refactor: split series module (#27)

Author: martinohmann

src/series/iter.rs

@@ -0,0 +1,58 @@
+use crate::series::Series;
+use crate::{Event, Pattern};
+use jiff::civil::DateTime;
+
+/// An iterator over the events of a [`Series`].
+///
+/// This struct is created by the [`.iter()`][Series::iter] method of a `Series`. See its
+/// documentation for more.
+#[derive(Debug, Clone)]
+pub struct Iter<'a, P> {
+    series: &'a Series<P>,
+    first: bool,
+    cursor_front: Option<DateTime>,
+    cursor_back: Option<DateTime>,
+}
+
+impl<'a, P: Pattern> Iter<'a, P> {
+    pub(crate) fn new(series: &'a Series<P>) -> Iter<'a, P> {
+        Iter {
+            series,
+            first: true,
+            cursor_front: Some(series.start()),
+            cursor_back: Some(series.end()),
+        }
+    }
+}
+
+impl<P> Iterator for Iter<'_, P>
+where
+    P: Pattern,
+{
+    type Item = Event;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let cursor = self.cursor_front.take()?;
+        let event = if self.first {
+            self.first = false;
+            self.series.first_event()?
+        } else {
+            self.series.get_event_after(cursor)?
+        };
+
+        self.cursor_front = Some(event.start());
+        Some(event)
+    }
+}
+
+impl<P> DoubleEndedIterator for Iter<'_, P>
+where
+    P: Pattern,
+{
+    fn next_back(&mut self) -> Option<Self::Item> {
+        let cursor = self.cursor_back.take()?;
+        let event = self.series.get_event_before(cursor)?;
+        self.cursor_back = Some(event.start());
+        Some(event)
+    }
+}