On 3/10/2016 10:02 AM, Frank Mittelbach wrote:
Am 10.03.16 um 09:51 schrieb Hans Hagen:
On 3/9/2016 8:48 PM, Frank Mittelbach wrote:
I think I found a bug in tex.linebreak.
Consider the following code
function prelinebreak (head, groupnode) --- for pre_linebreak_filter
--- for example
local n,t
n, t = tex.linebreak(node.copy_list(head), {looseness = -1})
print("looseness=" .. t.looseness)
n, t = tex.linebreak(node.copy_list(head), {looseness = 0})
print("looseness=" .. t.looseness)
return true
end
and pass it in head a long enough hlist so that looseness -1 actually
works. The second line breaking with looseness=0 reports the previous
looseness ... same happens if you have looseness=+2 or +1 or so
it seems that tex.linebreak always reports the looseness of the previous
linebreak action in case you pass it a "0"
it helps if you also set some more (either explicit or at the tex
level), like:
looseness=1,
tolerance=4500,
pretolerance=100,
emergencystretch=655360
not sure I understand Hans, on the TeX they are set (once) -- are you
saying one needs to set them as part of the params table for
tex.linebreak as in
{ looseness = 0, tolerance = tex.tolerance ....
just re-providing to tex.linebreak what is already set on the TeX level?
my thoughts without having seen the internal code of tex.linebreak is
that if looseness = 0 the value that is reported at the end is actually
never set so retains whatever the last time was put there (which is not
making a problem while it is always 0 but shows the wrong value once you
ever set it to non-zero and later back
\setbox0\hbox{\input tufte }
\directlua{
local n,t,head
head = tex.box[0].head
n, t = tex.linebreak(node.copy_list(head), {looseness=1})
print("1.1",t.looseness)
n, t = tex.linebreak(node.copy_list(head), {looseness=0})
print("1.2",t.looseness)
}
\directlua{
local n,t,head
head = tex.box[0].head
n, t = tex.linebreak(node.copy_list(head), {looseness=1,
tolerance=4500, pretolerance=100, emergencystretch=655360 })
print("2.1",t.looseness)
n, t = tex.linebreak(node.copy_list(head), {looseness=0,
tolerance=4500, pretolerance=100, emergencystretch=655360 })
print("2.2",t.looseness)
}
\tolerance4500 \pretolerance100 \emergencystretch10pt
\directlua{
local n,t,head
head = tex.box[0].head
n, t = tex.linebreak(node.copy_list(head), {looseness=1})
print("3.1",t.looseness)
n, t = tex.linebreak(node.copy_list(head), {looseness=0})
print("3.2",t.looseness)
}
1.1 0
1.2 0
2.1 1
2.2 1
3.1 1
3.2 1
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Hans Hagen | PRAGMA ADE
Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
tel: 038 477 53 69 | www.pragma-ade.com | www.pragma-pod.nl
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