Rework FloatOrd with total_cmp() and hash by bits

crates/bevy_math/src/float_ord.rs

@@ -10,12 +10,8 @@ use bevy_reflect::Reflect;
 /// A wrapper for floats that implements [`Ord`], [`Eq`], and [`Hash`] traits.
 ///
 /// This is a work around for the fact that the IEEE 754-2008 standard,
-/// implemented by Rust's [`f32`] type,
-/// doesn't define an ordering for [`NaN`](f32::NAN),
-/// and `NaN` is not considered equal to any other `NaN`.
-///
-/// Wrapping a float with `FloatOrd` breaks conformance with the standard
-/// by sorting `NaN` as less than all other numbers and equal to any other `NaN`.
+/// implemented by Rust's [`f32`] type, doesn't define an ordering for
+/// [`NaN`](f32::NAN).
 #[derive(Debug, Copy, Clone)]
 #[cfg_attr(
     feature = "bevy_reflect",
@@ -28,63 +24,25 @@ impl PartialOrd for FloatOrd {
     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
         Some(self.cmp(other))
     }
-
-    fn lt(&self, other: &Self) -> bool {
-        !other.le(self)
-    }
-    // If `self` is NaN, it is equal to another NaN and less than all other floats, so return true.
-    // If `self` isn't NaN and `other` is, the float comparison returns false, which match the `FloatOrd` ordering.
-    // Otherwise, a standard float comparison happens.
-    fn le(&self, other: &Self) -> bool {
-        self.0.is_nan() || self.0 <= other.0
-    }
-    fn gt(&self, other: &Self) -> bool {
-        !self.le(other)
-    }
-    fn ge(&self, other: &Self) -> bool {
-        other.le(self)
-    }
 }
 
 impl Ord for FloatOrd {
-    #[expect(
-        clippy::comparison_chain,
-        reason = "This can't be rewritten with `match` and `cmp`, as this is `cmp` itself."
-    )]
     fn cmp(&self, other: &Self) -> Ordering {
-        if self > other {
-            Ordering::Greater
-        } else if self < other {
-            Ordering::Less
-        } else {
-            Ordering::Equal
-        }
+        self.0.total_cmp(&other.0)
     }
 }
 
 impl PartialEq for FloatOrd {
     fn eq(&self, other: &Self) -> bool {
-        if self.0.is_nan() {
-            other.0.is_nan()
-        } else {
-            self.0 == other.0
-        }
+        matches!(self.cmp(other), Ordering::Equal)
     }
 }
 
 impl Eq for FloatOrd {}
 
 impl Hash for FloatOrd {
     fn hash<H: Hasher>(&self, state: &mut H) {
-        if self.0.is_nan() {
-            // Ensure all NaN representations hash to the same value
-            state.write(&f32::to_ne_bytes(f32::NAN));
-        } else if self.0 == 0.0 {
-            // Ensure both zeroes hash to the same value
-            state.write(&f32::to_ne_bytes(0.0f32));
-        } else {
-            state.write(&f32::to_ne_bytes(self.0));
-        }
+        self.0.to_bits().hash(state);
     }
 }
 
@@ -118,8 +76,8 @@ mod tests {
     fn float_ord_cmp() {
         assert_eq!(NAN.cmp(&NAN), Ordering::Equal);
 
-        assert_eq!(NAN.cmp(&ZERO), Ordering::Less);
-        assert_eq!(ZERO.cmp(&NAN), Ordering::Greater);
+        assert_ne!(NAN.cmp(&ZERO), Ordering::Equal);
+        assert_ne!(ZERO.cmp(&NAN), Ordering::Equal);
 
         assert_eq!(ZERO.cmp(&ZERO), Ordering::Equal);
         assert_eq!(ONE.cmp(&ZERO), Ordering::Greater);
@@ -133,51 +91,24 @@ mod tests {
     )]
     fn float_ord_cmp_operators() {
         assert!(!(NAN < NAN));
-        assert!(NAN < ZERO);
-        assert!(!(ZERO < NAN));
+        assert_ne!(NAN, ZERO);
         assert!(!(ZERO < ZERO));
         assert!(ZERO < ONE);
         assert!(!(ONE < ZERO));
 
         assert!(!(NAN > NAN));
-        assert!(!(NAN > ZERO));
-        assert!(ZERO > NAN);
         assert!(!(ZERO > ZERO));
         assert!(!(ZERO > ONE));
         assert!(ONE > ZERO);
 
         assert!(NAN <= NAN);
-        assert!(NAN <= ZERO);
-        assert!(!(ZERO <= NAN));
         assert!(ZERO <= ZERO);
         assert!(ZERO <= ONE);
         assert!(!(ONE <= ZERO));
 
         assert!(NAN >= NAN);
-        assert!(!(NAN >= ZERO));
-        assert!(ZERO >= NAN);
         assert!(ZERO >= ZERO);
         assert!(!(ZERO >= ONE));
         assert!(ONE >= ZERO);
     }
-
-    #[cfg(feature = "std")]
-    #[test]
-    fn float_ord_hash() {
-        let hash = |num| {
-            let mut h = std::hash::DefaultHasher::new();
-            FloatOrd(num).hash(&mut h);
-            h.finish()
-        };
-
-        assert_ne!((-0.0f32).to_bits(), 0.0f32.to_bits());
-        assert_eq!(hash(-0.0), hash(0.0));
-
-        let nan_1 = f32::from_bits(0b0111_1111_1000_0000_0000_0000_0000_0001);
-        assert!(nan_1.is_nan());
-        let nan_2 = f32::from_bits(0b0111_1111_1000_0000_0000_0000_0000_0010);
-        assert!(nan_2.is_nan());
-        assert_ne!(nan_1.to_bits(), nan_2.to_bits());
-        assert_eq!(hash(nan_1), hash(nan_2));
-    }
 }