    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    /**
    018     * Tracks which <em>leaf</em> nodes of a {@link TreeModel} are currently selected. The {@linkplain DefaultTreeSelectionModel default
    019     * implementation} simply stores a set of {@linkplain TreeNode#getId() unique node
    020     * ids} to identify selected nodes. The selection model is updated whenever the user clicks on the label for a leaf node.
    021     * <p/>
    022     * In the future, new methods may be added that will support selection of folders as well as leafs, and define the rules for
    023     * how selections and de-selections propagate down to children or up to parents.
    024     *
    025     * @param <T> type of node
    026     * @see org.apache.tapestry5.corelib.components.Tree
    027     * @since 5.3
    028     */
    029    public interface TreeSelectionModel<T>
    030    {
    031
    032        /**
    033         * Returns {@code true}, if the given node is selected.
    034         *
    035         * @param node node to check
    036         */
    037        boolean isSelected(TreeNode<T> node);
    038
    039        /**
    040         * Selects a node.
    041         *
    042         * @param node node to select
    043         */
    044        void select(TreeNode<T> node);
    045
    046        /**
    047         * Unselects a node.
    048         *
    049         * @param node node to unselect
    050         */
    051        void unselect(TreeNode<T> node);
    052
    053        /**
    054         * Clears the selection.
    055         */
    056        void clear();
    057    }