Merge pull request #39 from moia-oss/tw_overlap

src/lib.rs

@@ -39,6 +39,7 @@
 //! ```
 use core::fmt;
 use std::cmp::max;
+use std::cmp::min;
 use std::cmp::Ordering;
 use std::error::Error;
 use std::fmt::Debug;
@@ -551,7 +552,6 @@ impl TimeWindow {
     /// # Examples
     ///
     /// ```
-    /// # use tinytime::Time;
     /// # use tinytime::TimeWindow;
     /// let mut x = TimeWindow::from_seconds(5, 10);
     /// assert!(x.overlaps(&TimeWindow::from_seconds(5, 10)));
@@ -568,6 +568,63 @@ impl TimeWindow {
         self.start < that.end && that.start < self.end
     }
 
+    /// Returns time window that is an intersection between this time window and
+    /// another one. Returns None if time windows don't overlap.
+    /// # Examples
+    ///
+    /// ```
+    /// # use tinytime::TimeWindow;
+    /// let x = TimeWindow::from_seconds(5, 10);
+    /// assert_eq!(
+    ///     Some(TimeWindow::from_seconds(5, 10)),
+    ///     x.intersect(&TimeWindow::from_seconds(5, 10)),
+    ///     "time windows are equal"
+    /// );
+    /// assert_eq!(
+    ///     Some(TimeWindow::from_seconds(5, 10)),
+    ///     x.intersect(&TimeWindow::from_seconds(3, 12)),
+    ///     "that contains x"
+    /// );
+    /// assert_eq!(
+    ///     Some(TimeWindow::from_seconds(6, 9)),
+    ///     x.intersect(&TimeWindow::from_seconds(6, 9)),
+    ///     "x contains that"
+    /// );
+    /// assert_eq!(
+    ///     Some(TimeWindow::from_seconds(6, 10)),
+    ///     x.intersect(&TimeWindow::from_seconds(6, 12))
+    /// );
+    /// assert_eq!(
+    ///     Some(TimeWindow::from_seconds(5, 9)),
+    ///     x.intersect(&TimeWindow::from_seconds(3, 9))
+    /// );
+    /// assert_eq!(
+    ///     None,
+    ///     x.intersect(&TimeWindow::from_seconds(1, 4)),
+    ///     "that is before x"
+    /// );
+    /// assert_eq!(
+    ///     Some(TimeWindow::from_seconds(5, 5)),
+    ///     x.intersect(&TimeWindow::from_seconds(1, 5)),
+    ///     "single-point intersection"
+    /// );
+    /// assert_eq!(
+    ///     Some(TimeWindow::from_seconds(10, 10)),
+    ///     x.intersect(&TimeWindow::from_seconds(10, 15)),
+    ///     "single-point intersection"
+    /// );
+    /// assert_eq!(
+    ///     None,
+    ///     x.intersect(&TimeWindow::from_seconds(11, 15)),
+    ///     "that is after x"
+    /// );
+    /// ```
+    pub fn intersect(&self, that: &TimeWindow) -> Option<TimeWindow> {
+        let start = max(self.start, that.start);
+        let end = min(self.end, that.end);
+        (start <= end).then(|| TimeWindow::new(start, end))
+    }
+
     /// Shifts this time window by `duration` into the future. Affects both
     /// `start` and `end` equally.
     ///