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Java > Open Source Codes > org > archive > util > JavaLiterals


1 /* JavaLiterals
2  *
3  * Created on Dec 31, 2003
4  *
5  * Copyright (C) 2004 Internet Archive.
6  *
7  * This file is part of the Heritrix web crawler (crawler.archive.org).
8  *
9  * Heritrix is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU Lesser Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * any later version.
13  *
14  * Heritrix is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17  * GNU Lesser Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser Public License
20  * along with Heritrix; if not, write to the Free Software
21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22  */
23 package org.archive.util;
24
25 /**
26  * Utility functions to escape or unescape Java literal strings.
27  *
28  * @author gojomo
29  *
30  */
31 public class JavaLiterals {
32
33   public static String JavaDoc escape(String JavaDoc raw) {
34     StringBuffer JavaDoc escaped = new StringBuffer JavaDoc();
35     for(int i = 0; i<raw.length(); i++) {
36       char c = raw.charAt(i);
37       switch (c) {
38         case '\b':
39           escaped.append("\\b");
40           break;
41         case '\t':
42           escaped.append("\\t");
43           break;
44         case '\n':
45           escaped.append("\\n");
46           break;
47         case '\f':
48           escaped.append("\\f");
49           break;
50         case '\r':
51           escaped.append("\\r");
52           break;
53         case '\"':
54           escaped.append("\\\"");
55           break;
56         case '\'':
57           escaped.append("\\'");
58           break;
59         case '\\':
60           escaped.append("\\\\");
61           break;
62         default:
63           if(Character.getType(c)==Character.CONTROL) {
64             String JavaDoc unicode = Integer.toHexString((int)c);
65             while(unicode.length()<4) {
66               unicode = "0"+unicode;
67             }
68             escaped.append("\\u"+unicode);
69           } else {
70             escaped.append(c);
71           }
72       }
73
74     }
75     return escaped.toString();
76   }
77
78   public static String JavaDoc unescape(String JavaDoc escaped) {
79     StringBuffer JavaDoc raw = new StringBuffer JavaDoc();
80     for(int i = 0; i<escaped.length(); i++) {
81       char c = escaped.charAt(i);
82       if (c!='\\') {
83         raw.append(c);
84       } else {
85         i++;
86         if(i>=escaped.length()) {
87           // trailing '/'
88 raw.append(c);
89           continue;
90         }
91         c = escaped.charAt(i);
92         switch (c) {
93           case 'b':
94             raw.append('\b');
95             break;
96           case 't':
97             raw.append('\t');
98             break;
99           case 'n':
100             raw.append('\n');
101             break;
102           case 'f':
103             raw.append('\f');
104             break;
105           case 'r':
106             raw.append('r');
107             break;
108           case '"':
109             raw.append('\"');
110             break;
111           case '\'':
112             raw.append('\'');
113             break;
114           case '\\':
115             raw.append('\\');
116             break;
117           case 'u':
118             // unicode hex escape
119 try {
120               int unicode = Integer.parseInt(escaped.substring(i+1,i+5),16);
121               raw.append((char)unicode);
122               i = i + 4;
123             } catch (IndexOutOfBoundsException JavaDoc e) {
124               // err
125 raw.append("\\u");
126             }
127             break;
128           default:
129               if(Character.isDigit(c)) {
130                 // octal escape
131 int end = Math.min(i+4,escaped.length());
132                 int octal = Integer.parseInt(escaped.substring(i+1,end),8);
133                 if(octal<256) {
134                   raw.append((char)octal);
135                   i = end - 1;
136                 } else {
137                   // err
138 raw.append('\\');
139                   raw.append(c);
140                 }
141               }
142               break;
143         }
144       }
145     }
146     return raw.toString();
147   }
148 }
149
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