On 11-9-2012 19:22, Thomas A. Schmitz wrote:
Hi all,
I have a question about xml processing and I think that what I want/need
can best be achieved by using lua code, but so far, I'm not really sure
how to proceed, so any help from one of the resident lua gurus would be
welcome.
So: the question. xml allows to provide elements with unique identifiers
so that one can add cross-references within the document structure. Here
is a sample xml file that shows what I mean:
<document>
<bibitem xml:id="hagen2011">
<author>Hans Hagen</author>
<title>The Meaning of Life Is 42</title>
<journal>The Rhetoric of Mathematics</journal>
<date>2011</date>
</bibitem>
<bibitem xml:id="hagen2012">
<author>Hans Hagen</author>
<title>The New Meaning is Now 43</title>
<journal>High Energy Metaphysics</journal>
<date>2012</date>
</bibitem>
<text>
<p>This has been successfully proven in papers by <bib
ref="#hagen2011"/> and <bib ref="#hagen2012"/>.</p>
</text>
</document>
[Note: the TEI guidelines add the hash character in the attribute value
to such references, but after much googling, I'm still not sure if this
is standard or necessary or bizarre.]
So: at the point of the reference (which may be empty, like here, or
contain text), I want to refer back to the bibitems. The typesetting
engine should then be instructed to pick up the information, so that
this is, e.g., typeset as "This has been successfully proven in papers
by Hans Hagen (2011) and Hans Hagen (2012)."
My idea: since the xml:id attributes must be unique across the document,
it would be easiest to collect them into a lua table, with the xml:id as
key, so their content could be accessed and typeset later. But
unfortunately, I have no clue how to go about this... Could somebody
provide a pointer?
Thanks for your interest, if you've read this far!
If the number of bib items is not that large hashing does not save much.
(In x-xfdf.mkiv you can see another example).
\starttext
\startbuffer[demo]
<document>
<bibitem xml:id="hagen2011">
<author>Hans Hagen</author>
<title>The Meaning of Life Is 42</title>
<journal>The Rhetoric of Mathematics</journal>
<date>2011</date>
</bibitem>
<bibitem xml:id="hagen2012">
<author>Hans Hagen</author>
<title>The New Meaning is Now 43</title>
<journal>High Energy Metaphysics</journal>
<date>2012</date>
</bibitem>
<text>
<p>This has been successfully proven in papers by <bib
ref="#hagen2011"/> and <bib ref="#hagen2012"/>.</p>
</text>
</document>
\stopbuffer
\startxmlsetups xml:define
\xmlsetsetup{#1}{*}{xml:*}
\stopxmlsetups
\startxmlsetups xml:document
\xmlall{#1}{/text}
\stopxmlsetups
\startxmlsetups xml:text
\xmlflush{#1}
\stopxmlsetups
\startxmlsetups xml:p
\xmlflush{#1}
\par
\stopxmlsetups
\startxmlsetups xml:bib
\BibAuthor{#1}{\xmlatt{#1}{ref}}
\stopxmlsetups
\startxmlsetups xml:author
[[\xmlflush{#1}]]
\stopxmlsetups
\def\BibAuthor#1#2{[1:\xmlfirst{whatever}{/document/bibitem[@xml:id==string.sub('#2',2)]/author}]}
\xmlregistersetup{xml:define}
\xmlprocessbuffer{whatever}{demo}{}
\startluacode
userdata = userdata or { }
userdata.bibitems = { }
\stopluacode
\startxmlsetups xml:document
\xmlflush{#1}
\stopxmlsetups
\startxmlsetups xml:bibitem
\ctxlua{userdata.bibitems["\letterhash\xmlatt{#1}{xml:id}"] = "#1"}
\stopxmlsetups
\def\BibAuthor#1#2{[2:\xmlfirst{\cldcontext{userdata.bibitems['#2']}}{/author}]}
\xmlprocessbuffer{whatever}{demo}{}
\stoptext
(I ran into a recently introduced side effect of an optimization so I'll
generate you a new beta. Older versions should work anyway as no special
trickery is used.)
Hans
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