Function parseDuration

postgres/parser/sem/tree/interval.go:521–570

parseDuration parses a duration in the "traditional" Postgres format (e.g. '1 day 2 hours', '1 day 03:02:04', etc.) or golang format (e.g. '1d2h', '1d3h2m4s', etc.)

(s string, itm types.IntervalTypeMetadata)

// format (e.g. '1 day 2 hours', '1 day 03:02:04', etc.) or golang
// format (e.g. '1d2h', '1d3h2m4s', etc.)
func parseDuration(s string, itm types.IntervalTypeMetadata) (duration.Duration, error) {
	var d duration.Duration
	l := intervalLexer{str: s, offset: 0, err: nil}
	l.consumeSpaces()
	l.consumeAts()    // remove all @ characters
	l.consumeSpaces() // remove spaces that come after @s

	if l.offset == len(l.str) {
		return d, pgerror.Newf(
			pgcode.InvalidDatetimeFormat, "interval: invalid input syntax: %q", l.str)
	}
	for l.offset != len(l.str) {
		// To support -00:XX:XX we record the sign here since -0 doesn't exist
		// as an int64.
		sign := l.str[l.offset] == '-'
		// Parse the next number.
		v, hasDecimal, vp := l.consumeNum()
		l.consumeSpaces()

		if l.offset < len(l.str) && l.str[l.offset] == ':' && !hasDecimal {
			// Special case: HH:MM[:SS.ffff] or MM:SS.ffff
			delta, err := l.parseShortDuration(v, sign, itm)
			if err != nil {
				return d, err
			}
			d = d.Add(delta)
			continue
		}

		// Parse the unit.
		u := l.consumeUnit(' ')
		l.consumeSpaces()
		if unit, ok := unitMap[strings.ToLower(u)]; ok {
			// A regular number followed by a unit, such as "9 day".
			d = d.Add(unit.Mul(v))
			if hasDecimal {
				d = addFrac(d, unit, vp)
			}
			continue
		}

		if u != "" {
			return d, pgerror.Newf(
				pgcode.InvalidDatetimeFormat, "interval: unknown unit %q in duration %q", u, s)
		}
		return d, pgerror.Newf(
			pgcode.InvalidDatetimeFormat, "interval: missing unit at position %d: %q", l.offset, s)
	}
	return d, l.err
}

func (l *intervalLexer) parseShortDuration(
	h int64, hasSign bool, itm types.IntervalTypeMetadata,