Implement Sum for Angle

src/angle.rs

@@ -17,6 +17,7 @@
 
 use std::fmt;
 use std::f64;
+use std::iter;
 use std::ops::*;
 
 use rand::{Rand, Rng};
@@ -72,6 +73,20 @@ macro_rules! impl_angle {
             }
         }
 
+        impl<S: BaseFloat> iter::Sum<$Angle<S>> for $Angle<S> {
+            #[inline]
+            fn sum<I: Iterator<Item=$Angle<S>>>(iter: I) -> $Angle<S> {
+                iter.fold($Angle::zero(), Add::add)
+            }
+        }
+
+        impl<'a, S: 'a + BaseFloat> iter::Sum<&'a $Angle<S>> for $Angle<S> {
+            #[inline]
+            fn sum<I: Iterator<Item=&'a $Angle<S>>>(iter: I) -> $Angle<S> {
+                iter.fold($Angle::zero(), Add::add)
+            }
+        }
+
         impl<S: BaseFloat> Angle for $Angle<S> {
             type Unitless = S;
 

src/structure.rs

@@ -551,6 +551,8 @@ pub trait Angle where
     Self: Mul<<Self as Angle>::Unitless, Output = Self>,
     Self: Div<Self, Output = <Self as Angle>::Unitless>,
     Self: Div<<Self as Angle>::Unitless, Output = Self>,
+
+    Self: iter::Sum,
 {
     type Unitless: BaseFloat;
 

tests/angle.rs

@@ -20,7 +20,7 @@ extern crate cgmath;
 use cgmath::{Rad, Deg};
 
 #[test]
-fn conv() {
+fn test_conv() {
     let angle: Rad<_> = Deg(-5.0f64).into();
     let angle: Deg<_> = angle.into();
     assert_ulps_eq!(&angle, &Deg(-5.0f64));
@@ -37,3 +37,23 @@ fn conv() {
     let angle: Rad<_> = angle.into();
     assert_ulps_eq!(&angle, &Rad(30.0f64));
 }
+
+mod rad {
+    use cgmath::Rad;
+
+    #[test]
+    fn test_iter_sum() {
+        assert_eq!(Rad(2.0) + Rad(3.0) + Rad(4.0), [Rad(2.0), Rad(3.0), Rad(4.0)].iter().sum());
+        assert_eq!(Rad(2.0) + Rad(3.0) + Rad(4.0), [Rad(2.0), Rad(3.0), Rad(4.0)].iter().cloned().sum());
+    }
+}
+
+mod deg {
+    use cgmath::Deg;
+
+    #[test]
+    fn test_iter_sum() {
+        assert_eq!(Deg(2.0) + Deg(3.0) + Deg(4.0), [Deg(2.0), Deg(3.0), Deg(4.0)].iter().sum());
+        assert_eq!(Deg(2.0) + Deg(3.0) + Deg(4.0), [Deg(2.0), Deg(3.0), Deg(4.0)].iter().cloned().sum());
+    }
+}

tests/quaternion.rs

@@ -59,6 +59,7 @@ mod operators {
         let q3 = Quaternion::from(Euler { x: Rad(1f32), y: Rad(1f32), z: Rad(2f32) });
 
         assert_eq!(q1 + q2 + q3, [q1, q2, q3].iter().sum());
+        assert_eq!(q1 + q2 + q3, [q1, q2, q3].iter().cloned().sum());
     }
 
     #[test]
@@ -68,6 +69,7 @@ mod operators {
         let q3 = Quaternion::from(Euler { x: Rad(1f32), y: Rad(1f32), z: Rad(2f32) });
 
         assert_eq!(q1 * q2 * q3, [q1, q2, q3].iter().product());
+        assert_eq!(q1 * q2 * q3, [q1, q2, q3].iter().cloned().product());
     }
 }