John Maddock wrote: <snip>

It might be best to add a facility to add new character classes as a list of characters and ranges to include, something like:

register_character_class("myname", "d-f");

Then we add all the Unicode block ranges as standard for wide character regexes.

Aside from the unified Han characters (kanji/hanzi), characters of the same category generally aren't neatly grouped together in Unicode. The 128-character blocks tend to correspond to locales, communities of use or specific legacy encodings and not to categories. You need a look-up table (or more efficiently two levels of table) to check character categories.