Re: [callbacks] proper registration, node subtypes

[Hans Hagen <pragma@wxs.nl>]

On 25-6-2012 16:50, Philipp Gesang wrote:
> ···<date: 2012-06-25, Monday>···<from: Hans Hagen>···
>
>> On 25-6-2012 15:39, Philipp Gesang wrote:
>>
>>>    - Does the difference wrt node subtype matter assuming I only
>>>      (a) copy glyph nodes and (b) manipulate their .char field?
>>
>> not that much, it's just a state signal for font processing
>
> Good to know.
>
>>> Any insights on this matter would be greatly appreciated. Regards
>>> Philipp
>>
>> it all depends on what you want to do
>
> Traverse the node list of a paragraph before line break from head
> to tail in sequential order, recursing into sublists where they
> appear. The callback removes and inserts nodes: which ones
> depends on the nodes already processed (has a state).
>
> Using the previous example code,
>
>    \startfoo
>      a\hbox{b}c
>    \stopfoo
>
> should result in the traversal <glyph a>, <hlist ...>, <glyph c>.

\starttext

\startluacode

local function processnestedlist(head,n)
     local current, done = head, false
     while current do
         local id = current.id
         if id == nodes.nodecodes.hlist or id == nodes.nodecodes.vlist then
             local _, d = processnestedlist(current.list,n)
             if d then
                 done = true
             end
         elseif id == nodes.nodecodes.hglue_code and current.leader then
             local _, d = processnestedlist(current.leader,n)
             if d then
                 done = true
             end
         elseif id == nodes.nodecodes.glyph then -- todo: dics nodes
             n = n + 1
             print(n,utf.char(current.char))
         end
         current = current.next
     end
     return head, done, n
end


thirddata      = thirddata      or {}
thirddata.test = thirddata.test or { }

thirddata.test.one = function(head)
     local head, done, n = processnestedlist(head,0)
     print("n of glyphs",n)
     return head, done
end

nodes.tasks.appendaction ("processors","before","thirddata.test.one")

\stopluacode

\ruledhbox to 10cm {\strut hello \ruledhbox{brave new} world 
\cleaders\hbox{!}\hfil}

\stoptext

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------


___________________________________________________________________________________
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://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________