001    // Copyright 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.grid;
016    
017    import java.util.List;
018    
019    /**
020     * Models the sorting applied to the a {@link org.apache.tapestry5.grid.GridDataSource}.
021     */
022    public interface GridSortModel
023    {
024        /**
025         * Identifies how (or if) a column is sorted.
026         *
027         * @param columnId
028         * @return the sort for the indicated column or {@link org.apache.tapestry5.grid.ColumnSort#UNSORTED} if the column
029         *         is not used for sorting
030         */
031        ColumnSort getColumnSort(String columnId);
032    
033        /**
034         * Updates the column sort.  The receiver determines how to handle the sort request.
035         *
036         * @param columnId property id of column to sort on
037         */
038        void updateSort(String columnId);
039    
040        /**
041         * Returns a list of sort constraints, identifying which columns are sorted, and how.  May return an empty list (but
042         * won't return null).
043         *
044         * @see org.apache.tapestry5.grid.GridDataSource#prepare(int, int, java.util.List)
045         */
046        List<SortConstraint> getSortConstraints();
047    
048        void clear();
049    }