Class 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 Detail

      • MergeCombiner

        public MergeCombiner()
    • Method Detail

      • matchAttributes

        private static boolean matchAttributes​(java.util.Map<java.lang.String,​java.lang.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
      • 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,
                                           java.util.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