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 java.util.Set;
018    
019    import org.apache.tapestry5.BaseOptimizedSessionPersistedObject;
020    import 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     */
029    public 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    }