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Re: with XPath 1.0, select all following sibling eleme

Subject: Re: with XPath 1.0, select all following sibling elements of name "foo" up to the first non-"foo" element
From: "Wendell Piez wapiez@xxxxxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
Date: Thu, 18 Feb 2021 21:01:02 -0000
Re:  with XPath 1.0
Wolfhart,

What Ken says is correct, name() is not namespace-safe. Here we hit a wall
in XPath 1.0. In 2.0 there is a function node-name() to help with that.

As for the notion of 'preceding-sibling::current()' that fails because
current() is not an XPath 1.0 node test, so it does not parse as a path
expression. (It is an XSLT 1.0 function.)

The self::... business is interesting. Generally this is preferred to using
name tests, for sure. (Because, as Ken would surely hasten to point out, it
is namespace safe.) However, when it is not the axis (self::) but the node
test (the ... i.e. the name test in this case) that needs to be dynamic, it
isn't much help.

However, if you know in advance you are looking for boo elements you can
simultaneously address any potential namespace problems:

<xsl:variable name="followers" select="following-sibling::boo"/>
<xsl:variable name="interlopers" select="following-sibling::*[not(self::boo)]
| following-sibling::* [not(self::boo)]/following-sibling::*"/>
<xsl:variable name="invited" select=". | $followers[not(count(.|$
interlopers)=count($interlopers))]"/>

Cheers, Wendell


On Thu, Feb 18, 2021 at 1:43 PM Wolfhart Totschnig
wolfhart.totschnig@xxxxxxxxxxx <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
wrote:

> Hello again,
>
> Thank you, Wendell!
>
> The proposed solutions leave me with two questions:
>
>
> 1) Is there a way to do what I originally had in mind, i.e., go forward to
> the first non-"foo" sibling and from there go backwards, taking all the
> "foo" siblings up to the current node? Asked differently, can the
> following XPath expression be fixed?
>
>
> following-sibling::*[not(self::source)][1]/preceding-sibling::*[self::source][preceding-sibling::current()]
>
> Specifically, can "preceding-sibling::current()" be fixed?
>
>
> 2) Liam's and Wendell's proposals involve the expression [name()=...],
> whereas I have used [self:: ...]. Are these strictly equivalent, or is
> there a reason to prefer the one over the other?
>
>
> Thanks again for your help!
> Wolfhart
>
>
> On 18-02-21 13:06, Wendell Piez wapiez@xxxxxxxxxxxxxxx wrote:
>
> Hi,
>
> With a sequence of variable declarations:
>
> <xsl:variable name="name" select="name()"/>
> <xsl:variable name="followers"
> select="following-sibling::*[name()=$name]"/>
> <xsl:variable name="interlopers"
> select="following-sibling::*[not(name()=$name)] |
> following-sibling::*[not(name()=$name)]/following-sibling::*"/>
> <xsl:variable name="invited" select=". |
> $followers[not(count(.|$interlopers)=count($interlopers))]"/>
>
> Note: untested.
>
> Good luck,
> Wendell
>
>
> On Wed, Feb 17, 2021 at 8:32 PM Wolfhart Totschnig
> wolfhart.totschnig@xxxxxxxxxxx <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
> wrote:
>
>> Dear list,
>>
>> I am facing an XPath problem for which I cannot find the solution. I
>> want to select all following sibling elements of name "foo" up to the
>> first non-"foo" element. So, in the following case, the first two <foo>
>> elements should be selected:
>>
>> <foo/>
>> <foo/>
>> <bar/>
>> <foo/>
>>
>> In the following case, all three <foo> elements should be selected:
>>
>> <foo/>
>> <foo/>
>> <foo/>
>>
>> And in the following case, nothing should be selected:
>>
>> <bar/>
>> <foo/>
>> <foo/>
>>
>> I came up with the following non-working approach:
>>
>>              <xsl:choose>
>>                  <xsl:when
>> test="not(following-sibling::*[not(self::foo)])">
>>                      <xsl:value-of select="following-sibling::*"/>
>>                  </xsl:when>
>>                  <xsl:otherwise>
>>                      <xsl:value-of
>>
>> select="following-sibling::*[not(self::source)][1]/preceding-sibling::*[self::source][preceding-sibling::current()]"/>
>>                  </xsl:otherwise>
>>              </xsl:choose>
>>
>> That is, test whether there are non-"foo" following siblings. If there
>> are none, take all following siblings. If there are, go forward to the
>> first non-"foo" sibling, and from there go backwards, taking all the
>> "foo" siblings up to the current node.
>>
>> But this does not work. Apparently, the expression
>> "preceding-sibling::current()" is not a valid construct. So what is the
>> correct way to do what I have in mind (or a simpler solution, if there
>> is one). Please note that this stylesheet needs to be executed by a web
>> browser, and so the solution has to remain within XPath 1.0.
>>
>> Thanks in advance for your help!
>> Wolfhart
>>
>>
>>
>
> --
> ...Wendell Piez... ...wendell -at- nist -dot- gov...
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-- 
...Wendell Piez... ...wendell -at- nist -dot- gov...
...wendellpiez.com... ...pellucidliterature.org... ...pausepress.org...
...github.com/wendellpiez... ...gitlab.coko.foundation/wendell...

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