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RE: XPath/XSLT 2.0: What is the most efficient way to find if a sequence is empty?

2003-10-05 07:46:18
There are two complementary functions empty($seq) and exists($seq).

I would expect any decent optimizer to generate exactly the same code
for these as for count($x)=0 - but I guess there are processors out
there that don't have decent optimizers.

Michael Kay

-----Original Message-----
From: owner-xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com 
[mailto:owner-xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com] On Behalf Of 
Dimitre Novatchev
Sent: 04 October 2003 22:00
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: [xsl] XPath/XSLT 2.0: What is the most efficient way 
to find if a sequence is empty?


In XSLT/XPath 1.0 one would use:

  not($node-set)

to find if $node-set is the empty node-set.

However, the same test on a sequence in XPath 2.0:

  not($seq)

may return 'true' for a non-empty sequence -- e.g. for:
   ( false() )

or for

       (0)

My question: Is there a more efficient test for an empty sequence than

  count($seq) = 0




=====
Cheers,

Dimitre Novatchev.
http://fxsl.sourceforge.net/ -- the home of FXSL




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