001// Licensed under the Apache License, Version 2.0 (the "License");
002// you may not use this file except in compliance with the License.
003// You may obtain a copy of the License at
004//
005// http://www.apache.org/licenses/LICENSE-2.0
006//
007// Unless required by applicable law or agreed to in writing, software
008// distributed under the License is distributed on an "AS IS" BASIS,
009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
010// See the License for the specific language governing permissions and
011// limitations under the License.
012
013package org.apache.tapestry5.internal.services;
014
015import org.apache.tapestry5.Block;
016import org.apache.tapestry5.ComponentResources;
017import org.apache.tapestry5.annotations.Id;
018import org.apache.tapestry5.internal.transform.ReadOnlyComponentFieldConduit;
019import org.apache.tapestry5.ioc.ObjectLocator;
020import org.apache.tapestry5.ioc.annotations.Inject;
021import org.apache.tapestry5.ioc.internal.util.InternalUtils;
022import org.apache.tapestry5.model.MutableComponentModel;
023import org.apache.tapestry5.plastic.FieldConduit;
024import org.apache.tapestry5.plastic.InstanceContext;
025import org.apache.tapestry5.plastic.PlasticField;
026import org.apache.tapestry5.services.transform.InjectionProvider2;
027
028/**
029 * Identifies fields of type {@link Block} that have the {@link Inject} annotation and converts them
030 * into read-only
031 * fields containing the injected Block from the template. The annotation's value is the id of the
032 * block to inject; if
033 * omitted, the block id is deduced from the field id.
034 *
035 * Must be scheduled before {@link DefaultInjectionProvider} because it uses the same annotation, Inject, with a
036 * different interpretation.
037 */
038public class BlockInjectionProvider implements InjectionProvider2
039{
040    private static final String BLOCK_TYPE_NAME = Block.class.getName();
041
042    public boolean provideInjection(PlasticField field, ObjectLocator locator, MutableComponentModel componentModel)
043    {
044        if (!field.getTypeName().equals(BLOCK_TYPE_NAME))
045        {
046            return false;
047        }
048
049        Id annotation = field.getAnnotation(Id.class);
050
051        String blockId = getBlockId(field.getName(), annotation);
052
053        FieldConduit<Object> conduit = createConduit(field, blockId);
054
055        field.setConduit(conduit);
056
057        return true; // claim the field
058    }
059
060    private FieldConduit<Object> createConduit(PlasticField field, final String blockId)
061    {
062        final String className = field.getPlasticClass().getClassName();
063        final String fieldName = field.getName();
064
065        return new ReadOnlyComponentFieldConduit(className, fieldName)
066        {
067            public Object get(Object instance, InstanceContext context)
068            {
069                ComponentResources resources = context.get(ComponentResources.class);
070
071                return resources.getBlock(blockId);
072            }
073        };
074    }
075
076    private String getBlockId(String fieldName, Id annotation)
077    {
078        return annotation != null ? annotation.value() : InternalUtils.stripMemberName(fieldName);
079    }
080}