001    // Copyright 2005 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    
015    package org.apache.tapestry.services.impl;
016    
017    import org.apache.hivemind.Location;
018    import org.apache.hivemind.internal.Module;
019    import org.apache.hivemind.schema.Translator;
020    
021    /**
022     * An encapsulation of an invocation of
023     * {@link org.apache.hivemind.schema.Translator#translate(org.apache.hivemind.internal.Module, java.lang.Class, java.lang.String, org.apache.hivemind.Location)},
024     * allowing the actual invocation (and all the object creation, etc., that entails) to be deferred,
025     * or even avoided all together.
026     * 
027     * @author Howard M. Lewis Ship
028     * @since 4.0
029     */
030    public class DeferredObjectImpl implements DeferredObject
031    {
032        private final Module _module;
033    
034        private final Translator _objectTranslator;
035    
036        private final String _objectReference;
037    
038        private final Location _location;
039    
040        private Object _object;
041    
042        public DeferredObjectImpl(final Translator objectTranslator, final Module module,
043                final String objectReference, final Location location)
044        {
045            _objectTranslator = objectTranslator;
046            _module = module;
047            _objectReference = objectReference;
048            _location = location;
049        }
050    
051        public synchronized Object getObject()
052        {
053            if (_object == null)
054                _object = _objectTranslator.translate(
055                        _module,
056                        Object.class,
057                        _objectReference,
058                        _location);
059    
060            return _object;
061        }
062    
063        public Location getLocation()
064        {
065            return _location;
066        }
067    }