Class MergeCombiner

java.lang.Object
org.apache.commons.configuration2.tree.NodeCombiner
org.apache.commons.configuration2.tree.MergeCombiner

public class MergeCombiner extends NodeCombiner

A specialized implementation of the NodeCombiner interface that performs a merge from two passed in node hierarchies.

This combiner performs the merge using a few rules:

  1. Nodes can be merged when attributes that appear in both have the same value.
  2. Only a single node in the second file is considered a match to the node in the first file.
  3. Attributes in nodes that match are merged.
  4. Nodes in both files that do not match are added to the result.
Since:
1.7
  • Constructor Details

    • MergeCombiner

      public MergeCombiner()
  • Method Details

    • combine

      public ImmutableNode combine(ImmutableNode node1, ImmutableNode node2)
      Combines the given nodes to a new union node.
      Specified by:
      combine in class NodeCombiner
      Parameters:
      node1 - the first source node
      node2 - the second source node
      Returns:
      the union node
    • addAttributes

      protected void addAttributes(ImmutableNode.Builder result, ImmutableNode node1, ImmutableNode node2)
      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.
      Parameters:
      result - the builder for the resulting node
      node1 - the first node
      node2 - the second node
    • canCombine

      protected ImmutableNode canCombine(ImmutableNode node2, ImmutableNode child, List<ImmutableNode> children2)
      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.
      Parameters:
      node2 - the second node
      child - the child node (of the first node)
      children2 - the children of the 2nd node
      Returns:
      a child of the second node, with which a combination is possible
    • matchAttributes

      private static boolean matchAttributes(Map<String,Object> attrs1, ImmutableNode node)
      Checks whether the attributes of the passed in node are compatible.
      Parameters:
      attrs1 - the attributes of the first node
      node - the 2nd node
      Returns:
      a flag whether these nodes can be combined regarding their attributes