001    /*
002     $Id: AbstractReaderSource.java 2361 2005-06-19 15:41:38Z cstein $
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 2361 2005-06-19 15:41:38Z cstein $
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            if (configuration == null) {
077                throw new IllegalArgumentException("Compiler configuration must not be null!");
078                // ... or more relaxed?
079                // configuration = CompilerConfiguration.DEFAULT;
080            }
081            this.configuration = configuration;
082        }
083        
084        
085       /**
086        *  Returns true if the source can be restarted (ie. if getReader()
087        *  will return non-null on subsequent calls.
088        */
089        
090        public boolean canReopenSource()
091        {
092            return true;
093        }
094        
095        
096        
097      //---------------------------------------------------------------------------
098      // LINE SUPPLY
099    
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    }