/* *******************************************************************
 * Copyright (c) 2005 Contributors.
 * All rights reserved. 
 * This program and the accompanying materials are made available 
 * under the terms of the Eclipse Public License v1.0 
 * which accompanies this distribution and is available at 
 * http://eclipse.org/legal/epl-v10.html 
 *  
 * 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);
/**
 * 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 <code>AjType&lt;Foo&gt; fooType = AjTypeSystem.getAjType(Foo.class);</code>
 */
public class AjTypeSystem {
	
		private static Map<Class, WeakReference<AjType>> ajTypes = 
			Collections.synchronizedMap(new WeakHashMap<Class,WeakReference<AjType>>());

		
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.
Params:
fromClass – the class for which to discover the AjType
Type parameters:
<T> – the expected type associated with the returned AjType
Returns:
the AjType corresponding to the input class/**
		 * 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 <T> 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 <T> AjType<T> getAjType(Class<T> fromClass) {
			WeakReference<AjType> weakRefToAjType =  ajTypes.get(fromClass);
			if (weakRefToAjType!=null) {
				AjType<T> theAjType = weakRefToAjType.get();
				if (theAjType != null) {
					return theAjType;
				} else {
					theAjType = new AjTypeImpl<T>(fromClass);
					ajTypes.put(fromClass, new WeakReference<AjType>(theAjType));
					return theAjType;
				}
			}
			// neither key nor value was found
			AjType<T> theAjType =  new AjTypeImpl<T>(fromClass);
			ajTypes.put(fromClass, new WeakReference<AjType>(theAjType));
			return theAjType;
		}
}