Re: [xsl] check if a node is empty

Subject: Re: [xsl] check if a node is empty
From: David Carlisle <davidc@xxxxxxxxx>
Date: Thu, 17 Oct 2002 16:40:54 +0100
> <xsl:when test="count(*)=0"> ( to check for empty child elements)
> be any inefficient ?( was just  thinking of other ways to do it besides the 
> standard ones you have suggested )

you almost never need to check against =0 in XPath as 0 and empty node
sets coerce to false.

If you go

<xsl:when test="*"
then the semantics of the language tell you it's true if there are any
elements so that's all the system need check.

if you go

then the semantics of count(*) would seem to imply that the system need
check exactly how many there are (which may take longer of there are
1000000001 of them. On the other hand the chances are that your system
will optimise both of these expressions to some internal system-specific
test-if-empty function and so it probably doesn't make any difference
what you do.


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