| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.configuration2.tree; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.LinkedList; |
| import java.util.List; |
| import java.util.Map; |
| |
| import org.apache.commons.lang3.ObjectUtils; |
| |
| /** |
| * <p> |
| * A specialized implementation of the {@code NodeCombiner} interface |
| * that performs a merge from two passed in node hierarchies. |
| * </p> |
| * <p> |
| * This combiner performs the merge using a few rules: |
| * </p> |
| * <ol> |
| * <li>Nodes can be merged when attributes that appear in both have the same value.</li> |
| * <li>Only a single node in the second file is considered a match to the node in the first file.</li> |
| * <li>Attributes in nodes that match are merged. |
| * <li>Nodes in both files that do not match are added to the result.</li> |
| * </ol> |
| * |
| * @version $Id$ |
| * @since 1.7 |
| */ |
| public class MergeCombiner extends NodeCombiner |
| { |
| /** |
| * Combines the given nodes to a new union node. |
| * |
| * @param node1 the first source node |
| * @param node2 the second source node |
| * @return the union node |
| */ |
| |
| @Override |
| public ImmutableNode combine(ImmutableNode node1, ImmutableNode node2) |
| { |
| ImmutableNode.Builder result = new ImmutableNode.Builder(); |
| result.name(node1.getNodeName()); |
| result.value(node1.getValue()); |
| addAttributes(result, node1, node2); |
| |
| // Check if nodes can be combined |
| List<ImmutableNode> children2 = new LinkedList<ImmutableNode>(node2.getChildren()); |
| for (ImmutableNode child1 : node1.getChildren()) |
| { |
| ImmutableNode child2 = canCombine(node2, child1, children2); |
| if (child2 != null) |
| { |
| result.addChild(combine(child1, child2)); |
| children2.remove(child2); |
| } |
| else |
| { |
| result.addChild(child1); |
| } |
| } |
| |
| // Add remaining children of node 2 |
| for (ImmutableNode c : children2) |
| { |
| result.addChild(c); |
| } |
| return result.create(); |
| } |
| |
| /** |
| * Handles the attributes during a combination process. First all attributes |
| * of the first node will be added to the result. Then all attributes of the |
| * second node, which are not contained in the first node, will also be |
| * added. |
| * |
| * @param result the builder for the resulting node |
| * @param node1 the first node |
| * @param node2 the second node |
| */ |
| protected void addAttributes(ImmutableNode.Builder result, ImmutableNode node1, |
| ImmutableNode node2) |
| { |
| Map<String, Object> attributes = new HashMap<String, Object>(); |
| attributes.putAll(node1.getAttributes()); |
| for (Map.Entry<String, Object> e : node2.getAttributes().entrySet()) |
| { |
| if (!attributes.containsKey(e.getKey())) |
| { |
| attributes.put(e.getKey(), e.getValue()); |
| } |
| } |
| result.addAttributes(attributes); |
| } |
| |
| /** |
| * Tests if the first node can be combined with the second node. A node can |
| * only be combined if its attributes are all present in the second node and |
| * they all have the same value. |
| * |
| * @param node2 the second node |
| * @param child the child node (of the first node) |
| * @param children2 the children of the 2nd node |
| * @return a child of the second node, with which a combination is possible |
| */ |
| protected ImmutableNode canCombine(ImmutableNode node2, |
| ImmutableNode child, List<ImmutableNode> children2) |
| { |
| Map<String, Object> attrs1 = child.getAttributes(); |
| List<ImmutableNode> nodes = new ArrayList<ImmutableNode>(); |
| |
| List<ImmutableNode> children = |
| HANDLER.getChildren(node2, child.getNodeName()); |
| for (ImmutableNode node : children) |
| { |
| if (matchAttributes(attrs1, node)) |
| { |
| nodes.add(node); |
| } |
| } |
| |
| if (nodes.size() == 1) |
| { |
| return nodes.get(0); |
| } |
| if (nodes.size() > 1 && !isListNode(child)) |
| { |
| for (ImmutableNode node : nodes) |
| { |
| children2.remove(node); |
| } |
| } |
| |
| return null; |
| } |
| |
| /** |
| * Checks whether the attributes of the passed in node are compatible. |
| * |
| * @param attrs1 the attributes of the first node |
| * @param node the 2nd node |
| * @return a flag whether these nodes can be combined regarding their |
| * attributes |
| */ |
| private static boolean matchAttributes(Map<String, Object> attrs1, |
| ImmutableNode node) |
| { |
| Map<String, Object> attrs2 = node.getAttributes(); |
| for (Map.Entry<String, Object> e : attrs1.entrySet()) |
| { |
| if (attrs2.containsKey(e.getKey()) |
| && !ObjectUtils |
| .equals(e.getValue(), attrs2.get(e.getKey()))) |
| { |
| return false; |
| } |
| } |
| return true; |
| } |
| } |