Incremental DOM->DOM XSLT processor?

Hello,

I'm trying to find an XSLT processor that works in the following 
fashion:

    1) A source DOM document is transformed into a result DOM 
       document.

    2) The processor uses DOM events to listen for changes made 
       to the source document.  When a change is made, the 
       processor applies the appropriate deltas to the result 
       document by means of its DOM modification methods.

The idea is to avoid completely retransforming a document that
is undergoing minor edits (such as the addition of new nodes).

Is there anything out there that supports this behavior?  If not, 
does anyone have a sense of how difficult it would be to add 
something like this to one of the existing processors?

Thanks,
Luke

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