Coverage Report - org.apache.commons.configuration.tree.NodeCombiner
 
Classes in this File Line Coverage Branch Coverage Complexity
NodeCombiner
100%
8/8
N/A
1
 
 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.Collections;
 20  
 import java.util.HashSet;
 21  
 import java.util.Set;
 22  
 
 23  
 /**
 24  
  * <p>
 25  
  * A base class for node combiner implementations.
 26  
  * </p>
 27  
  * <p>
 28  
  * A <em>node combiner</em> is an object that knows how two hierarchical node
 29  
  * structures can be combined into a single one. Of course, there are many
 30  
  * possible ways of implementing such a combination, e.g. constructing a union,
 31  
  * an intersection, or an "override" structure (were nodes in the first
 32  
  * hierarchy take precedence over nodes in the second hierarchy). This abstract
 33  
  * base class only provides some helper methods and defines the common interface
 34  
  * for node combiners. Concrete sub classes will implement the diverse
 35  
  * combination algorithms.
 36  
  * </p>
 37  
  * <p>
 38  
  * For some concrete combiner implementations it is important to distinguish
 39  
  * whether a node is a single node or whether it belongs to a list structure.
 40  
  * Alone from the input structures, the combiner will not always be able to make
 41  
  * this decision. So sometimes it may be necessary for the developer to
 42  
  * configure the combiner and tell it, which nodes should be treated as list
 43  
  * nodes. For this purpose the {@code addListNode()} method exists. It
 44  
  * can be passed the name of a node, which should be considered a list node.
 45  
  * </p>
 46  
  *
 47  
  * @author <a
 48  
  * href="http://commons.apache.org/configuration/team-list.html">Commons
 49  
  * Configuration team</a>
 50  
  * @version $Id: NodeCombiner.java 1206476 2011-11-26 16:19:53Z oheger $
 51  
  * @since 1.3
 52  
  */
 53  
 public abstract class NodeCombiner
 54  
 {
 55  
     /** Stores a list with node names that are known to be list nodes. */
 56  
     protected Set<String> listNodes;
 57  
 
 58  
     /**
 59  
      * Creates a new instance of {@code NodeCombiner}.
 60  
      */
 61  
     public NodeCombiner()
 62  141
     {
 63  141
         listNodes = new HashSet<String>();
 64  141
     }
 65  
 
 66  
     /**
 67  
      * Adds the name of a node to the list of known list nodes. This means that
 68  
      * nodes with this name will never be combined.
 69  
      *
 70  
      * @param nodeName the name to be added
 71  
      */
 72  
     public void addListNode(String nodeName)
 73  
     {
 74  36
         listNodes.add(nodeName);
 75  36
     }
 76  
 
 77  
     /**
 78  
      * Returns a set with the names of nodes that are known to be list nodes.
 79  
      *
 80  
      * @return a set with the names of list nodes
 81  
      */
 82  
     public Set<String> getListNodes()
 83  
     {
 84  7
         return Collections.unmodifiableSet(listNodes);
 85  
     }
 86  
 
 87  
     /**
 88  
      * Checks if a node is a list node. This implementation tests if the given
 89  
      * node name is contained in the set of known list nodes. Derived classes
 90  
      * which use different criteria may overload this method.
 91  
      *
 92  
      * @param node the node to be tested
 93  
      * @return a flag whether this is a list node
 94  
      */
 95  
     public boolean isListNode(ConfigurationNode node)
 96  
     {
 97  615
         return listNodes.contains(node.getName());
 98  
     }
 99  
 
 100  
     /**
 101  
      * Combines the hierarchies represented by the given root nodes. This method
 102  
      * must be defined in concrete sub classes with the implementation of a
 103  
      * specific combination algorithm.
 104  
      *
 105  
      * @param node1 the first root node
 106  
      * @param node2 the second root node
 107  
      * @return the resulting combined node structure
 108  
      */
 109  
     public abstract ConfigurationNode combine(ConfigurationNode node1,
 110  
             ConfigurationNode node2);
 111  
 
 112  
     /**
 113  
      * Creates a new view node. This method will be called whenever a new view
 114  
      * node is to be created. It can be overridden to create special view nodes.
 115  
      * This base implementation returns a new instance of
 116  
      * {@link ViewNode}.
 117  
      *
 118  
      * @return the new view node
 119  
      */
 120  
     protected ViewNode createViewNode()
 121  
     {
 122  8047
         return new ViewNode();
 123  
     }
 124  
 }