joining parallel markup

Hello,

  would you please suggest if there are libraries to join markup? For
example, having two fragments

<x><b>some dummy</b> text</x> and
<x>some <i>dummy text</i></x>,

 I'd like to get

<x><b>some <i>dummy</i></b><i> text</i></x>,

  or something like it.



-- 
Oleg Parashchenko  olpa@ http://xmlhack.ru/  XML news in Russian
http://uucode.com/blog/  Generative Programming, XML, TeX, Scheme