// 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 org.apache.hivemind.service.BodyBuilder;
import org.apache.hivemind.service.ClassFabUtils;
import org.apache.hivemind.service.MethodSignature;
import org.apache.hivemind.util.Defense;
import org.apache.tapestry.engine.state.ApplicationStateManager;
import org.apache.tapestry.event.PageDetachListener;
import org.apache.tapestry.spec.InjectSpecification;
/**
* 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 InjectEnhancementWorker
{
private ApplicationStateManager _applicationStateManager;
public void performEnhancement(EnhancementOperation op, InjectSpecification spec)
{
injectState(op, spec.getObject(), spec.getProperty());
}
public void injectState(EnhancementOperation op, String objectName, String propertyName)
{
Defense.notNull(op, "op");
Defense.notNull(objectName, "objectName");
Defense.notNull(propertyName, "propertyName");
Class propertyType = EnhanceUtils.extractPropertyType(op, propertyName, null);
String fieldName = "_$" + propertyName;
op.claimProperty(propertyName);
op.addField(fieldName, propertyType);
String managerField = op.addInjectedField(
"_$applicationStateManager",
ApplicationStateManager.class,
_applicationStateManager);
BodyBuilder builder = new BodyBuilder();
// Accessor
builder.begin();
builder.addln("if ({0} == null)", fieldName);
builder.addln(" {0} = ({1}) {2}.get(\"{3}\");", new Object[]
{ fieldName, ClassFabUtils.getJavaClassName(propertyType), managerField, 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("{0}.store(\"{1}\", $1);", managerField, 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;
}
}