begin implementing the most basic recurrences

.gitignore

@@ -0,0 +1,4 @@
+
+/target/
+**/*.rs.bk
+Cargo.lock

src/lib.rs

@@ -1,6 +1,11 @@
 extern crate chrono;
 use chrono::{Datelike, Timelike, DateTime, Weekday, TimeZone};
 
+mod util;
+use util::Increment;
+
+//use std::default::Default;
+
 pub enum Frequency {
     Yearly,
     Weekly,
@@ -21,6 +26,7 @@ pub struct Recurrence<Tz: TimeZone> {
     pub count: Option<u32>,
     pub interval: Option<i32>,
 
+    pub bysecond: Option<Vec<u32>>,
     pub byminute: Option<Vec<u32>>,
     pub byhour: Option<Vec<u32>>,
     pub byday: Option<Vec<ByDay>>,
@@ -33,32 +39,127 @@ pub struct Recurrence<Tz: TimeZone> {
 
 impl<Tz: TimeZone> Recurrence<Tz> {
     pub fn iter (&self, start: DateTime<Tz>) -> DateTimeIterator<Tz> {
-        DateTimeIterator {
-            recurrence: &self,
-            start: start,
-            next_datetimes: vec![]
-        }
+        DateTimeIterator::new(self, start)
     }
 }
 
 pub struct DateTimeIterator<'a, Tz: TimeZone + 'a> {
     recurrence: &'a Recurrence<Tz>,
     start: DateTime<Tz>,
-
-    next_datetimes: Vec<DateTime<Tz>>
+    next_datetimes: Vec<DateTime<Tz>>,
+    count: u32
 }
 
 impl<'a, Tz: TimeZone + 'a> DateTimeIterator<'a, Tz> {
+    fn new (recurrence: &Recurrence<Tz>, start: DateTime<Tz>) -> DateTimeIterator<Tz> {
+        DateTimeIterator {
+            recurrence: &recurrence,
+            start: start,
+            next_datetimes: vec![],
+            count: 0
+        }
+    }
+
     fn generate_next_datetimes (&mut self) {
+        self.next_datetimes = self.generate_by_month(
+            self.generate_by_monthday(
+                self.generate_by_hour(
+                    self.generate_by_minute(
+                        self.generate_by_second(vec![self.start.clone()])
+                    )
+                )
+            )
+        );
+
         let interval = self.recurrence.interval.unwrap_or(1);
         self.start = match self.recurrence.frequency {
-            Frequency::Yearly => self.start.with_year(self.start.year() + interval).unwrap(),
-            Frequency::Monthly => self.start.with_month(self.start.month() + interval as u32).unwrap(),
-            Frequency::Weekly => self.start.with_day(self.start.day() + (7 * interval as u32)).unwrap(),
-            Frequency::Daily => self.start.with_day(self.start.day() + interval as u32).unwrap(),
-            Frequency::Hourly => self.start.with_hour(self.start.hour() + interval as u32).unwrap(),
-            Frequency::Minutely => self.start.with_minute(self.start.minute() + interval as u32).unwrap(),
-            Frequency::Secondly => self.start.with_second(self.start.second() + interval as u32).unwrap()
+            Frequency::Yearly => self.start.add_years(interval),
+            Frequency::Monthly => self.start.add_months(interval as u32),
+            Frequency::Weekly => self.start.add_weeks(interval as u32),
+            Frequency::Daily => self.start.add_days(interval as u32),
+            Frequency::Hourly => self.start.add_hours(interval as u32),
+            Frequency::Minutely => self.start.add_minutes(interval as u32),
+            Frequency::Secondly => self.start.add_seconds(interval as u32)
+        };
+    }
+
+    fn generate_by_second (&self, starting_datetimes: Vec<DateTime<Tz>>) -> Vec<DateTime<Tz>> {
+        if let Some(ref bysecond) = self.recurrence.bysecond {
+            let mut next_datetimes = vec![];
+            for start in starting_datetimes {
+                for second in bysecond {
+                    if let Some(datetime) = start.with_second(*second) {
+                        next_datetimes.push(datetime);
+                    }
+                }
+            }
+            next_datetimes
+        } else {
+            starting_datetimes
+        }
+    }
+
+    fn generate_by_minute (&self, starting_datetimes: Vec<DateTime<Tz>>) -> Vec<DateTime<Tz>> {
+        if let Some(ref byminute) = self.recurrence.byminute {
+            let mut next_datetimes = vec![];
+            for start in starting_datetimes {
+                for minute in byminute {
+                    if let Some(datetime) = start.with_minute(*minute) {
+                        next_datetimes.push(datetime);
+                    }
+                }
+            }
+            next_datetimes
+        } else {
+            starting_datetimes
+        }
+    }
+
+    fn generate_by_hour (&self, starting_datetimes: Vec<DateTime<Tz>>) -> Vec<DateTime<Tz>> {
+        if let Some(ref byhour) = self.recurrence.byhour {
+            let mut next_datetimes = vec![];
+            for start in starting_datetimes {
+                for hour in byhour {
+                    if let Some(datetime) = start.with_hour(*hour) {
+                        next_datetimes.push(datetime);
+                    }
+                }
+            }
+            next_datetimes
+        } else {
+            starting_datetimes
+        }
+    }
+
+    fn generate_by_monthday (&self, starting_datetimes: Vec<DateTime<Tz>>) -> Vec<DateTime<Tz>> {
+        if let Some(ref bymonthday) = self.recurrence.bymonthday {
+            let mut next_datetimes = vec![];
+            for start in starting_datetimes {
+                for monthday in bymonthday {
+                    if let Some(datetime) = start.with_day(*monthday) {
+                        next_datetimes.push(datetime);
+                    }
+                }
+            }
+            next_datetimes
+        } else {
+            starting_datetimes
+        }
+    }
+
+    fn generate_by_month (&self, starting_datetimes: Vec<DateTime<Tz>>) -> Vec<DateTime<Tz>> {
+        if let Some(ref bymonth) = self.recurrence.bymonth {
+            let mut next_datetimes = vec![];
+            for start in starting_datetimes {
+                for month in bymonth {
+                    if let Some(datetime) = start.with_month(*month) {
+                        next_datetimes.push(datetime);
+                    }
+                }
+            }
+            next_datetimes
+        } else {
+            starting_datetimes
         }
     }
 }
@@ -71,14 +172,66 @@ impl<'a, Tz: TimeZone + 'a> Iterator for DateTimeIterator<'a, Tz> {
             self.generate_next_datetimes();
         }
 
+        self.count = self.count + 1;
+        if let Some(count) = self.recurrence.count {
+            if count < self.count {
+                return None;
+            }
+        }
+
         self.next_datetimes.pop()
     }
 }
 
 #[cfg(test)]
 mod tests {
+    use {Recurrence, Frequency};
+    use chrono::DateTime;
+    use chrono::offset::Local;
+
     #[test]
-    fn it_works() {
-        assert_eq!(2 + 2, 4);
+    fn test_daily_recurrence () {
+        let recurrence = Recurrence {
+            frequency: Frequency::Daily,
+            count: Some(10),
+            interval: Some(1),
+
+            byhour: Some(vec![4]),
+            bysecond: Some(vec![0]),
+            byminute: Some(vec![20]),
+            byday: None,
+            byweekno: None,
+            bymonth: None,
+            bymonthday: None,
+
+            until: None
+        };
+
+        for datetime in recurrence.iter(Local::now()) {
+            println!("{:?}", datetime);
+        }
+    }
+
+    #[test]
+    fn test_yearly_recurrence () {
+        let recurrence = Recurrence {
+            frequency: Frequency::Yearly,
+            count: Some(10),
+            interval: Some(1),
+
+            byhour: None,
+            bysecond: None,
+            byminute: None,
+            byday: None,
+            byweekno: None,
+            bymonth: Some(vec![2]),
+            bymonthday: Some(vec![14]),
+
+            until: None
+        };
+
+        for datetime in recurrence.iter(Local::now()) {
+            println!("{:?}", datetime);
+        }
     }
 }

src/util.rs

@@ -0,0 +1,72 @@
+use chrono::{Datelike, DateTime, TimeZone, Timelike, NaiveDate};
+
+pub trait Increment {
+    fn add_years (&self, interval: i32) -> Self;
+    fn add_months (&self, interval: u32) -> Self;
+    fn add_weeks (&self, interval: u32) -> Self;
+    fn add_days (&self, interval: u32) -> Self;
+    fn add_hours (&self, interval: u32) -> Self;
+    fn add_minutes (&self, interval: u32) -> Self;
+    fn add_seconds (&self, interval: u32) -> Self;
+}
+
+impl<Tz: TimeZone> Increment for DateTime<Tz> {
+    fn add_years (&self, interval: i32) -> DateTime<Tz> {
+        self.with_year(self.year() + interval).unwrap()
+    }
+
+    fn add_months (&self, interval: u32) -> DateTime<Tz> {
+        let months = self.month() + interval;
+        if months >= 12 {
+            self.with_month(months % 12).unwrap().add_years((months / 12) as i32)
+        } else {
+            self.with_month(months).unwrap()
+        }
+    }
+
+    fn add_weeks (&self, interval: u32) -> DateTime<Tz> {
+        self.add_days(interval * 7)
+    }
+
+    fn add_days (&self, interval: u32) -> DateTime<Tz> {
+        let last_day = last_day_of_month(self.year(), self.month());
+        let days = self.day() + interval;
+        if days > last_day {
+            self.with_day(days % last_day).unwrap().add_months(days / last_day)
+        } else {
+            self.with_day(days).unwrap()
+        }
+    }
+
+    fn add_hours (&self, interval: u32) -> DateTime<Tz> {
+        let hours = self.hour() + interval;
+        if hours >= 24 {
+            self.with_hour(hours % 24).unwrap().add_days(hours / 24)
+        } else {
+            self.with_hour(hours).unwrap()
+        }
+    }
+
+    fn add_minutes (&self, interval: u32) -> DateTime<Tz> {
+        let minutes = self.minute() + interval;
+        if minutes >= 60 {
+            self.with_minute(minutes % 60).unwrap().add_hours(minutes / 60)
+        } else {
+            self.with_minute(minutes).unwrap()
+        }
+    }
+
+    fn add_seconds (&self, interval: u32) -> DateTime<Tz> {
+        let seconds = self.second() + interval;
+        if seconds >= 60 {
+            self.with_second(seconds % 60).unwrap().add_minutes(seconds / 60)
+        } else {
+            self.with_second(seconds).unwrap()
+        }
+    }
+}
+
+// from https://github.com/chronotope/chrono/issues/29#issuecomment-84492746
+pub fn last_day_of_month (year: i32, month: u32) -> u32 {
+    NaiveDate::from_ymd_opt(year, month + 1, 1).unwrap_or(NaiveDate::from_ymd(year + 1, 1, 1)).pred().day()
+}