Coverage Report - org.apache.commons.configuration.tree.OverrideCombiner
 
Classes in this File Line Coverage Branch Coverage Complexity
OverrideCombiner
100%
25/25
95%
19/20
4,667
 
 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  
 
 20  
 /**
 21  
  * <p>
 22  
  * A concrete combiner implementation that is able to construct an override
 23  
  * combination.
 24  
  * </p>
 25  
  * <p>
 26  
  * An <em>override combination</em> means that nodes in the first node
 27  
  * structure take precedence over nodes in the second, or - in other words -
 28  
  * nodes of the second structure are only added to the resulting structure if
 29  
  * they do not occur in the first one. This is especially suitable for dealing
 30  
  * with the properties of configurations that are defined in an
 31  
  * {@code override} section of a configuration definition file (hence the
 32  
  * name).
 33  
  * </p>
 34  
  * <p>
 35  
  * This combiner will iterate over the second node hierarchy and find all nodes
 36  
  * that are not contained in the first hierarchy; these are added to the result.
 37  
  * If a node can be found in both structures, it is checked whether a
 38  
  * combination (in a recursive way) can be constructed for the two, which will
 39  
  * then be added. Per default, nodes are combined, which occur only once in both
 40  
  * structures. This test is implemented in the {@code canCombine()}
 41  
  * method.
 42  
  * </p>
 43  
  * <p>
 44  
  * As is true for the {@link UnionCombiner}, for this combiner
 45  
  * list nodes are important. The {@code addListNode()} can be called to
 46  
  * declare certain nodes as list nodes. This has the effect that these nodes
 47  
  * will never be combined.
 48  
  * </p>
 49  
  *
 50  
  * @author <a
 51  
  * href="http://commons.apache.org/configuration/team-list.html">Commons
 52  
  * Configuration team</a>
 53  
  * @version $Id: OverrideCombiner.java 1301991 2012-03-17 20:18:02Z sebb $
 54  
  * @since 1.3
 55  
  */
 56  72
 public class OverrideCombiner extends NodeCombiner
 57  
 {
 58  
     /**
 59  
      * Constructs an override combination for the passed in node structures.
 60  
      *
 61  
      * @param node1 the first node
 62  
      * @param node2 the second node
 63  
      * @return the resulting combined node structure
 64  
      */
 65  
     @Override
 66  
     public ConfigurationNode combine(ConfigurationNode node1,
 67  
             ConfigurationNode node2)
 68  
     {
 69  263
         ViewNode result = createViewNode();
 70  263
         result.setName(node1.getName());
 71  
 
 72  
         // Process nodes from the first structure, which override the second
 73  263
         for (ConfigurationNode child : node1.getChildren())
 74  
         {
 75  2412
             ConfigurationNode child2 = canCombine(node1, node2, child);
 76  2412
             if (child2 != null)
 77  
             {
 78  157
                 result.addChild(combine(child, child2));
 79  
             }
 80  
             else
 81  
             {
 82  2255
                 result.addChild(child);
 83  
             }
 84  2412
         }
 85  
 
 86  
         // Process nodes from the second structure, which are not contained
 87  
         // in the first structure
 88  263
         for (ConfigurationNode child : node2.getChildren())
 89  
         {
 90  1470
             if (node1.getChildrenCount(child.getName()) < 1)
 91  
             {
 92  1207
                 result.addChild(child);
 93  
             }
 94  1470
         }
 95  
 
 96  
         // Handle attributes and value
 97  263
         addAttributes(result, node1, node2);
 98  263
         result.setValue((node1.getValue() != null) ? node1.getValue() : node2
 99  
                 .getValue());
 100  
 
 101  263
         return result;
 102  
     }
 103  
 
 104  
     /**
 105  
      * Handles the attributes during a combination process. First all attributes
 106  
      * of the first node will be added to the result. Then all attributes of the
 107  
      * second node, which are not contained in the first node, will also be
 108  
      * added.
 109  
      *
 110  
      * @param result the resulting node
 111  
      * @param node1 the first node
 112  
      * @param node2 the second node
 113  
      */
 114  
     protected void addAttributes(ViewNode result, ConfigurationNode node1,
 115  
             ConfigurationNode node2)
 116  
     {
 117  263
         result.appendAttributes(node1);
 118  263
         for (ConfigurationNode attr : node2.getAttributes())
 119  
         {
 120  27
             if (node1.getAttributeCount(attr.getName()) == 0)
 121  
             {
 122  20
                 result.addAttribute(attr);
 123  
             }
 124  27
         }
 125  263
     }
 126  
 
 127  
     /**
 128  
      * Tests if a child node of the second node can be combined with the given
 129  
      * child node of the first node. If this is the case, the corresponding node
 130  
      * will be returned, otherwise <b>null</b>. This implementation checks
 131  
      * whether the child node occurs only once in both hierarchies and is no
 132  
      * known list node.
 133  
      *
 134  
      * @param node1 the first node
 135  
      * @param node2 the second node
 136  
      * @param child the child node (of the first node)
 137  
      * @return a child of the second node, with which a combination is possible
 138  
      */
 139  
     protected ConfigurationNode canCombine(ConfigurationNode node1,
 140  
             ConfigurationNode node2, ConfigurationNode child)
 141  
     {
 142  2412
         if (node2.getChildrenCount(child.getName()) == 1
 143  
                 && node1.getChildrenCount(child.getName()) == 1
 144  
                 && !isListNode(child))
 145  
         {
 146  157
             return node2.getChildren(child.getName()).get(0);
 147  
         }
 148  
         else
 149  
         {
 150  2255
             return null;
 151  
         }
 152  
     }
 153  
 }