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


1 package org.codehaus.groovy.syntax.lexer;
2
3 import org.codehaus.groovy.syntax.ReadException;
4 import org.codehaus.groovy.syntax.Token;
5
6 /**
7  * The minimal interface provided by all Lexers.
8  *
9  * @author Bob Mcwhirter
10  * @author James Strachan
11  * @author John Wilson
12  * @author Chris Poirier
13  */
14
15 public interface Lexer
16 {
17
18
19    /**
20     * Gets the lexer that is actually doing the <code>nextToken()</code>
21     * work, if it isn't us.
22     */
23
24     public Lexer getDelegate();
25
26
27
28    /**
29     * Gets the lexer from which this lexer is obtaining characters.
30     */
31
32     public Lexer getSource();
33
34
35
36    /**
37     * Finds and returns (consuming) the next token from the underlying stream.
38     * Returns null when out of tokens.
39     */
40
41     public Token nextToken() throws ReadException, LexerException;
42
43
44
45
46   //---------------------------------------------------------------------------
47 // DELEGATION
48
49
50    /**
51     * Resets a lexer for reuse.
52     */
53
54     public void reset();
55
56
57
58    /**
59     * Delegates our duties to another Lexer.
60     */
61
62     public void delegate( Lexer to );
63
64
65
66    /**
67     * Retakes responsibility for our duties.
68     */
69
70     public void undelegate();
71
72
73
74    /**
75     * Returns true if we are delegated.
76     */
77
78     public boolean isDelegated();
79
80
81
82    /**
83     * Sets the source lexer.
84     */
85
86     public void setSource( Lexer source );
87
88
89
90    /**
91     * Unsets the source lexer.
92     */
93
94     public void unsetSource( );
95
96
97
98    /**
99     * Returns true if we have an external source.
100     */
101
102     public boolean isExternallySourced();
103
104
105
106
107   //---------------------------------------------------------------------------
108 // STREAM ROUTINES
109
110
111    /**
112     * Returns the current line number.
113     */
114
115     public int getLine();
116
117
118
119    /**
120     * Returns the current column on that line.
121     */
122
123     public int getColumn();
124
125
126
127
128    /**
129     * Returns the next character, without consuming it.
130     */
131
132     public char la() throws LexerException, ReadException;
133
134
135
136    /**
137     * Returns the next <code>k</code>th character, without consuming any.
138     */
139
140     public char la(int k) throws LexerException, ReadException;
141
142
143
144    /**
145     * Eats a single character from the input stream.
146     */
147
148     public char consume() throws LexerException, ReadException;
149
150
151 }
152
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