001    // Copyright 2007, 2008 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.grid;
016    
017    import org.apache.tapestry5.grid.GridDataSource;
018    import org.apache.tapestry5.grid.SortConstraint;
019    
020    import java.util.List;
021    
022    /**
023     * An implementation of {@link org.apache.tapestry5.grid.GridDataSource} used when the value null is provided as the
024     * source.
025     */
026    public class NullDataSource implements GridDataSource
027    {
028        public int getAvailableRows()
029        {
030            return 0;
031        }
032    
033        public Class getRowType()
034        {
035            return null;
036        }
037    
038        public void prepare(int startIndex, int endIndex, List<SortConstraint> sortConstraints)
039        {
040        }
041    
042        public Object getRowValue(int index)
043        {
044            return null;
045        }
046    
047    }