| // Copyright 2006, 2007, 2008, 2009, 2011 The Apache Software Foundation |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package org.apache.tapestry5.ioc.internal; |
| |
| import java.util.Collections; |
| import java.util.List; |
| |
| import org.apache.tapestry5.ioc.Invokable; |
| import org.apache.tapestry5.ioc.ObjectCreator; |
| import org.apache.tapestry5.ioc.ServiceDecorator; |
| import org.apache.tapestry5.ioc.def.ServiceDef3; |
| |
| /** |
| * Responsible for constructing the interceptor stack, on demand, by invoking an ordered series of decorators ( |
| * {@link org.apache.tapestry5.ioc.def.DecoratorDef} (which are converted into {@link ServiceDecorator}s). |
| */ |
| public class InterceptorStackBuilder implements ObjectCreator |
| { |
| private final ServiceDef3 serviceDef; |
| |
| private final ObjectCreator delegate; |
| |
| private final InternalRegistry registry; |
| |
| /** |
| * @param serviceDef |
| * service begin decorated |
| * @param delegate |
| * responsible for creating the object to be decorated |
| * @param registry |
| * access to service decorators |
| */ |
| public InterceptorStackBuilder(ServiceDef3 serviceDef, ObjectCreator delegate, InternalRegistry registry) |
| { |
| this.serviceDef = serviceDef; |
| this.delegate = delegate; |
| this.registry = registry; |
| } |
| |
| @Override |
| public Object createObject() |
| { |
| Object current = delegate.createObject(); |
| |
| List<ServiceDecorator> decorators = registry.findDecoratorsForService(serviceDef); |
| |
| // We get the decorators ordered according to their dependencies. However, we want to |
| // process from the last interceptor to the first, so we reverse the list. |
| |
| Collections.reverse(decorators); |
| |
| for (final ServiceDecorator decorator : decorators) |
| { |
| final Object delegate = current; |
| |
| Object interceptor = registry.invoke("Invoking " + decorator, new Invokable<Object>() |
| { |
| @Override |
| public Object invoke() |
| { |
| return decorator.createInterceptor(delegate); |
| } |
| }); |
| |
| // Decorator methods may return null; this indicates that the decorator chose not to |
| // decorate. |
| |
| if (interceptor != null) |
| current = interceptor; |
| } |
| |
| // The stack of interceptors (plus the core service implementation) are "represented" to the |
| // outside world |
| // as the outermost interceptor. That will still be buried inside the service proxy. |
| |
| return current; |
| } |
| } |