Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
OverrideCombiner |
|
| 3.6666666666666665;3,667 |
1 | /* | |
2 | * Licensed to the Apache Software Foundation (ASF) under one or more | |
3 | * contributor license agreements. See the NOTICE file distributed with | |
4 | * this work for additional information regarding copyright ownership. | |
5 | * The ASF licenses this file to You under the Apache License, Version 2.0 | |
6 | * (the "License"); you may not use this file except in compliance with | |
7 | * the License. You may obtain a copy of the License at | |
8 | * | |
9 | * http://www.apache.org/licenses/LICENSE-2.0 | |
10 | * | |
11 | * Unless required by applicable law or agreed to in writing, software | |
12 | * distributed under the License is distributed on an "AS IS" BASIS, | |
13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
14 | * See the License for the specific language governing permissions and | |
15 | * limitations under the License. | |
16 | */ | |
17 | package org.apache.commons.configuration.tree; | |
18 | ||
19 | import java.util.Iterator; | |
20 | ||
21 | /** | |
22 | * <p> | |
23 | * A concrete combiner implementation that is able to construct an override | |
24 | * combination. | |
25 | * </p> | |
26 | * <p> | |
27 | * An <em>override combination</em> means that nodes in the first node | |
28 | * structure take precedence over nodes in the second, or - in other words - | |
29 | * nodes of the second structure are only added to the resulting structure if | |
30 | * they do not occure in the first one. This is especially suitable for dealing | |
31 | * with the properties of configurations that are defined in an | |
32 | * <code>override</code> section of a configuration definition file (hence the | |
33 | * name). | |
34 | * </p> | |
35 | * <p> | |
36 | * This combiner will iterate over the second node hierarchy and find all nodes | |
37 | * that are not contained in the first hierarchy; these are added to the result. | |
38 | * If a node can be found in both structures, it is checked whether a | |
39 | * combination (in a recursive way) can be constructed for the two, which will | |
40 | * then be added. Per default, nodes are combined, which occur only once in both | |
41 | * structures. This test is implemented in the <code>canCombine()</code> | |
42 | * method. | |
43 | * </p> | |
44 | * <p> | |
45 | * As is true for the <code>{@link UnionCombiner}</code>, for this combiner | |
46 | * list nodes are important. The <code>addListNode()</code> can be called to | |
47 | * declare certain nodes as list nodes. This has the effect that these nodes | |
48 | * will never be combined. | |
49 | * </p> | |
50 | * | |
51 | * @author <a | |
52 | * href="http://jakarta.apache.org/commons/configuration/team-list.html">Commons | |
53 | * Configuration team</a> | |
54 | * @version $Id: OverrideCombiner.java 439648 2006-09-02 20:42:10Z oheger $ | |
55 | * @since 1.3 | |
56 | */ | |
57 | 25 | public class OverrideCombiner extends NodeCombiner |
58 | { | |
59 | /** | |
60 | * Constructs an override combination for the passed in node structures. | |
61 | * | |
62 | * @param node1 the first node | |
63 | * @param node2 the second node | |
64 | * @return the resulting combined node structure | |
65 | */ | |
66 | public ConfigurationNode combine(ConfigurationNode node1, | |
67 | ConfigurationNode node2) | |
68 | { | |
69 | 157 | ViewNode result = createViewNode(); |
70 | 157 | result.setName(node1.getName()); |
71 | ||
72 | // Process nodes from the first structure, which override the second | |
73 | 882 | for (Iterator it = node1.getChildren().iterator(); it.hasNext();) |
74 | { | |
75 | 568 | ConfigurationNode child = (ConfigurationNode) it.next(); |
76 | 568 | ConfigurationNode child2 = canCombine(node1, node2, child); |
77 | 568 | if (child2 != null) |
78 | { | |
79 | 122 | result.addChild(combine(child, child2)); |
80 | } | |
81 | else | |
82 | { | |
83 | 446 | result.addChild(child); |
84 | } | |
85 | } | |
86 | ||
87 | // Process nodes from the second structure, which are not contained | |
88 | // in the first structure | |
89 | 699 | for (Iterator it = node2.getChildren().iterator(); it.hasNext();) |
90 | { | |
91 | 385 | ConfigurationNode child = (ConfigurationNode) it.next(); |
92 | 385 | if (node1.getChildrenCount(child.getName()) < 1) |
93 | { | |
94 | 216 | result.addChild(child); |
95 | } | |
96 | } | |
97 | ||
98 | // Handle attributes and value | |
99 | 157 | addAttributes(result, node1, node2); |
100 | 157 | result.setValue((node1.getValue() != null) ? node1.getValue() : node2 |
101 | .getValue()); | |
102 | ||
103 | 157 | return result; |
104 | } | |
105 | ||
106 | /** | |
107 | * Handles the attributes during a combination process. First all attributes | |
108 | * of the first node will be added to the result. Then all attributes of the | |
109 | * second node, which are not contained in the first node, will also be | |
110 | * added. | |
111 | * | |
112 | * @param result the resulting node | |
113 | * @param node1 the first node | |
114 | * @param node2 the second node | |
115 | */ | |
116 | protected void addAttributes(ViewNode result, ConfigurationNode node1, | |
117 | ConfigurationNode node2) | |
118 | { | |
119 | 157 | result.appendAttributes(node1); |
120 | 334 | for (Iterator it = node2.getAttributes().iterator(); it.hasNext();) |
121 | { | |
122 | 20 | ConfigurationNode attr = (ConfigurationNode) it.next(); |
123 | 20 | if (node1.getAttributeCount(attr.getName()) == 0) |
124 | { | |
125 | 14 | result.addAttribute(attr); |
126 | } | |
127 | } | |
128 | 157 | } |
129 | ||
130 | /** | |
131 | * Tests if a child node of the second node can be combined with the given | |
132 | * child node of the first node. If this is the case, the corresponding node | |
133 | * will be returned, otherwise <b>null</b>. This implementation checks | |
134 | * whether the child node occurs only once in both hierarchies and is no | |
135 | * known list node. | |
136 | * | |
137 | * @param node1 the first node | |
138 | * @param node2 the second node | |
139 | * @param child the child node (of the first node) | |
140 | * @return a child of the second node, with which a combination is possible | |
141 | */ | |
142 | protected ConfigurationNode canCombine(ConfigurationNode node1, | |
143 | ConfigurationNode node2, ConfigurationNode child) | |
144 | { | |
145 | 568 | if (node2.getChildrenCount(child.getName()) == 1 |
146 | && node1.getChildrenCount(child.getName()) == 1 | |
147 | && !isListNode(child)) | |
148 | { | |
149 | 122 | return (ConfigurationNode) node2.getChildren(child.getName()) |
150 | .get(0); | |
151 | } | |
152 | else | |
153 | { | |
154 | 446 | return null; |
155 | } | |
156 | } | |
157 | } |