001    /*
002     $Id: AbstractReaderSource.java,v 1.1 2004/04/19 07:29:44 cpoirier Exp $
003    
004     Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
005    
006     Redistribution and use of this software and associated documentation
007     ("Software"), with or without modification, are permitted provided
008     that the following conditions are met:
009    
010     1. Redistributions of source code must retain copyright
011        statements and notices.  Redistributions must also contain a
012        copy of this document.
013    
014     2. Redistributions in binary form must reproduce the
015        above copyright notice, this list of conditions and the
016        following disclaimer in the documentation and/or other
017        materials provided with the distribution.
018    
019     3. The name "groovy" must not be used to endorse or promote
020        products derived from this Software without prior written
021        permission of The Codehaus.  For written permission,
022        please contact info@codehaus.org.
023    
024     4. Products derived from this Software may not be called "groovy"
025        nor may "groovy" appear in their names without prior written
026        permission of The Codehaus. "groovy" is a registered
027        trademark of The Codehaus.
028    
029     5. Due credit should be given to The Codehaus -
030        http://groovy.codehaus.org/
031    
032     THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
033     ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
034     NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
035     FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
036     THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
037     INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
038     (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
039     SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
040     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
041     STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
042     ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
043     OF THE POSSIBILITY OF SUCH DAMAGE.
044    
045     */
046    
047    package org.codehaus.groovy.control.io;
048    
049    import java.io.BufferedReader;
050    import java.io.IOException;
051    
052    import org.codehaus.groovy.control.CompilerConfiguration;
053    import org.codehaus.groovy.control.Janitor;
054    
055    
056    /**
057     *  For ReaderSources that can choose a parent class, a base that
058     *  provides common functionality.
059     *
060     *  @author <a href="mailto:cpoirier@dreaming.org">Chris Poirier</a>
061     *
062     *  @version $Id: AbstractReaderSource.java,v 1.1 2004/04/19 07:29:44 cpoirier Exp $
063     */
064    
065    public abstract class AbstractReaderSource implements ReaderSource
066    {
067        protected CompilerConfiguration configuration;   // Configuration data
068    
069        
070       /**
071        *  Standard construction stuff.
072        */
073        
074        public AbstractReaderSource( CompilerConfiguration configuration )
075        {
076            this.configuration = configuration;
077        }
078        
079        
080       /**
081        *  Returns true if the source can be restarted (ie. if getReader()
082        *  will return non-null on subsequent calls.
083        */
084        
085        public boolean canReopenSource()
086        {
087            return true;
088        }
089        
090        
091        
092      //---------------------------------------------------------------------------
093      // LINE SUPPLY
094    
095        
096        private BufferedReader lineSource = null;    // If set, a reader on the current source file
097        private String         line       = null;    // The last line read from the current source file
098        private int            number     = 0;       // The last line number read 
099    
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 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( getReader() ); } catch( Exception 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 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 e ) {}
170            }
171            
172            lineSource = null;
173            line       = null;
174            number     = 0;
175        }
176        
177    }