On 23-12-2009 18:29, Paweł Jackowski wrote:
Taco Hoekwater wrote:
Paweł Jackowski wrote:
someglyph.next = someother
discretionary.pre = someglyph
is not the same. Why?
Hans:
indeed strange ... a quick hack is to use node.copy on b
Copying the node works in that case, thanks.
Taco:
Because a discretionary's pre, post, and replace lists are a bit
special: internally the discretionary does not just have a next and
a prev link for each of the head nodes, but also a 'tail' link.
That last one points to the last node in the list for each of
the three fields. That extra link is used during hyphenation and
at end-of-line situations (those parts of the code would be much
more complex == slower without it).
Agh, having the disc.tail link(s) at lua level would simplify processing
discretionaries a lot! Why you decided not to interface tails?
we had node.slide (for making two way linked node lists) and now also
have node.tail so you can find the tail if needed
tail = node.tail(n.pre)
I also noticed that assigning disc sublists introduces nested_list nodes:
someglyph.prev = nil
disc.pre = someglyph
assert(someglyph.prev.id==node.id"nested_list")
Is this related here? Is the user supposed to take care about
nested_list nodes (to create them, to destroy them)?
normally not ; similar effects can occur when messing around with boxes
(.list) ... it is often best to work with a copy and assign the result
of messing with the copy ... the speed penalty is neglectable
Hans
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