Subject: RE: [xsl] XPath/XSLT 2.0: What is the most efficient way to find if a sequence is empty? From: "Michael Kay" <mhk@xxxxxxxxx> Date: Sun, 5 Oct 2003 15:46:18 +0100 |
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($x)=0 - but I guess there are processors out there that don't have decent optimizers. Michael Kay > -----Original Message----- > From: owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx > [mailto:owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx] On Behalf Of > Dimitre Novatchev > Sent: 04 October 2003 22:00 > To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx > Subject: [xsl] XPath/XSLT 2.0: What is the most efficient way > to find if a sequence is empty? > > > In XSLT/XPath 1.0 one would use: > > not($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 > > > > > XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list > XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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