001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket.extensions.markup.html.repeater.tree;
018
019import java.util.Iterator;
020
021import org.apache.wicket.model.IDetachable;
022import org.apache.wicket.model.IModel;
023
024/**
025 * Provider of a tree.
026 * 
027 * You can use the {@link IDetachable#detach()} method for cleaning up your ITreeProvider instance.
028 * 
029 * @see IDetachable
030 * @see AbstractTree
031 * 
032 * @author svenmeier
033 * @param <T>
034 *            the node type
035 */
036public interface ITreeProvider<T> extends IDetachable
037{
038
039        /**
040         * Get the roots of the tree.
041         * 
042         * @return roots
043         */
044        Iterator<? extends T> getRoots();
045
046        /**
047         * Does the given object have children - note that this method may return <code>true</code> even
048         * if {@link #getChildren(Object)} returns an empty iterator.
049         * 
050         * @param node
051         *            the node to check for children
052         * @return {@code true} if node has children
053         */
054        boolean hasChildren(T node);
055
056        /**
057         * Get the children of the given node.
058         * 
059         * @param node
060         *            node to get children for
061         * @return children of node
062         */
063        Iterator<? extends T> getChildren(T node);
064
065        /**
066         * Callback used by the consumer of this tree provider to wrap objects retrieved from
067         * {@link #getRoots()} or {@link #getChildren(Object)} with a model (usually a detachable one).
068         * <p>
069         * Important note: The model must implement {@link Object#equals(Object)} and
070         * {@link Object#hashCode()} !
071         * 
072         * @param object
073         *            the object that needs to be wrapped
074         * 
075         * @return the model representation of the object
076         */
077        IModel<T> model(T object);
078}