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1   /*
2    $Id: AbstractReaderSource.java,v 1.2 2005/06/19 15:41:38 cstein 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;
50  import java.io.IOException;
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 1.2 2005/06/19 15:41:38 cstein 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          if (configuration == null) {
77              throw new IllegalArgumentException("Compiler configuration must not be null!");
78              // ... or more relaxed?
79              // configuration = CompilerConfiguration.DEFAULT;
80          }
81          this.configuration = configuration;
82      }
83      
84      
85     /***
86      *  Returns true if the source can be restarted (ie. if getReader()
87      *  will return non-null on subsequent calls.
88      */
89      
90      public boolean canReopenSource()
91      {
92          return true;
93      }
94      
95      
96      
97    //---------------------------------------------------------------------------
98    // LINE SUPPLY
99  
100     
101     private BufferedReader lineSource = null;    // If set, a reader on the current source file
102     private String         line       = null;    // The last line read from the current source file
103     private int            number     = 0;       // The last line number read 
104 
105    
106    /***
107     *  Returns a line from the source, or null, if unavailable.  If
108     *  you supply a Janitor, resources will be cached.
109     */
110     
111     public String getLine( int lineNumber, Janitor janitor )
112     {
113         //
114         // If the source is already open and is passed the line we
115         // want, close it.
116         
117         if( lineSource != null && number > lineNumber )
118         {
119             cleanup();
120         }
121     
122         
123         //
124         // If the line source is closed, try to open it.
125         
126         if( lineSource == null )
127         {
128             try { lineSource = new BufferedReader( getReader() ); } catch( Exception e ) {}
129             number = 0;
130         }
131         
132         
133         //
134         // Read until the appropriate line number.
135 
136         if( lineSource != null )
137         {
138             while( number < lineNumber )
139             {
140                 try
141                 {
142                     line = lineSource.readLine();
143                     number++;
144                 }
145                 catch( IOException e )
146                 {
147                     cleanup();
148                 }
149             }
150             
151             if( janitor == null )
152             {
153                 cleanup();
154             }
155             else
156             {
157                 janitor.register( this );
158             }
159         }
160         
161         return line; 
162     }
163     
164     
165     
166    /***
167     *  Cleans up any cached resources used by getLine().
168     */
169     
170     public void cleanup()
171     {
172         if( lineSource != null ) 
173         {
174             try { lineSource.close(); } catch( Exception e ) {}
175         }
176         
177         lineSource = null;
178         line       = null;
179         number     = 0;
180     }
181     
182 }