// 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
func iso8601ToDuration(s string) (duration.Duration, error) {
var d duration.Duration
if len(s) == 0 || s[0] != 'P' {
return d, fmt.Errorf("interval: invalid iso8601 duration %s", 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, fmt.Errorf("interval: unknown unit %s in iso8601 duration %s", u, s)
}
}
return d, nil
}
// EncodeDurationDescending is the descending version of EncodeDurationAscending.
func EncodeDurationDescending(b []byte, d duration.Duration) ([]byte, error) {
sortNanos, months, days, err := d.Encode()
if err != nil {
// TODO(dan): Handle this using d.EncodeBigInt() and the
// durationBigNeg/durationBigPos markers.
return b, err
}
b = append(b, durationMarker)
b = EncodeVarintDescending(b, sortNanos)
b = EncodeVarintDescending(b, months)
b = EncodeVarintDescending(b, days)
return b, nil
}
// Parses a duration in the "traditional" Postgres format.
func postgresToDuration(s string) (duration.Duration, error) {
var d duration.Duration
l := intervalLexer{str: s, offset: 0, err: nil}
for l.offset != len(l.str) {
v := l.consumeInt()
l.consumeSpaces()
u := l.consumeUnit(' ')
l.consumeSpaces()
if unit, ok := postgresUnitMap[u]; ok {
d = d.Add(unit.Mul(v))
} else {
return d, fmt.Errorf("interval: unknown unit %s in postgres duration %s", u, s)
}
}
return d, nil
}