001// Copyright 2007, 2010, 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.internal.transform;
016
017import org.apache.tapestry5.func.F;
018import org.apache.tapestry5.func.Flow;
019import org.apache.tapestry5.func.Predicate;
020import org.apache.tapestry5.func.Worker;
021import org.apache.tapestry5.model.MutableComponentModel;
022import org.apache.tapestry5.plastic.*;
023import org.apache.tapestry5.runtime.PageLifecycleListener;
024import org.apache.tapestry5.services.transform.ComponentClassTransformWorker2;
025import org.apache.tapestry5.services.transform.TransformationSupport;
026
027import java.lang.annotation.Annotation;
028
029/**
030 * Similar to {@link org.apache.tapestry5.internal.transform.RenderPhaseMethodWorker} but applies to annotations/methods
031 * related to the overall page lifecycle. Page lifecycle methods are always void and take no parameters.
032 */
033public class PageLifecycleAnnotationWorker implements ComponentClassTransformWorker2
034{
035    private final Class<? extends Annotation> methodAnnotationClass;
036
037    private final MethodDescription lifecycleMethodDescription;
038
039    private final String methodAlias;
040
041    private final Predicate<PlasticMethod> MATCHER = new Predicate<PlasticMethod>()
042    {
043        public boolean accept(PlasticMethod method)
044        {
045            return method.getDescription().methodName.equalsIgnoreCase(methodAlias)
046                    || method.hasAnnotation(methodAnnotationClass);
047        }
048    };
049
050    private final Worker<PlasticMethod> VALIDATE = new Worker<PlasticMethod>()
051    {
052        public void work(PlasticMethod method)
053        {
054            if (!method.isVoid())
055                throw new RuntimeException(String.format("Method %s is a lifecycle method and should return void.", method
056                        .getMethodIdentifier()));
057
058            if (!method.getParameters().isEmpty())
059                throw new RuntimeException(String.format("Method %s is a lifecycle method and should take no parameters.",
060                        method.getMethodIdentifier()));
061
062        }
063    };
064
065    public PageLifecycleAnnotationWorker(Class<? extends Annotation> methodAnnotationClass,
066                                         MethodDescription lifecycleMethodDescription, String methodAlias)
067    {
068        this.methodAnnotationClass = methodAnnotationClass;
069        this.lifecycleMethodDescription = lifecycleMethodDescription;
070        this.methodAlias = methodAlias;
071    }
072
073    public void transform(PlasticClass plasticClass, TransformationSupport support, MutableComponentModel model)
074    {
075        Flow<PlasticMethod> methods = matchLifecycleMethods(plasticClass);
076
077        if (methods.isEmpty())
078        {
079            return;
080        }
081
082        plasticClass.introduceInterface(PageLifecycleListener.class);
083
084        for (PlasticMethod method : methods)
085        {
086            invokeMethodWithinLifecycle(plasticClass, method);
087        }
088    }
089
090
091    private void invokeMethodWithinLifecycle(PlasticClass plasticClass, PlasticMethod method)
092    {
093        MethodHandle handle = method.getHandle();
094
095        plasticClass.introduceMethod(lifecycleMethodDescription).addAdvice(createAdvice(handle));
096    }
097
098    private MethodAdvice createAdvice(final MethodHandle handle)
099    {
100        return new MethodAdvice()
101        {
102            public void advise(MethodInvocation invocation)
103            {
104                invocation.proceed();
105
106                handle.invoke(invocation.getInstance()).rethrow();
107            }
108        };
109    }
110
111    private Flow<PlasticMethod> matchLifecycleMethods(PlasticClass plasticClass)
112    {
113        return F.flow(plasticClass.getMethods()).filter(MATCHER).each(VALIDATE);
114    }
115}