// Copyright 2005 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.tapestry.enhance;
import java.lang.reflect.Modifier;
import java.util.Iterator;
import java.util.List;
import org.apache.hivemind.ErrorLog;
import org.apache.hivemind.service.BodyBuilder;
import org.apache.hivemind.service.ClassFabUtils;
import org.apache.hivemind.service.MethodSignature;
import org.apache.tapestry.engine.state.ApplicationStateManager;
import org.apache.tapestry.event.PageDetachListener;
import org.apache.tapestry.spec.IComponentSpecification;
import org.apache.tapestry.spec.InjectStateSpecification;
/**
* Worker for injecting application state objects as properties of the component. These properties
* are read/write and must be "live" (changes are propogated back into the
* {@link org.apache.tapestry.engine.state.ApplicationStateManager}). They should also cache in a
* local variable for efficiency, and clear out that variable at the end of the request.
*
* @author Howard M. Lewis Ship
* @since 4.0
*/
public class InjectStateWorker implements EnhancementWorker
{
private ErrorLog _errorLog;
private ApplicationStateManager _applicationStateManager;
public void performEnhancement(EnhancementOperation op, IComponentSpecification spec)
{
List injects = spec.getInjectStateSpecifications();
if (injects.isEmpty())
return;
// TODO: The EnhancementOperation should have a way of assigning non-conflicting
// attribute names. What if someone injects a property named "applicationStateManager"
// as well?
op.addField(
"_$applicationStateManager",
ApplicationStateManager.class,
_applicationStateManager);
Iterator i = injects.iterator();
while (i.hasNext())
{
InjectStateSpecification iss = (InjectStateSpecification) i.next();
try
{
injectState(op, iss.getProperty(), iss.getObjectName());
}
catch (Exception ex)
{
_errorLog.error(EnhanceMessages.errorAddingProperty(iss.getProperty(), op
.getBaseClass(), ex), iss.getLocation(), ex);
}
}
}
private void injectState(EnhancementOperation op, String propertyName, String objectName)
{
Class propertyType =
EnhanceUtils.extractPropertyType(op, propertyName, null);
String fieldName = "_$" + propertyName;
op.claimProperty(propertyName);
op.addField(fieldName, propertyType);
BodyBuilder builder = new BodyBuilder();
// Accessor
builder.begin();
builder.addln("if ({0} == null)", fieldName);
builder.addln(
" {0} = ({1}) _$applicationStateManager.get(\"{2}\");",
fieldName,
ClassFabUtils.getJavaClassName(propertyType),
objectName);
builder.addln("return {0};", fieldName);
builder.end();
String methodName = op.getAccessorMethodName(propertyName);
MethodSignature sig = new MethodSignature(propertyType, methodName, null, null);
op.addMethod(Modifier.PUBLIC, sig, builder.toString());
// Mutator
builder.clear();
builder.begin();
builder.addln("_$applicationStateManager.store(\"{0}\", $1);", objectName);
builder.addln("{0} = $1;", fieldName);
builder.end();
sig = new MethodSignature(void.class, EnhanceUtils.createMutatorMethodName(propertyName),
new Class[]
{ propertyType }, null);
op.addMethod(Modifier.PUBLIC, sig, builder.toString());
// Extend pageDetached() to clean out the cached field value.
op.extendMethodImplementation(
PageDetachListener.class,
EnhanceUtils.PAGE_DETACHED_SIGNATURE,
fieldName + " = null;");
}
public void setApplicationStateManager(ApplicationStateManager applicationStateManager)
{
_applicationStateManager = applicationStateManager;
}
public void setErrorLog(ErrorLog errorLog)
{
_errorLog = errorLog;
}
}