modules/compiler/src/java/flex2/tools/SwcChecksums.java - flex-sdk - Git at Google

 /*
  *
  *  Licensed to the Apache Software Foundation (ASF) under one or more
  *  contributor license agreements.  See the NOTICE file distributed with
  *  this work for additional information regarding copyright ownership.
  *  The ASF licenses this file to You under the Apache License, Version 2.0
  *  (the "License"); you may not use this file except in compliance with
  *  the License.  You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  *  Unless required by applicable law or agreed to in writing, software
  *  distributed under the License is distributed on an "AS IS" BASIS,
  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  *
  */

 package flex2.tools;

 import java.io.File;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;

 import flash.util.Trace;
 import flex2.compiler.CompilationUnit;
 import flex2.compiler.CompilerSwcContext;
 import flex2.compiler.Source;
 import flex2.compiler.config.ConfigurationBuffer;
 import flex2.compiler.io.LocalFile;
 import flex2.compiler.io.VirtualFile;
 import flex2.compiler.swc.SwcScript;
 import flex2.compiler.util.QName;

 /**
  * A value object used to store checksums during an incremental
  * compilation.
  */
 public class SwcChecksums
 {
     /**
      * Used for incremental builds to verify the stored cache.
      * checksums[0] - checksum
      * checksums[1] = cmdChecksum - must be set with expected value before loading cache
      * checksums[2] = linkChecksum
      * checksums[3] = swcChecksum
      */
     int checksums[];

    /**
      * Map definition to signature checksum.
      */
     private Map<QName, Long> swcDefSignatureChecksums = new HashMap<QName, Long>(); // Map<QName, Long>

     /**
      * Map swc file to checksum (modification timestamp).
      */
     private Map<String, Long> swcFileChecksums = new HashMap<String, Long>(); // Map<String, Long>

     /**
      * Map archive files to checksum (modification timestamp).
      */
     private Map<String, Long> archiveFileChecksums = new HashMap<String, Long>(); // Map<String, Long>

     private CompilerSwcContext swcContext;
     private ConfigurationBuffer cfgbuf;

     /**
      * If true, checksum the signatures in the swc rather than the mod time on
      * the entire swc file.  This can save recompiles if there is a change but
      * the signature doesn't change.
      */
     private boolean isSwcChecksumEnabled;

     protected SwcChecksums(CompilerSwcContext swcContext, ConfigurationBuffer cfgbuf,
             ToolsConfiguration configuration)
     {
         this.swcContext = swcContext;
         this.cfgbuf = cfgbuf;
         this.isSwcChecksumEnabled = configuration.isSwcChecksumEnabled();

         // This array is used to load and persist the cache for the incremental
         // compile.  Initialize it for the load.
         checksums = new int[4];
         checksums[0] = 0;
         checksums[1] = cfgbuf.checksum_ts();
         checksums[2] = cfgbuf.link_checksum_ts();
         checksums[3] = swcContext.checksum();
     }

     /**
      * Save the compiler units signature checksums.
      * These will be used by the next compilation to determine if we
      * can do an incremental compiler or if a full recompilation is required.
      *
      * @param units - compilation units, may be null
      */
     protected void saveSignatureChecksums(List<CompilationUnit> units)
     {
         if (!isSwcChecksumEnabled)
         {
             swcDefSignatureChecksums = null;
             return;
         }

         if (units != null)
         {
             swcDefSignatureChecksums = new HashMap<QName, Long>();
             for (CompilationUnit unit : units)
             {
                 Source source = unit == null ? null : unit.getSource();
                 if (source != null && source.isSwcScriptOwner() && !source.isInternal())
                 {
                     addSignatureChecksumToData(unit);
                 }
             }
           }
     }

     /**
      * Save the swc file checksums.
      */
     protected void saveSwcFileChecksums()
     {
         if (!isSwcChecksumEnabled)
         {
             swcFileChecksums = null;
             return;
         }

         for (Map.Entry<String, VirtualFile> entry: swcContext.getFiles().entrySet())
         {
             String filename = entry.getKey();
             VirtualFile file = entry.getValue();
             swcFileChecksums.put(filename, new Long(file.getLastModified()));
         }

         for (VirtualFile themeStyleSheet : swcContext.getThemeStyleSheets())
         {
             swcFileChecksums.put(themeStyleSheet.getName(),
                                  new Long(themeStyleSheet.getLastModified()));
         }
     }

     /**
      * Save the checksums for the resources that get written to the swc.  These
      * may not have compile dependencies so mods won't get detected during
      * the compile phase.
      *
      * @param m - Map(filename, VirtualFile) of resources
      */
     protected void saveArchiveFilesChecksums(Map<String, VirtualFile> m)
     {
         if (!isSwcChecksumEnabled)
         {
             swcFileChecksums = null;
             return;
         }

         for (Map.Entry<String, VirtualFile> entry : m.entrySet())
         {
             VirtualFile file = entry.getValue();
             archiveFileChecksums.put(file.getName(), new Long(file.getLastModified()));
         }
    }

     /**
      * Save the checksums that are going to be persisted to the store file.
      *
      * @param units - compilation units
      */
     protected void saveChecksums(List<CompilationUnit> units)
     {
         saveSwcFileChecksums();
         saveSignatureChecksums(units);

         // Ensure this is current.
         updateChecksum();
     }

     /**
      * Loop thru the saved signature and file checksums in the persisted data
      * and compare them with the signature and file checksums in the swc context.
      *
      * @return true if all the signature and file checksums in cached data match the checksums
      *         in the swc context.
      */
     protected boolean isRecompilationNeeded(int[] loadedChecksums)
     {
         // Now that the load is done, which can change swcDefSignatureChecksums,
         // recalculate the checksum and see if it matches the loaded one from the
         // cache.
         this.checksums[0] = calculateChecksum();

         // if the checksum from last time and the current checksum do not match,
         // then we need to recompile.
         if (this.checksums[0] != loadedChecksums[0])
         {
             if (Trace.swcChecksum)
             {
                 Trace.trace("isRecompilationNeeded: calculated checksum differs from last checksum, recompile");
             }
             return true;
         }

         // if we got here and swc checksums are disabled, then
         // the checksums are equal and a recompilation is not needed.
         // Otherwise continue on and compare the swc checksums.
         if (!isSwcChecksumEnabled)
         {
             if (Trace.swcChecksum)
             {
                 Trace.trace("isRecompilationNeeded: checksums equal, swc-checksum disabled, incremental compile");
             }
             return false;
         }

         Map<QName, Long> signatureChecksums = swcDefSignatureChecksums;
         if (signatureChecksums == null)
         {
             if (Trace.swcChecksum)
             {
                 Trace.trace("isRecompilationNeeded: checksums equal, signatureChecksums is null, incremental compile");
             }
         }
         else
         {
             for (Map.Entry<QName, Long> entry : signatureChecksums.entrySet())
             {
                 // lookup definition in swc context
                 QName qName = (QName) entry.getKey();
                 Long dataSignatureChecksum = (Long)entry.getValue();
                 Long swcSignatureChecksum = swcContext.getChecksum(qName);
                 if (swcSignatureChecksum == null && qName != null)
                 {
                     Source source = swcContext.getSource(qName.getNamespace(), qName.getLocalPart());
                     if (source != null)
                     {
                         swcSignatureChecksum = new Long(source.getLastModified());
                     }
                 }
                 if (Trace.swcChecksum)
                 {
                     if (dataSignatureChecksum == null)
                     {
                         throw new IllegalStateException("dataSignatureChecksum should never be null");
                     }
                 }

                 if (dataSignatureChecksum != null && swcSignatureChecksum == null)
                 {
                     if (Trace.swcChecksum)
                     {
                         Trace.trace("isRecompilationNeeded: signature checksums not equal, recompile");
                         Trace.trace("compare " + entry.getKey());
                         Trace.trace("data =  " + dataSignatureChecksum);
                         Trace.trace("swc  =  " + swcSignatureChecksum);
                     }
                     return true;
                 }

                 if (dataSignatureChecksum != null)
                 {
                     if (dataSignatureChecksum.longValue() != swcSignatureChecksum.longValue())
                     {
                         if (Trace.swcChecksum)
                         {
                             Trace.trace("isRecompilationNeeded: signature checksums not equal, recompile");
                             Trace.trace("compare " + entry.getKey());
                             Trace.trace("data =  " + dataSignatureChecksum);
                             Trace.trace("swc  =  " + swcSignatureChecksum);
                         }
                         return true;
                     }
                 }
                 else
                 {
                     // dataSignatureChecksum should never be null, but if it is then recompile.
                     return true;
                 }
             }
         }

         boolean result = !areSwcFileChecksumsEqual();

         if (Trace.swcChecksum)
         {
             Trace.trace("isRecompilationNeeded: " + (result ? "recompile" : "incremental compile"));
         }

         return result;
     }

     /**
      * If the link timestamp is different, or the resources in the swc have been
      * updated, a relink is necessary.
      *
      * @return true if relink is needed.
      */
     protected boolean isRelinkNeeded(int[] loadedChecksums)
     {
         // If the link checksum from last time and the current checksum do not match,
         // then we need to relink.
         if (this.checksums[2] != loadedChecksums[2])
         {
             if (Trace.swcChecksum)
             {
                 Trace.trace("isRecompilationNeeded: calculated checksum differs from last checksum, relink");
             }
             return true;
         }

         // Verify that the timestamps on the archive files haven't changed.
         boolean result = !areArchiveFileChecksumsEqual();

         if (Trace.swcChecksum)
         {
             Trace.trace("isRelinkNeeded: " + result);
         }

         return result;
      }

     /**
      * Add all top level definitions.
      * @param unit
      */
     private void addSignatureChecksumToData(CompilationUnit unit)
     {
         Long signatureChecksum = unit.getSignatureChecksum();
         if (signatureChecksum == null)
         {
             SwcScript script = (SwcScript) unit.getSource().getOwner();
             signatureChecksum = new Long(script.getLastModified());
         }

         if (swcDefSignatureChecksums != null)
         {
             for (Iterator<QName> iter = unit.topLevelDefinitions.iterator(); iter.hasNext();)
             {
                 QName qname = iter.next();
                 swcDefSignatureChecksums.put(qname, signatureChecksum);
             }
         }
     }


     /**
      * Test if the files in the compiler swc context have changed since the last compile.
      *
      * @return true it the swc files compiled with last time are the same as this time.
      */
     private boolean areSwcFileChecksumsEqual()
     {
         if (swcFileChecksums == null)
         {
             if (Trace.swcChecksum)
             {
                 Trace.trace("areSwcFileChecksumsEqual: no file checksum map, not equal");
             }

             return false;
         }

         Map<String, VirtualFile> swcFiles = swcContext.getFiles();

         for (VirtualFile themeStyleSheet : swcContext.getThemeStyleSheets())
         {
             swcFiles.put(themeStyleSheet.getName(), themeStyleSheet);
         }

         Set<Map.Entry<String, Long>> dataSet = swcFileChecksums.entrySet();

         if (swcFiles.size() < dataSet.size())
         {
             if (Trace.swcChecksum)
             {
                 Trace.trace("areSwcFileChecksumsEqual: less files than before, not equal");
             }

             return false;
         }

         for (Map.Entry<String, Long> entry : dataSet)
         {
             String filename = entry.getKey();
             Long dataFileLastModified = entry.getValue();
             Long swcFileLastModified = null;
             VirtualFile swcFile = swcFiles.get(filename);
             if (swcFile != null)
             {
                 swcFileLastModified = new Long(swcFile.getLastModified());
             }

             if (!dataFileLastModified.equals(swcFileLastModified))
             {
                 if (Trace.swcChecksum)
                 {
                     Trace.trace("areSwcFileChecksumsEqual: not equal");
                     Trace.trace("filename = " + filename);
                     Trace.trace("last modified1 = " + dataFileLastModified);
                     Trace.trace("last modified2 = " + swcFileLastModified);
                 }
                 return false;
             }
         }

         if (Trace.swcChecksum)
         {
             Trace.trace("areSwcFileChecksumsEqual: equal");
         }

         return true;
     }

     /**
      * Test if the archive files in the swc have changed since the last compile.
      *
      * @return true it the swc files compiled with last time are the same as this time.
      */
     private boolean areArchiveFileChecksumsEqual()
     {
         if (swcFileChecksums == null)
         {
             if (Trace.swcChecksum)
             {
                 Trace.trace("areArchiveFileChecksumsEqual: no file checksum map, not equal");
             }

             return false;
         }

         Set<Map.Entry<String, Long>> dataSet = archiveFileChecksums.entrySet();

         for (Map.Entry<String, Long> entry : dataSet)
         {
             String filename = entry.getKey();
             Long dataFileLastModified = entry.getValue();
             Long localFileLastModified = null;

             LocalFile localFile = new LocalFile(new File(filename));
             localFileLastModified = new Long(localFile.getLastModified());

             if (!dataFileLastModified.equals(localFileLastModified))
             {
                 if (Trace.swcChecksum)
                 {
                     Trace.trace("areArchiveFileChecksumsEqual: not equal");
                     Trace.trace("filename = " + filename);
                     Trace.trace("last modified1 = " + dataFileLastModified);
                     Trace.trace("last modified2 = " + localFileLastModified);
                 }

                 return false;
             }
         }

         if (Trace.swcChecksum)
         {
             Trace.trace("areArchiveFileChecksumsEqual: equal");
         }

         return true;
     }

     /**
      * Calculate the data checksum on configuration buffer and the
      * swcContext.  If the configuration changes the checksum changes.
      *
      * @return checksum
      */
      protected int calculateChecksum()
      {
          // Checksum on the oonfiguration buffer.
          int checksum = cfgbuf.checksum_ts();

          // If swc checksums are disabled or there are no checksums to compare,
          // then include the swc timestamp as part of the checksum.
          if (!isSwcChecksumEnabled ||
                  swcDefSignatureChecksums == null ||
                  swcDefSignatureChecksums.size() == 0)
          {
              checksum += swcContext.checksum();
          }

          return checksum;
      }

 //     protected int getChecksum()
 //     {
 //        return checksums[0];
 //     }

     /**
      * Set the checksum with the recalculated value.
      */
     protected void updateChecksum()
     {
         checksums[0] = calculateChecksum();
     }

     /**
      * @return a copy of the stored checksum array
      */
     protected int[] copy()
     {
         int[] copy = (int[])this.checksums.clone();
         return copy;
     }

     /**
      *
      * @return array of checksums
      */
     protected int[] getChecksums()
     {
         return checksums;
     }

     protected Map<QName, Long> getSwcDefSignatureChecksums()
     {
         return swcDefSignatureChecksums;
     }

     protected Map<String, Long> getSwcFileChecksums()
     {
         return swcFileChecksums;
     }

     protected Map<String, Long> getArchiveFileChecksums()
     {
         return archiveFileChecksums;
     }
 }
	/*
	*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*
	*/

	package flex2.tools;

	import java.io.File;
	import java.util.HashMap;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;

	import flash.util.Trace;
	import flex2.compiler.CompilationUnit;
	import flex2.compiler.CompilerSwcContext;
	import flex2.compiler.Source;
	import flex2.compiler.config.ConfigurationBuffer;
	import flex2.compiler.io.LocalFile;
	import flex2.compiler.io.VirtualFile;
	import flex2.compiler.swc.SwcScript;
	import flex2.compiler.util.QName;

	/**
	* A value object used to store checksums during an incremental
	* compilation.
	*/
	public class SwcChecksums
	{
	/**
	* Used for incremental builds to verify the stored cache.
	* checksums[0] - checksum
	* checksums[1] = cmdChecksum - must be set with expected value before loading cache
	* checksums[2] = linkChecksum
	* checksums[3] = swcChecksum
	*/
	int checksums[];

	/**
	* Map definition to signature checksum.
	*/
	private Map<QName, Long> swcDefSignatureChecksums = new HashMap<QName, Long>(); // Map<QName, Long>

	/**
	* Map swc file to checksum (modification timestamp).
	*/
	private Map<String, Long> swcFileChecksums = new HashMap<String, Long>(); // Map<String, Long>

	/**
	* Map archive files to checksum (modification timestamp).
	*/
	private Map<String, Long> archiveFileChecksums = new HashMap<String, Long>(); // Map<String, Long>

	private CompilerSwcContext swcContext;
	private ConfigurationBuffer cfgbuf;

	/**
	* If true, checksum the signatures in the swc rather than the mod time on
	* the entire swc file. This can save recompiles if there is a change but
	* the signature doesn't change.
	*/
	private boolean isSwcChecksumEnabled;

	protected SwcChecksums(CompilerSwcContext swcContext, ConfigurationBuffer cfgbuf,
	ToolsConfiguration configuration)
	{
	this.swcContext = swcContext;
	this.cfgbuf = cfgbuf;
	this.isSwcChecksumEnabled = configuration.isSwcChecksumEnabled();

	// This array is used to load and persist the cache for the incremental
	// compile. Initialize it for the load.
	checksums = new int[4];
	checksums[0] = 0;
	checksums[1] = cfgbuf.checksum_ts();
	checksums[2] = cfgbuf.link_checksum_ts();
	checksums[3] = swcContext.checksum();
	}

	/**
	* Save the compiler units signature checksums.
	* These will be used by the next compilation to determine if we
	* can do an incremental compiler or if a full recompilation is required.
	*
	* @param units - compilation units, may be null
	*/
	protected void saveSignatureChecksums(List<CompilationUnit> units)
	{
	if (!isSwcChecksumEnabled)
	{
	swcDefSignatureChecksums = null;
	return;
	}

	if (units != null)
	{
	swcDefSignatureChecksums = new HashMap<QName, Long>();
	for (CompilationUnit unit : units)
	{
	Source source = unit == null ? null : unit.getSource();
	if (source != null && source.isSwcScriptOwner() && !source.isInternal())
	{
	addSignatureChecksumToData(unit);
	}
	}
	}
	}

	/**
	* Save the swc file checksums.
	*/
	protected void saveSwcFileChecksums()
	{
	if (!isSwcChecksumEnabled)
	{
	swcFileChecksums = null;
	return;
	}

	for (Map.Entry<String, VirtualFile> entry: swcContext.getFiles().entrySet())
	{
	String filename = entry.getKey();
	VirtualFile file = entry.getValue();
	swcFileChecksums.put(filename, new Long(file.getLastModified()));
	}

	for (VirtualFile themeStyleSheet : swcContext.getThemeStyleSheets())
	{
	swcFileChecksums.put(themeStyleSheet.getName(),
	new Long(themeStyleSheet.getLastModified()));
	}
	}

	/**
	* Save the checksums for the resources that get written to the swc. These
	* may not have compile dependencies so mods won't get detected during
	* the compile phase.
	*
	* @param m - Map(filename, VirtualFile) of resources
	*/
	protected void saveArchiveFilesChecksums(Map<String, VirtualFile> m)
	{
	if (!isSwcChecksumEnabled)
	{
	swcFileChecksums = null;
	return;
	}

	for (Map.Entry<String, VirtualFile> entry : m.entrySet())
	{
	VirtualFile file = entry.getValue();
	archiveFileChecksums.put(file.getName(), new Long(file.getLastModified()));
	}
	}

	/**
	* Save the checksums that are going to be persisted to the store file.
	*
	* @param units - compilation units
	*/
	protected void saveChecksums(List<CompilationUnit> units)
	{
	saveSwcFileChecksums();
	saveSignatureChecksums(units);

	// Ensure this is current.
	updateChecksum();
	}

	/**
	* Loop thru the saved signature and file checksums in the persisted data
	* and compare them with the signature and file checksums in the swc context.
	*
	* @return true if all the signature and file checksums in cached data match the checksums
	* in the swc context.
	*/
	protected boolean isRecompilationNeeded(int[] loadedChecksums)
	{
	// Now that the load is done, which can change swcDefSignatureChecksums,
	// recalculate the checksum and see if it matches the loaded one from the
	// cache.
	this.checksums[0] = calculateChecksum();

	// if the checksum from last time and the current checksum do not match,
	// then we need to recompile.
	if (this.checksums[0] != loadedChecksums[0])
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("isRecompilationNeeded: calculated checksum differs from last checksum, recompile");
	}
	return true;
	}

	// if we got here and swc checksums are disabled, then
	// the checksums are equal and a recompilation is not needed.
	// Otherwise continue on and compare the swc checksums.
	if (!isSwcChecksumEnabled)
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("isRecompilationNeeded: checksums equal, swc-checksum disabled, incremental compile");
	}
	return false;
	}

	Map<QName, Long> signatureChecksums = swcDefSignatureChecksums;
	if (signatureChecksums == null)
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("isRecompilationNeeded: checksums equal, signatureChecksums is null, incremental compile");
	}
	}
	else
	{
	for (Map.Entry<QName, Long> entry : signatureChecksums.entrySet())
	{
	// lookup definition in swc context
	QName qName = (QName) entry.getKey();
	Long dataSignatureChecksum = (Long)entry.getValue();
	Long swcSignatureChecksum = swcContext.getChecksum(qName);
	if (swcSignatureChecksum == null && qName != null)
	{
	Source source = swcContext.getSource(qName.getNamespace(), qName.getLocalPart());
	if (source != null)
	{
	swcSignatureChecksum = new Long(source.getLastModified());
	}
	}
	if (Trace.swcChecksum)
	{
	if (dataSignatureChecksum == null)
	{
	throw new IllegalStateException("dataSignatureChecksum should never be null");
	}
	}

	if (dataSignatureChecksum != null && swcSignatureChecksum == null)
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("isRecompilationNeeded: signature checksums not equal, recompile");
	Trace.trace("compare " + entry.getKey());
	Trace.trace("data = " + dataSignatureChecksum);
	Trace.trace("swc = " + swcSignatureChecksum);
	}
	return true;
	}

	if (dataSignatureChecksum != null)
	{
	if (dataSignatureChecksum.longValue() != swcSignatureChecksum.longValue())
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("isRecompilationNeeded: signature checksums not equal, recompile");
	Trace.trace("compare " + entry.getKey());
	Trace.trace("data = " + dataSignatureChecksum);
	Trace.trace("swc = " + swcSignatureChecksum);
	}
	return true;
	}
	}
	else
	{
	// dataSignatureChecksum should never be null, but if it is then recompile.
	return true;
	}
	}
	}

	boolean result = !areSwcFileChecksumsEqual();

	if (Trace.swcChecksum)
	{
	Trace.trace("isRecompilationNeeded: " + (result ? "recompile" : "incremental compile"));
	}

	return result;
	}

	/**
	* If the link timestamp is different, or the resources in the swc have been
	* updated, a relink is necessary.
	*
	* @return true if relink is needed.
	*/
	protected boolean isRelinkNeeded(int[] loadedChecksums)
	{
	// If the link checksum from last time and the current checksum do not match,
	// then we need to relink.
	if (this.checksums[2] != loadedChecksums[2])
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("isRecompilationNeeded: calculated checksum differs from last checksum, relink");
	}
	return true;
	}

	// Verify that the timestamps on the archive files haven't changed.
	boolean result = !areArchiveFileChecksumsEqual();

	if (Trace.swcChecksum)
	{
	Trace.trace("isRelinkNeeded: " + result);
	}

	return result;
	}

	/**
	* Add all top level definitions.
	* @param unit
	*/
	private void addSignatureChecksumToData(CompilationUnit unit)
	{
	Long signatureChecksum = unit.getSignatureChecksum();
	if (signatureChecksum == null)
	{
	SwcScript script = (SwcScript) unit.getSource().getOwner();
	signatureChecksum = new Long(script.getLastModified());
	}

	if (swcDefSignatureChecksums != null)
	{
	for (Iterator<QName> iter = unit.topLevelDefinitions.iterator(); iter.hasNext();)
	{
	QName qname = iter.next();
	swcDefSignatureChecksums.put(qname, signatureChecksum);
	}
	}
	}


	/**
	* Test if the files in the compiler swc context have changed since the last compile.
	*
	* @return true it the swc files compiled with last time are the same as this time.
	*/
	private boolean areSwcFileChecksumsEqual()
	{
	if (swcFileChecksums == null)
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("areSwcFileChecksumsEqual: no file checksum map, not equal");
	}

	return false;
	}

	Map<String, VirtualFile> swcFiles = swcContext.getFiles();

	for (VirtualFile themeStyleSheet : swcContext.getThemeStyleSheets())
	{
	swcFiles.put(themeStyleSheet.getName(), themeStyleSheet);
	}

	Set<Map.Entry<String, Long>> dataSet = swcFileChecksums.entrySet();

	if (swcFiles.size() < dataSet.size())
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("areSwcFileChecksumsEqual: less files than before, not equal");
	}

	return false;
	}

	for (Map.Entry<String, Long> entry : dataSet)
	{
	String filename = entry.getKey();
	Long dataFileLastModified = entry.getValue();
	Long swcFileLastModified = null;
	VirtualFile swcFile = swcFiles.get(filename);
	if (swcFile != null)
	{
	swcFileLastModified = new Long(swcFile.getLastModified());
	}

	if (!dataFileLastModified.equals(swcFileLastModified))
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("areSwcFileChecksumsEqual: not equal");
	Trace.trace("filename = " + filename);
	Trace.trace("last modified1 = " + dataFileLastModified);
	Trace.trace("last modified2 = " + swcFileLastModified);
	}
	return false;
	}
	}

	if (Trace.swcChecksum)
	{
	Trace.trace("areSwcFileChecksumsEqual: equal");
	}

	return true;
	}

	/**
	* Test if the archive files in the swc have changed since the last compile.
	*
	* @return true it the swc files compiled with last time are the same as this time.
	*/
	private boolean areArchiveFileChecksumsEqual()
	{
	if (swcFileChecksums == null)
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("areArchiveFileChecksumsEqual: no file checksum map, not equal");
	}

	return false;
	}

	Set<Map.Entry<String, Long>> dataSet = archiveFileChecksums.entrySet();

	for (Map.Entry<String, Long> entry : dataSet)
	{
	String filename = entry.getKey();
	Long dataFileLastModified = entry.getValue();
	Long localFileLastModified = null;

	LocalFile localFile = new LocalFile(new File(filename));
	localFileLastModified = new Long(localFile.getLastModified());

	if (!dataFileLastModified.equals(localFileLastModified))
	{
	if (Trace.swcChecksum)
	{
	Trace.trace("areArchiveFileChecksumsEqual: not equal");
	Trace.trace("filename = " + filename);
	Trace.trace("last modified1 = " + dataFileLastModified);
	Trace.trace("last modified2 = " + localFileLastModified);
	}

	return false;
	}
	}

	if (Trace.swcChecksum)
	{
	Trace.trace("areArchiveFileChecksumsEqual: equal");
	}

	return true;
	}

	/**
	* Calculate the data checksum on configuration buffer and the
	* swcContext. If the configuration changes the checksum changes.
	*
	* @return checksum
	*/
	protected int calculateChecksum()
	{
	// Checksum on the oonfiguration buffer.
	int checksum = cfgbuf.checksum_ts();

	// If swc checksums are disabled or there are no checksums to compare,
	// then include the swc timestamp as part of the checksum.
	if (!isSwcChecksumEnabled \|\|
	swcDefSignatureChecksums == null \|\|
	swcDefSignatureChecksums.size() == 0)
	{
	checksum += swcContext.checksum();
	}

	return checksum;
	}

	// protected int getChecksum()
	// {
	// return checksums[0];
	// }

	/**
	* Set the checksum with the recalculated value.
	*/
	protected void updateChecksum()
	{
	checksums[0] = calculateChecksum();
	}

	/**
	* @return a copy of the stored checksum array
	*/
	protected int[] copy()
	{
	int[] copy = (int[])this.checksums.clone();
	return copy;
	}

	/**
	*
	* @return array of checksums
	*/
	protected int[] getChecksums()
	{
	return checksums;
	}

	protected Map<QName, Long> getSwcDefSignatureChecksums()
	{
	return swcDefSignatureChecksums;
	}

	protected Map<String, Long> getSwcFileChecksums()
	{
	return swcFileChecksums;
	}

	protected Map<String, Long> getArchiveFileChecksums()
	{
	return archiveFileChecksums;
	}
	}