001// Copyright 2006, 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.ioc.internal.services; 016 017import java.lang.reflect.Method; 018import java.lang.reflect.Modifier; 019 020import org.apache.tapestry5.ioc.services.Builtin; 021import org.apache.tapestry5.ioc.services.PlasticProxyFactory; 022import org.apache.tapestry5.ioc.services.PropertyAccess; 023import org.apache.tapestry5.ioc.services.PropertyAdapter; 024import org.apache.tapestry5.ioc.services.PropertyShadowBuilder; 025import org.apache.tapestry5.plastic.ClassInstantiator; 026import org.apache.tapestry5.plastic.Condition; 027import org.apache.tapestry5.plastic.WhenCallback; 028import org.apache.tapestry5.plastic.InstructionBuilder; 029import org.apache.tapestry5.plastic.InstructionBuilderCallback; 030import org.apache.tapestry5.plastic.MethodDescription; 031import org.apache.tapestry5.plastic.PlasticClass; 032import org.apache.tapestry5.plastic.PlasticClassTransformer; 033import org.apache.tapestry5.plastic.PlasticField; 034import org.apache.tapestry5.plastic.PlasticMethod; 035 036public class PropertyShadowBuilderImpl implements PropertyShadowBuilder 037{ 038 private final PropertyAccess propertyAccess; 039 040 private final PlasticProxyFactory proxyFactory; 041 042 public PropertyShadowBuilderImpl(@Builtin 043 PlasticProxyFactory proxyFactory, 044 045 PropertyAccess propertyAccess) 046 { 047 this.proxyFactory = proxyFactory; 048 this.propertyAccess = propertyAccess; 049 } 050 051 public <T> T build(final Object source, final String propertyName, final Class<T> propertyType) 052 { 053 final Class sourceClass = source.getClass(); 054 final PropertyAdapter adapter = propertyAccess.getAdapter(sourceClass).getPropertyAdapter(propertyName); 055 056 // TODO: Perhaps extend ClassPropertyAdapter to do these checks? 057 058 if (adapter == null) 059 throw new RuntimeException(ServiceMessages.noSuchProperty(sourceClass, propertyName)); 060 061 if (!adapter.isRead()) 062 throw new RuntimeException(ServiceMessages.readNotSupported(source, propertyName)); 063 064 if (!propertyType.isAssignableFrom(adapter.getType())) 065 throw new RuntimeException(ServiceMessages.propertyTypeMismatch(propertyName, sourceClass, 066 adapter.getType(), propertyType)); 067 068 ClassInstantiator instantiator = proxyFactory.createProxy(propertyType, new PlasticClassTransformer() 069 { 070 public void transform(PlasticClass plasticClass) 071 { 072 final PlasticField sourceField = plasticClass.introduceField(sourceClass, "source").inject(source); 073 074 PlasticMethod delegateMethod = plasticClass.introducePrivateMethod(propertyType.getName(), 075 "readProperty", null, null); 076 077 // You don't do this using MethodAdvice, because then we'd have to use reflection to access the read 078 // method. 079 080 delegateMethod.changeImplementation(new InstructionBuilderCallback() 081 { 082 public void doBuild(InstructionBuilder builder) 083 { 084 builder.loadThis().getField(sourceField); 085 builder.invoke(sourceClass, propertyType, adapter.getReadMethod().getName()); 086 087 // Now add the null check. 088 089 builder.dupe().when(Condition.NULL, new InstructionBuilderCallback() 090 { 091 public void doBuild(InstructionBuilder builder) 092 { 093 builder.throwException( 094 NullPointerException.class, 095 String.format( 096 "Unable to delegate method invocation to property '%s' of %s, because the property is null.", 097 propertyName, source)); 098 } 099 }); 100 101 builder.returnResult(); 102 } 103 }); 104 105 for (Method m : propertyType.getMethods()) 106 { 107 plasticClass.introduceMethod(m).delegateTo(delegateMethod); 108 } 109 110 plasticClass.addToString(String.format("<Shadow: property %s of %s>", propertyName, source)); 111 } 112 }); 113 114 return propertyType.cast(instantiator.newInstance()); 115 } 116}