xml-dev - Re: Streaming XSL Stylesheets - Was: XML::Writer 0.1 available

[David Megginson <david@megginson.com>]

Alex Milowski writes:

 > Not quite.  You could develop a stream-based DSSSL processor given that
 > you do the appropriate analysis of the stylesheet upfront and determine
 > where "caching" would have be put into place.

In DSSSL, at least, it would be probably unmanageably difficult, at
least not in the general case -- the problem is that someone could use
character data (perhaps after much arbitrary manipulation) later in
the document to decide what to select earlier, and vice-versa, using
DSSSL's navigational functions.  

For example, in DSSSL, I could specify something like the following:

  a. Take all of the character data of this element
  b. remove all whitespace
  c. reverse the order of the characters
  d. remove every character where its Unicode value mod 7 is 0
  e. look up the resulting string in a top-level a-list
  f. process all elements in a second document that have a 'foo'
     attribute whose value is lexically <= the a-list value, and
     concatenate their character data
  g. process the element in the first document with a 'bar' attribute
     containing a number equal to the number of characters extracted
     from the second document in step f.

Hopefully, things aren't quite this bad for XSL.  Good luck -- I'll be
very excited if you can solve this.


All the best,


David

-- 
David Megginson                 david@megginson.com
           http://www.megginson.com/

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