    001// Copyright 2006, 2007, 2008, 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.internal.transform;
    016
    017import org.apache.tapestry5.annotations.Environmental;
    018import org.apache.tapestry5.internal.services.ComponentClassCache;
    019import org.apache.tapestry5.model.MutableComponentModel;
    020import org.apache.tapestry5.plastic.*;
    021import org.apache.tapestry5.services.Environment;
    022import org.apache.tapestry5.services.transform.ComponentClassTransformWorker2;
    023import org.apache.tapestry5.services.transform.TransformationSupport;
    024
    025/**
    026 * Obtains a value from the {@link Environment} service based on the field type. This is triggered by the presence of
    027 * the {@link Environmental} annotation.
    028 */
    029@SuppressWarnings("rawtypes")
    030public class EnvironmentalWorker implements ComponentClassTransformWorker2
    031{
    032    private final Environment environment;
    033
    034    private final ComponentClassCache classCache;
    035
    036
    037    @SuppressWarnings("unchecked")
    038    private final class EnvironmentalConduit implements FieldConduit
    039    {
    040        private final String componentClassName;
    041
    042        private final String fieldName;
    043
    044        private final Class environmentalType;
    045
    046        private final boolean required;
    047
    048        private EnvironmentalConduit(String componentClassName, String fieldName, final Class environmentalType,
    049                boolean required)
    050        {
    051            this.componentClassName = componentClassName;
    052            this.fieldName = fieldName;
    053            this.environmentalType = environmentalType;
    054            this.required = required;
    055        }
    056
    057        public Object get(Object instance, InstanceContext context)
    058        {
    059            return required ? environment.peekRequired(environmentalType) : environment.peek(environmentalType);
    060        }
    061
    062        public void set(Object instance, InstanceContext context, Object newValue)
    063        {
    064            throw new RuntimeException(String.format("Field %s.%s is read only.", componentClassName, fieldName));
    065        }
    066    }
    067
    068    public EnvironmentalWorker(Environment environment, ComponentClassCache classCache)
    069    {
    070        this.environment = environment;
    071
    072        this.classCache = classCache;
    073    }
    074
    075    public void transform(PlasticClass plasticClass, TransformationSupport support, MutableComponentModel model)
    076    {
    077        for (PlasticField field : plasticClass.getFieldsWithAnnotation(Environmental.class))
    078        {
    079            transform(model.getComponentClassName(), field);
    080        }
    081    }
    082
    083    private void transform(final String componentClassName, PlasticField field)
    084    {
    085        Environmental annotation = field.getAnnotation(Environmental.class);
    086
    087        field.claim(annotation);
    088
    089        final String fieldName = field.getName();
    090
    091        final Class fieldType = classCache.forName(field.getTypeName());
    092
    093        final boolean required = annotation.value();
    094
    095        ComputedValue<FieldConduit<Object>> provider = new ComputedValue<FieldConduit<Object>>()
    096        {
    097            public FieldConduit<Object> get(InstanceContext context)
    098            {
    099                return new EnvironmentalConduit(componentClassName, fieldName, fieldType, required);
    100            }
    101
    102            public void set(Object instance, InstanceContext context, Object newValue)
    103            {
    104                throw new RuntimeException(
    105                        String.format("Field %s of component %s is read only.", fieldName, componentClassName));
    106            }
    107        };
    108
    109        field.setComputedConduit(provider);
    110    }
    111
    112}