    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    }