Dear Hans,
that is really great. Thank's a lot. Ill check the next beta and try to
wikifiy (maybe I need further help for that)
Achim
-----Ursprüngliche Nachricht-----
Von: ntg-context <ntg-context-boun...@ntg.nl> Im Auftrag von Hans Hagen
Gesendet: Mittwoch, 2. Oktober 2019 18:53
An: mailing list for ConTeXt users <ntg-context@ntg.nl>; mf
<mass...@fastwebnet.it>
Betreff: Re: [NTG-context] Access current element in xmlsetsetup via
xml.expressions
On 10/2/2019 12:32 PM, mf wrote:
> The answer is in lxml-lpt.lua, where built-in expressions are defined.
> You need a good knowledge of LPEG that i miss.
>
> Some built-in expressions get the current element as first argument,
> like count() or child() (lines 1300-1307 of lxml-lpt.lua):
>
> expressions.child = function(e,pattern)
> return applylpath(e,pattern) -- todo: cache end
>
> expressions.count = function(e,pattern) -- what if pattern == empty or
> nil
> local collected = applylpath(e,pattern) -- todo: cache
> return pattern and (collected and #collected) or 0 end
>
> Some other expressions use a template that passes the "list", "ll", "l"
> and "order" arguments you find cited in the XML manual §4.1 "Path
> expressions - Expressions and filters".
> These are the lines 738-743 in lxml-lpt.lua:
>
> local template_e = [[
> local expr = xml.expressions
> return function(list,ll,l,order)
> return %s
> end
> ]]
>
> That template is used by the function that registers a new expression
> (lines 807-812 in lxml-lpt.lua):
>
> local function register_expression(expression)
> local converted = lpegmatch(converter,expression)
> local runner = load(format(template_e,converted))
> runner = (runner and runner()) or function()
> errorrunner_e(expression,converted) end
> return { kind = "expression", expression = expression, converted
> = converted, evaluator = runner } end
>
> Anyway i could not find a way to define an expression with a function
> like this:
>
> xml.expressions.myexpr( ... )
>
> that gets access to those arguments.
>
> The only arguments it gets are the ones you specify in your LPATH
> expressions; AFAIK they are attributes values -- with the @attr syntax
> -- and strings.
Live is complex isn't it? The problem, is that we also support the normal path
expressions which in retrospect maybe was a bad idea ...
better be explicit. Strings without quotes are actually intercepted as element
references (just like the @ is).
So, I added a few extra accessors:
\startbuffer[text]
<para>
A <inline style="sup">sup 1</inline>
B <inline style="sub">sub 1</inline>
C <inline style="sup">sup 2</inline>
D <inline style="sub">sub 2</inline>
E <inline style="sup">sup 3</inline>
F <inline style="sup">sup 4</inline>
G <inline style="sup">sup 5</inline>
H <inline style="sub">sub 5</inline>
I <inline style="sup">sup 6</inline> </para> \stopbuffer
\startluacode
function xml.expressions.MyCheck(list,position,what)
-- print("list", list)
-- print("position",position)
-- print("what", what)
local n = list[position+1]
return n and n.at.style == what
end
\stopluacode
\enabletrackers[lxml.*]
\startxmlsetups xml:textsetups
\xmlsetsetup{#1}{para|inline}{xml:*}
% with a helper:
% \xmlsetsetup{#1}{inline[@style='sup' and
MyCheck(list(),position(),"sub")]}{xml:supsub}
% \xmlsetsetup{#1}{inline[@style='sup' and
MyCheck(list(),position(),"sup")]}{xml:supsup}
% rather verbose, we *need* to use ['at'] and not .at
% \xmlsetsetup{#1}{inline[@style='sup' and (position() < last() and
list()[position()+1]['at']['style']=='sub')]}{xml:supsub}
% \xmlsetsetup{#1}{inline[@style='sup' and (position() < last() and
list()[position()+1]['at']['style']=='sup')]}{xml:supsup}
% also ok
% \xmlsetsetup{#1}{inline[@style='sup' and (position() < last() and
attribute(list()[position()+1],'style')=='sub')]}{xml:supsub}
% \xmlsetsetup{#1}{inline[@style='sup' and (position() < last() and
attribute(list()[position()+1],'style')=='sup')]}{xml:supsup}
% direct checking
% \xmlsetsetup{#1}{inline[@style='sup' and (position() < last() and
attribute(list()[position()+1],'style','sub'))]}{xml:supsub}
% \xmlsetsetup{#1}{inline[@style='sup' and (position() < last() and
attribute(list()[position()+1],'style','sup'))]}{xml:supsup}
% shorter
\xmlsetsetup{#1}{inline[@style='sup' and
(attribute(list()[position()+1],'style','sub'))]}{xml:supsub}
\xmlsetsetup{#1}{inline[@style='sup' and
(attribute(list()[position()+1],'style','sup'))]}{xml:supsup}
\stopxmlsetups
\xmlregistersetup{xml:textsetups}
\startxmlsetups xml:para
\xmlflush{#1}\par
\stopxmlsetups
\startxmlsetups xml:supsub
\color[red]{\xmlflush{#1}}
\stopxmlsetups
\startxmlsetups xml:supsup
\color[blue]{\xmlflush{#1}}
\stopxmlsetups
\startxmlsetups xml:inline
\color[green]{\xmlflush{#1}}
\stopxmlsetups
\starttext
\xmlprocessbuffer{main}{text}{}
\stoptext
In the next beta. Now, who is going to wikify this ...
Hans
-----------------------------------------------------------------
Hans Hagen | PRAGMA ADE
Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
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Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive :
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wiki : http://contextgarden.net
___________________________________________________________________________________
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the
Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage : http://www.pragma-ade.nl / http://context.aanhet.net
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
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