  
40      int followIndex = -1;  // index of char following the latest backslash
41      while (i != -1) {
42        outBuf.append(inBuf.subSequence(followIndex + 1, i));
43        followIndex = i + 1;
44        char c = inBuf.charAt(followIndex);
45        switch (c) {
46          case 'u':
47            char unicodeChar = readUnicode(inBuf, followIndex + 1);
48            outBuf.append(unicodeChar);
49            followIndex += 4;
50            break;
51          case 'n':
52            outBuf.append('\n');
53            break;
54          case 'r':
55            outBuf.append('\r');
56            break;
57          case 't':
58            outBuf.append('\t');
59            break;
60          case 'f':
61            outBuf.append('\f');
62            break;
63          case ':': // see http://tinyurl.com/bprdgnk , i.e. the javadocs for Properties.store()
64          case '#':
65          case '!':
66          case '=':
67            outBuf.append(c);
68            break;
69          default:
70            outBuf.append('\\');
71            outBuf.append(c);
72        }
73        // search for the next \
74        i = inBuf.indexOf("\\", followIndex + 1);
75      }
76      outBuf.append(inBuf.subSequence(followIndex + 1, inBuf.length()));
77      return outBuf;
78    }
79  
80    // see http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#95504
81  
82    private static char readUnicode(StringBuilder inBuf, int i) {
83      int r = 0;
84      for (int j = i; j < i + 4; j++) {
85        char atJ = inBuf.charAt(j);
86  
87        if (atJ >= '0' && atJ <= '9') {
88          r = (r << 4) + atJ - '0';
89          continue;
90        }
91        if (atJ >= 'A' && atJ <= 'F') {
92          // '7' = 'A' - 10
93          r = (r << 4) + atJ - '7';
94          continue;
95        }
96        if (atJ >= 'a' && atJ <= 'f') {
97          // 'W' = 'a' - 10
98          r = (r << 4) + atJ - 'W';
99          continue;
100       }
101     }
102     return (char) r;
103   }
104 }