Package org.apache.commons.configuration.tree

Class MergeCombiner

java.lang.Object

org.apache.commons.configuration.tree.NodeCombiner

org.apache.commons.configuration.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

Version:

$Id: MergeCombiner.java 1301991 2012-03-17 20:18:02Z sebb $

Author:

Commons Configuration team

Field Summary

Fields inherited from class org.apache.commons.configuration.tree.NodeCombiner

listNodes

Constructor Summary

Constructors

Constructor	Description
MergeCombiner()

Method Summary

Modifier and Type	Method	Description
protected void	addAttributes(ViewNode result, ConfigurationNode node1, ConfigurationNode node2)	Handles the attributes during a combination process.
protected ConfigurationNode	canCombine(ConfigurationNode node1, ConfigurationNode node2, ConfigurationNode child, java.util.List<ConfigurationNode> children2)	Tests if the first node can be combined with the second node.
ConfigurationNode	combine(ConfigurationNode node1, ConfigurationNode node2)	Combines the given nodes to a new union node.

Methods inherited from class org.apache.commons.configuration.tree.NodeCombiner

addListNode, createViewNode, getListNodes, isListNode

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MergeCombiner

public MergeCombiner()

Method Detail

combine

public ConfigurationNode combine(ConfigurationNode node1,
                                 ConfigurationNode 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(ViewNode result,
                             ConfigurationNode node1,
                             ConfigurationNode 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 resulting node

node1 - the first node

node2 - the second node

canCombine

protected ConfigurationNode canCombine(ConfigurationNode node1,
                                       ConfigurationNode node2,
                                       ConfigurationNode child,
                                       java.util.List<ConfigurationNode> 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:

node1 - the first node

node2 - the second node

child - the child node (of the first node)

Returns:

a child of the second node, with which a combination is possible