    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}