[Dev-luatex] "strange" node

Taco Hoekwater taco at elvenkind.com
Sun Aug 29 15:23:15 CEST 2010


On 08/29/2010 02:59 PM, Patrick Gundlach wrote:
> Hi,
>
> I have this box:
>
> \setbox0\vbox{x}
>
> when I analyze the nodelist, I find a somewhat strange hlist node:
>
> <node    nil<      30>     nil : hlist 0>
>
> which is referenced from the whatsit (local_par)/prev node pointer. See "n30" in the attached image. Is it safe to ignore this hlist?
>
> (is this the parindent box? - answer from the other mail?)

Oh, right. No, it is not. The 'next' pointer is the parindent box.
The prev of local_par is nonsense (it originally points to a temp
node that was the current head, but temp nodes often end up junk
after they are no longer needed).

I should clear that field when the head is split off, but it will
take some time before I can find the correct location. Just ignore
it, please.

> Another related question: sometimes I come across "nested_list" and "temp" nodes. Can I ignore these as well?
>
> I wonder why two hlists point back to the same nested_list (n155).

Same thing happens here. In general, the back pointer of the first
item of a list of nodes contains a pointer to a temp node that was
created to start the current chain (discretionary sublists are the
exception).

Best wishes,
Taco


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