auto merge of #4831 : bjz/rust/incoming, r=pcwalton

This is useful for comparing more complex types that include floats.

src/libstd/cmp.rs

@@ -14,16 +14,16 @@
 use core::f64;
 use core::float;
 
-const fuzzy_epsilon: float = 1.0e-6;
+pub const FUZZY_EPSILON: float = 1.0e-6;
 
-pub trait FuzzyEq {
+pub trait FuzzyEq<Eps> {
     pure fn fuzzy_eq(&self, other: &Self) -> bool;
-    pure fn fuzzy_eq_eps(&self, other: &Self, epsilon: &Self) -> bool;
+    pure fn fuzzy_eq_eps(&self, other: &Self, epsilon: &Eps) -> bool;
 }
 
-impl float: FuzzyEq {
+impl float: FuzzyEq<float> {
     pure fn fuzzy_eq(&self, other: &float) -> bool {
-        self.fuzzy_eq_eps(other, &fuzzy_epsilon)
+        self.fuzzy_eq_eps(other, &FUZZY_EPSILON)
     }
 
     pure fn fuzzy_eq_eps(&self, other: &float, epsilon: &float) -> bool {
@@ -31,9 +31,9 @@ impl float: FuzzyEq {
     }
 }
 
-impl f32: FuzzyEq {
+impl f32: FuzzyEq<f32> {
     pure fn fuzzy_eq(&self, other: &f32) -> bool {
-        self.fuzzy_eq_eps(other, &(fuzzy_epsilon as f32))
+        self.fuzzy_eq_eps(other, &(FUZZY_EPSILON as f32))
     }
 
     pure fn fuzzy_eq_eps(&self, other: &f32, epsilon: &f32) -> bool {
@@ -41,9 +41,9 @@ impl f32: FuzzyEq {
     }
 }
 
-impl f64: FuzzyEq {
+impl f64: FuzzyEq<f64> {
     pure fn fuzzy_eq(&self, other: &f64) -> bool {
-        self.fuzzy_eq_eps(other, &(fuzzy_epsilon as f64))
+        self.fuzzy_eq_eps(other, &(FUZZY_EPSILON as f64))
     }
 
     pure fn fuzzy_eq_eps(&self, other: &f64, epsilon: &f64) -> bool {
@@ -63,3 +63,40 @@ fn test_fuzzy_eq_eps() {
     assert (&1.2f).fuzzy_eq_eps(&0.9, &0.5);
     assert !(&1.5f).fuzzy_eq_eps(&0.9, &0.5);
 }
+
+#[test]
+mod test_complex{
+    use cmp::*;
+
+    struct Complex { r: float, i: float }
+
+    impl Complex: FuzzyEq<float> {
+        pure fn fuzzy_eq(&self, other: &Complex) -> bool {
+            self.fuzzy_eq_eps(other, &FUZZY_EPSILON)
+        }
+
+        pure fn fuzzy_eq_eps(&self, other: &Complex,
+                             epsilon: &float) -> bool {
+            self.r.fuzzy_eq_eps(&other.r, epsilon) &&
+            self.i.fuzzy_eq_eps(&other.i, epsilon)
+        }
+    }
+
+    #[test]
+    fn test_fuzzy_equals() {
+        let a = Complex {r: 0.9, i: 0.9};
+        let b = Complex {r: 0.9, i: 0.9};
+
+        assert (a.fuzzy_eq(&b));
+    }
+
+    #[test]
+    fn test_fuzzy_eq_eps() {
+        let other = Complex {r: 0.9, i: 0.9};
+
+        assert (&Complex {r: 0.9, i: 1.2}).fuzzy_eq_eps(&other, &0.5);
+        assert (&Complex {r: 1.2, i: 0.9}).fuzzy_eq_eps(&other, &0.5);
+        assert !(&Complex {r: 0.9, i: 1.5}).fuzzy_eq_eps(&other, &0.5);
+        assert !(&Complex {r: 1.5, i: 0.9}).fuzzy_eq_eps(&other, &0.5);
+    }
+}

src/test/run-pass/trait-inheritance-num.rs

@@ -18,7 +18,7 @@
 
 pub trait NumExt: Num Eq Ord {}
 
-pub trait FloatExt: NumExt FuzzyEq {}
+pub trait FloatExt: NumExt FuzzyEq<Self> {}
 
 fn greater_than_one<T:NumExt>(n: &T) -> bool { *n > from_int(1) }
 fn greater_than_one_float<T:FloatExt>(n: &T) -> bool { *n > from_int(1) }

src/test/run-pass/trait-inheritance-num2.rs

@@ -94,7 +94,7 @@ pub impl i64: IntegerExt {}
 pub impl int: IntegerExt {}
 
 
-pub trait FloatExt: NumExt FuzzyEq {}
+pub trait FloatExt: NumExt FuzzyEq<Self> {}
 
 pub impl f32: FloatExt {}
 pub impl f64: FloatExt {}