Auto merge of #40 - mbrubeck:ops, r=emilio

Implement `i32 * Au`, `Au / Au`, and `Au % Au` operations

None

Author: bors-servo

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "app_units"
-version = "0.6.0"
+version = "0.6.1"
 authors = ["The Servo Project Developers"]
 description = "Servo app units type (Au)"
 documentation = "http://doc.servo.org/app_units/"

src/app_unit.rs

@@ -83,6 +83,21 @@ impl Sub for Au {
 
 }
 
+impl Mul<Au> for i32 {
+    type Output = Au;
+
+    #[inline]
+    fn mul(self, other: Au) -> Au {
+        if let Some(new) = other.0.checked_mul(self) {
+            Au(new).clamp()
+        } else if (self > 0) ^ (other.0 > 0) {
+            MIN_AU
+        } else {
+            MAX_AU
+        }
+    }
+}
+
 impl Mul<i32> for Au {
     type Output = Au;
 
@@ -98,6 +113,15 @@ impl Mul<i32> for Au {
     }
 }
 
+impl Div for Au {
+    type Output = i32;
+
+    #[inline]
+    fn div(self, other: Au) -> i32 {
+        self.0 / other.0
+    }
+}
+
 impl Div<i32> for Au {
     type Output = Au;
 
@@ -107,6 +131,15 @@ impl Div<i32> for Au {
     }
 }
 
+impl Rem for Au {
+    type Output = Au;
+
+    #[inline]
+    fn rem(self, other: Au) -> Au {
+        Au(self.0 % other.0)
+    }
+}
+
 impl Rem<i32> for Au {
     type Output = Au;
 
@@ -273,12 +306,21 @@ fn operations() {
     assert_eq!(MIN_AU - Au(1), MIN_AU);
 
     assert_eq!(Au(7) * 5, Au(35));
+    assert_eq!(5 * Au(7), Au(35));
     assert_eq!(MAX_AU * -1, MIN_AU);
     assert_eq!(MIN_AU * -1, MAX_AU);
+    assert_eq!(-1 * MAX_AU, MIN_AU);
+    assert_eq!(-1 * MIN_AU, MAX_AU);
+
+    assert_eq!((Au(14) / 5) * 5 + Au(14) % 5, Au(14));
+    assert_eq!((Au(14) / Au(5)) * Au(5) + Au(14) % Au(5), Au(14));
 
     assert_eq!(Au(35) / 5, Au(7));
     assert_eq!(Au(35) % 6, Au(5));
 
+    assert_eq!(Au(35) / Au(5), 7);
+    assert_eq!(Au(35) / Au(5), 7);
+
     assert_eq!(-Au(7), Au(-7));
 }