001    // Copyright 2007 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;
016    
017    /**
018     * Callback interface that allows for visiting the option groups and option models of a select model in correct render
019     * order.
020     */
021    public interface SelectModelVisitor
022    {
023        /**
024         * Invoked once for each {@link OptionGroupModel}, just before invoking {@link #option(OptionModel)} for each
025         * embedded option within the group.
026         */
027        void beginOptionGroup(OptionGroupModel groupModel);
028    
029        /**
030         * Invoked for each option within a group, and at the end, for each ungrouped option.
031         *
032         * @param optionModel
033         */
034        void option(OptionModel optionModel);
035    
036        /**
037         * Invoked after all options within the group have been visited.
038         */
039        void endOptionGroup(OptionGroupModel groupModel);
040    }