// 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
}
// 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
}
// Parse dash separated date string to interval.
// We parse sql stardard string to interval by two steps.
// Parsing the date part and parsing the time part.
// See the following links for exampels:
// - http://www.postgresql.org/docs/9.1/static/datatype-datetime.html#DATATYPE-INTERVAL-INPUT-EXAMPLES
func dateToDuration(s string) (duration.Duration, error) {
var d duration.Duration
if len(s) == 0 {
return d, fmt.Errorf(errInvalidSQLDuration, s)
}
parts := strings.Split(s, "-")
var v int
var err error
switch len(parts) {
case 1:
v, err = strconv.Atoi(parts[0])
if err != nil {
return d, fmt.Errorf(errInvalidSQLDuration, s)
}
d = d.Add(duration.Duration{Days: 1}.Mul(int64(v)))
case 2:
v, err = strconv.Atoi(parts[0])
if err != nil {
return d, fmt.Errorf(errInvalidSQLDuration, s)
}
d = d.Add(duration.Duration{Months: 12}.Mul(int64(v)))
v, err = strconv.Atoi(parts[1])
if err != nil {
return d, fmt.Errorf(errInvalidSQLDuration, s)
}
d = d.Add(duration.Duration{Months: 1}.Mul(int64(v)))
case 3:
v, err = strconv.Atoi(parts[0])
if err != nil {
return d, fmt.Errorf(errInvalidSQLDuration, s)
}
d = d.Add(duration.Duration{Months: 12}.Mul(int64(v)))
v, err = strconv.Atoi(parts[1])
if err != nil {
return d, fmt.Errorf(errInvalidSQLDuration, s)
}
d = d.Add(duration.Duration{Months: 1}.Mul(int64(v)))
v, err = strconv.Atoi(parts[2])
if err != nil {
return d, fmt.Errorf(errInvalidSQLDuration, s)
}
d = d.Add(duration.Duration{Days: 1}.Mul(int64(v)))
default:
return d, fmt.Errorf(errInvalidSQLDuration, s)
}
return d, nil
}