Merging common XML tree

Hi there,

  I am trying to find a solution for the following problem. Let's
assume that my input XML tree looks like:

<dirs>
  <dir name="A">
    <dir name="B">
      <file name="C">
    </dir>
  </dir>
  <dir name="A">
    <dir name="B">
      <file name="D">
    </dir>
  </dir>
</dirs>

and my target output tree should looks like:

<dirs>
  <dir name="A">
    <dir name="B">
      <file name="C">
      <file name="D">
    </dir>
  </dir>
</dirs>

Basically I am trying to represent a dir/file structure in XML, where
I am not allowed to repeat common subdirectory. What XSL function
could I use to do that (XSTL 1.0 if possible).

Thanks !
-- 
Mathieu