FuzzyEq improvements

src/libstd/cmp.rs

@@ -1,4 +1,4 @@
-// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 #[forbid(deprecated_mode)];
-/// Additional general-purpose comparison functionality.
+//! Additional general-purpose comparison functionality.
 
 use core::f32;
 use core::f64;
@@ -18,31 +18,49 @@ use core::float;
 const fuzzy_epsilon: float = 1.0e-6;
 
 pub trait FuzzyEq {
-    pure fn fuzzy_eq(other: &self) -> bool;
+    pure fn fuzzy_eq(&self, other: &self) -> bool;
+    pure fn fuzzy_eq_eps(&self, other: &self, epsilon: &self) -> bool;
 }
 
 impl float: FuzzyEq {
-    pure fn fuzzy_eq(other: &float) -> bool {
-        return float::abs(self - *other) < fuzzy_epsilon;
+    pure fn fuzzy_eq(&self, other: &float) -> bool {
+        self.fuzzy_eq_eps(other, fuzzy_epsilon)
+    }
+
+    pure fn fuzzy_eq_eps(&self, other: &float, epsilon: &float) -> bool {
+        float::abs(*self - *other) < *epsilon
     }
 }
 
 impl f32: FuzzyEq {
-    pure fn fuzzy_eq(other: &f32) -> bool {
-        return f32::abs(self - *other) < (fuzzy_epsilon as f32);
+    pure fn fuzzy_eq(&self, other: &f32) -> bool {
+        self.fuzzy_eq_eps(other, fuzzy_epsilon as f32)
+    }
+
+    pure fn fuzzy_eq_eps(&self, other: &f32, epsilon: &f32) -> bool {
+        f32::abs(*self - *other) < *epsilon
     }
 }
 
 impl f64: FuzzyEq {
-    pure fn fuzzy_eq(other: &f64) -> bool {
-        return f64::abs(self - *other) < (fuzzy_epsilon as f64);
+    pure fn fuzzy_eq(&self, other: &f64) -> bool {
+        self.fuzzy_eq_eps(other, fuzzy_epsilon as f64)
+    }
+
+    pure fn fuzzy_eq_eps(&self, other: &f64, epsilon: &f64) -> bool {
+        f64::abs(*self - *other) < *epsilon
     }
 }
 
 #[test]
 fn test_fuzzy_equals() {
-    assert ((&1.0).fuzzy_eq(&1.0));
-    assert ((&1.0f32).fuzzy_eq(&1.0f32));
-    assert ((&1.0f64).fuzzy_eq(&1.0f64));
+    assert (&1.0).fuzzy_eq(&1.0);
+    assert (&1.0f32).fuzzy_eq(&1.0f32);
+    assert (&1.0f64).fuzzy_eq(&1.0f64);
 }
 
+#[test]
+fn test_fuzzy_eq_eps() {
+    assert (&1.2).fuzzy_eq_eps(&0.9, &0.5);
+    assert !(&1.5).fuzzy_eq_eps(&0.9, &0.5);
+}