[XeTeX] xunicode for maths

[Jonathan Kew]

On 17 Feb 2006, at 4:18 am, Will Robertson wrote:
>
> One thing that occurs to me in accessing these plane 1 maths  
> characters is that on first impressions, it seems \XeTeXcharglyph  
> can't be used to see if they exist...I don't know if that's  
> something that we want to investigate, though, because it would be  
> costly in terms of performance. Any thoughts?

You're right, that won't work. \XeTeXcharglyph takes a "character  
code" in XeTeX terms and looks it up in the font. But these codes are  
really UTF-16 code units, not full Unicode characters once we're  
outside Plane 0. And it's not meaningful to look up single surrogate  
values, of course.

Maybe I should extend \char so as to directly handle values up to  
"10FFFF, generating a pair of nodes when necessary, and similarly  
extend \XeTeXcharglyph to handle the same range. I was wondering this  
just the other day.

JK