issue with lpath

issue with lpath

[Pablo Rodriguez via ntg-context]

Dear list,

I have this sample:

  \startbuffer[demo]
  <xml>
    <div class="section level3">
      <h3>One</h3>
      <p>Standard paragraph</p>
      <blockquote>
        <p>Quoted text</p>
      </blockquote>
    </div>
    <div class="section level3">
      <h3>Two</h3>
      <blockquote>
        <p>Direct quote</p>
      </blockquote>
    </div>
  </xml>
  \stopbuffer

  \startxmlsetups xml:initialize
    \xmlsetsetup{#1}
      {p|blockquote}
      {xml:*}
    \xmlsetsetup{#1}
      {(div|section)[contains(@class,'level3')]/h3/../!p/../h3}
      {xml:section}
  \stopxmlsetups

  \xmlregistersetup{xml:initialize}

  \startxmlsetups xml:p
    \startpar\xmlflush{#1}\stoppar
  \stopxmlsetups

  \startxmlsetups xml:blockquote
    \startblockquote\xmlflush{#1}\stopblockquote
  \stopxmlsetups

  \startxmlsetups xml:section
    \section{\xmlflush{#1}}
  \stopxmlsetups

  \starttext
     \xmlprocessbuffer{main}{demo}{}
  \stoptext

I need an lpath to select the h3 node above, but only the one with "h3 +
blockquote" as a CSS selector (which could be added the lpath "../h3"
after).

It would be "<h3>Two</h3>" and not "<h3>Two</h3>" in this sample.

Excuse my ignorance, but which is the way to achieve this?

Many thanks for your help,

Pablo
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Re: issue with lpath

[Taco Hoekwater via ntg-context]

> On 2 Aug 2022, at 21:14, Pablo Rodriguez via ntg-context <ntg-context@ntg.nl> wrote:
> 
> Dear list,
> 
> 
> I need an lpath to select the h3 node above, but only the one with "h3 +
> blockquote" as a CSS selector (which could be added the lpath "../h3"
> after).

Lpath supports CSS selectors between curly braces as parts, so simply:

  \xmlsetsetup{#1}{{h3 + blockquote}/../h3} {xml:section}

should do. The xml-mkiv.pdf manual has lots of other lpath examples as well.

Best wishes,
Taco

— 
Taco Hoekwater              E: taco@bittext.nl
genderfluid (all pronouns)



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___________________________________________________________________________________

Re: issue with lpath

[Pablo Rodriguez via ntg-context]

On 8/3/22 09:09, Taco Hoekwater via ntg-context wrote:
>> On 2 Aug 2022, at 21:14, Pablo Rodriguez via ntg-context <ntg-context@ntg.nl> wrote:
>> [...]
>> I need an lpath to select the h3 node above, but only the one with "h3 +
>> blockquote" as a CSS selector (which could be added the lpath "../h3"
>> after).
>
> Lpath supports CSS selectors between curly braces as parts, so simply:
>
>   \xmlsetsetup{#1}{{h3 + blockquote}/../h3} {xml:section}

Taco,

I knew that, but I wasn’t sure how to mix both. I’d say yesterday I
tried something similar to:

  \xmlsetsetup{#1}{{h3 + blockquote}../h3} {xml:section}

Which, of course, couldn’t work.

> The xml-mkiv.pdf manual has lots of other lpath examples as well.

I know, I have read them many times. And I read them from time to time.
But I’m not smart enough to understand them.

BTW, is there any way to rephrase "{h3 + blockquote}" in proper Lua?

Something like "/h3/../!p/../blockquote" selected both "h3 + p" (which I
didn’t want and "h3 + blockquote" (the one intended).

Many thanks for your help,

Pablo
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___________________________________________________________________________________

Re: issue with lpath

[Taco Hoekwater via ntg-context]

> On 3 Aug 2022, at 15:54, Pablo Rodriguez via ntg-context <ntg-context@ntg.nl> wrote:
> 
> BTW, is there any way to rephrase "{h3 + blockquote}" in proper Lua?


I was wondering about that as well, and I really had no clue how to do that. Some
reading and studying later, I realised that there is a preceding-sibling:: axis. 

That is not documented in xml-mkiv.pdf I think, but it inherited from xpath, and that means this works:

  \xmlsetsetup{#1}{blockquote/preceding-sibling::h3[-1]/} {xml:section}

“Take all blockquotes, then tests their immediate preceding siblings (index [-1]) that are h3."

But the CSS version is nicer. Still, both solutions fail on generic input.

Sorry, out of clues


Best wishes,Taco


— 
Taco Hoekwater              E: taco@bittext.nl
genderfluid (all pronouns)



___________________________________________________________________________________
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___________________________________________________________________________________

Re: issue with lpath

[Hans Hagen via ntg-context]

On 8/4/2022 12:22 PM, Taco Hoekwater via ntg-context wrote:
> 
> 
>> On 3 Aug 2022, at 15:54, Pablo Rodriguez via ntg-context <ntg-context@ntg.nl> wrote:
>>
>> BTW, is there any way to rephrase "{h3 + blockquote}" in proper Lua?
> 
> 
> I was wondering about that as well, and I really had no clue how to do that. Some
> reading and studying later, I realised that there is a preceding-sibling:: axis.
> 
> That is not documented in xml-mkiv.pdf I think, but it inherited from xpath, and that means this works:
> 
>    \xmlsetsetup{#1}{blockquote/preceding-sibling::h3[-1]/} {xml:section}
> 
> “Take all blockquotes, then tests their immediate preceding siblings (index [-1]) that are h3."
> 
> But the CSS version is nicer. Still, both solutions fail on generic input.
> 
> Sorry, out of clues
\startbuffer[demo]
<xml>
<div class="section level3">
   <h3>One</h3>
   <p>Standard paragraph</p>
   <blockquote>
     <p>Quoted text</p>
   </blockquote>
</div>
<div class="section level3">
   <h3>Two</h3>
   <blockquote>
     <p>Direct quote</p>
   </blockquote>
</div>
</xml>
\stopbuffer

\startxmlsetups xml:initialize
     \xmlsetsetup{#1}
       {xml|p|blockquote|div}
       {xml:*}
     \xmlsetsetup{#1}
       {/xml/div[contains(@class,'level3')]}
       {xml:section:level3}
\stopxmlsetups

\xmlregistersetup{xml:initialize}

\startxmlsetups xml:xml
     \xmlall{#1}{/div}
\stopxmlsetups

\startxmlsetups xml:p
     \startpar\xmlflush{#1}\stoppar
\stopxmlsetups

\startxmlsetups xml:blockquote
     \startblockquote\xmlflush{#1}\stopblockquote
\stopxmlsetups

\startxmlsetups xml:section:level3
     \xmldoif{#1}{/blockquote} {
         \xmldoifnot{#1}{/p} {
             \section{\xmlflush{#1}}
         }
     }
\stopxmlsetups

\starttext
     \xmlprocessbuffer{main}{demo}{}
\stoptext



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               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
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___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / https://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________

Re: issue with lpath

[Pablo Rodriguez via ntg-context]

On 8/4/22 12:22, Taco Hoekwater via ntg-context wrote:
>> On 3 Aug 2022, at 15:54, Pablo Rodriguez via ntg-context <ntg-context@ntg.nl> wrote:
>> BTW, is there any way to rephrase "{h3 + blockquote}" in proper Lua?
>
> I was wondering about that as well, and I really had no clue how to
> do that. Some reading and studying later, I realised that there is a
> preceding-sibling:: axis.
>
> That is not documented in xml-mkiv.pdf I think, but it inherited
> from xpath, and that means this works:>
>   \xmlsetsetup{#1}{blockquote/preceding-sibling::h3[-1]/} {xml:section}
>
> “Take all blockquotes, then tests their immediate preceding siblings
> (index [-1]) that are h3."

Many thanks for your reply, Taco.

It isn’t documented, but I have just discovered that it is used inside a
function:

  https://www.pragma-ade.com/general/manuals/xml-mkiv.pdf#search=sibling

> But the CSS version is nicer.

I agree. But using CSS for LPaths feels like cheating to me.

Many thanks for your help again,

Pablo

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___________________________________________________________________________________

Re: issue with lpath

[Taco Hoekwater via ntg-context]

> On 4 Aug 2022, at 16:07, Hans Hagen <j.hagen@xs4all.nl> wrote:
> 
> On 8/4/2022 12:22 PM, Taco Hoekwater via ntg-context wrote:
>>> On 3 Aug 2022, at 15:54, Pablo Rodriguez via ntg-context <ntg-context@ntg.nl> wrote:
>>> 
>>> BTW, is there any way to rephrase "{h3 + blockquote}" in proper Lua?
>> I was wondering about that as well, and I really had no clue how to do that. Some
>> reading and studying later, I realised that there is a preceding-sibling:: axis.
>> That is not documented in xml-mkiv.pdf I think, but it inherited from xpath, and that means this works:
>>   \xmlsetsetup{#1}{blockquote/preceding-sibling::h3[-1]/} {xml:section}
>> “Take all blockquotes, then tests their immediate preceding siblings (index [-1]) that are h3."
>> But the CSS version is nicer. Still, both solutions fail on generic input.
>> Sorry, out of clues
> \startbuffer[demo]
> ...


That puts the whole <div> content inside the \section, and I don’t think that was the intent. I understood that Pablo only wants the “h3” node.

In the original request, the CSS “{h3 + blockquote}” matches a “blockquote” anyplace where it is immediately preceded by a “h3” (and nowhere else). 
After that, some trickery was needed to try and get back to the actual “h3”. 

My trick above with preceding-sibling above also gets the “h3” that is immediately followed by a “blockquote”, but it got easily
confused if there were multiple “h3” or “blockquote” objects in the input.

Best wishes,
Taco

PS This sort of confusing filtering is why I do most of my xml processing from the lua end, where it is much clearer to me what is what.

— 
Taco Hoekwater              E: taco@bittext.nl
genderfluid (all pronouns)



___________________________________________________________________________________
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___________________________________________________________________________________

Re: issue with lpath

[Pablo Rodriguez via ntg-context]

On 8/4/22 17:32, Taco Hoekwater via ntg-context wrote:
> [...]
> PS This sort of confusing filtering is why I do most of my xml
> processing from the lua end, where it is much clearer to me what is
> what.
Many thanks for clarifying the issue, Taco.

BTW, according to the last slide from
https://meeting.contextgarden.net/2019/talks/02-xmlprocessing/02-xmlprocessing.pdf,
you had plans to document how to deal with XML in proper Lua.

I wonder whether you are still interested in adding this information to
the manual.

Many thanks for your help,

Pablo
___________________________________________________________________________________
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___________________________________________________________________________________

Re: issue with lpath

[Taco Hoekwater via ntg-context]

> On 4 Aug 2022, at 18:39, Pablo Rodriguez via ntg-context <ntg-context@ntg.nl> wrote:
> 
> On 8/4/22 17:32, Taco Hoekwater via ntg-context wrote:
>> [...]
>> PS This sort of confusing filtering is why I do most of my xml
>> processing from the lua end, where it is much clearer to me what is
>> what.
> Many thanks for clarifying the issue, Taco.
> 
> BTW, according to the last slide from
> https://meeting.contextgarden.net/2019/talks/02-xmlprocessing/02-xmlprocessing.pdf,
> you had plans to document how to deal with XML in proper Lua.
> 
> I wonder whether you are still interested in adding this information to
> the manual.

In theory, yes. In reality, life is too short, and it is on the bottom of an ever rising pile of things to do. :sadface

Best wishes,
Taco

Taco Hoekwater              E: taco@bittext.nl
genderfluid (all pronouns)



___________________________________________________________________________________
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