    001// Copyright 2007, 2009, 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 org.apache.tapestry5.ioc.*;
    018import org.apache.tapestry5.ioc.annotations.PreventServiceDecoration;
    019import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
    020import org.apache.tapestry5.ioc.services.MasterObjectProvider;
    021import org.apache.tapestry5.plastic.PlasticUtils;
    022
    023import java.util.List;
    024
    025@PreventServiceDecoration
    026public class MasterObjectProviderImpl implements MasterObjectProvider
    027{
    028    private final List<ObjectProvider> configuration;
    029
    030    private final OperationTracker tracker;
    031
    032    public MasterObjectProviderImpl(List<ObjectProvider> configuration, OperationTracker tracker)
    033    {
    034        this.configuration = CollectionFactory.newList(configuration);
    035        this.tracker = tracker;
    036
    037        // Add this special case to the front of the list.
    038        this.configuration.add(0, new StaticObjectProvider(OperationTracker.class, tracker));
    039    }
    040
    041    @Override
    042    public <T> T provide(final Class<T> objectType, final AnnotationProvider annotationProvider,
    043                         final ObjectLocator locator,
    044                         final boolean required)
    045    {
    046        return tracker.invoke(String.format("Resolving object of type %s using MasterObjectProvider",
    047                PlasticUtils.toTypeName(objectType)), new Invokable<T>()
    048        {
    049            @Override
    050            public T invoke()
    051            {
    052                for (ObjectProvider provider : configuration)
    053                {
    054                    T result = provider.provide(objectType, annotationProvider, locator);
    055
    056                    if (result != null) return result;
    057                }
    058
    059                // If required, then we must obtain it the hard way, by
    060                // seeing if there's a single service that implements the interface.
    061
    062                if (required) return locator.getService(objectType);
    063
    064                return null;
    065            }
    066        });
    067    }
    068}