Coverage Report - org.apache.commons.configuration.tree.OverrideCombiner
 
Classes in this File Line Coverage Branch Coverage Complexity
OverrideCombiner
100%
25/25
100%
8/8
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  
 }