[luatex] prev field in discretionary nodes

[Taco Hoekwater]

On 21 Jan 2014, at 21:01, Stephan Hennig <mailing_list at arcor.de> wrote:

> Am 20.01.2014 11:37, schrieb Taco Hoekwater:
>> On 19 Jan 2014, at 23:11, Stephan Hennig <mailing_list at arcor.de> wrote:
>> 
>>> Is reusing node lists in general safe?  
>> 
>> Assuming you are certain that there are no internal TeX references
>> to that node list left after your manipulation. Otherwise no.
> 
> What about the nodes pointed to by first prev fields in discretionary
> nodes?  Can discretionary nodes be safely removed from a list or can
> that break something due to the internal references described in your
> other mail?

It should be safe to mess with the list as long as it is not added to the 
vertical list yet (so no messing about inside post_linebreak_filter).

> And they set-up prev fields in sub-lists of discretionary nodes, which
> cannot be done manually.  Are there any other such nodes that /require/
> the use of insert_before/after?

I don’t think so (but do not have the sources handy).

Best wishes,
Taco