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    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;
    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 1.1 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 lineSource = null;    // If set, a reader on the current source file
    97      private String         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 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 }