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Java > Open Source Codes > org > codehaus > groovy > control > io > AbstractReaderSource


1 /*
2  $Id: AbstractReaderSource.java,v 1.1 2004/04/19 07:29:44 cpoirier Exp $
3
4  Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
5
6  Redistribution and use of this software and associated documentation
7  ("Software"), with or without modification, are permitted provided
8  that the following conditions are met:
9
10  1. Redistributions of source code must retain copyright
11     statements and notices. Redistributions must also contain a
12     copy of this document.
13
14  2. Redistributions in binary form must reproduce the
15     above copyright notice, this list of conditions and the
16     following disclaimer in the documentation and/or other
17     materials provided with the distribution.
18
19  3. The name "groovy" must not be used to endorse or promote
20     products derived from this Software without prior written
21     permission of The Codehaus. For written permission,
22     please contact info@codehaus.org.
23
24  4. Products derived from this Software may not be called "groovy"
25     nor may "groovy" appear in their names without prior written
26     permission of The Codehaus. "groovy" is a registered
27     trademark of The Codehaus.
28
29  5. Due credit should be given to The Codehaus -
30     http://groovy.codehaus.org/
31
32  THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
33  ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
34  NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
35  FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
36  THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
37  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
38  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
39  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
40  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
41  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
42  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
43  OF THE POSSIBILITY OF SUCH DAMAGE.
44
45  */
46
47 package org.codehaus.groovy.control.io;
48
49 import java.io.BufferedReader JavaDoc;
50 import java.io.IOException JavaDoc;
51
52 import org.codehaus.groovy.control.CompilerConfiguration;
53 import org.codehaus.groovy.control.Janitor;
54
55
56 /**
57  * For ReaderSources that can choose a parent class, a base that
58  * provides common functionality.
59  *
60  * @author <a HREF="mailto:cpoirier@dreaming.org">Chris Poirier</a>
61  *
62  * @version $Id: AbstractReaderSource.java,v 1.1 2004/04/19 07:29:44 cpoirier Exp $
63  */
64
65 public abstract class AbstractReaderSource implements ReaderSource
66 {
67     protected CompilerConfiguration configuration; // Configuration data
68
69     
70    /**
71     * Standard construction stuff.
72     */
73     
74     public AbstractReaderSource( CompilerConfiguration configuration )
75     {
76         this.configuration = configuration;
77     }
78     
79     
80    /**
81     * Returns true if the source can be restarted (ie. if getReader()
82     * will return non-null on subsequent calls.
83     */
84     
85     public boolean canReopenSource()
86     {
87         return true;
88     }
89     
90     
91     
92   //---------------------------------------------------------------------------
93 // LINE SUPPLY
94
95     
96     private BufferedReader JavaDoc lineSource = null; // If set, a reader on the current source file
97 private String JavaDoc line = null; // The last line read from the current source file
98 private int number = 0; // The last line number read
99
100    
101    /**
102     * Returns a line from the source, or null, if unavailable. If
103     * you supply a Janitor, resources will be cached.
104     */
105     
106     public String JavaDoc getLine( int lineNumber, Janitor janitor )
107     {
108         //
109 // If the source is already open and is passed the line we
110 // want, close it.
111
112         if( lineSource != null && number > lineNumber )
113         {
114             cleanup();
115         }
116     
117         
118         //
119 // If the line source is closed, try to open it.
120
121         if( lineSource == null )
122         {
123             try { lineSource = new BufferedReader JavaDoc( getReader() ); } catch( Exception JavaDoc e ) {}
124             number = 0;
125         }
126         
127         
128         //
129 // Read until the appropriate line number.
130
131         if( lineSource != null )
132         {
133             while( number < lineNumber )
134             {
135                 try
136                 {
137                     line = lineSource.readLine();
138                     number++;
139                 }
140                 catch( IOException JavaDoc e )
141                 {
142                     cleanup();
143                 }
144             }
145             
146             if( janitor == null )
147             {
148                 cleanup();
149             }
150             else
151             {
152                 janitor.register( this );
153             }
154         }
155         
156         return line;
157     }
158     
159     
160     
161    /**
162     * Cleans up any cached resources used by getLine().
163     */
164     
165     public void cleanup()
166     {
167         if( lineSource != null )
168         {
169             try { lineSource.close(); } catch( Exception JavaDoc e ) {}
170         }
171         
172         lineSource = null;
173         line = null;
174         number = 0;
175     }
176     
177 }
178
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