001// Licensed under the Apache License, Version 2.0 (the "License");
002// you may not use this file except in compliance with the License.
003// You may obtain a copy of the License at
004//
005// http://www.apache.org/licenses/LICENSE-2.0
006//
007// Unless required by applicable law or agreed to in writing, software
008// distributed under the License is distributed on an "AS IS" BASIS,
009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
010// See the License for the specific language governing permissions and
011// limitations under the License.
012
013package org.apache.tapestry5.tree;
014
015/**
016 * Tracks which <em>leaf</em> nodes of a {@link TreeModel} are currently selected. The {@linkplain DefaultTreeSelectionModel default
017 * implementation} simply stores a set of {@linkplain TreeNode#getId() unique node
018 * ids} to identify selected nodes. The selection model is updated whenever the user clicks on the label for a leaf node.
019 *
020 * In the future, new methods may be added that will support selection of folders as well as leafs, and define the rules for
021 * how selections and de-selections propagate down to children or up to parents.
022 *
023 * @param <T> type of node
024 * @see org.apache.tapestry5.corelib.components.Tree
025 * @since 5.3
026 */
027public interface TreeSelectionModel<T>
028{
029
030    /**
031     * Returns {@code true}, if the given node is selected.
032     *
033     * @param node node to check
034     */
035    boolean isSelected(TreeNode<T> node);
036
037    /**
038     * Selects a node.
039     *
040     * @param node node to select
041     */
042    void select(TreeNode<T> node);
043
044    /**
045     * Unselects a node.
046     *
047     * @param node node to unselect
048     */
049    void unselect(TreeNode<T> node);
050
051    /**
052     * Clears the selection.
053     */
054    void clear();
055}