Method read_hex

std/re/src/main/parser.rs:328–336

(&mut self, n: usize)

    }

    fn read_hex(&mut self, n: usize) -> Result<char, ParseError> {
        let mut acc: u32 = 0;
        for _ in 0..n {
            let d = self.peek().and_then(|c| c.to_digit(16)).ok_or(self.err("bad hex escape"))?;
            acc = acc * 16 + d;
            self.bump();
        }
        char::from_u32(acc).ok_or(self.err("invalid codepoint"))
    }
}

fn single(item: ClassItem) -> Vec<ClassItem> {