Implement Distribution for Range(Inclusive)

Author: Ralith

src/distributions/uniform.rs

@@ -290,6 +290,19 @@ impl<X: SampleUniform> From<::core::ops::RangeInclusive<X>> for Uniform<X> {
     }
 }
 
+impl<T: SampleUniform> Distribution<T> for ::core::ops::Range<T> {
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> T {
+        T::Sampler::sample_single(&self.start, &self.end, rng)
+    }
+}
+
+#[cfg(rustc_1_27)]
+impl<T: SampleUniform> Distribution<T> for ::core::ops::RangeInclusive<T> {
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> T {
+        Uniform::new_inclusive(self.start(), self.end()).sample(rng)
+    }
+}
+
 /// Helper trait similar to [`Borrow`] but implemented
 /// only for SampleUniform and references to SampleUniform in
 /// order to resolve ambiguity issues.
@@ -1279,6 +1292,17 @@ mod tests {
         assert_eq!(r.inner.scale, 5.0);
     }
 
+    #[test]
+    fn test_std_range_distribution() {
+        let mut rng = ::test::rng(474);
+        for _ in 0..100 {
+            let x = rng.sample(0..10);
+            assert!(x >= 0 && x < 10);
+            let x = rng.sample(0..=10);
+            assert!(x >= 0 && x <= 10);
+        }
+    }
+
     #[cfg(rustc_1_27)]
     #[test]
     fn test_uniform_from_std_range_inclusive() {