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.List;
018
019/**
020 * Used with {@link DefaultTreeModel} to define how to extract labels and child nodes from a value.
021 *
022 * @since 5.3
023 */
024public interface TreeModelAdapter<T>
025{
026    /**
027     * Determines if the value is a leaf or a (potential) container of children.
028     *
029     * @see TreeNode#isLeaf()
030     */
031    boolean isLeaf(T value);
032
033    /**
034     * Returns true if the value has children (only invoked for non-leaf values).
035     *
036     * @see TreeNode#getHasChildren()
037     */
038    boolean hasChildren(T value);
039
040    /**
041     * Returns the children, in the order they should be presented to the client.
042     * This should return the childen in the correct presentation or, or return null or an empty list.
043     *
044     * @see TreeNode#getChildren()
045     */
046    List<T> getChildren(T value);
047
048    /**
049     * Returns a text label for the value, which may be presented to the client.
050     *
051     * @see TreeNode#getLabel()
052     */
053    String getLabel(T value);
054}