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