001    // Copyright May 31, 2006 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    package org.apache.tapestry.data;
015    
016    import org.apache.tapestry.services.DataSqueezer;
017    
018    /**
019     * Handles null data assumedly?
020     * 
021     * @author jcarman
022     */
023    public class NullDataSqueezerFilter extends AbstractDataSqueezerFilter
024    {
025        private static final String NULL_STRING = "X";
026        
027        public String squeeze(Object data, DataSqueezer dataSqueezer)
028        {
029            if (data == null)
030                return NULL_STRING;
031            
032            return dataSqueezer.squeeze(data);
033        }
034    
035        public Object unsqueeze(String string, DataSqueezer dataSqueezer)
036        {
037            if (NULL_STRING.equals(string))
038                return null;
039            
040            return dataSqueezer.unsqueeze(string);
041        }
042    }