Function inTimeZone

common/stdlib/standard.go:1044–1081

(ts, tz ref.Val)

}

func inTimeZone(ts, tz ref.Val) (time.Time, error) {
	t := ts.(types.Timestamp)
	val := string(tz.(types.String))
	ind := strings.Index(val, ":")
	if ind == -1 {
		loc, err := time.LoadLocation(val)
		if err != nil {
			return time.Time{}, err
		}
		return t.In(loc), nil
	}

	// If the input is not the name of a timezone (for example, 'US/Central'), it should be a numerical offset from UTC
	// in the format ^(+|-)([01]\d|2[0-3]):[0-5][0-9]$. The numerical input is parsed in terms of hours and minutes.
	hr, err := strconv.Atoi(string(val[0:ind]))
	if err != nil {
		return time.Time{}, err
	}
	min, err := strconv.Atoi(string(val[ind+1:]))
	if err != nil {
		return time.Time{}, err
	}
	if hr < -23 || hr > 23 {
		return time.Time{}, fmt.Errorf("timezone offset hours out of range [-23, 23]: %s", val)
	}
	if min < 0 || min > 59 {
		return time.Time{}, fmt.Errorf("timezone offset minutes out of range [0, 59]: %s", val)
	}
	var offset int
	if string(val[0]) == "-" {
		offset = hr*60 - min
	} else {
		offset = hr*60 + min
	}
	secondsEastOfUTC := int((time.Duration(offset) * time.Minute).Seconds())
	timezone := time.FixedZone("", secondsEastOfUTC)
	return t.In(timezone), nil
}