Split Tolerance to absolute and relative

src/lib.rs

@@ -125,12 +125,38 @@ pub trait AbsError<Rhs: ?Sized = Self, Diff = Self> {
     fn abs_error(&self, expected: &Rhs) -> ApproEqResult<Diff>;
 }
 
+#[cfg_attr(feature = "docs", stable(feature = "default", since = "0.2.0"))]
+pub trait AbsTolerance<Diff = Self> {
+    #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.2.0"))]
+    fn abs_tolerance() -> Diff;
+}
+
+#[cfg_attr(feature = "docs", stable(feature = "default", since = "0.2.0"))]
+pub trait RelTolerance<Diff = Self> {
+    #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.2.0"))]
+    fn rel_tolerance() -> Diff;
+}
+
 #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.1.0"))]
 pub trait Tolerance<Diff = Self> {
     #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.1.0"))]
     fn tolerance() -> Diff;
 }
 
+#[cfg_attr(feature = "docs", stable(feature = "default", since = "0.2.0"))]
+impl<Diff: Tolerance<Diff>> AbsTolerance<Diff> for Diff {
+    fn abs_tolerance() -> Diff {
+        Diff::tolerance()
+    }
+}
+
+#[cfg_attr(feature = "docs", stable(feature = "default", since = "0.2.0"))]
+impl<Diff: Tolerance<Diff>> RelTolerance<Diff> for Diff {
+    fn rel_tolerance() -> Diff {
+        Diff::tolerance()
+    }
+}
+
 /// Trait for approximately equality comparisons.
 #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.1.0"))]
 pub trait AbsApproEqWithTol<Rhs: ?Sized = Self, Diff = Self> {
@@ -179,10 +205,10 @@ pub trait AbsApproEq<Rhs: ?Sized = Self, Diff = Self> {
 }
 
 #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.1.0"))]
-impl<Rhs, Diff: PartialOrd + Tolerance<Diff>, T: AbsApproEqWithTol<Rhs, Diff>> AbsApproEq<Rhs, Diff>
+impl<Rhs, Diff: PartialOrd + AbsTolerance<Diff>, T: AbsApproEqWithTol<Rhs, Diff>> AbsApproEq<Rhs, Diff>
     for T {
     fn abs_appro_eq(&self, other: &Rhs) -> bool {
-        self.abs_appro_eq_with_tol(other, &Diff::tolerance())
+        self.abs_appro_eq_with_tol(other, &Diff::abs_tolerance())
     }
 }
 
@@ -234,13 +260,14 @@ pub trait RelApproEq<Rhs: ?Sized = Self, Diff = Self> {
 }
 
 #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.1.0"))]
-impl<Rhs, Diff: PartialOrd + Tolerance<Diff>, T: RelApproEqWithTol<Rhs, Diff>> RelApproEq<Rhs, Diff>
+impl<Rhs, Diff: PartialOrd + RelTolerance<Diff>, T: RelApproEqWithTol<Rhs, Diff>> RelApproEq<Rhs, Diff>
     for T {
     fn rel_appro_eq(&self, other: &Rhs) -> bool {
-        self.rel_appro_eq_with_tol(other, &Diff::tolerance())
+        self.rel_appro_eq_with_tol(other, &Diff::rel_tolerance())
     }
 }
 
+/// tolerance is 1e-6 for f32
 #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.1.0"))]
 impl Tolerance for f32 {
     fn tolerance() -> f32 {
@@ -266,6 +293,7 @@ impl RelError for f32 {
     }
 }
 
+/// tolerance is 1e-6 for f64
 #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.1.0"))]
 impl Tolerance for f64 {
     fn tolerance() -> f64 {
@@ -330,6 +358,7 @@ impl RelError<f32, f32> for f64 {
 macro_rules! itype_impls {
     ($($T:ty)+) => {
         $(
+            /// tolerance is zero for $T
             #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.1.0"))]
             impl Tolerance for $T {
                 fn tolerance() -> $T {
@@ -597,10 +626,19 @@ impl<A: ?Sized, D: PartialOrd, B: RelError<A, D> + ?Sized> RelError<RefCell<A>,
     }
 }
 
+/// absolute tolerance is 1s for Duration
+#[cfg_attr(feature = "docs", stable(feature = "default", since = "0.2.0"))]
+impl AbsTolerance for Duration {
+    fn abs_tolerance() -> Duration {
+        Duration::new(1, 0) // 1s
+    }
+}
+
+/// relative tolerance is 1ms(1/1000) for Duration
 #[cfg_attr(feature = "docs", stable(feature = "default", since = "0.2.0"))]
-impl Tolerance for Duration {
-    fn tolerance() -> Duration {
-        Duration::new(0, 1000000)
+impl RelTolerance for Duration {
+    fn rel_tolerance() -> Duration {
+        Duration::new(0, 1000000) // 1ms (1/1000)
     }
 }