adding wcwidth for char in libcore

[kwantam]

It would be nice to have a wcwidth-alike, presumably living in core::unicode and exposed as a char method. I've got a working local implementation of this that automatically generates the search tables for 0- and double-width characters from the latest unicode data (this does not need to be done at build time, only when the unicode charsets are updated).

If this is a desirable feature, can you give me some guidance as to

1. What the function should be called (wcwidth is pretty C-ish and maybe not so Rustic).
2. Where the autogen stuff should live (maybe in src/etc/unicode_width?)
3. Whether you'd like me to add a wcwidth_cjk-equivalent function, whose behavior is slightly different on certain spacing characters, as described in http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c (see comment above the mk_wcwidth_cjk function).

Any other thoughts are, of course, appreciated.

[huonw]

What the function should be called (wcwidth is pretty C-ish and maybe not so Rustic).

It can be a function/method on char like 'a'.width() or something.

Where the autogen stuff should live (maybe in src/etc/unicode_width?)

There's a unicode.py script already.

Whether you'd like me to add a wcwidth_cjk-equivalent function, whose behavior is slightly different on certain spacing characters, as described in http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c (see comment above the mk_wcwidth_cjk function).

The comment suggests that this is mainly a legacy thing, and so (in my mind) isn't a high priority.