// Copyright 2006 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.ioc.internal.services;
import static java.lang.String.format;
import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
import org.apache.tapestry.ioc.services.ClassFab;
import org.apache.tapestry.ioc.services.ClassFactory;
import org.apache.tapestry.ioc.services.MethodSignature;
import org.apache.tapestry.ioc.services.PropertyAccess;
import org.apache.tapestry.ioc.services.PropertyAdapter;
import org.apache.tapestry.ioc.services.PropertyShadowBuilder;
/**
*
*/
public class PropertyShadowBuilderImpl implements PropertyShadowBuilder
{
private final ClassFactory _classFactory;
private final PropertyAccess _propertyAccess;
public PropertyShadowBuilderImpl(ClassFactory classFactory, PropertyAccess propertyAccess)
{
_classFactory = classFactory;
_propertyAccess = propertyAccess;
}
public <T> T build(Object source, String propertyName, Class<T> propertyType)
{
Class sourceClass = source.getClass();
PropertyAdapter adapter = _propertyAccess.getAdapter(sourceClass).getPropertyAdapter(
propertyName);
// TODO: Perhaps extend ClassPropertyAdapter to do these checks?
if (adapter == null)
throw new RuntimeException(ServiceMessages.noSuchProperty(sourceClass, propertyName));
if (!adapter.isRead())
throw new RuntimeException(ServiceMessages.readNotSupported(source, propertyName));
if (!propertyType.isAssignableFrom(adapter.getType()))
throw new RuntimeException(ServiceMessages.propertyTypeMismatch(
propertyName,
sourceClass,
adapter.getType(),
propertyType));
ClassFab cf = _classFactory.newClass(propertyType);
cf.addField("_source", sourceClass);
cf.addConstructor(new Class[]
{ sourceClass }, null, "_source = $1;");
String body = format("return _source.%s();", adapter.getReadMethod().getName());
MethodSignature sig = new MethodSignature(propertyType, "_delegate", null, null);
cf.addMethod(Modifier.PRIVATE, sig, body);
String toString = format("<Shadow: property %s of %s>", propertyName, source);
cf.proxyMethodsToDelegate(propertyType, "_delegate()", toString);
Class shadowClass = cf.createClass();
try
{
Constructor cc = shadowClass.getConstructors()[0];
Object instance = cc.newInstance(source);
return propertyType.cast(instance);
}
catch (Exception ex)
{
// Should not be reachable
throw new RuntimeException(ex);
}
}
}