// Copyright 2006, 2007 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.internal.transform;

 import org.apache.tapestry5.model.MutableComponentModel;

 import org.apache.tapestry5.services.ClassTransformation;

 import org.apache.tapestry5.services.ComponentClassTransformWorker;

 import static org.apache.tapestry5.services.TransformConstants.CONTAINING_PAGE_DID_DETACH_SIGNATURE;

 import static org.apache.tapestry5.services.TransformConstants.CONTAINING_PAGE_DID_LOAD_SIGNATURE;

 import java.lang.reflect.Modifier;

 import java.util.List;

 /**

  * Designed to be just about the last worker in the pipeline. Its job is to add cleanup code that restores transient

  * fields back to their initial (null) value. Fields that have been previously {@link

  * org.apache.tapestry5.services.ClassTransformation#claimField(String, Object) claimed} are ignored, as are fields that

  * are final.

  */

 public final class UnclaimedFieldWorker implements ComponentClassTransformWorker

 {

     public void transform(ClassTransformation transformation, MutableComponentModel model)

     {

         List<String> fieldNames = transformation.findUnclaimedFields();

         for (String fieldName : fieldNames)

         {

             transformField(fieldName, transformation);

         }

     }

     private void transformField(String fieldName, ClassTransformation transformation)

     {

         int modifiers = transformation.getFieldModifiers(fieldName);

         if (Modifier.isFinal(modifiers))

             return;

         String type = transformation.getFieldType(fieldName);

         String defaultFieldName = transformation.addField(Modifier.PRIVATE, type, fieldName

                 + "_default");

         transformation.extendMethod(CONTAINING_PAGE_DID_LOAD_SIGNATURE, defaultFieldName + " = "

                 + fieldName + ";");

         // At the end of the request, we want to move the default value back over the

         // active field value. This will most often be null.

         transformation.extendMethod(CONTAINING_PAGE_DID_DETACH_SIGNATURE, fieldName + " = "

                 + defaultFieldName + ";");

     }

 }