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Java > Open Source Codes > com > tc > aspectwerkz > expression > ast > Token


1 /*
2  * All content copyright (c) 2003-2006 Terracotta, Inc., except as may otherwise be noted in a separate copyright notice. All rights reserved.
3  */
4 package com.tc.aspectwerkz.expression.ast;
5
6 /**
7  * Describes the input token stream.
8  */
9
10 public class Token {
11
12   /**
13    * An integer that describes the kind of this token. This numbering system is determined by JavaCCParser, and a
14    * table of these numbers is stored in the file ...Constants.java.
15    */
16   public int kind;
17
18   /**
19    * beginLine and beginColumn describe the position of the first character of this token; endLine and endColumn
20    * describe the position of the last character of this token.
21    */
22   public int beginLine, beginColumn, endLine, endColumn;
23
24   /**
25    * The string image of the token.
26    */
27   public String JavaDoc image;
28
29   /**
30    * A reference to the next regular (non-special) token from the input stream. If this is the last token from the
31    * input stream, or if the token manager has not read tokens beyond this one, this field is set to null. This is
32    * true only if this token is also a regular token. Otherwise, see below for a description of the contents of this
33    * field.
34    */
35   public Token next;
36
37   /**
38    * This field is used to access special tokens that occur prior to this token, but after the immediately preceding
39    * regular (non-special) token. If there are no such special tokens, this field is set to null. When there are more
40    * than one such special token, this field refers to the last of these special tokens, which in turn refers to the
41    * next previous special token through its specialToken field, and so on until the first special token (whose
42    * specialToken field is null). The next fields of special tokens refer to other special tokens that immediately
43    * follow it (without an intervening regular token). If there is no such token, this field is null.
44    */
45   public Token specialToken;
46
47   /**
48    * Returns the image.
49    */
50   public String JavaDoc toString() {
51     return image;
52   }
53
54   /**
55    * Returns a new Token object, by default. However, if you want, you can create and return subclass objects based on
56    * the value of ofKind. Simply add the cases to the switch for all those special cases. For example, if you have a
57    * subclass of Token called IDToken that you want to create if ofKind is ID, simlpy add something like : case
58    * MyParserConstants.ID : return new IDToken(); to the following switch statement. Then you can cast matchedToken
59    * variable to the appropriate type and use it in your lexical actions.
60    */
61   public static final Token newToken(int ofKind) {
62     switch (ofKind) {
63       default:
64         return new Token();
65     }
66   }
67
68 }
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