Auto merge of #248 - dnsl48:ratio_into_pair, r=cuviper

rational: Into<(T,T)> implementation

Right now it appears impossible to get integers without cloning them. Converting into a pair can be a cheap and easy way to extract the data.

rational/src/lib.rs

@@ -268,6 +268,14 @@ impl<T> From<T> for Ratio<T> where T: Clone + Integer {
     }
 }
 
+
+// From pair (through the `new` constructor)
+impl<T> From<(T, T)> for Ratio<T> where T: Clone + Integer {
+    fn from(pair: (T, T)) -> Ratio<T> {
+        Ratio::new(pair.0, pair.1)
+    }
+}
+
 // Comparisons
 
 // Mathematically, comparing a/b and c/d is the same as comparing a*d and b*c, but it's very easy
@@ -594,6 +602,12 @@ impl<T: FromStr + Clone + Integer> FromStr for Ratio<T> {
     }
 }
 
+impl<T> Into<(T, T)> for Ratio<T> {
+    fn into(self) -> (T, T) {
+        (self.numer, self.denom)
+    }
+}
+
 #[cfg(feature = "serde")]
 impl<T> serde::Serialize for Ratio<T>
     where T: serde::Serialize + Clone + Integer + PartialOrd
@@ -1144,4 +1158,19 @@ mod test {
         assert!(::hash(&_0) != ::hash(&_1));
         assert!(::hash(&_0) != ::hash(&_3_2));
     }
+
+    #[test]
+    fn test_into_pair() {
+        assert_eq! ((0, 1), _0.into());
+        assert_eq! ((-2, 1), _NEG2.into());
+        assert_eq! ((1, -2), _1_NEG2.into());
+    }
+
+    #[test]
+    fn test_from_pair() {
+        assert_eq! (_0, Ratio::from ((0, 1)));
+        assert_eq! (_1, Ratio::from ((1, 1)));
+        assert_eq! (_NEG2, Ratio::from ((-2, 1)));
+        assert_eq! (_1_NEG2, Ratio::from ((1, -2)));
+    }
 }