Function string_to_datetime

arrow-cast/src/parse.rs:176–228

Accepts a string and parses it relative to the provided `timezone` In addition to RFC3339 / ISO8601 standard timestamps, it also accepts strings that use a space ` ` to separate the date and time as well as strings that have no explicit timezone offset. Examples of accepted inputs: `1997-01-31T09:26:56.123Z` # RCF3339 `1997-01-31T09:26:56.123-05:00` # RCF3339 `1997-01-31 09:26:56.123-05

(timezone: &T, s: &str)

///
/// [IANA timezones]: https://www.iana.org/time-zones
pub fn string_to_datetime<T: TimeZone>(timezone: &T, s: &str) -> Result<DateTime<T>, ArrowError> {
    let err =
        |ctx: &str| ArrowError::ParseError(format!("Error parsing timestamp from '{s}': {ctx}"));

    let bytes = s.as_bytes();
    if bytes.len() < 10 {
        return Err(err("timestamp must contain at least 10 characters"));
    }

    let parser = TimestampParser::new(bytes);
    let date = parser.date().ok_or_else(|| err("error parsing date"))?;
    if bytes.len() == 10 {
        let datetime = date.and_time(NaiveTime::from_hms_opt(0, 0, 0).unwrap());
        return timezone
            .from_local_datetime(&datetime)
            .single()
            .ok_or_else(|| err("error computing timezone offset"));
    }

    if !parser.test(10, b'T') && !parser.test(10, b't') && !parser.test(10, b' ') {
        return Err(err("invalid timestamp separator"));
    }

    let (time, mut tz_offset) = parser.time().ok_or_else(|| err("error parsing time"))?;
    let datetime = date.and_time(time);

    if tz_offset == 32 {
        // Decimal overrun
        while tz_offset < bytes.len() && bytes[tz_offset].is_ascii_digit() {
            tz_offset += 1;
        }
    }

    if bytes.len() <= tz_offset {
        return timezone
            .from_local_datetime(&datetime)
            .single()
            .ok_or_else(|| err("error computing timezone offset"));
    }

    if (bytes[tz_offset] == b'z' || bytes[tz_offset] == b'Z') && tz_offset == bytes.len() - 1 {
        return Ok(timezone.from_utc_datetime(&datetime));
    }

    // Parse remainder of string as timezone
    let parsed_tz: Tz = s[tz_offset..].trim_start().parse()?;
    let parsed = parsed_tz
        .from_local_datetime(&datetime)
        .single()
        .ok_or_else(|| err("error computing timezone offset"))?;

    Ok(parsed.with_timezone(timezone))
}

/// Accepts a string in RFC3339 / ISO8601 standard format and some
/// variants and converts it to a nanosecond precision timestamp.