pub fn is_cjk(c: char) -> boolExpand description
Whether this is a “CJK character” as the CJK-adjacent emphasis policy sees it.
This is a different question from display width. Using one function for both gets two
cases wrong — halfwidth katakana (ｱｲｳ) has width 1 but is CJK and needs padding, while
emoji have width 2 but are not CJK and need no padding.
The rule follows the CJK-friendly amendment to CommonMark — a character is CJK if its East
Asian Width is W, F, or H and it is not emoji presentation, or if its script is Hangul.
(https://github.com/tats-u/markdown-cjk-friendly)