1
2 package net.sourceforge.pmd.ast;
3
4 /***
5 * This exception is thrown when parse errors are encountered.
6 * You can explicitly create objects of this exception type by
7 * calling the method generateParseException in the generated
8 * parser.
9 * <p/>
10 * You can modify this class to customize your error reporting
11 * mechanisms so long as you retain the public fields.
12 */
13 public class ParseException extends RuntimeException {
14
15 /***
16 * This constructor is used by the method "generateParseException"
17 * in the generated parser. Calling this constructor generates
18 * a new object of this type with the fields "currentToken",
19 * "expectedTokenSequences", and "tokenImage" set. The boolean
20 * flag "specialConstructor" is also set to true to indicate that
21 * this constructor was used to create this object.
22 * This constructor calls its super class with the empty string
23 * to force the "toString" method of parent class "Throwable" to
24 * print the error message in the form:
25 * ParseException: <result of getMessage>
26 */
27 public ParseException(Token currentTokenVal,
28 int[][] expectedTokenSequencesVal,
29 String[] tokenImageVal) {
30 super("");
31 specialConstructor = true;
32 currentToken = currentTokenVal;
33 expectedTokenSequences = expectedTokenSequencesVal;
34 tokenImage = tokenImageVal;
35 }
36
37 /***
38 * The following constructors are for use by you for whatever
39 * purpose you can think of. Constructing the exception in this
40 * manner makes the exception behave in the normal way - i.e., as
41 * documented in the class "Throwable". The fields "errorToken",
42 * "expectedTokenSequences", and "tokenImage" do not contain
43 * relevant information. The JavaCC generated code does not use
44 * these constructors.
45 */
46
47 public ParseException() {
48 super();
49 specialConstructor = false;
50 }
51
52 public ParseException(String message) {
53 super(message);
54 specialConstructor = false;
55 }
56
57 /***
58 * This variable determines which constructor was used to create
59 * this object and thereby affects the semantics of the
60 * "getMessage" method (see below).
61 */
62 protected boolean specialConstructor;
63
64 /***
65 * This is the last token that has been consumed successfully. If
66 * this object has been created due to a parse error, the token
67 * followng this token will (therefore) be the first error token.
68 */
69 public Token currentToken;
70
71 /***
72 * Each entry in this array is an array of integers. Each array
73 * of integers represents a sequence of tokens (by their ordinal
74 * values) that is expected at this point of the parse.
75 */
76 public int[][] expectedTokenSequences;
77
78 /***
79 * This is a reference to the "tokenImage" array of the generated
80 * parser within which the parse error occurred. This array is
81 * defined in the generated ...Constants interface.
82 */
83 public String[] tokenImage;
84
85 /***
86 * This method has the standard behavior when this object has been
87 * created using the standard constructors. Otherwise, it uses
88 * "currentToken" and "expectedTokenSequences" to generate a parse
89 * error message and returns it. If this object has been created
90 * due to a parse error, and you do not catch it (it gets thrown
91 * from the parser), then this method is called during the printing
92 * of the final stack trace, and hence the correct error message
93 * gets displayed.
94 */
95 public String getMessage() {
96 if (!specialConstructor) {
97 return super.getMessage();
98 }
99 StringBuffer expected = new StringBuffer();
100 int maxSize = 0;
101 for (int i = 0; i < expectedTokenSequences.length; i++) {
102 if (maxSize < expectedTokenSequences[i].length) {
103 maxSize = expectedTokenSequences[i].length;
104 }
105 for (int j = 0; j < expectedTokenSequences[i].length; j++) {
106 expected.append(tokenImage[expectedTokenSequences[i][j]]).append(" ");
107 }
108 if (expectedTokenSequences[i][expectedTokenSequences[i].length - 1] != 0) {
109 expected.append("...");
110 }
111 expected.append(eol).append(" ");
112 }
113 String retval = "Encountered \"";
114 Token tok = currentToken.next;
115 for (int i = 0; i < maxSize; i++) {
116 if (i != 0) retval += " ";
117 if (tok.kind == 0) {
118 retval += tokenImage[0];
119 break;
120 }
121 retval += add_escapes(tok.image);
122 tok = tok.next;
123 }
124 retval += "\" at line " + currentToken.next.beginLine + ", column " + currentToken.next.beginColumn;
125 retval += "." + eol;
126 if (expectedTokenSequences.length == 1) {
127 retval += "Was expecting:" + eol + " ";
128 } else {
129 retval += "Was expecting one of:" + eol + " ";
130 }
131 retval += expected.toString();
132 return retval;
133 }
134
135 /***
136 * The end of line string for this machine.
137 */
138 protected String eol = System.getProperty("line.separator", "\n");
139
140 /***
141 * Used to convert raw characters to their escaped version
142 * when these raw version cannot be used as part of an ASCII
143 * string literal.
144 */
145 protected String add_escapes(String str) {
146 StringBuffer retval = new StringBuffer();
147 char ch;
148 for (int i = 0; i < str.length(); i++) {
149 switch (str.charAt(i)) {
150 case 0:
151 continue;
152 case '\b':
153 retval.append("//b");
154 continue;
155 case '\t':
156 retval.append("//t");
157 continue;
158 case '\n':
159 retval.append("//n");
160 continue;
161 case '\f':
162 retval.append("//f");
163 continue;
164 case '\r':
165 retval.append("//r");
166 continue;
167 case '\"':
168 retval.append("//\"");
169 continue;
170 case '\'':
171 retval.append("//\'");
172 continue;
173 case '//':
174 retval.append("////");
175 continue;
176 default:
177 if ((ch = str.charAt(i)) < 0x20 || ch > 0x7e) {
178 String s = "0000" + Integer.toString(ch, 16);
179 retval.append("//u" + s.substring(s.length() - 4, s.length()));
180 } else {
181 retval.append(ch);
182 }
183 continue;
184 }
185 }
186 return retval.toString();
187 }
188
189 }