Subject: RE: filtering elements by single xpath
From: "Tomas Kolaci" <kolaci@xxxxxxx>
Date: Thu, 6 Apr 2006 11:24:54 +0200
|
Thank you, Michael, for all these useful hints! Br, Tomas
> -----Original Message-----
> From: Michael Kay [mailto:mike@xxxxxxxxxxxx]
> Sent: Wednesday, April 05, 2006 7:12 PM
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: RE: filtering elements by single xpath
>
> Try to avoid using copy-of here - copying nodes is expensive and often
> unnecessary.
>
> The simplest way is to avoid the inner predicate:
>
> <xsl:variable
> name="filtered-items"
> select="item[/root/item-filter/allow-items/@with-name = @name]"
> />
>
> Saxon 8.x will do this automatically, but 6.x and other processors will
> perform better if you pull the constant expression out of the loop:
>
> <xsl:variable name="names"
> select="/root/item-filter/allow-items/@with-name"/>
> <xsl:variable
> name="filtered-items"
> select="item[$names = @name]"
> />
>
> Better still is to use keys:
>
> <xsl:key name="k" match="allow-items" use="@with-name"/>
>
> then
>
> select="item[key('k', @name)]"
>
> Michael Kay
> http://www.saxonica.com/
>
>
> > -----Original Message-----
> > From: Tomas Kolaci [mailto:kolaci@xxxxxxx]
> > Sent: 05 April 2006 15:46
> > To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> > Subject: filtering elements by single xpath
> >
> > Hi!
> >
> > I'm using XSLT 1.1 and Saxon 6.5.3.
> >
> > I have following XML structure:
> >
> > <root>
> > <body>
> > <item pos="1" name="n1"/>
> > <item pos="2" name="n2"/>
> > <item pos="3" name="n2"/>
> > <item pos="4" name="n3"/>
> > <item pos="5" name="n4"/>
> > </body>
> > <item-filter>
> > <allow-items with-name="n2"/>
> > <allow-items with-name="n4"/>
> > </item-filter>
> > </root>
> >
> > and in template:
> >
> > <xsl:template match="body">
> > <xsl:variable
> > name="filtered-items"
> > select="item[/root/item-filter/allow-items[@with-name =
> > ???/@name]"
> > />
> > ...
> > </xsl:template>
> >
> > I'm trying to fill variable filtered-items with elements item
> > with "allowed"
> > name (= there is an element /root/item-filter/allow-items
> > with attribute
> > @with-name containing same value as item's @name)*, but I
> > don't know how to
> > reach current item on ??? position in my select (function
> > current() points
> > to current body element).
> >
> > I can handle it by sequential processing (copy of item is
> > good enough for
> > my needs):
> >
> > <xsl:variable name="filtered-items">
> > <xsl:for-each select="item">
> > <xsl:if
> > test="/root/item-filter/allow-items[@with-name =
> > current()/@name]">
> > <xsl:copy-of select="."/>
> > </xsl:if>
> > </xsl:for-each>
> > </xsl:variable>
> >
> > but I'm just curious if it is possible to achieve this by
> > single xpath?
> >
> > Thanks in advance!
> >
> > Best regards, Tomas
> >
> > *resultant filtered-items content for given example should be:
> >
> > <item pos="2" name="n2"/>
> > <item pos="3" name="n2"/>
> > <item pos="5" name="n4"/>
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Michael Kay - 5 Apr 2006 17:12:29 -0000
Tomas Kolaci - 6 Apr 2006 09:25:20 -0000 <=
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