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AspectJ tools most notably contains the AspectJ compiler (AJC). AJC applies aspects to Java classes during compilation, fully replacing Javac for plain Java classes and also compiling native AspectJ or annotation-based @AspectJ syntax. Furthermore, AJC can weave aspects into existing class files in a post-compile binary weaving step. This library is a superset of AspectJ weaver and hence also of AspectJ runtime.

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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 (https://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 [email protected].
 *
 * 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
 * .
 */

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.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 1.6 2009/09/09 19:56:20 aclement Exp $
 * @author M. Dahm
 * @author David Dixon-Peugh
 *
 */
public class NonCachingClassLoaderRepository implements Repository {
	private static java.lang.ClassLoader bootClassLoader = null;

	private final ClassLoaderReference loaderRef;
	private final Map loadedClasses = new SoftHashMap();

	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);
			}
		}

		@Override
		public Object get(Object key) {
			SpecialValue value = 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();
			}
		}

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

		@Override
		public Set entrySet() {
			return map.entrySet();
		}

		@Override
		public void clear() {
			processQueue();
			Set keys = map.keySet();
			for (Object name : keys) {
				map.remove(name);
			}
		}

		@Override
		public int size() {
			processQueue();
			return map.size();
		}

		@Override
		public Object remove(Object k) {
			processQueue();
			SpecialValue value = 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) {
		synchronized (loadedClasses) {
			loadedClasses.put(clazz.getClassName(), clazz);
		}
		clazz.setRepository(this);
	}

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

	/**
	 * Find an already defined JavaClass.
	 */
	public JavaClass findClass(String className) {
		synchronized (loadedClasses) {
			return loadedClasses.getOrDefault(className, null);
		}
	}

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

	/**
	 * Lookup a JavaClass object from the Class Name provided.
	 */
	public JavaClass loadClass(String className) throws ClassNotFoundException {

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

		javaClass = loadJavaClass(className);
		storeClass(javaClass);

		return javaClass;
	}

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

	private JavaClass loadJavaClass(String className) throws ClassNotFoundException {
		String classFile = className.replace('.', '/');
		try {
			InputStream is = loaderRef.getClassLoader().getResourceAsStream(classFile + ".class");

			if (is == null) {
				throw new ClassNotFoundException(className + " not found.");
			}

			ClassParser parser = new ClassParser(is, className);
			return parser.parse();
		} catch (IOException e) {
			throw new ClassNotFoundException(e.toString());
		}
	}

}
 















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