Re: xxRe: [xsl] efficient use of key element and function

[Manfred Staudinger <manfred.staudinger@xxxxxxxxx>]

Hi David,

in my original post I wrote (sorry for the typo "xxRe: [xsl] ..."):
>Given a rather long list of unique names I want to know for a
>certain name if it is on that list. The stylesheet below does
>this, but is this the best (most efficient) solution? In the most
>common case around 95% of the names will be found.
>
>In the real stylesheet the names represent files and are used
>to avoid a file-not-found for doc(). They are retrieved by means
>of collection().

The stylesheet below is the original one, except for the
key element. Instead of
<xsl:key name="find" match="*" use="."/>
it is now
<xsl:key name="find" match="name" use="text()"/>
Is this the best (most efficient) solution?

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="2.0"
           xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
<xsl:key name="find" match="name" use="text()"/>
<xsl:template match="/">
<xsl:variable name="Index-alt">
   <doc>
       <name>
           <xsl:text>schmid_hans</xsl:text>
       </name>
       <name>
           <xsl:text>prunauer_katharina</xsl:text>
       </name>
       <name>
           <xsl:text>senkenwald_wolfgang</xsl:text>
       </name>
   </doc>
</xsl:variable>
<xsl:value-of select="empty(key('find', 'prunauer_regina', $Index-alt))"/>
<xsl:value-of select="empty(key('find', 'strada_jacopo', $Index-alt))"/>
</xsl:template>
</xsl:stylesheet>


On 9/7/05, David Carlisle <davidc@xxxxxxxxx> wrote:
>
> > I was thinking the use attribute only comes into play _after_ a match
> > was found and in some way can be viewed as a return value (per node)
>
> no you have that backwards, the use attribute specifies the allowe
> _arguments_ to the key function, the match attribute specifies teh
> returned value.
>
> key('x',...) (in xslt1) is a function from strings to node sets
>
> key('x','"foo") returns a set of nodes with key "foo".
>
> The way this is function is defined is that the set of nodes returned is
> the set of nodes that match the match attribute, and have a use
> attribute that evaluates to "foo".
>
> > > If might be better to match on text() than on *
> >For my test-case it should be the same.
>
> They will only be the same if your input document only has one element
> (and no comments).
>
> If you have
>
> <xsl:key match="*" use="."/>
>
> Then the key for the top level element will be all the character data in
> the document, concatenated. The system will then have to ake a hash
> table entry using that large string as label.
>
> key('x',string(/*)) would then return this element, but you would be a
> lot more efficient just to use
> /*
> without using keys at all.
>
> David
>
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