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package time
// Parsing ISO 8601 date/time strings into time.Time.
import dt "core:time/datetime"
/*
Parse an ISO 8601 string into a time with UTC offset applied to it.
This procedure parses an ISO 8601 string of roughly the following format:
```text
YYYY-MM-DD[Tt]HH:mm:ss[.nn][Zz][+-]HH:mm
```
And returns time, in UTC represented by that string. In case the timezone offset
is specified in the string, that timezone is applied to time.
**Inputs**:
- `iso_datetime`: The string to be parsed.
- `is_leap`: Optional output parameter, specifying if the moment was a leap second.
**Returns**:
- `res`: The time represented by `iso_datetime`, with UTC offset applied.
- `consumed`: Number of bytes consumed by parsing the string.
**Notes**:
- Only 4-digit years are accepted.
- Leap seconds are smeared into 23:59:59.
*/
iso8601_to_time_utc :: proc(iso_datetime: string, is_leap: ^bool = nil) -> (res: Time, consumed: int) {
offset: int
res, offset, consumed = iso8601_to_time_and_offset(iso_datetime, is_leap)
res._nsec += (i64(-offset) * i64(Minute))
return res, consumed
}
/*
Parse an ISO 8601 string into a time and a UTC offset in minutes.
This procedure parses an ISO 8601 string of roughly the following format:
```text
YYYY-MM-DD[Tt]HH:mm:ss[.nn][Zz][+-]HH:mm
```
And returns time, in UTC represented by that string, and the UTC offset, in
minutes.
**Inputs**:
- `iso_datetime`: The string to be parsed.
- `is_leap`: Optional output parameter, specifying if the moment was a leap second.
**Returns**:
- `res`: The time in UTC.
- `utc_offset`: The UTC offset of the time, in minutes.
- `consumed`: Number of bytes consumed by parsing the string.
**Notes**:
- Only 4-digit years are accepted.
- Leap seconds are smeared into 23:59:59.
*/
iso8601_to_time_and_offset :: proc(iso_datetime: string, is_leap: ^bool = nil) -> (res: Time, utc_offset: int, consumed: int) {
moment, offset, leap_second, count := iso8601_to_components(iso_datetime)
if count == 0 {
return
}
if is_leap != nil {
is_leap^ = leap_second
}
if _res, ok := datetime_to_time(moment.year, moment.month, moment.day, moment.hour, moment.minute, moment.second, moment.nano); !ok {
return {}, 0, 0
} else {
return _res, offset, count
}
}
/*
Parse an ISO 8601 string into a datetime and a UTC offset in minutes.
This procedure parses an ISO 8601 string of roughly the following format:
```text
YYYY-MM-DD[Tt]HH:mm:ss[.nn][Zz][+-]HH:mm
```
And returns datetime, in UTC represented by that string, and the UTC offset, in
minutes.
**Inputs**:
- `iso_datetime`: The string to be parsed
**Returns**:
- `res`: The parsed datetime, in UTC.
- `utc_offset`: The UTC offset, in minutes.
- `is_leap`: Specifies whether the moment was a leap second.
- `consumed`: The number of bytes consumed by parsing the string.
**Notes**:
- This procedure performs no validation on whether components are valid,
e.g. it'll return hour = 25 if that's what it's given in the specified
string.
*/
iso8601_to_components :: proc(iso_datetime: string) -> (res: dt.DateTime, utc_offset: int, is_leap: bool, consumed: int) {
moment, offset, count, leap_second, ok := _iso8601_to_components(iso_datetime)
if !ok {
return
}
return moment, offset, leap_second, count
}
// Parses an ISO 8601 string and returns datetime.DateTime.
// Performs no validation on whether components are valid, e.g. it'll return hour = 25 if that's what it's given
@(private)
_iso8601_to_components :: proc(iso_datetime: string) -> (res: dt.DateTime, utc_offset: int, consumed: int, is_leap: bool, ok: bool) {
// A compliant date is at minimum 20 characters long, e.g. YYYY-MM-DDThh:mm:ssZ
(len(iso_datetime) >= 20) or_return
// Scan and eat YYYY-MM-DD[Tt], then scan and eat HH:MM:SS, leave separator
year := scan_digits(iso_datetime[0:], "-", 4) or_return
month := scan_digits(iso_datetime[5:], "-", 2) or_return
day := scan_digits(iso_datetime[8:], "Tt ", 2) or_return
hour := scan_digits(iso_datetime[11:], ":", 2) or_return
minute := scan_digits(iso_datetime[14:], ":", 2) or_return
second := scan_digits(iso_datetime[17:], "", 2) or_return
nanos := 0
count := 19
// Scan fractional seconds
if iso_datetime[count] == '.' {
count += 1 // consume '.'
multiplier := 100_000_000
for digit in iso_datetime[count:] {
if multiplier >= 1 && int(digit) >= '0' && int(digit) <= '9' {
nanos += int(digit - '0') * multiplier
multiplier /= 10
count += 1
} else {
break
}
}
}
// Leap second handling
if minute == 59 && second == 60 {
second = 59
is_leap = true
}
err: dt.Error
if res, err = dt.components_to_datetime(year, month, day, hour, minute, second, nanos); err != .None {
return {}, 0, 0, false, false
}
if len(iso_datetime[count:]) == 0 {
return res, utc_offset, count, is_leap, true
}
// Scan UTC offset
switch iso_datetime[count] {
case 'Z', 'z':
utc_offset = 0
count += 1
case '+', '-':
(len(iso_datetime[count:]) >= 6) or_return
offset_hour := scan_digits(iso_datetime[count+1:], ":", 2) or_return
offset_minute := scan_digits(iso_datetime[count+4:], "", 2) or_return
utc_offset = 60 * offset_hour + offset_minute
utc_offset *= -1 if iso_datetime[count] == '-' else 1
count += 6
}
return res, utc_offset, count, is_leap, true
}
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