Re: XML - accessing parental children attribute (was: some troubles)

[Hans Hagen <pragma@wxs.nl>]

On 2/17/2015 3:25 PM, Procházka Lukáš Ing. - Pontex s. r. o. wrote:
> Hello,
>
> a slightly modified example:
>
> ---- t.xml
>
> <a>
>    <aa number="111">AA</aa>
>    <ab number="222">AB</ab>
> </a>
>
> ----
>
> and the Ctx source:
>
> ---- t.mkiv
>
> \startxmlsetups xml:T
>    \xmlfunction{#1}{test}
>    \xmlsetsetup{\xmldocument}{*}{+}
>    % \xmlsetsetup{\xmldocument}{*}{-} % Empties output?!
>    \xmlsetsetup{\xmldocument}{a/aa}{xml:*}
>    \xmlsetsetup{\xmldocument}{a/ab}{xml:*}
> \stopxmlsetups
>
> \startluacode
>    local aux = aux; if not aux then aux = {}; _G.aux = aux end
>
>    xml.functions.aa = function(t)
>      aux.num = t.at.number
>    end
> \stopluacode
>
> \startxmlsetups xml:aa
>    \xmlfunction{#1}{aa}
> \stopxmlsetups
>
> \startxmlsetups xml:ab
>    \xmlfunction{#1}{ab}
>    \ctxlua{context.section("New section " .. (aux.num or "??"))}
>    \xmlflush{#1}
> \stopxmlsetups
>
> \xmlregistersetup{xml:T}
>
> \starttext
>    Hello
>
>    \xmlprocessfile{id}{t.xml}{}
> \stoptext
>
> ----
>
> Two (remaining) questions:
>
> 1)
>
> Why the line "\xmlsetsetup{\xmldocument}{*}{-}" (try to uncomment!)
> causes the whole output is empty, even if I specify another operation
> for "a/ab" elements later?
>
> My intention is to have "{*}{-}" (don't flush anything by default),
> excluding elements specified later, e.g. "a/ab" (with another operation
> specified);
> how to achieve this?
>
> 2)
>
> How to get "aa.number" from within "ab" element?
>
> I believed "\xmlatt{#1/../aa}{number}" within "a/ab" will do that,
> but....? How to do that?
>
> I have a partial solution: when processing "a/aa", I save an attribute
> value to a Lua variable, which I use later;
> but this solution doesn't look very "clean" for me;
> I'd rather find a way to access parental (first) child attributes form
> within a node...

\startbuffer[demo]
<a>
   <aa number="--">--</aa>
   <aa number="a1">A1</aa>
   <ax number="x1">X1</ab>
   <ab number="b1">B1</ab>
   <aa number="--">--</aa>
   <aa number="a2">A2</aa>
   <ax number="x2">X2</ab>
   <ab number="b2">B2</ab>
   <aa number="--">--</aa>
   <aa number="a3">A3</aa>
   <ax number="x3">X3</ab>
   <ab number="b3">B3</ab>
</a>
\stopbuffer

\startxmlsetups xml:initialize
     \xmlsetsetup{#1}{*}{xml:*}
\stopxmlsetups

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

\startxmlsetups xml:aa
     \par
     <aa>\xmlflush{#1}</aa>
     \par
\stopxmlsetups

\startxmlsetups xml:ax
     \par
     <ax>\xmlflush{#1}</ax>
     \par
\stopxmlsetups

\startxmlsetups xml:ab
     \par
     <ab>
     \xmlflush{#1}:\space
     aa: \xmlfilter{#1}{reverse-sibling::[tag() == 
'aa']/attribute('number')}\space
     ax: \xmlfilter{#1}{reverse-sibling::[tag() == 
'ax']/attribute('number')}\space
     </ab>
     \par
\stopxmlsetups

\xmlregistersetup{xml:initialize}

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

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                                           Hans Hagen | PRAGMA ADE
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