Function read_four_hex_digits

src/string.rs:191–204

(
  chars: &mut T,
  buf: &mut [u8; 4],
)

}

fn read_four_hex_digits<'a, T: CharProvider<'a>>(
  chars: &mut T,
  buf: &mut [u8; 4],
) -> Result<u32, ParseStringErrorKind> {
  for slot in buf.iter_mut() {
    match chars.move_next_char() {
      Some(c) if c.is_ascii_hexdigit() => *slot = c as u8,
      _ => return Err(ParseStringErrorKind::ExpectedFourHexDigits),
    }
  }
  // safety: buf contains only ASCII hex digits
  let hex_str = std::str::from_utf8(buf).unwrap();
  u32::from_str_radix(hex_str, 16).map_err(|_| ParseStringErrorKind::InvalidUnicodeEscapeSequence(hex_str.to_string()))
}

fn hex_buf_to_str(buf: &[u8; 4]) -> String {
  std::str::from_utf8(buf).unwrap().to_string()