org.aspectj/bcel-builder/src/org/aspectj/apache/bcel/util/NonCachingClassLoaderRepository.java

package org.aspectj.apache.bcel.util;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 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 end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``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 APACHE SOFTWARE FOUNDATION 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.AbstractMap;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.aspectj.apache.bcel.classfile.ClassParser;
import org.aspectj.apache.bcel.classfile.JavaClass;

/**
 * The repository maintains information about which classes have
 * been loaded.
 *
 * It loads its data from the ClassLoader implementation
 * passed into its constructor.
 *
 * @see org.aspectj.apache.bcel.Repository
 *
 * @version $Id: NonCachingClassLoaderRepository.java,v 1.1.4.4 2008/05/28 00:02:49 aclement Exp $
 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 * @author David Dixon-Peugh
 * 
 */
public class NonCachingClassLoaderRepository
  implements Repository
{  
  private static java.lang.ClassLoader bootClassLoader = null;

  private ClassLoaderReference loaderRef;
  private Map loadedClasses =
    new SoftHashMap(); // CLASSNAME X JAVACLASS
  
	public static class SoftHashMap extends AbstractMap {
		  private Map map;
		  private ReferenceQueue rq = new ReferenceQueue(); 
		  
	      public SoftHashMap(Map map) { this.map = map; }
		  public SoftHashMap() { this(new HashMap()); }
		  public SoftHashMap(Map map, boolean b) { this(map); }
		
		  class SpecialValue extends SoftReference {
			  private final Object key;
			  SpecialValue(Object k,Object v) {
			    super(v,rq);
			    this.key = k;
			  }
		  }  

		  private void processQueue() {
			SpecialValue sv = null;
			while ((sv = (SpecialValue)rq.poll())!=null) {
				map.remove(sv.key);
			}
		  }
		
		  public Object get(Object key) {
			SpecialValue value = (SpecialValue)map.get(key);
			if (value==null) return null;
			if (value.get()==null) {
				// it got GC'd
				map.remove(value.key);
				return null;
			} else {
				return value.get();
			}
		  }

		  public Object put(Object k, Object v) {
			processQueue();
			return map.put(k, new SpecialValue(k,v));
		  }

		  public Set entrySet() {
			return map.entrySet();
		  }
		
		  public void clear() {
			processQueue();
			Set keys = map.keySet();
			for (Iterator iterator = keys.iterator(); iterator.hasNext();) {
				Object name = (Object) iterator.next();
				map.remove(name);
			}
		  }
		
		  public int size() {
			processQueue();
			return map.size();
		  }
		
		  public Object remove(Object k) {
			processQueue();
			SpecialValue value = (SpecialValue)map.remove(k);
			if (value==null) return null;
			if (value.get()!=null) {
				return value.get();
			}
			return null;
		  }
	  }

    public NonCachingClassLoaderRepository(java.lang.ClassLoader loader) {
        this.loaderRef = new DefaultClassLoaderReference((loader != null) ? loader : getBootClassLoader());
    }

    public NonCachingClassLoaderRepository(ClassLoaderReference loaderRef) {
        this.loaderRef = loaderRef;
    }

  private static synchronized java.lang.ClassLoader getBootClassLoader() {
	  if (bootClassLoader == null) {
		  bootClassLoader = new URLClassLoader(new URL[0]);
	  }
	  return bootClassLoader;
  }
  
  /**
   * Store a new JavaClass into this Repository.
   */
  public void storeClass( JavaClass clazz ) {
    loadedClasses.put( clazz.getClassName(),
		       clazz );
    clazz.setRepository( this );
  }

  /**
   * Remove class from repository
   */
  public void removeClass(JavaClass clazz) {
    loadedClasses.remove(clazz.getClassName());
  }

  /**
   * Find an already defined JavaClass.
   */
  public JavaClass findClass( String className ) {
    if ( loadedClasses.containsKey( className )) {
      return (JavaClass) loadedClasses.get( className );
    } else {
      return null;
    }
  }

  /**
   * Lookup a JavaClass object from the Class Name provided.
   */
  public JavaClass loadClass( String className ) 
    throws ClassNotFoundException
  {
    String classFile = className.replace('.', '/');

    JavaClass RC = findClass( className );
    if (RC != null) { return RC; }

    try {
      InputStream is = 
          loaderRef.getClassLoader().getResourceAsStream(classFile + ".class");
	    
      if(is == null) {
	throw new ClassNotFoundException(className + " not found.");
      }

      ClassParser parser = new ClassParser( is, className );
      RC = parser.parse();
	    
      storeClass( RC );

      return RC;
    } catch (IOException e) {
      throw new ClassNotFoundException( e.toString() );
    }
  }

  public JavaClass loadClass(Class clazz) throws ClassNotFoundException {
    return loadClass(clazz.getName());
  }

  /** Clear all entries from cache.
   */
  public void clear() {
    loadedClasses.clear();
  }
}