Is there a way to use the Unicode tables in the Rust regex crate to match a single char without turning it into a String or &str? It seems like the internals must have a way to do this, but perhaps not exposed? Is there a trick?
It might be vague in Unicode, but regexes certainly understand them ("character class") and characters in Rust do represent Unicode characters. And there are crates like unicode-xid and the unstable unicode internals in rustc that serve this purpose...