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.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 * @since 1.3
046 * @param <T> the type of nodes this class can handle
047 */
048public class NodeAddData<T> {
049    /** Stores the parent node of the add operation. */
050    private final T parent;
051
052    /**
053     * Stores a list with the names of nodes that are on the path between the parent node and the new node.
054     */
055    private final List<String> pathNodes;
056
057    /** Stores the name of the new node. */
058    private final String newNodeName;
059
060    /** Stores the attribute flag. */
061    private final boolean attribute;
062
063    /**
064     * Creates a new instance of {@code NodeAddData} and initializes it.
065     *
066     * @param parentNode the parent node of the add operation
067     * @param newName the name of the new node
068     * @param isAttr flag whether the new node is an attribute
069     * @param intermediateNodes an optional collection with path nodes
070     */
071    public NodeAddData(final T parentNode, final String newName, final boolean isAttr, final Collection<String> intermediateNodes) {
072        parent = parentNode;
073        newNodeName = newName;
074        attribute = isAttr;
075        pathNodes = createPathNodes(intermediateNodes);
076    }
077
078    /**
079     * Returns a flag if the new node to be added is an attribute.
080     *
081     * @return <b>true</b> for an attribute node, <b>false</b> for a child node
082     */
083    public boolean isAttribute() {
084        return attribute;
085    }
086
087    /**
088     * Gets the name of the new node.
089     *
090     * @return the new node's name
091     */
092    public String getNewNodeName() {
093        return newNodeName;
094    }
095
096    /**
097     * Gets the parent node.
098     *
099     * @return the parent node
100     */
101    public T getParent() {
102        return parent;
103    }
104
105    /**
106     * Gets a list with further nodes that must be added. This is needed if a complete branch is to be added at once. For
107     * instance, imagine that there exists only a node {@code database}. Now the key
108     * {@code database.connection.settings.username} (assuming the syntax of the default expression engine) is to be added.
109     * Then {@code username} is the name of the new node, but the nodes {@code connection} and {@code settings} must be
110     * added to the parent node first. In this example these names would be returned by this method.
111     *
112     * @return a list with the names of nodes that must be added as parents of the new node (never <b>null</b>)
113     */
114    public List<String> getPathNodes() {
115        return pathNodes;
116    }
117
118    /**
119     * Creates the list with path nodes. Handles null input.
120     *
121     * @param intermediateNodes the nodes passed to the constructor
122     * @return an unmodifiable list of path nodes
123     */
124    private static List<String> createPathNodes(final Collection<String> intermediateNodes) {
125        if (intermediateNodes == null) {
126            return Collections.emptyList();
127        }
128        return Collections.unmodifiableList(new ArrayList<>(intermediateNodes));
129    }
130}