Re: [xsl] How to do macro substitution in XPath?

["Martin Honnen martin.honnen@xxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

On 02/12/2023 16:36, Roger L Costello costello@xxxxxxxxx wrote:
> Hi Folks,
>
> I am converting prose like this:
>
> If the title = "Path to Power" and the author = "Robert A. Caro" (Lyndon
Baines Johnson (LBJ)), then
> process LBJ as follows
>      action 1
> If the title = "Power Broker" and the author = "Robert A. Caro" (Robert
Moses (RM)), then
> process RM as follows
>      action 2
> Neither LBJ nor RM
>      action 3
>
> I need the XPath to be as like the prose as possible.
>
> Suppose the XPath will operate on XML documents like this:
>
> <Book>
>    <Title>Path to Power</Title>
>    <Author>Robert A. Caro</Author>
> </Book>
>
> Below is one approach to writing the XPath. See the XPath in the
xsl:value-of element. Notice the use of XML ENTITIES.
> The advantage of that approach is the XPath looks like the prose.
>
> The disadvantage with that approach is that ENTITIES are not XPath. I need
to stick with pure XPath. What XPath do you recommend?
> <?xml version="1.0" encoding="UTF-8"?>
> <!DOCTYPE xsl:stylesheet[
>      <!ENTITY LBJ "((/Book/Title eq 'Path to Power') and (/Book/Author eq
'Robert A. Caro'))">
>      <!ENTITY RM "((/Book/Title eq 'Power Broker') and (/Book/Author eq
'Robert A. Caro'))">
> ]>
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
version="3.0">
>      <xsl:template match="/">
>          <xsl:value-of select="
>              if &LBJ; then
>                  'action 1'
>              else if &RM; then
>                  'action 2'
>              else if (not((&LBJ;) or (&RM;))) then
>                  'action 3'
>              else
>                  'Error'
>              "/>
>      </xsl:template>
> </xsl:stylesheet>


You ca do the following using static parameters and shadow attributes:


<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
version="3.0"
B B B  xmlns:xs="http://www.w3.org/2001/XMLSchema";
B B B  exclude-result-prefixes="#all">

B B B  <xsl:param name="LBJ" as="xs:string" static="yes"
select="'((/Book/Title eq ''Path to Power'') and (/Book/Author eq
''Robert A. Caro''))'"/>
B B B  <xsl:param name="RM" as="xs:string" static="yes"
select="'((/Book/Title eq ''Power Broker'') and (/Book/Author eq
''Robert A. Caro''))'"/>

B B B  <xsl:template match="/">
B B B B B B B  <xsl:value-of _select="
B B B B B B B B B B B  if {$LBJ} then
B B B B B B B B B B B B B B B  'action 1'
B B B B B B B B B B B  else if {$RM} then
B B B B B B B B B B B B B B B  'action 2'
B B B B B B B B B B B  else if (not(({$LBJ}) or ({$RM}))) then
B B B B B B B B B B B B B B B  'action 3'
B B B B B B B B B B B  else
B B B B B B B B B B B B B B B  'Error'
B B B B B B B B B B B  "/>
B B B  </xsl:template>


Whether that is helpful or readable/maintainable in the end, I am not
sure, but you asked for a way without entities, so I am trying to show one.