    001// Copyright 2011, 2013 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.BaseOptimizedSessionPersistedObject;
    018import org.apache.tapestry5.commons.util.CollectionFactory;
    019
    020import java.util.Set;
    021
    022/**
    023 * Manages a Set of String {@link TreeNode} ids.
    024 *
    025 * @param <T> the type of the tree.
    026 * @since 5.3
    027 * @see TreeModel
    028 */
    029public class DefaultTreeExpansionModel<T> extends BaseOptimizedSessionPersistedObject implements TreeExpansionModel<T>
    030{
    031    private static final long serialVersionUID = -2776835739067510365L;
    032
    033    private final Set<String> expandedIds = CollectionFactory.newSet();
    034
    035    public boolean isExpanded(TreeNode<T> node)
    036    {
    037        assert node != null;
    038
    039        return expandedIds.contains(node.getId());
    040    }
    041
    042    public void markExpanded(TreeNode<T> node)
    043    {
    044        assert node != null;
    045
    046        if (expandedIds.add(node.getId()))
    047            markDirty();
    048    }
    049
    050    public void markCollapsed(TreeNode<T> node)
    051    {
    052        assert node != null;
    053
    054        if (expandedIds.remove(node.getId()))
    055            markDirty();
    056    }
    057
    058    public void clear()
    059    {
    060        if (!expandedIds.isEmpty())
    061        {
    062            expandedIds.clear();
    063            markDirty();
    064        }
    065    }
    066}