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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 }