Re: [xsl] XSLT splitting (grouping?) hierarchical structure

["Joel Kalvesmaki director@xxxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Hello Matthieu,

I've approached this task in XSLT 3.0 with the TAN functions 
tan:tree-to-sequence() and tan:sequence-to-tree(), which are the core 
processes of about four different applications and functions that do 
something similar to what you want to do.

The best way to seem them in action is to look at tan:chop-tree(), which 
takes a tree and a set of integers (the integers being a proxy for your 
<split>s), and splits/chops the tree at those positions in the overall 
text value of the tree:
https://github.com/textalign/TAN-2021/blob/90ce604d2834f1a26aab20dbbf5a5c612a3e5d3e/functions/nodes/TAN-fn-nodes-standard.xsl#L1824

Best wishes,

jk

On 2022-02-10 02:02, Michael Kay mike@xxxxxxxxxxxx wrote:
> Since you're looking for design patterns, in Jackson Structured
> Programming ( revisited using modern terminology at
> http://mcs.open.ac.uk/mj665/JSPDDevt.pdf ) this is known as a
> "boundary clash" problem, and the usual solution is to flatten the
> heirarchy into a sequence of leaf nodes each containing details of its
> own ancestry, and then reconstruct the new heirarchy by a grouping
> operation on this sequence of leaf nodes. The original JSP book from
> 1975 is quite tough going nowadays, it all rather assumes you're well
> versed in sort-merge processing of hierarchical data files on magnetic
> tape. But the overall philosophy of transforming hierarchies using a
> pipeline of successive tree-walking transformations is isomorphic to
> the world we live in.
>
> Although it's instinctive to reach for an XSLT solution, I think I
> once solved a problem like this at the SAX level: keep a stack of open
> elements, and when you hit a <split/>, emit endElement events to close
> open elements up to a certain level, then output the <split/>, then
> re-open the elements that you closed, in reverse order; you've then
> got a structure that's relatively easy to break into sections using
> conventional grouping.
>
> Michael Kay
> Saxonica
>
> > On 10 Feb 2022, at 08:20, Matthieu Ricaud-Dussarget
> > ricaudm@xxxxxxxxx <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Dear XSL List,
> >
> > It's not the first time I'm facing a splitting problem working with
> > publishing documents.
> > I used to find kind of tricky/verbose solutions but I'm wondering if
> > I'm missing something obvious, especially with XSLT 3.0 new features
> > ?
> >
> > My XML looks like this :<root>
> > <section>
> > <title>Title</title>
> > <content>
> > <p>paragraph #1</p>
> > <p>paragraph #2 to split <split id="split-1"/> here</p>
> > <p>paragraph #3</p>
> > <p>paragraph #4 <strong> to split <split id="split-2"/>
> > here</strong> if possible</p>
> > <p>paragraph #5</p>
> > <ul>
> > <li>Item #1</li>
> > <li>Item #2 to split <split id="split-3"/> here</li>
> > <li>Item #3</li>
> > <li>
> > <ul>
> > <li>Item #4</li>
> > <li>Item #5 to <em>split <split id="split-4"/></em> here
> > if possible</li>
> > <li>Item #6</li>
> > </ul>
> > </li>
> > </ul>
> > <p>paragraph #6</p>
> > </content>
> > </section>
> > </root>
> >
> > The goal is to split the section on every <split> element (just like
> > a page would break the flowing text anywhere in the structure).
> >
> > Expected result :
> >
> > <root>
> > <section>
> > <title>Title</title>
> > <content>
> > <p>paragraph #1</p>
> > <p>paragraph #2 to split</p>
> > </content>
> > </section>
> > <split id="split-1"/>
> > <section>
> > <title>Title</title>
> > <content>
> > <p>paragraph #3</p>
> > <p>paragraph #4 <strong> to split</strong></p>
> > </content>
> > </section>
> > <split id="split-2"/>
> > <section>
> > <title>Title</title>
> > <content>
> > <p><strong> here</strong> if possible</p>
> > <p>paragraph #5</p>
> > <ul>
> > <li>Item #1</li>
> > <li>Item #2 to split </li>
> > </ul>
> > </content>
> > </section>
> > <split id="split-3"/>
> > <section>
> > <title>Title</title>
> > <content>
> > <ul>
> > <li> here</li>
> > <li>Item #3</li>
> > <li>
> > <ul>
> > <li>Item #4</li>
> > <li>Item #5 to <em>split</em></li>
> > </ul>
> > </li>
> > </ul>
> > </content>
> > </section>
> > <split id="split-4"/>
> > <section>
> > <title>Title</title>
> > <content>
> > <ul>
> > <ul>
> > <li> here if possible</li>
> > </ul>
> > <li>Item #6</li>
> > </ul>
> > <p>paragraph #6</p>
> > </content>
> > </section>
> > </root>
> >
> > My idea was to iterate from 1 to the number of split elements + 1
> > and working on the section with tunnel params so I can test for each
> > node if it's before / after / in between (current) splits elements,
> > and then decide to keep the node or not according to this position.
> >
> > I already used this kind of solution on a similar problem, long time
> > ago. So I'll give it a try though I'm not not totally confident with
> > it (because split elements can appear as inline content here).
> >
> > Please let me know if you have ideas, if my solution is the right or
> > wrong way to go?
> > Are there special design patterns for this kind of problem ?
> > And last, have you ever faced this kind of splitting issue, any
> > feedback welcome :)
> >
> > Cheers,
> > Matthieu Ricaud-Dussarget
> >
> > --
> > Matthieu Ricaud-Dussarget
> > +33 6.63.25.95.58
> >
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--
Joel Kalvesmaki
Director, Text Alignment Network
http://textalign.net