Function iso8601ToDuration

pkg/sql/sem/tree/interval.go:416–449

Parses an ISO8601 (with designators) string. See the following links for examples: - http://www.postgresql.org/docs/9.1/static/datatype-datetime.html#DATATYPE-INTERVAL-INPUT-EXAMPLES - https://en.wikipedia.org/wiki/ISO_8601#Time_intervals - https://en.wikipedia.org/wiki/ISO_8601#Durations

(s string)

//  - https://en.wikipedia.org/wiki/ISO_8601#Time_intervals
//  - https://en.wikipedia.org/wiki/ISO_8601#Durations
func iso8601ToDuration(s string) (duration.Duration, error) {
	var d duration.Duration
	if len(s) == 0 || s[0] != 'P' {
		return d, newInvalidSQLDurationError(s)
	}

	// Advance to offset 1, since we don't care about the leading P.
	l := intervalLexer{str: s, offset: 1, err: nil}
	unitMap := isoDateUnitMap

	for l.offset < len(s) {
		// Check if we're in the time part yet.
		if s[l.offset] == 'T' {
			unitMap = isoTimeUnitMap
			l.offset++
		}

		v := l.consumeInt()
		u := l.consumeUnit('T')
		if l.err != nil {
			return d, l.err
		}

		if unit, ok := unitMap[u]; ok {
			d = d.Add(unit.Mul(v))
		} else {
			return d, pgerror.Newf(
				pgcode.InvalidDatetimeFormat,
				"interval: unknown unit %s in ISO-8601 duration %s", u, s)
		}
	}

	return d, nil
}

// unitMap defines for each unit name what is the time duration for
// that unit.