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.util.Iterator;
018    
019    import org.apache.hivemind.ErrorLog;
020    import org.apache.hivemind.Location;
021    import org.apache.hivemind.service.BodyBuilder;
022    import org.apache.hivemind.service.ClassFabUtils;
023    import org.apache.hivemind.util.Defense;
024    import org.apache.tapestry.IComponent;
025    import org.apache.tapestry.TapestryUtils;
026    import org.apache.tapestry.spec.IComponentSpecification;
027    import org.apache.tapestry.spec.IContainedComponent;
028    
029    /**
030     * Injects components for which the property attribute of the <component> element was
031     * specified. This makes it easier to reference a particular component from Java code.
032     * 
033     * @author Howard M. Lewis Ship
034     * @since 4.0
035     */
036    public class InjectComponentWorker implements EnhancementWorker
037    {
038        private ErrorLog _errorLog;
039    
040        public void performEnhancement(EnhancementOperation op, IComponentSpecification spec)
041        {
042            Iterator i = spec.getComponentIds().iterator();
043    
044            while (i.hasNext())
045            {
046                String id = (String) i.next();
047    
048                IContainedComponent cc = spec.getComponent(id);
049    
050                String propertyName = cc.getPropertyName();
051    
052                if (propertyName != null)
053                {
054                    try
055                    {
056                        injectComponent(op, id, propertyName, cc.getLocation());
057                    }
058                    catch (Exception ex)
059                    {
060                        _errorLog.error(EnhanceMessages.errorAddingProperty(propertyName, op
061                                .getBaseClass(), ex), cc.getLocation(), ex);
062                    }
063                }
064            }
065        }
066    
067        public void injectComponent(EnhancementOperation op, String componentId, String propertyName,
068                Location location)
069        {
070            Defense.notNull(op, "op");
071            Defense.notNull(componentId, "componentId");
072            Defense.notNull(propertyName, "propertyName");
073    
074            Class propertyType = EnhanceUtils.extractPropertyType(op, propertyName, null);
075    
076            op.claimReadonlyProperty(propertyName);
077    
078            String fieldName = "_$" + propertyName;
079            String classField = op.getClassReference(propertyType);
080            String locationField = op.addInjectedField(
081                    fieldName + "$location",
082                    Location.class,
083                    location);
084    
085            op.addField(fieldName, propertyType);
086    
087            EnhanceUtils.createSimpleAccessor(op, fieldName, propertyName, propertyType, location);
088    
089            // I.e. _$fred = (IComponent) TapestryUtils.getComponent(this, "fred", IComponent.class,
090            // location)
091    
092            BodyBuilder builder = new BodyBuilder();
093    
094            builder.add("{0} = ({1}) ", fieldName, ClassFabUtils.getJavaClassName(propertyType));
095            builder.add("{0}#getComponent(this, ", TapestryUtils.class.getName());
096            builder.addQuoted(componentId);
097            builder.add(", {0}, {1});", classField, locationField);
098    
099            op.extendMethodImplementation(IComponent.class, EnhanceUtils.FINISH_LOAD_SIGNATURE, builder
100                    .toString());
101        }
102    
103        public void setErrorLog(ErrorLog errorLog)
104        {
105            _errorLog = errorLog;
106        }
107    }