[XeTeX] additional beginL endL nodes in math

[David Carlisle]

On 14 April 2015 at 21:14, Khaled Hosny <khaledhosny at eglug.org> wrote:
> On Tue, Apr 14, 2015 at 05:47:29PM +0100, David Carlisle wrote:
>> As noted in the release notes direction support now works in math
>> which is a good thing but a side effect seems to be that beginL endL
>> nodes are added to every math list
>
> This is part of the TeX-XeT code actually and not related to the
> mentioned change. This is the part that ensure math is always set
> left-to-right even if the surrounding text is set right-to-left.
>

I suspected as much but basically no one has used tex-xet for years as
they have used the xetex variant, so this is effectively introducing a third
incompatible directional system making pdftex, xetex and luatex mutually
incompatible, which is a rather scary prospect for supporting cross-engine
formats like latex.


>> Would it be possible for the automatic beginL node _not_ to be added
>> if the current context was already left to right?
>
> That should be theoretically possible, but I don’t know how. My naïve
> attempt below does not work (in the sense that the condition is always
> false even if the text was surrounded by \beginR/\endR. So if someone
> can come up with a working patch, I’ll happily apply it.

Thanks for looking, I hope someone can, and this can be changed before
texlive 2015
is frozen...


David