org.aspectj/bcel-builder/src/main/java/org/aspectj/apache/bcel/util/SyntheticRepository.java

package org.aspectj.apache.bcel.util;

/* ====================================================================
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 *
 * 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.
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 *    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
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 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
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 *
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 * 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.util.HashMap;
import java.util.WeakHashMap;

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

/**
 * This repository is used in situations where a Class is created outside the realm of a ClassLoader. Classes are loaded from the
 * file systems using the paths specified in the given class path. By default, this is the value returned by
 * ClassPath.getClassPath(). <br>
 * It is designed to be used as a singleton, however it can also be used with custom classpaths.
 * 
 * /** Abstract definition of a class repository. Instances may be used to load classes from different sources and may be used in
 * the Repository.setRepository method.
 * 
 * @see org.aspectj.apache.bcel.Repository
 * 
 * @version $Id: SyntheticRepository.java,v 1.8 2009/09/09 19:56:20 aclement Exp $
 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 * @author David Dixon-Peugh
 */
public class SyntheticRepository implements Repository {
	private static final String DEFAULT_PATH = ClassPath.getClassPath();

	private static HashMap<ClassPath, SyntheticRepository> _instances = new HashMap<>(); // CLASSPATH
																														// X
																														// REPOSITORY

	private ClassPath _path = null;
	private WeakHashMap<String, JavaClass> _loadedClasses = new WeakHashMap<>(); // CLASSNAME X JAVACLASS

	private SyntheticRepository(ClassPath path) {
		_path = path;
	}

	public static SyntheticRepository getInstance() {
		return getInstance(ClassPath.getSystemClassPath());
	}

	public static SyntheticRepository getInstance(ClassPath classPath) {
		SyntheticRepository rep = _instances.get(classPath);

		if (rep == null) {
			rep = new SyntheticRepository(classPath);
			_instances.put(classPath, rep);
		}

		return rep;
	}

	/**
	 * Store a new JavaClass instance 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 (cached) JavaClass object by name.
	 */
	public JavaClass findClass(String className) {
		return _loadedClasses.get(className);
	}

	/**
	 * Load a JavaClass object for the given class name using the CLASSPATH environment variable.
	 */
	public JavaClass loadClass(String className) throws ClassNotFoundException {
		if (className == null || className.equals("")) {
			throw new IllegalArgumentException("Invalid class name " + className);
		}

		className = className.replace('/', '.'); // Just in case, canonical form

		try {
			return loadClass(_path.getInputStream(className), className);
		} catch (IOException e) {
			throw new ClassNotFoundException("Exception while looking for class " + className + ": " + e.toString());
		}
	}

	/**
	 * Try to find class source via getResourceAsStream().
	 * 
	 * @see Class
	 * @return JavaClass object for given runtime class
	 */
	public JavaClass loadClass(Class clazz) throws ClassNotFoundException {
		String className = clazz.getName();
		String name = className;
		int i = name.lastIndexOf('.');

		if (i > 0) {
			name = name.substring(i + 1);
		}

		return loadClass(clazz.getResourceAsStream(name + ".class"), className);
	}

	private JavaClass loadClass(InputStream is, String className) throws ClassNotFoundException {
		JavaClass clazz = findClass(className);

		if (clazz != null) {
			return clazz;
		}

		try {
			if (is != null) {
				ClassParser parser = new ClassParser(is, className);
				clazz = parser.parse();

				storeClass(clazz);

				return clazz;
			}
		} catch (IOException e) {
			throw new ClassNotFoundException("Exception while looking for class " + className + ": " + e.toString());
		}

		throw new ClassNotFoundException("SyntheticRepository could not load " + className);
	}

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