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Java > Open Source Codes > org > eclipse > ui > editors > text > DocumentInputStream


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 package org.eclipse.ui.editors.text;
12
13 import java.io.IOException JavaDoc;
14 import java.io.InputStream JavaDoc;
15
16 import org.eclipse.jface.text.Assert;
17 import org.eclipse.jface.text.BadLocationException;
18 import org.eclipse.jface.text.DocumentEvent;
19 import org.eclipse.jface.text.IDocument;
20 import org.eclipse.jface.text.IDocumentListener;
21 import org.eclipse.ui.internal.editors.text.NLSUtility;
22
23
24 /**
25  * An <code>InputStream</code> that reads from an <code>IDocument</code>.
26  * The input stream ensures that its content is the same as the document
27  * content when the stream was created.
28  * <p>
29  * Note that {@link #close()} must be called to release any acquired
30  * resources.
31  * </p>
32  *
33  * @since 3.1
34  */
35 class DocumentInputStream extends InputStream JavaDoc {
36
37     /**
38      * Document based character sequence.
39      */
40     private static class DocumentCharSequence implements CharSequence JavaDoc {
41
42         /** Document */
43         private IDocument fDocument;
44
45         /**
46          * Initialize with the sequence of characters in the given
47          * document.
48          *
49          * @param document the document
50          */
51         public DocumentCharSequence(IDocument document) {
52             fDocument= document;
53         }
54
55         /*
56          * @see java.lang.CharSequence#length()
57          */
58         public int length() {
59             return fDocument.getLength();
60         }
61
62         /*
63          * @see java.lang.CharSequence#charAt(int)
64          */
65         public char charAt(int index) {
66             try {
67                 return fDocument.getChar(index);
68             } catch (BadLocationException x) {
69                 throw new IndexOutOfBoundsException JavaDoc(x.getLocalizedMessage());
70             }
71         }
72
73         /*
74          * @see java.lang.CharSequence#subSequence(int, int)
75          */
76         public CharSequence JavaDoc subSequence(int start, int end) {
77             try {
78                 return fDocument.get(start, end - start);
79             } catch (BadLocationException x) {
80                 throw new IndexOutOfBoundsException JavaDoc(x.getLocalizedMessage());
81             }
82         }
83     }
84
85     /**
86      * Internal document listener.
87      */
88     private class InternalDocumentListener implements IDocumentListener {
89
90         /*
91          * @see org.eclipse.jface.text.IDocumentListener#documentAboutToBeChanged(org.eclipse.jface.text.DocumentEvent)
92          */
93         public void documentAboutToBeChanged(DocumentEvent event) {
94             handleDocumentAboutToBeChanged();
95         }
96
97         /*
98          * @see org.eclipse.jface.text.IDocumentListener#documentChanged(org.eclipse.jface.text.DocumentEvent)
99          */
100         public void documentChanged(DocumentEvent event) {
101         }
102     }
103
104     /** The character sequence. */
105     private volatile CharSequence JavaDoc fCharSequence;
106
107     /** Document length. */
108     private int fLength;
109
110     /** The current offset. */
111     private int fOffset= 0;
112
113     /** The document. */
114     private IDocument fDocument;
115
116     /** The document listener. */
117     private IDocumentListener fDocumentListener= new InternalDocumentListener();
118
119     /**
120      * Creates a new document input stream and initializes
121      * the stream to read from the given document.
122      *
123      * @param document the document
124      */
125     public DocumentInputStream(IDocument document) {
126         Assert.isNotNull(document);
127         fDocument= document;
128         fCharSequence= new DocumentCharSequence(fDocument);
129         fDocument.addDocumentListener(fDocumentListener);
130         fLength= fCharSequence.length();
131     }
132
133     /*
134      * @see java.io.InputStream#read()
135      */
136     public int read() throws IOException JavaDoc {
137         try {
138             return fOffset < fLength ? fCharSequence.charAt(fOffset++) : -1;
139         } catch (NullPointerException JavaDoc x) {
140             throw new IOException JavaDoc(TextEditorMessages.DocumentInputStream_error_streamClosed);
141         } catch (IndexOutOfBoundsException JavaDoc x) {
142             throw new IOException JavaDoc(NLSUtility.format(TextEditorMessages.DocumentInputStream_error_read, x.getLocalizedMessage()));
143         }
144     }
145
146     /*
147      * @see java.io.InputStream#close()
148      */
149     public void close() throws IOException JavaDoc {
150         synchronized (this) {
151             fCharSequence= null;
152         }
153         releaseDocument();
154     }
155
156     /**
157      * Copies the document prior to modification and removes the document listener.
158      */
159     private void handleDocumentAboutToBeChanged() {
160         IDocument document= fDocument;
161         if (fCharSequence == null || document == null)
162             return;
163         String JavaDoc content= document.get();
164         synchronized (this) {
165             if (fCharSequence == null)
166                 return;
167             fCharSequence= content;
168         }
169         releaseDocument();
170     }
171
172     /**
173      * Removes the document listener.
174      */
175     private synchronized void releaseDocument() {
176         if (fDocument != null)
177             fDocument.removeDocumentListener(fDocumentListener);
178         fDocument= null;
179         fDocumentListener= null;
180     }
181 }
182
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