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|
#[derive(PartialEq, Debug)]
pub struct DateTime {
/// The year, e.g. 2016
pub year: u32,
/// The month (0 is January and 11 is December).
pub month: i8,
/// The date (one-indexed, so 31 would indicate the last date in January).
pub date: i8,
/// The hour (zero-indexed, valid values are 0 to 23 inclusive)
pub hour: i8,
/// The minute (zero-indexed, valid values are 0 to 59 inclusive)
pub minute: i8,
/// The second (zero-indexed, valid values are 0 to 59 inclusive)
pub second: i8,
}
enum DateParseState {
Date,
Month,
Year,
Hour,
Minute,
Second,
Timezone,
}
fn days_in_month(month: i8, year: u32) -> i8 {
match month {
0 | 2 | 4 | 6 | 7 | 9 | 11 => 31,
3 | 5 | 8 | 10 => 30,
1 => {
if (year % 400) == 0 {
29
} else if (year % 100) == 0 {
28
} else if (year % 4) == 0 {
29
} else {
28
}
},
_ => 0,
}
}
pub fn dateparse(date: &str) -> Result<DateTime, &'static str> {
let mut result = DateTime { year: 0, month: 0, date: 1, hour: 0, minute: 0, second: 0 };
let mut state = DateParseState::Date;
for tok in date.split(|c| c == ' ' || c == ':') {
if tok.is_empty() {
continue;
}
match state {
DateParseState::Date => {
match tok.parse::<i8>() {
Ok(v) => {
result.date = v;
state = DateParseState::Month;
},
Err(_) => (),
};
continue;
},
DateParseState::Month => {
result.month = match tok.to_uppercase().as_str() {
"JAN" | "JANUARY" => 0,
"FEB" | "FEBRUARY" => 1,
"MAR" | "MARCH" => 2,
"APR" | "APRIL" => 3,
"MAY" => 4,
"JUN" | "JUNE" => 5,
"JUL" | "JULY" => 6,
"AUG" | "AUGUST" => 7,
"SEP" | "SEPTEMBER" => 8,
"OCT" | "OCTOBER" => 9,
"NOV" | "NOVEMBER" => 10,
"DEC" | "DECEMBER" => 11,
_ => return Err("Unrecognized month"),
};
state = DateParseState::Year;
continue;
},
DateParseState::Year => {
result.year = match tok.parse::<u32>() {
Ok(v) if v < 70 => 2000 + v,
Ok(v) if v < 100 => 1900 + v,
Ok(v) => v,
Err(_) => return Err("Invalid year"),
};
state = DateParseState::Hour;
continue;
},
DateParseState::Hour => {
result.hour = match tok.parse::<i8>() {
Ok(v) => v,
Err(_) => return Err("Invalid hour"),
};
state = DateParseState::Minute;
continue;
},
DateParseState::Minute => {
result.minute = match tok.parse::<i8>() {
Ok(v) => v,
Err(_) => return Err("Invalid minute"),
};
state = DateParseState::Second;
continue;
},
DateParseState::Second => {
result.second = match tok.parse::<i8>() {
Ok(v) => v,
Err(_) => return Err("Invalid second"),
};
state = DateParseState::Timezone;
continue;
},
DateParseState::Timezone => {
let (tz, tz_sign) = match tok.parse::<i16>() {
Ok(v) if v < 0 => (-v, -1),
Ok(v) => (v, 1),
Err(_) => return Err("Invalid timezone"),
};
let tz_hours = (tz / 100) as i8;
let tz_mins = (tz % 100) as i8;
if tz_sign < 0 {
result.hour += tz_hours;
result.minute += tz_mins;
} else {
result.hour -= tz_hours;
result.minute -= tz_mins;
}
while result.minute < 0 {
result.hour -= 1;
result.minute += 60;
}
while result.minute >= 60 {
result.hour += 1;
result.minute -= 60;
}
while result.hour < 0 {
result.date -= 1;
result.hour += 24;
}
while result.hour >= 24 {
result.date += 1;
result.hour -= 24;
}
let num_days = days_in_month(result.month % 12, result.year);
if result.date < 0 || result.date > num_days + 1 {
return Err("Invalid date after normalization");
}
if result.date < 1 {
result.month -= 1;
result.date = days_in_month(result.month % 12, result.year);
} else if result.date > num_days {
result.month += 1;
result.date = 1;
}
while result.month < 0 {
result.year -= 1;
result.month += 12;
}
while result.month >= 12 {
result.year += 1;
result.month -= 12;
}
break;
},
}
}
Ok(result)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn parse_dates() {
assert_eq!(dateparse("Sun, 25 Sep 2016 18:36:33 -0400").unwrap(),
DateTime{ year: 2016, month: 8, date: 25, hour: 22, minute: 36, second: 33 });
}
}
|
