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Diffstat (limited to 'doc/context/sources/general/manuals/luatex/luatex-nodes.tex')
| -rw-r--r-- | doc/context/sources/general/manuals/luatex/luatex-nodes.tex | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/doc/context/sources/general/manuals/luatex/luatex-nodes.tex b/doc/context/sources/general/manuals/luatex/luatex-nodes.tex index 32e641789..21ef0232d 100644 --- a/doc/context/sources/general/manuals/luatex/luatex-nodes.tex +++ b/doc/context/sources/general/manuals/luatex/luatex-nodes.tex @@ -201,6 +201,26 @@ its internal link structure is correct, otherwise an error may be result. The subtype numbers~4 and~5 belong to the \quote {of-f-ice} explanation given elsewhere. +These disc nodes are kind of special as at some point they also keep information +about breakpoints and nested ligatures. The \type {pre}, \type {post} and \type +{replace} fields at the \LUA\ end are in fact indirectly accessed and have a +\type {prev} pointer that is not \type {nil}. This means that when you mess +around with the head of these (three) lists, you also need to reassign them +because that will restore the proper \type {prev} pointer, so: + +\starttyping +pre = d.pre +-- change the list starting with pre +d.pre = pre +\stoptyping + +Otherwise you can end up with an invalid internal perception of reality and +\LUATEX\ might even decide to crash on you. It also means that running forward +over for instance \type {pre} is ok but backward you need to stop at \type {pre}. +And you definitely must not mess with the node that \type {prev} points to, if +only because it is not really an node but part of the disc data structure (so +freeing it again might crash \LUATEX). + \subsubsection{math nodes} \starttabulate[|lT|l|p|] |