[NTG-context] Re: XML processing beginner's question

[Hans Hagen via ntg-context <ntg-context@ntg.nl>]

On 8/21/2023 6:56 PM, Thomas A. Schmitz wrote:
> On 8/21/23 18:36, Michael Löscher wrote:
>> Thank you so far. But what I would like to understand first ist how 
>> the different setups work togehter. How are they processed? What is 
>> the order of processing, which are the stets taken by the enginge when 
>> processing an xml document? Without understanding how that works, it 
>> is not possible to apply certain tests on the xml nodes.
>>
> As the manual mk.pdf, chapter XVII states: it's a mixture of streaming 
> parser and tree manipulation. The whole xml document is transformed into 
> a Lua table and then processed. But I definitely get the "do my homework 
> for me" vibe, so this will be all from me.
in addition:

you need a bit of imagination because basically (depends a bit on what 
you do) one big nested expansion is going on, as Thomas explained: using 
setups which are basically macros. The #1 is the current node (but you 
can store it in a macro and use it later if needed). So, only references 
are passed around.

for thomas: we now also have (in lmtx)

\ifxml         {id}{pattern}      \else \fi
\ifxmltext     {id}{pattern}      \else \fi
\ifxmlatt      {id}{name}{value}  \else \fi
\ifxmlattempty {id}{pattern}      \else \fi
\ifxmlempty    {id}{pattern}      \else \fi
\ifxmlselfempty{id}               \else \fi

which in some cases is more efficient

there is also \xmllastatt etc which can be used after a test which 
avoids a second lookup

Hans



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