package ca.ubc.cs.spl.aspectPatterns.patternLibrary; /* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- * * This file is part of the design patterns project at UBC * * The contents of this file are subject to the Mozilla Public License * Version 1.1 (the "License"); you may not use this file except in * compliance with the License. You may obtain a copy of the License at * either https://www.mozilla.org/MPL/ or https://aspectj.org/MPL/. * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is ca.ubc.cs.spl.aspectPatterns. * * For more details and the latest version of this code, please see: * https://www.cs.ubc.ca/labs/spl/projects/aodps.html * * Contributor(s): */ import org.aspectj.lang.JoinPoint; /** * Defines the abstracted Proxy design pattern.

* * Concrete sub-aspects define the following:

* * @author Jan Hannemann * @author Gregor Kiczales * @version 1.1, 02/17/04 */ public abstract aspect ProxyProtocol { /** * Defines the Subject role (used for correct typing) */ protected interface Subject {} /** * Captures all accesses to the subject that should be covered by * this pattern instance. */ protected abstract pointcut requests(); /** * Extends the requests() pointcut to include a * field for the joinpoint. Used internally only. */ private pointcut requestsByCaller(Object caller): requests() && this(caller); /** * Intercepts accesses to protected parts of the OutputSubject. * If access is proxy protected, the method * handleProxyProtection(..) is called instead. * * @param caller the object responsible for the protected access * @param subject the subject receiving the call */ Object around(Object caller, Subject subject): requestsByCaller(caller) && target(subject) { if (! isProxyProtected(caller, subject, thisJoinPoint) ) return proceed(caller, subject); return handleProxyProtection(caller, subject, thisJoinPoint); } /** * Checks whether the request should be handled by the Proxy or not * * @param caller the object responsible for the protected access * @param subject the subject receiving the call * @param joinPoint the joinpoint associated with the protected access * * @return true if the access is covered by the proxy, false otherwise */ protected abstract boolean isProxyProtected(Object caller, Subject subject, JoinPoint joinPoint); /** * For delegation: Provides an alternative return value if access * is proxy protected. A default implementation is supplied so that * concrete subaspects are not forced to implement the method. * * @param caller the object responsible for the proxy protected access * @param subject the subject receiving the call * @param joinPoint the joinpoint associated with the proxy protected * access * * @return an alternative return value */ protected Object handleProxyProtection(Object caller, Subject subject, JoinPoint joinPoint) { return null; } }