001 // Copyright 2005 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
015 package org.apache.tapestry.enhance;
016
017 import java.lang.reflect.Modifier;
018
019 import org.apache.hivemind.Location;
020 import org.apache.hivemind.service.BodyBuilder;
021 import org.apache.hivemind.service.ClassFabUtils;
022 import org.apache.hivemind.service.MethodSignature;
023 import org.apache.hivemind.util.Defense;
024 import org.apache.tapestry.engine.state.ApplicationStateManager;
025 import org.apache.tapestry.event.PageDetachListener;
026 import org.apache.tapestry.spec.InjectSpecification;
027
028 /**
029 * Worker for injecting application state objects as properties of the component. These properties
030 * are read/write and must be "live" (changes are propogated back into the
031 * {@link org.apache.tapestry.engine.state.ApplicationStateManager}). They should also cache in a
032 * local variable for efficiency, and clear out that variable at the end of the request.
033 *
034 * @author Howard M. Lewis Ship
035 * @since 4.0
036 */
037 public class InjectStateWorker implements InjectEnhancementWorker
038 {
039 private ApplicationStateManager _applicationStateManager;
040
041 public void performEnhancement(EnhancementOperation op, InjectSpecification spec)
042 {
043 injectState(op, spec.getObject(), spec.getProperty(), spec.getLocation());
044 }
045
046 void injectState(EnhancementOperation op, String objectName, String propertyName,
047 Location location)
048 {
049 Defense.notNull(op, "op");
050 Defense.notNull(objectName, "objectName");
051 Defense.notNull(propertyName, "propertyName");
052
053 Class propertyType = EnhanceUtils.extractPropertyType(op, propertyName, null);
054 String fieldName = "_$" + propertyName;
055
056 // State properties are read/write
057
058 op.claimProperty(propertyName);
059
060 op.addField(fieldName, propertyType);
061
062 String managerField = op.addInjectedField(
063 "_$applicationStateManager",
064 ApplicationStateManager.class,
065 _applicationStateManager);
066
067 BodyBuilder builder = new BodyBuilder();
068
069 // Accessor
070
071 builder.begin();
072 builder.addln("if ({0} == null)", fieldName);
073 builder.addln(" {0} = ({1}) {2}.get(\"{3}\");", new Object[]
074 { fieldName, ClassFabUtils.getJavaClassName(propertyType), managerField, objectName });
075 builder.addln("return {0};", fieldName);
076 builder.end();
077
078 String methodName = op.getAccessorMethodName(propertyName);
079
080 MethodSignature sig = new MethodSignature(propertyType, methodName, null, null);
081
082 op.addMethod(Modifier.PUBLIC, sig, builder.toString(), location);
083
084 // Mutator
085
086 builder.clear();
087 builder.begin();
088 builder.addln("{0}.store(\"{1}\", $1);", managerField, objectName);
089 builder.addln("{0} = $1;", fieldName);
090 builder.end();
091
092 sig = new MethodSignature(void.class, EnhanceUtils.createMutatorMethodName(propertyName),
093 new Class[]
094 { propertyType }, null);
095
096 op.addMethod(Modifier.PUBLIC, sig, builder.toString(), location);
097
098 // Extend pageDetached() to clean out the cached field value.
099
100 op.extendMethodImplementation(
101 PageDetachListener.class,
102 EnhanceUtils.PAGE_DETACHED_SIGNATURE,
103 fieldName + " = null;");
104 }
105
106 public void setApplicationStateManager(ApplicationStateManager applicationStateManager)
107 {
108 _applicationStateManager = applicationStateManager;
109 }
110 }