Re: [xsl] Using node-set variables in predicates (another node comparison question)

["Wendell Piez wapiez@xxxxxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Very reassuring -- I hope you're having a great 2022 so far Eliot!

Cheers, Wendell

On Tue, Jan 4, 2022 at 3:53 PM Eliot Kimber eliot.kimber@xxxxxxxxxxxxxx <
xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:

> Note that this function:
>
>
>
> <xsl:function name="mine:is-trim-element" as="xs:boolean">
>
>     <xsl:param name="elt" as="node()"/>
>
>     <xsl:value-of select="exists($elt[self::desc or self::dt or
> self::endnote or self::entry or self::example-title or self::glossterm or
> self::li or self::msg-severity or self::p or self::shortdesc or self::title
> or self::value-allowed or self::value-default or self::value-type])"/>
>
>   </xsl:function>
>
>
>
> Should use xsl:sequence instead of value-of as you want to return a
> Boolean value.
>
>
>
> By using value-of you are effectively constructing a Boolean (result of
> exists()) then converting that to a text node (result of value-of) and then
> XSLT implicitly converts that back to a Boolean using the string value of
> the text node.
>
>
>
> In general, you almost always want xsl:sequence unless what you really
> want is a text node (for example, because youbre contributing to the
> content of a result element).
>
>
>
> [Wendell beat me to this suggestion but Ibd already written it:]
>
>
>
> As for the question of determining the type: I think I would follow
> Dimitrebs advice and use templates :
>
>
>
> <xsl:function name=bmine:is-trim-elementb as=bxs:booleanb>
>
>     <xsl:param name="elt" as="node()"/>
>   <xsl:apply-templates select=b$eltb mode=b mine:is-trim-elementb/>
>
> </xsl:function>
>
>
>
> <xsl:template mode=b mine:is-trim-elementb as=bxs:Booleanb
>
>   match=bdesc | endnote | dtb
>
>  >
>
>   <xsl:sequence select=btrue()b/>
>
> </xsl:template>
>
>
>
> <xsl:template mode=b mine:is-trim-elementb as=bxs:Booleanb
priority=b-1b
> match=b*b>
>
>   <xsl:sequence select=bfalse()b
>
> </xsl:template>
>
> This makes the logic for determining type extensible using normal
> extension mechanisms.
>
>
>
> Cheers,
>
>
>
> E.
>
> _____________________________________________
>
> *Eliot Kimber*
>
> Sr Staff Content Engineer
>
> O: 512 554 9368
>
> M: 512 554 9368
>
> servicenow.com <https://www.servicenow.com>
>
> LinkedIn <https://www.linkedin.com/company/servicenow> | Twitter
> <https://twitter.com/servicenow> | YouTube
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>
>
>
> *From: *Chris Papademetrious christopher.papademetrious@xxxxxxxxxxxx <
> xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
> *Date: *Tuesday, January 4, 2022 at 2:37 PM
> *To: *xsl-list@xxxxxxxxxxxxxxxxxxxxxx <xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
> *Subject: *Re: [xsl] Using node-set variables in predicates (another node
> comparison question)
>
> *[External Email]*
>
>
>
> Hi Dimitre,
>
>
>
> That is good advice about functions b I will keep it in mind!
>
>
>
>
>
> Hi everyone,
>
>
>
> So I ran into a limitation of using document node-set variables in
> template match expressions:
>
>
>
>   <!-- put document nodes in $trim-elements -->
>
>   <xsl:variable name="trim-elements"
> select="//(desc|dt|entry|glossterm|li|p|shortdesc|title)"/>
>
>
>
>   <!-- reference elements in $trim-elements -->
>
>   <xsl:template match="text()
>
>                        [matches(., '^\s+')]
>
>                        [ancestor::*[. intersect
> $trim-elements][not(descendant::*[. intersect $trim-elements])]]
>
>                        [not(ancestor-or-self::node()
>
>                          [ancestor::*[. intersect
> $trim-elements][not(descendant::*[. intersect $trim-elements])]]
>
>                          [preceding-sibling::node()])]">
>
>
>
> When I constructed a temporary <p> node in a variable:
>
>
>
> xsl:variable name="temporary-p">
>
>    <p><xsl:copy-of select=bb&blah blahb&b></p>
>
> </xsl:variable>
>
>
>
> then called <xsl:apply-templates> to apply the template:
>
>
>
> <xsl:apply-templates select="$temporary-p"/>
>
>
>
> the template did not get applied. This makes perfect sense b my temporary
> <p> variable does not contain any document nodes at all, so the template
> match expression would never match!
>
>
>
> But with Dimitrebs advice about functions fresh in my mind, I converted
my
> document-node variable into a node-type function:
>
>
>
>   <xsl:function name="mine:is-trim-element" as="xs:boolean">
>
>     <xsl:param name="elt" as="node()"/>
>
>     <xsl:value-of select="exists($elt[self::desc or self::dt or
> self::endnote or self::entry or self::example-title or self::glossterm or
> self::li or self::msg-severity or self::p or self::shortdesc or self::title
> or self::value-allowed or self::value-default or self::value-type])"/>
>
>   </xsl:function>
>
>
>
> Now I can use the function instead of the variable in the match expression:
>
>
>
>   <xsl:template match="text()
>
>                        [matches(., '^\s+')]
>
>
>
[ancestor::*[mine:is-trim-element(.)][not(descendant::*[mine:is-trim-element(
.)])]]
>
>                        [not(ancestor-or-self::node()
>
>
>
[ancestor::*[mine:is-trim-element(.)][not(descendant::*[mine:is-trim-element(
.)])]]
>
>
> [preceding-sibling::node()[not(mine:is-invisible(.))]])]">
>
>
>
> and the template applies as expected to my temporary variable!
>
>
>
> Follow-up question b is there some syntactic sugar that would allow me to
> write
>
>
>
> self::(a|b|c)
>
>
>
> instead of
>
>
>
> (self::a or self::b or self::c)
>
>
>
> or some other way of testing the element type in $elt altogether? I have
> another function that matches several dozen element types, and a more
> compact representation would be nice. I thought about matching local-name()
> against a list of tag names using bintersectb, but that is not much
shorter
> and it seems operationally clunkier.
>
>
>
> Thanks, this has been an enjoyable exercise for learning!
>
>
>
>    - Chris
>
>
>
>
>
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--
...Wendell Piez... ...wendell -at- nist -dot- gov...
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