    001// Copyright 2006, 2007, 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.ioc.internal.services;
    016
    017import java.util.Map;
    018
    019import org.apache.tapestry5.commons.services.PlasticProxyFactory;
    020import org.apache.tapestry5.commons.util.CollectionFactory;
    021import org.apache.tapestry5.ioc.services.Builtin;
    022import org.apache.tapestry5.ioc.services.DefaultImplementationBuilder;
    023import org.apache.tapestry5.plastic.ClassInstantiator;
    024import org.apache.tapestry5.plastic.PlasticClass;
    025import org.apache.tapestry5.plastic.PlasticClassTransformer;
    026
    027public class DefaultImplementationBuilderImpl implements DefaultImplementationBuilder
    028{
    029    private final Map<Class, Object> cache = CollectionFactory.newConcurrentMap();
    030
    031    private final PlasticProxyFactory proxyFactory;
    032
    033    public DefaultImplementationBuilderImpl(@Builtin
    034    PlasticProxyFactory proxyFactory)
    035    {
    036        this.proxyFactory = proxyFactory;
    037    }
    038
    039    @Override
    040    public <S> S createDefaultImplementation(Class<S> serviceInterface)
    041    {
    042        S instance = serviceInterface.cast(cache.get(serviceInterface));
    043
    044        if (instance == null)
    045        {
    046            instance = createInstance(serviceInterface);
    047            cache.put(serviceInterface, instance);
    048        }
    049
    050        return instance;
    051    }
    052
    053    /**
    054     * Creates a class and an instance of that class. Updates the cache and returns the instance.
    055     */
    056    private <S> S createInstance(final Class<S> serviceInterface)
    057    {
    058        ClassInstantiator instantiator = proxyFactory.createProxy(serviceInterface, new PlasticClassTransformer()
    059        {
    060            @Override
    061            public void transform(PlasticClass plasticClass)
    062            {
    063                plasticClass.addToString(String.format("<NoOp %s>", serviceInterface.getName()));
    064            }
    065        });
    066
    067        return serviceInterface.cast(instantiator.newInstance());
    068    }
    069}