    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.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     */
    024    public 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    }