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 }