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 *     https://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.commons.configuration2.tree;
018
019import java.util.ArrayList;
020import java.util.Collection;
021import java.util.Collections;
022import java.util.List;
023
024/**
025 * <p>
026 * A simple data class used by {@link ExpressionEngine} to store the results of the {@code prepareAdd()} operation.
027 * </p>
028 * <p>
029 * If a new property is to be added to a configuration, the affected {@code Configuration} object must know, where in
030 * its hierarchy of configuration nodes new elements have to be added. This information is obtained by an
031 * {@code ExpressionEngine} object that interprets the key of the new property. This expression engine will pack all
032 * information necessary for the configuration to perform the add operation in an instance of this class.
033 * </p>
034 * <p>
035 * Information managed by this class contains:
036 * </p>
037 * <ul>
038 * <li>the configuration node, to which new elements must be added</li>
039 * <li>the name of the new node</li>
040 * <li>whether the new node is a child node or an attribute node</li>
041 * <li>if a whole branch is to be added at once, the names of all nodes between the parent node (the target of the add
042 * operation) and the new node</li>
043 * </ul>
044 *
045 * @param <T> the type of nodes this class can handle
046 * @since 1.3
047 */
048public class NodeAddData<T> {
049
050    /**
051     * Creates the list with path nodes. Handles null input.
052     *
053     * @param intermediateNodes the nodes passed to the constructor
054     * @return an unmodifiable list of path nodes
055     */
056    private static List<String> createPathNodes(final Collection<String> intermediateNodes) {
057        if (intermediateNodes == null) {
058            return Collections.emptyList();
059        }
060        return Collections.unmodifiableList(new ArrayList<>(intermediateNodes));
061    }
062
063    /** Stores the parent node of the add operation. */
064    private final T parent;
065
066    /**
067     * Stores a list with the names of nodes that are on the path between the parent node and the new node.
068     */
069    private final List<String> pathNodes;
070
071    /** Stores the name of the new node. */
072    private final String newNodeName;
073
074    /** Stores the attribute flag. */
075    private final boolean attribute;
076
077    /**
078     * Creates a new instance of {@code NodeAddData} and initializes it.
079     *
080     * @param parentNode the parent node of the add operation
081     * @param newName the name of the new node
082     * @param isAttr flag whether the new node is an attribute
083     * @param intermediateNodes an optional collection with path nodes
084     */
085    public NodeAddData(final T parentNode, final String newName, final boolean isAttr, final Collection<String> intermediateNodes) {
086        parent = parentNode;
087        newNodeName = newName;
088        attribute = isAttr;
089        pathNodes = createPathNodes(intermediateNodes);
090    }
091
092    /**
093     * Gets the name of the new node.
094     *
095     * @return the new node's name
096     */
097    public String getNewNodeName() {
098        return newNodeName;
099    }
100
101    /**
102     * Gets the parent node.
103     *
104     * @return the parent node
105     */
106    public T getParent() {
107        return parent;
108    }
109
110    /**
111     * Gets a list with further nodes that must be added. This is needed if a complete branch is to be added at once. For
112     * instance, imagine that there exists only a node {@code database}. Now the key
113     * {@code database.connection.settings.username} (assuming the syntax of the default expression engine) is to be added.
114     * Then {@code username} is the name of the new node, but the nodes {@code connection} and {@code settings} must be
115     * added to the parent node first. In this example these names would be returned by this method.
116     *
117     * @return a list with the names of nodes that must be added as parents of the new node (never <strong>null</strong>)
118     */
119    public List<String> getPathNodes() {
120        return pathNodes;
121    }
122
123    /**
124     * Returns a flag if the new node to be added is an attribute.
125     *
126     * @return <strong>true</strong> for an attribute node, <strong>false</strong> for a child node
127     */
128    public boolean isAttribute() {
129        return attribute;
130    }
131}