001    // Copyright 2008, 2010 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.tapestry5.internal.services;
016    
017    import org.apache.tapestry5.NullFieldStrategy;
018    import org.apache.tapestry5.ioc.util.AvailableValues;
019    import org.apache.tapestry5.ioc.util.UnknownValueException;
020    import org.apache.tapestry5.services.NullFieldStrategySource;
021    
022    import java.util.Map;
023    
024    public class NullFieldStrategySourceImpl implements NullFieldStrategySource
025    {
026        private final Map<String, NullFieldStrategy> configuration;
027    
028        public NullFieldStrategySourceImpl(Map<String, NullFieldStrategy> configuration)
029        {
030            this.configuration = configuration;
031        }
032    
033        public NullFieldStrategy get(String name)
034        {
035            NullFieldStrategy result = configuration.get(name);
036    
037            if (result != null) return result;
038            
039            throw new UnknownValueException(String.format("Unrecognized name '%s' locating a null field strategy.", name),
040                    new AvailableValues("Configured null field strategies", configuration));
041    
042        }
043    }