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Java > Open Source Codes > org > codehaus > groovy > syntax > lexer > TextLexerBase


1 package org.codehaus.groovy.syntax.lexer;
2
3 import org.codehaus.groovy.syntax.ReadException;
4
5 /**
6  * A base class for Lexers that process embedded text.
7  *
8  * @author Chris Poirier
9  */
10
11 public class TextLexerBase extends LexerBase implements Delimiter
12 {
13
14     protected boolean delimited = true; // When true, the lexer can do its delimiting
15 protected boolean finished = true; // When true, the lexer is dry
16
17
18    /**
19     * Turns delimiting on or off. This should affect <code>la()</code>
20     * and <code>consume()</code>. However, once the delimiter has been
21     * reached, this routine should have no effect.
22     */
23
24     public void delimit( boolean delimited )
25     {
26         this.delimited = delimited;
27     }
28
29
30
31    /**
32     * Returns true if the lexer is applying its delimiter policy.
33     */
34
35     public boolean isDelimited()
36     {
37         return this.delimited;
38     }
39
40
41
42    /**
43     * Returns true if the lexer stream is dry.
44     */
45
46     public boolean isFinished()
47     {
48         return finished;
49     }
50
51
52
53    /**
54     * Restarts the lexer stream after a <code>finish()</code>
55     * and some intevening act (like a new source).
56     */
57
58     protected void restart()
59     {
60         finished = false;
61     }
62
63
64
65    /**
66     * Stops the lexer stream.
67     */
68
69     protected void finish()
70     {
71         finished = true;
72     }
73
74
75
76
77
78   //---------------------------------------------------------------------------
79 // STREAM ROUTINES
80
81
82    /**
83     * Returns the next <code>k</code>th character, without consuming any.
84     */
85
86     public char la(int k) throws LexerException, ReadException
87     {
88         if( finished )
89         {
90             return CharStream.EOS;
91         }
92         else if( source != null )
93         {
94             return source.la(k);
95         }
96         else
97         {
98             return CharStream.EOS;
99         }
100     }
101
102
103
104    /**
105     * Eats a character from the input stream.
106     */
107
108     public char consume() throws LexerException, ReadException
109     {
110         if( finished )
111         {
112             return CharStream.EOS;
113         }
114         else if( source != null )
115         {
116             return source.consume();
117         }
118         else
119         {
120             return CharStream.EOS;
121         }
122     }
123
124 }
125
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