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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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/* *******************************************************************
 * Copyright (c) 2005 Contributors.
 * All rights reserved.
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Public License v 2.0
 * which accompanies this distribution and is available at
 * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
 *
 * Contributors:
 *   Adrian Colyer			Initial implementation
 * ******************************************************************/
package org.aspectj.lang.reflect;

import java.lang.ref.WeakReference;
import java.util.Collections;
import java.util.Map;
import java.util.WeakHashMap;

import org.aspectj.internal.lang.reflect.AjTypeImpl;

/**
 * This is the anchor for the AspectJ runtime type system.
 * Typical usage to get the AjType representation of a given type
 * at runtime is to call AjType<Foo> fooType = AjTypeSystem.getAjType(Foo.class);
 */
public class AjTypeSystem {

		private static Map> ajTypes =
			Collections.synchronizedMap(new WeakHashMap<>());

		/**
		 * Return the AspectJ runtime type representation of the given Java type.
		 * Unlike java.lang.Class, AjType understands pointcuts, advice, declare statements,
		 * and other AspectJ type members. AjType is the recommended reflection API for
		 * AspectJ programs as it offers everything that java.lang.reflect does, with
		 * AspectJ-awareness on top.
		 * @param  the expected type associated with the returned AjType
		 * @param fromClass the class for which to discover the AjType
		 * @return the AjType corresponding to the input class
		 */
		public static  AjType getAjType(Class fromClass) {
			WeakReference weakRefToAjType =  ajTypes.get(fromClass);
			if (weakRefToAjType!=null) {
				AjType theAjType = weakRefToAjType.get();
				if (theAjType != null) {
					return theAjType;
				} else {
					theAjType = new AjTypeImpl<>(fromClass);
					ajTypes.put(fromClass, new WeakReference<>(theAjType));
					return theAjType;
				}
			}
			// neither key nor value was found
			AjType theAjType = new AjTypeImpl<>(fromClass);
			ajTypes.put(fromClass, new WeakReference<>(theAjType));
			return theAjType;
		}
}