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
015package org.apache.tapestry5.tree;
016
017import 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 */
028public 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}