Copy one value over to another with xmltask - parsing

Question

Is it possible for an xml task to copy the value of one node into another node for each element in a list?
Source XML:
<a>
<b>
<c1>foo</c1>
<c2></c2>
</b>
<b>
<c1>bar</c1>
<c2></c2>
</b>
...
</a>
Destination XML:
<a>
<b>
<c1>foo</c1>
<c2>foo</c2>
</b>
<b>
<c1>bar</c1>
<c2>bar</c2>
</b>
...
</a>
I'm trying to accomplish the above in my ant task, but I con't seem to find a way to do it, here is what I am doing so far,
<target name="mergefile">
<!-- Read the source into a buffer -->
<xmltask source="source.xml" clearBuffers="list">
<copy path="/a" buffer="list" append="true"/>
</xmltask>
<!-- Write them to the output -->
<xmltask source="destination.xml" dest="destination.xml"
outputter="simple">
<!-- First clear all the old paths. -->
<remove path="/a/b"/>
<!-- Then add the resolved ones. -->
<paste path="/a" buffer="list"></paste>
<!-- Copy the value over? -->
<replace path="a/b/c2/text()" withText="No Idea"/>
</xmltask>
</target>
Any idea of how to copy the value from one node to the next for all the elements in the list?

Answer 1

As, I guess, is usually the case, writing my own task was the only way I could see to do it.
#Override
public void execute() throws BuildException {
//Read file line by line, regex test on each line,
//matches get written back twice.
}
Then calling it was,
<copyregmatch file="myfile.xml" regex=".*replace.*" />