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Java > Open Source Codes > net > sourceforge > pmd > rules > SuspiciousOctalEscape


1 package net.sourceforge.pmd.rules;
2
3 import net.sourceforge.pmd.AbstractRule;
4 import net.sourceforge.pmd.ast.ASTLiteral;
5
6 public class SuspiciousOctalEscape extends AbstractRule {
7
8     public Object JavaDoc visit(ASTLiteral node, Object JavaDoc data) {
9         String JavaDoc image = node.getImage();
10         if (image != null && image.startsWith("\"")) // make sure it's a string literal
11 {
12             // trim quotes
13 String JavaDoc s = image.substring(1, image.length() - 1);
14
15             // process escape sequences
16 int offset = 0;
17             for (int slash = s.indexOf('\\', offset);
18                  slash != -1 && slash < s.length() - 1;
19                  slash = s.indexOf('\\', offset)) {
20                 String JavaDoc escapeSequence = s.substring(slash + 1);
21                 char first = escapeSequence.charAt(0);
22                 if (isOctal(first)) {
23                     if (escapeSequence.length() > 1) {
24                         char second = escapeSequence.charAt(1);
25                         if (isOctal(second)) {
26                             if (escapeSequence.length() > 2) {
27                                 char third = escapeSequence.charAt(2);
28                                 if (isOctal(third)) {
29                                     // this is either a three digit octal escape or a two-digit
30 // octal escape followed by an octal digit. the value of
31 // the first digit in the sequence determines which is the
32 // case
33 if (first != '0' && first != '1' && first != '2' && first != '3') {
34                                         // VIOLATION: it's a two-digit octal escape followed by
35 // an octal digit -- legal but very confusing!
36 addViolation(data, node);
37                                     } else {
38                                         // if there is a 4th decimal digit, it could never be part of
39 // the escape sequence, which is confusing
40 if (escapeSequence.length() > 3) {
41                                             char fourth = escapeSequence.charAt(3);
42                                             if (isDecimal(fourth)) {
43                                                 addViolation(data, node);
44                                             }
45                                         }
46                                     }
47
48                                 } else if (isDecimal(third)) {
49                                     // this is a two-digit octal escape followed by a decimal digit
50 // legal but very confusing
51 addViolation(data, node);
52                                 }
53                             }
54                         } else if (isDecimal(second)) {
55                             // this is a one-digit octal escape followed by a decimal digit
56 // legal but very confusing
57 addViolation(data, node);
58                         }
59                     }
60                 }
61
62                 offset = slash + 1;
63             }
64         }
65
66         return super.visit(node, data);
67     }
68
69     private boolean isOctal(char c) {
70         switch (c) {
71             case '0':
72             case '1':
73             case '2':
74             case '3':
75             case '4':
76             case '5':
77             case '6':
78             case '7':
79                 return true;
80             default:
81                 return false;
82         }
83     }
84
85     private boolean isDecimal(char c) {
86         switch (c) {
87             case '0':
88             case '1':
89             case '2':
90             case '3':
91             case '4':
92             case '5':
93             case '6':
94             case '7':
95             case '8':
96             case '9':
97                 return true;
98             default:
99                 return false;
100         }
101     }
102 }
103
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