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Java > Open Source Codes > de > susebox > jtopas > spi > WhitespaceHandler


1 /*
2  * WhitespaceHandler.java: whitespace handling in tokenizers.
3  *
4  * Copyright (C) 2002 Heiko Blau
5  *
6  * This file belongs to the JTopas Library.
7  * JTopas is free software; you can redistribute it and/or modify it
8  * under the terms of the GNU Lesser General Public License as published by the
9  * Free Software Foundation; either version 2.1 of the License, or (at your
10  * option) any later version.
11  *
12  * This software is distributed in the hope that it will be useful, but WITHOUT
13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14  * FITNESS FOR A PARTICULAR PURPOSE.
15  * See the GNU Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public License along
18  * with JTopas. If not, write to the
19  *
20  * Free Software Foundation, Inc.
21  * 59 Temple Place, Suite 330,
22  * Boston, MA 02111-1307
23  * USA
24  *
25  * or check the Internet: http://www.fsf.org
26  *
27  * Contact:
28  * email: heiko@susebox.de
29  */
30
31 package de.susebox.jtopas.spi;
32
33
34 //-----------------------------------------------------------------------------
35 // Imports
36 //
37 import de.susebox.jtopas.TokenizerException;
38
39
40 //-----------------------------------------------------------------------------
41 // Interface WhitespaceHandler
42 //
43
44 /**<p>
45  * This interface declares the methods a {@link de.susebox.jtopas.Tokenizer} needs
46  * to deal with whitespaces.
47  *</p><p>
48  * Whitespaces are single characters that separate other tokens. In programming
49  * languages, the item whitespace also refers to comments. This does not apply
50  * to a <code>WhitespaceHandler</code> that only recognizes single characters.
51  * Comments are handled by the {@link SequenceHandler} interface.
52  *</p>
53  *
54  * @see de.susebox.jtopas.Tokenizer
55  * @see de.susebox.jtopas.TokenizerProperties
56  * @see de.susebox.jtopas.spi.DataMapper
57  * @see SequenceHandler
58  * @author Heiko Blau
59  */
60 public interface WhitespaceHandler {
61   
62   /**
63    * This method checks if the given character is a whitespace.
64    *
65    * @param testChar check this character
66    * @return <code>true</code> if the given character is a whitespace,
67    * <code>false</code> otherwise
68    * @see de.susebox.jtopas.TokenizerProperties#setWhitespaces
69    */
70   public boolean isWhitespace(char testChar);
71      
72   /**
73    * This method detects the number of whitespace characters the data range given
74    * through the {@link DataProvider} parameter starts with. An implementation
75    * should use a {@link de.susebox.jtopas.TokenizerException} to report problems.
76    *
77    * @param dataProvider the source to get the data range from
78    * @return number of whitespace characters starting from the given offset
79    * @throws TokenizerException generic exception
80    * @throws NullPointerException if no {@link DataProvider} is given
81    * @see DataProvider
82    */
83   public int countLeadingWhitespaces(DataProvider dataProvider)
84     throws TokenizerException, NullPointerException JavaDoc;
85   
86   /**
87    * If a {@link de.susebox.jtopas.Tokenizer} performs line counting, it is often
88    * nessecary to know if newline characters (Carriage return and line feed) are
89    * (currently) considered to be whitespaces, which is most often the case.
90    * This method informs interested callers about the current condition.
91    *<br>
92    * Note that this method should return <code>true</code> only if both newline
93    * characters are part of the current whitespace set.
94    *
95    * @return <code>true</code> if newline characters are in the current whitespace set,
96    * <code>false</code> otherwise
97    */
98   public boolean newlineIsWhitespace();
99 }
100
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