tapestry/tapestry-framework/src/java/org/apache/tapestry/enhance/InjectComponentWorker.java

// Copyright 2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.apache.tapestry.enhance;

import java.util.Iterator;

import org.apache.hivemind.ErrorLog;
import org.apache.hivemind.Location;
import org.apache.hivemind.service.BodyBuilder;
import org.apache.hivemind.service.ClassFabUtils;
import org.apache.hivemind.util.Defense;
import org.apache.tapestry.IComponent;
import org.apache.tapestry.TapestryUtils;
import org.apache.tapestry.spec.IComponentSpecification;
import org.apache.tapestry.spec.IContainedComponent;

/**
 * Injects components for which the property attribute of the <component>
 * element was specified. This makes it easier to reference a particular
 * component from Java code.
 * 
 * @author Howard M. Lewis Ship
 * @since 4.0
 */
public class InjectComponentWorker implements EnhancementWorker
{

    private ErrorLog _errorLog;

    public void performEnhancement(EnhancementOperation op,
            IComponentSpecification spec)
    {
        Iterator i = spec.getComponentIds().iterator();

        while(i.hasNext())
        {
            String id = (String) i.next();

            IContainedComponent cc = spec.getComponent(id);

            String propertyName = cc.getPropertyName();

            if (propertyName != null)
            {
                try
                {
                    injectComponent(op, id, propertyName, cc.getLocation());
                }
                catch (Exception ex)
                {
                    _errorLog.error(EnhanceMessages.errorAddingProperty(
                            propertyName, op.getBaseClass(), ex), cc
                            .getLocation(), ex);
                }
            }
        }
    }

    public void injectComponent(EnhancementOperation op, String componentId,
            String propertyName, Location location)
    {
        Defense.notNull(op, "op");
        Defense.notNull(componentId, "componentId");
        Defense.notNull(propertyName, "propertyName");

        Class propertyType = EnhanceUtils.extractPropertyType(op, propertyName,
                null);

        op.claimReadonlyProperty(propertyName);

        String fieldName = "_$" + propertyName;
        String classField = op.getClassReference(propertyType);
        String locationField = op.addInjectedField(fieldName + "$location",
                Location.class, location);

        op.addField(fieldName, propertyType);

        EnhanceUtils.createSimpleAccessor(op, fieldName, propertyName,
                propertyType, location);

        // I.e. _$fred = (IComponent) TapestryUtils.getComponent(this, "fred",
        // IComponent.class,
        // location)

        BodyBuilder builder = new BodyBuilder();

        builder.add("{0} = ({1}) ", fieldName, ClassFabUtils
                .getJavaClassName(propertyType));
        builder.add("{0}#getComponent(this, ", TapestryUtils.class.getName());
        builder.addQuoted(componentId);
        builder.add(", {0}, {1});", classField, locationField);

        op.extendMethodImplementation(IComponent.class,
                EnhanceUtils.FINISH_LOAD_SIGNATURE, builder.toString());
    }

    public void setErrorLog(ErrorLog errorLog)
    {
        _errorLog = errorLog;
    }
}