    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     * Returns 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     * Returns the parent node.
    098     *
    099     * @return the parent node
    100     */
    101    public T getParent() {
    102        return parent;
    103    }
    104
    105    /**
    106     * Returns 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}