[Dev-luatex] Traversing node list

[Hartmut Henkel]

On Fri, 31 Oct 2008, Khaled Hosny wrote:

> On Thu, Oct 30, 2008 at 11:32:48PM +0100, Hartmut Henkel wrote:
> > On Thu, 30 Oct 2008, Khaled Hosny wrote:
> > >
> > > \hbox{Not seen}
> >
> > that's just a \hbox{} within the page's \vbox{}, it's not starting a
> > paragraph. A \hbox{} at the beginning of a new paragraph you would get
> > e. g., by \leavevmode\hbox{Seen}.
>
> my question is how I go through the nodes in that \hbox not getting a
> box at start of paragraph.

seems it works through the hpack_filter:


% just to get rid of header/footer boxes from plain.tex
\catcode`@=11
\def\plainoutput{\shipout\vbox{\pagebody}%
  \advancepageno
  \ifnum\outputpenalty>-\@MM \else\dosupereject\fi}
\catcode`@=12

\directlua0{
local function traverse(h)
  for n in node.traverse (h)
    do texio.write_nl('node id='..node.type(n.id))
    if n.id == node.id('hlist') then
      traverse(n.list)
    end
  end
end
callback.register('hpack_filter',
  function(h,a)
    texio.write_nl("=== "..a)
    traverse(h)
    return true
  end
)
}

\hbox{Also seen}

Hello \hbox{seen}
\bye


Regards, Hartmut