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}