[XeTeX] Case changing for Greek

[Joseph Wright]

On 07/05/2015 13:40, Philip Taylor wrote:
> 
> 
> Joseph Wright wrote:
> 
>> For performance reasons that code has been set up to assume that a
>> sigma is final if it is followed by a space, a control sequence or a
>> character from the list
>>
>>     ) ] } . : ; , ! ? ' "
> 
> The inclusion of "a control sequence" worries me; may I ask why you do
> not propose to expand the control sequence (if expandable) or ascertain
> its equivalence (if \let, for example) in order to predicate the
> assessment as to whether or not the sigma is final on the expansion /
> equivalence of the control sequences as would seem at first sight to be
> required.

As the code here is for expl3, there is an assumption that such input is
either fully-expandable or engine protected. As such, application of
\edef in a preceding step will do the same without having to put in the
rather complex loops one needs otherwise (the code is expandable so
cannot itself include assignments). Note also that the code we have is
explicit intended for 'text': it seems unlikely that real user text will
intermix stored characters and literal ones and indeed defining the
logic either way could be questionable.

If it becomes clear that the current approach does not work then
alternatives can be considered. We don't have much in the way of
use-cases at present beyond ones we've thought of ourselves.
--
Joseph Wright