001    // Copyright 2011 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.tree;
016    
017    import org.apache.tapestry5.corelib.components.Tree;
018    
019    /**
020     * Tracks which nodes of a {@link TreeModel} are currently expanded. The {@linkplain DefaultTreeExpansionModel default
021     * implementation} simply stores a set of {@linkplain TreeNode#getId() unique node
022     * ids} to identify expanded nodes. The expansion model is updated whenever folders are expanded or
023     * collapsed on the client side.
024     *
025     * @since 5.3
026     * @see Tree
027     */
028    public interface TreeExpansionModel<T>
029    {
030        /**
031         * Returns true if the node has been previously {@linkplain #markExpanded(TreeNode) expanded}.
032         *
033         * @param node
034         *            node to check for expansion
035         * @return  true if expanded
036         */
037        boolean isExpanded(TreeNode<T> node);
038    
039        /** Marks the node as expanded. */
040        void markExpanded(TreeNode<T> node);
041    
042        /** Marks the node as collapsed (not expanded). */
043        void markCollapsed(TreeNode<T> node);
044    
045        /** Marks all nodes as collapsed. */
046        void clear();
047    }