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Java > Open Source Codes > org > eclipse > jdt > internal > ui > text > SubstitutionTextReader


1 /*******************************************************************************
2  * Copyright (c) 2000, 2005 IBM Corporation and others.
3  * All rights reserved. This program and the accompanying materials
4  * are made available under the terms of the Eclipse Public License v1.0
5  * which accompanies this distribution, and is available at
6  * http://www.eclipse.org/legal/epl-v10.html
7  *
8  * Contributors:
9  * IBM Corporation - initial API and implementation
10  *******************************************************************************/
11
12 package org.eclipse.jdt.internal.ui.text;
13
14
15 import java.io.IOException JavaDoc;
16 import java.io.Reader JavaDoc;
17
18 import org.eclipse.jdt.internal.corext.javadoc.SingleCharReader;
19
20
21 /**
22  * Reads the text contents from a reader and computes for each character
23  * a potential substitution. The substitution may eat more characters than
24  * only the one passed into the computation routine.
25  */
26 public abstract class SubstitutionTextReader extends SingleCharReader {
27
28     protected static final String JavaDoc LINE_DELIM= System.getProperty("line.separator", "\n"); //$NON-NLS-1$ //$NON-NLS-2$
29
30     private Reader JavaDoc fReader;
31     protected boolean fWasWhiteSpace;
32     private int fCharAfterWhiteSpace;
33
34     /**
35      * Tells whether white space characters are skipped.
36      */
37     private boolean fSkipWhiteSpace= true;
38
39     private boolean fReadFromBuffer;
40     private StringBuffer JavaDoc fBuffer;
41     private int fIndex;
42
43
44     protected SubstitutionTextReader(Reader JavaDoc reader) {
45         fReader= reader;
46         fBuffer= new StringBuffer JavaDoc();
47         fIndex= 0;
48         fReadFromBuffer= false;
49         fCharAfterWhiteSpace= -1;
50         fWasWhiteSpace= true;
51     }
52
53     /**
54      * Implement to compute the substitution for the given character and
55      * if necessary subsequent characters. Use <code>nextChar</code>
56      * to read subsequent characters.
57      */
58     protected abstract String JavaDoc computeSubstitution(int c) throws IOException JavaDoc;
59
60     /**
61      * Returns the internal reader.
62      */
63     protected Reader JavaDoc getReader() {
64         return fReader;
65     }
66
67     /**
68      * Returns the next character.
69      */
70     protected int nextChar() throws IOException JavaDoc {
71         fReadFromBuffer= (fBuffer.length() > 0);
72         if (fReadFromBuffer) {
73             char ch= fBuffer.charAt(fIndex++);
74             if (fIndex >= fBuffer.length()) {
75                 fBuffer.setLength(0);
76                 fIndex= 0;
77             }
78             return ch;
79         } else {
80             int ch= fCharAfterWhiteSpace;
81             if (ch == -1) {
82                 ch= fReader.read();
83             }
84             if (fSkipWhiteSpace && Character.isWhitespace((char)ch)) {
85                 do {
86                     ch= fReader.read();
87                 } while (Character.isWhitespace((char)ch));
88                 if (ch != -1) {
89                     fCharAfterWhiteSpace= ch;
90                     return ' ';
91                 }
92             } else {
93                 fCharAfterWhiteSpace= -1;
94             }
95             return ch;
96         }
97     }
98
99     /**
100      * @see Reader#read()
101      */
102     public int read() throws IOException JavaDoc {
103         int c;
104         do {
105
106             c= nextChar();
107             while (!fReadFromBuffer) {
108                 String JavaDoc s= computeSubstitution(c);
109                 if (s == null)
110                     break;
111                 if (s.length() > 0)
112                     fBuffer.insert(0, s);
113                 c= nextChar();
114             }
115
116         } while (fSkipWhiteSpace && fWasWhiteSpace && (c == ' '));
117         fWasWhiteSpace= (c == ' ' || c == '\r' || c == '\n');
118         return c;
119     }
120
121     /**
122      * @see Reader#ready()
123      */
124     public boolean ready() throws IOException JavaDoc {
125         return fReader.ready();
126     }
127
128     /**
129      * @see Reader#close()
130      */
131     public void close() throws IOException JavaDoc {
132         fReader.close();
133     }
134
135     /**
136      * @see Reader#reset()
137      */
138     public void reset() throws IOException JavaDoc {
139         fReader.reset();
140         fWasWhiteSpace= true;
141         fCharAfterWhiteSpace= -1;
142         fBuffer.setLength(0);
143         fIndex= 0;
144     }
145
146     protected final void setSkipWhitespace(boolean state) {
147         fSkipWhiteSpace= state;
148     }
149
150     protected final boolean isSkippingWhitespace() {
151         return fSkipWhiteSpace;
152     }
153 }
154
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