package org.drools.smf;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import org.drools.spi.ImportEntry;
import org.drools.spi.Importer;
/*
* $Id: DefaultImporter.java,v 1.3 2005/05/07 04:39:30 dbarnett Exp $
*
* Copyright 2001-2003 (C) The Werken Company. All Rights Reserved.
*
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided that the
* following conditions are met:
*
* 1. Redistributions of source code must retain copyright statements and
* notices. Redistributions must also contain a copy of this document.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The name "drools" must not be used to endorse or promote products derived
* from this Software without prior written permission of The Werken Company.
* For written permission, please contact bob@werken.com.
*
* 4. Products derived from this Software may not be called "drools" nor may
* "drools" appear in their names without prior written permission of The Werken
* Company. "drools" is a trademark of The Werken Company.
*
* 5. Due credit should be given to The Werken Company. (http://werken.com/)
*
* THIS SOFTWARE IS PROVIDED BY THE WERKEN COMPANY AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE WERKEN COMPANY OR ITS CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
public class DefaultImporter
implements
Importer
{
private Set importEntrySet = Collections.EMPTY_SET;
private Set importSet = Collections.EMPTY_SET;
private Map cachedImports = Collections.EMPTY_MAP;
public DefaultImporter()
{
super( );
}
/*
* (non-Javadoc)
*
* @see org.drools.semantics.base.Importer#getImports()
*/
public Set getImportEntries()
{
return this.importEntrySet;
}
/*
* (non-Javadoc)
*
* @see org.drools.semantics.base.Importer#getImports( Class clazz )
*/
public Set getImports()
{
if (! importEntrySet.isEmpty( ) )
{
if ( importSet == Collections.EMPTY_SET )
{
importSet = new HashSet( );
}
Iterator i = this.importEntrySet.iterator( );
while ( i.hasNext( ) )
{
importSet.add( ( (ImportEntry) i.next( ) ).getImportEntry() );
}
}
return importSet;
}
/*
* (non-Javadoc)
*
* @see org.drools.semantics.base.Importer#addImports(org.drools.spi.ImportEntry)
*/
public void addImport(ImportEntry importEntry)
{
if ( this.importEntrySet == Collections.EMPTY_SET )
{
this.importEntrySet = new HashSet( );
}
this.importEntrySet.add( importEntry );
}
public Class lookupFromCache(String className)
{
if ( cachedImports == Collections.EMPTY_MAP )
{
return null;
}
return (Class) cachedImports.get( className );
}
/*
* (non-Javadoc)
*
* @see org.drools.semantics.base.Importer#importClass(java.lang.ClassLoader,
* java.lang.String)
*/
public Class importClass(ClassLoader cl,
String className) throws ClassNotFoundException
{
Class clazz = null;
/* first try loading className */
try
{
clazz = cl.loadClass( className );
}
catch ( ClassNotFoundException e )
{
clazz = null;
}
/* Now try the ruleset object type cache */
if ( clazz == null )
{
clazz = lookupFromCache( className );
}
/* Now try the className with each of the given imports */
if ( clazz == null )
{
Set validClazzCandidates = new HashSet( );
Iterator it = importEntrySet.iterator( );
while ( it.hasNext( ) )
{
clazz = importClass( cl,
((ImportEntry) it.next( )).getImportEntry( ),
className.trim( ) );
if ( clazz != null )
{
validClazzCandidates.add( clazz );
}
}
/*
* If there are more than one possible resolutions, complain about
* the ambiguity
*/
if ( validClazzCandidates.size( ) > 1 )
{
StringBuffer sb = new StringBuffer( );
Iterator clazzCandIter = validClazzCandidates.iterator( );
while ( clazzCandIter.hasNext( ) )
{
if ( 0 != sb.length( ) )
{
sb.append( ", " );
}
sb.append( ((Class) clazzCandIter.next( )).getName( ) );
}
throw new Error( "Unable to find unambiguously defined class '" + className + "', candidates are: [" + sb.toString( ) + "]" );
}
else if ( validClazzCandidates.size( ) == 1 )
{
clazz = (Class) validClazzCandidates.toArray( )[0];
}
else
{
clazz = null;
}
}
/* We still can't find the class so throw an exception */
if ( clazz == null )
{
throw new ClassNotFoundException( "Unable to find class '" + className + "'" );
}
return clazz;
}
private Class importClass(ClassLoader cl,
String importText,
String className)
{
String qualifiedClass = null;
Class clazz = null;
String convertedImportText;
if ( importText.startsWith( "from " ) )
{
convertedImportText = convertFromPythonImport( importText );
}
else
{
convertedImportText = importText;
}
// not python
if ( convertedImportText.endsWith( "*" ) )
{
qualifiedClass = convertedImportText.substring( 0,
convertedImportText.indexOf( '*' ) ) + className;
}
else if ( convertedImportText.endsWith( "." + className ) )
{
qualifiedClass = convertedImportText;
}
else if ( convertedImportText.equals( className ) )
{
qualifiedClass = convertedImportText;
}
if ( qualifiedClass != null )
{
try
{
clazz = cl.loadClass( qualifiedClass );
}
catch ( ClassNotFoundException e )
{
clazz = null;
}
}
if ( clazz != null )
{
if ( this.cachedImports == Collections.EMPTY_MAP )
{
this.cachedImports = new HashMap( );
}
this.cachedImports.put( className,
clazz );
}
return clazz;
}
private String convertFromPythonImport(String packageText)
{
String fromString = "from ";
String importString = "import ";
int fromIndex = packageText.indexOf( fromString );
int importIndex = packageText.indexOf( importString );
return packageText.substring( fromIndex + fromString.length( ),
importIndex ).trim( ) + "." + packageText.substring( importIndex + importString.length( ) ).trim( );
}
public boolean isEmpty()
{
return this.importEntrySet.isEmpty( );
}
}