fn from_str()

in src/common/src/time_ext.rs [91:136]

• 45 lines of code
• 7 McCabe index (conditional complexity)

    fn from_str(dur_str: &str) -> std::result::Result<ReadableDuration, String> {
        let dur_str = dur_str.trim();
        if !dur_str.is_ascii() {
            return Err(format!("unexpected ascii string: {dur_str}"));
        }
        let err_msg = "valid duration, only d, h, m, s, ms are supported.".to_owned();
        let mut left = dur_str.as_bytes();
        let mut last_unit = DAY + 1;
        let mut dur = 0f64;
        while let Some(idx) = left.iter().position(|c| b"dhms".contains(c)) {
            let (first, second) = left.split_at(idx);
            let unit = if second.starts_with(b"ms") {
                left = &left[idx + 2..];
                MS
            } else {
                let u = match second[0] {
                    b'd' => DAY,
                    b'h' => HOUR,
                    b'm' => MINUTE,
                    b's' => SECOND,
                    _ => return Err(err_msg),
                };
                left = &left[idx + 1..];
                u
            };
            if unit >= last_unit {
                return Err("d, h, m, s, ms should occur in given order.".to_owned());
            }
            // do we need to check 12h360m?
            let number_str = unsafe { std::str::from_utf8_unchecked(first) };
            dur += match number_str.trim().parse::<f64>() {
                Ok(n) => n * unit as f64,
                Err(_) => return Err(err_msg),
            };
            last_unit = unit;
        }
        if !left.is_empty() {
            return Err(err_msg);
        }
        if dur.is_sign_negative() {
            return Err("duration should be positive.".to_owned());
        }
        let secs = dur as u64 / SECOND;
        let millis = (dur as u64 % SECOND) as u32 * 1_000_000;
        Ok(ReadableDuration(Duration::new(secs, millis)))
    }