// Copyright 2006, 2007 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.tapestry5.internal.services;

 import org.apache.tapestry5.ioc.AnnotationProvider;

 import org.apache.tapestry5.ioc.ObjectLocator;

 import org.apache.tapestry5.ioc.ObjectProvider;

 import org.apache.tapestry5.ioc.internal.util.CollectionFactory;

 import org.apache.tapestry5.services.Alias;

 import org.apache.tapestry5.services.AliasManager;

 import java.util.Map;

 public class AliasImpl implements Alias, ObjectProvider

 {

     // Derived from the managers when first needed

     private final Map<Class, Object> properties = CollectionFactory.newMap();

     private final String mode;

     private boolean initialized = false;

     private AliasManager masterManager;

     private AliasManager overridesManager;

     public AliasImpl(AliasManager masterManager, String mode, AliasManager overridesManager)

     {

         this.masterManager = masterManager;

         this.mode = mode;

         this.overridesManager = overridesManager;

     }

     public ObjectProvider getObjectProvider()

     {

         return this;

     }

     private synchronized void initialize()

     {

         if (initialized) return;

         properties.putAll(masterManager.getAliasesForMode(mode));

         properties.putAll(overridesManager.getAliasesForMode(mode));

         masterManager = null;

         overridesManager = null;

         initialized = true;

     }

     public <T> T provide(Class<T> objectType, AnnotationProvider annotationProvider,

                          ObjectLocator locator)

     {

         initialize();

         Object object = properties.get(objectType);

         // Let another provider handle this (probably the default object provider)

         if (object == null) return null;

         // A ClassCastException should never occur.

         return objectType.cast(object);

     }

 }