feat(time): implement Time (+|-|+=|-=) Duration

Author: yvt

src/constance/src/time/time.rs

@@ -1,4 +1,4 @@
-use core::{convert::TryInto, fmt};
+use core::{convert::TryInto, fmt, ops};
 
 use crate::{
     time::Duration,
@@ -159,6 +159,18 @@ impl Time {
                 .ok()?,
         ))
     }
+
+    /// Advance the time by `duration` and return the result.
+    #[inline]
+    pub const fn wrapping_add(&self, duration: Duration) -> Self {
+        Self::from_micros(self.micros.wrapping_add(duration.as_micros() as i64 as u64))
+    }
+
+    /// Put back the time by `duration` and return the result.
+    #[inline]
+    pub const fn wrapping_sub(&self, duration: Duration) -> Self {
+        Self::from_micros(self.micros.wrapping_sub(duration.as_micros() as i64 as u64))
+    }
 }
 
 impl fmt::Debug for Time {
@@ -167,5 +179,41 @@ impl fmt::Debug for Time {
     }
 }
 
+impl ops::Add<Duration> for Time {
+    type Output = Self;
+
+    /// Advance the time by `duration` and return the result.
+    #[inline]
+    fn add(self, rhs: Duration) -> Self::Output {
+        self.wrapping_add(rhs)
+    }
+}
+
+impl ops::AddAssign<Duration> for Time {
+    /// Advance the time by `duration` in place.
+    #[inline]
+    fn add_assign(&mut self, rhs: Duration) {
+        *self = *self + rhs;
+    }
+}
+
+impl ops::Sub<Duration> for Time {
+    type Output = Self;
+
+    /// Put back the time by `duration` and return the result.
+    #[inline]
+    fn sub(self, rhs: Duration) -> Self::Output {
+        self.wrapping_sub(rhs)
+    }
+}
+
+impl ops::SubAssign<Duration> for Time {
+    /// Put back the time by `duration` in place.
+    #[inline]
+    fn sub_assign(&mut self, rhs: Duration) {
+        *self = *self - rhs;
+    }
+}
+
 // TODO: Add more tests
 // TODO: Interoperation with `::chrono`

src/constance_test_suite/src/kernel_tests/time_misc.rs

@@ -66,8 +66,7 @@ fn task_body<System: Kernel, D: Driver<App<System>>>(_: usize) {
     log::trace!("sleeping for {:?}", d);
     System::sleep(d).unwrap();
 
-    // TODO: `impl Add<Duration> for Time`
-    let now4 = Time::from_micros(now3.as_micros().wrapping_add(d.as_micros() as _));
+    let now4 = now3 + d;
     let now4_got = System::time().unwrap();
     log::trace!("time = {:?} (expected >= {:?})", now4_got, now4);
     assert!(now4_got.as_micros() >= now4.as_micros());