    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.commons.*;
    018import org.apache.tapestry5.commons.util.CollectionFactory;
    019import org.apache.tapestry5.ioc.Invokable;
    020import org.apache.tapestry5.ioc.OperationTracker;
    021import org.apache.tapestry5.ioc.annotations.PreventServiceDecoration;
    022import org.apache.tapestry5.ioc.services.MasterObjectProvider;
    023import org.apache.tapestry5.plastic.PlasticUtils;
    024
    025import java.util.List;
    026
    027@PreventServiceDecoration
    028public class MasterObjectProviderImpl implements MasterObjectProvider
    029{
    030    private final List<ObjectProvider> configuration;
    031
    032    private final OperationTracker tracker;
    033
    034    public MasterObjectProviderImpl(List<ObjectProvider> configuration, OperationTracker tracker)
    035    {
    036        this.configuration = CollectionFactory.newList(configuration);
    037        this.tracker = tracker;
    038
    039        // Add this special case to the front of the list.
    040        this.configuration.add(0, new StaticObjectProvider(OperationTracker.class, tracker));
    041    }
    042
    043    @Override
    044    public <T> T provide(final Class<T> objectType, final AnnotationProvider annotationProvider,
    045                         final ObjectLocator locator,
    046                         final boolean required)
    047    {
    048        return tracker.invoke(String.format("Resolving object of type %s using MasterObjectProvider",
    049                PlasticUtils.toTypeName(objectType)), new Invokable<T>()
    050        {
    051            @Override
    052            public T invoke()
    053            {
    054                for (ObjectProvider provider : configuration)
    055                {
    056                    T result = provider.provide(objectType, annotationProvider, locator);
    057
    058                    if (result != null) return result;
    059                }
    060
    061                // If required, then we must obtain it the hard way, by
    062                // seeing if there's a single service that implements the interface.
    063
    064                if (required) return locator.getService(objectType);
    065
    066                return null;
    067            }
    068        });
    069    }
    070}