Many thanks Denis. Very useful tip on the injectors and generalised command
usage. That will definitely come in useful.

My problem is that I already have a lot of XML data with the existing
processing instructions in it. I know I could use an external preprocess in
something like Python to change them into injectors before they are fed
into ConTeXt, but I was hoping there was a way to handle them directly as
part of the ConTeXt / lua process.

Thanks again though.

Duncan




On Mon, 2 May 2022, 08:48 , <denis.maier@unibe.ch> wrote:

> That was too quick, sorry.
>
>
>
> Hi Duncan,
>
>
>
> I have used context’s own injectors for this :
>
>
>
> <?context-directive injector addlinetopage ?>
>
>
>
> \startsetups xml:directive:injector:addlinetopage
>
>   \adaptlayout[lines=+1]
>
> \stopsetups
>
>
>
> Or, for your line break example :
>
>
>
> <?context-directive injector newline ?>
>
>
>
> \startsetups xml:directive:injector:newline
>
>   \crlf
>
> \stopsetups
>
>
>
> Also, I have learned that you can just use arbitrary context code in xml:
>
>
>
> \def\xmltexdirective#1#2{\doif{#1}{command}{#2}}
>
>
>
> \xmlinstalldirective{tex}{xmltexdirective}
>
>
>
>          <?context-directive tex command \inframed{xxx} ?>
>
>          <?context-directive tex command \page ?>
>
>          <?context-directive tex command \crlf ?>
>
>
>
> Best,
>
> Denis
>
>
>
> *Von:* Maier, Denis Christian (UB)
> *Gesendet:* Montag, 2. Mai 2022 09:45
> *An:* 'mailing list for ConTeXt users' <ntg-context@ntg.nl>
> *Cc:* Duncan Hothersall <dh@capdm.com>
> *Betreff:* AW: [NTG-context] XML processing instructions
>
>
>
>
>
> *Von:* ntg-context <ntg-context-bounces@ntg.nl> *Im Auftrag von *Duncan
> Hothersall via ntg-context
> *Gesendet:* Montag, 2. Mai 2022 09:20
> *An:* mailing list for ConTeXt users <ntg-context@ntg.nl>
> *Cc:* Duncan Hothersall <dh@capdm.com>
> *Betreff:* [NTG-context] XML processing instructions
>
>
>
> I have a big set of existing XML books (held in a derivative of DocBook)
> which I'm looking to start processing directly with ConTeXt. (Up to now I
> have a system which converts the XML into ConTeXt code which is then
> processed, but this is inefficient and lots of the code is now unsupported.)
>
>
>
> I've had some success producing output, but my first real sticking point
> has come with processing instructions. The existing XML contains lots of
> processing instructions of the form
>
> <?capdm whatever?>, some of which can be conditional and introduce new
> data etc. But I'd be happy at this stage if I could just process the most
> basic one of them, which is used to introduce a line stop in a running
> paragraph of text.
>
>
>
> My best guess at how to do this was to use the lxml.preprocessor function
> to convert the processing instruction into an element, and then process the
> element as normal. But (a) my attempt didn't work, and (b) there may well
> be a better way.
>
>
>
> Minimal working example below, except that obviously the processing
> instruction bit doesn't work!
>
>
>
> Thanks for any help or insights.
>
>
>
> Duncan
>
>
>
>
>
> MWE:
>
> ------
>
>
>
> \startbuffer[demo]
> <book>
>   <para>A paragraph with<?capdm force_line_stop?>a processing
> instruction.</para>
> </book>
> \stopbuffer
>
> \startxmlsetups xml:demo:base
>  \xmlsetsetup{#1}{*}{xml:demo:*}
> \stopxmlsetups
> \xmlregisterdocumentsetup{demo}{xml:demo:base}
>
> \startxmlsetups xml:demo:book
>  \xmlflush{#1}
> \stopxmlsetups
>
> \startxmlsetups xml:demo:para
>  \xmlflush{#1}\endgraf
> \stopxmlsetups
>
> \startluacode
>  function lxml.preprocessor(data,settings)
>   return string.find(data,"<?capdm *force_line_stop?>")
>    and string.gsub(data,"<?capdm
> *force_line_stop?>","<capdmlinestop></capdmlinestop/>")
>    or data
>  end
> \stopluacode
>
> \startxmlsetups xml:demo:capdmlinestop
>  \crlf
>  \xmlflush{#1}
> \stopxmlsetups
>
> \setupbodyfont[modern]
> \starttext
> \xmlprocessbuffer{demo}{demo}{}
> \stoptext
>
>
>
> ------
>