Move RngReader to rand

Author: dhardy

rand_core/src/lib.rs

@@ -534,41 +534,6 @@ pub trait SeedableRng: Sized {
     }
 }
 
-/// Adapter to support [`std::io::Read`] over a [`TryRngCore`]
-///
-/// # Examples
-///
-/// ```no_run
-/// use std::{io, io::Read};
-/// use std::fs::File;
-/// use rand_core::{OsRng, RngReader};
-///
-/// io::copy(
-///     &mut RngReader(OsRng).take(100),
-///     &mut File::create("/tmp/random.bytes").unwrap()
-/// ).unwrap();
-/// ```
-#[cfg(feature = "std")]
-pub struct RngReader<R: TryRngCore>(pub R);
-
-#[cfg(feature = "std")]
-impl<R: TryRngCore> std::io::Read for RngReader<R> {
-    #[inline]
-    fn read(&mut self, buf: &mut [u8]) -> Result<usize, std::io::Error> {
-        self.0
-            .try_fill_bytes(buf)
-            .map_err(|err| std::io::Error::other(std::format!("RNG error: {err}")))?;
-        Ok(buf.len())
-    }
-}
-
-#[cfg(feature = "std")]
-impl<R: TryRngCore> std::fmt::Debug for RngReader<R> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_tuple("RngReader").finish()
-    }
-}
-
 #[cfg(test)]
 mod test {
     use super::*;
@@ -729,35 +694,4 @@ mod test {
         }
         assert_eq!(rng.next_u32(), 4);
     }
-
-    struct StepRng(u32, u32);
-    impl RngCore for StepRng {
-        fn next_u32(&mut self) -> u32 {
-            let x = self.0;
-            self.0 += self.1;
-            x
-        }
-        fn next_u64(&mut self) -> u64 {
-            le::next_u64_via_u32(self)
-        }
-        fn fill_bytes(&mut self, dest: &mut [u8]) {
-            le::fill_bytes_via_next(self, dest);
-        }
-    }
-
-    #[cfg(feature = "std")]
-    #[test]
-    fn rng_reader() {
-        use std::io::Read;
-
-        let mut rng = StepRng(255, 1);
-        let mut buf = [0u8; 16];
-        let expected = [255, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 2, 1, 0, 0];
-
-        RngReader(&mut rng).read_exact(&mut buf).unwrap();
-        assert_eq!(&buf, &expected);
-
-        RngReader(StepRng(255, 1)).read_exact(&mut buf).unwrap();
-        assert_eq!(&buf, &expected);
-    }
 }

src/lib.rs

@@ -129,6 +129,41 @@ pub use rng::{Fill, Rng};
 #[cfg(feature = "thread_rng")]
 use crate::distr::{Distribution, StandardUniform};
 
+/// Adapter to support [`std::io::Read`] over a [`TryRngCore`]
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::{io, io::Read};
+/// use std::fs::File;
+/// use rand::{rngs::OsRng, RngReader};
+///
+/// io::copy(
+///     &mut RngReader(OsRng).take(100),
+///     &mut File::create("/tmp/random.bytes").unwrap()
+/// ).unwrap();
+/// ```
+#[cfg(feature = "std")]
+pub struct RngReader<R: TryRngCore>(pub R);
+
+#[cfg(feature = "std")]
+impl<R: TryRngCore> std::io::Read for RngReader<R> {
+    #[inline]
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize, std::io::Error> {
+        self.0
+            .try_fill_bytes(buf)
+            .map_err(|err| std::io::Error::other(std::format!("RNG error: {err}")))?;
+        Ok(buf.len())
+    }
+}
+
+#[cfg(feature = "std")]
+impl<R: TryRngCore> std::fmt::Debug for RngReader<R> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_tuple("RngReader").finish()
+    }
+}
+
 /// Generate a random value using the thread-local random number generator.
 ///
 /// This function is shorthand for <code>[rng()].[random()](Rng::random)</code>:
@@ -337,6 +372,24 @@ mod test {
         }
     }
 
+    #[cfg(feature = "std")]
+    #[test]
+    fn rng_reader() {
+        use std::io::Read;
+
+        let mut rng = StepRng(255, 1);
+        let mut buf = [0u8; 24];
+        let expected = [
+            255, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0,
+        ];
+
+        RngReader(&mut rng).read_exact(&mut buf).unwrap();
+        assert_eq!(&buf, &expected);
+
+        RngReader(StepRng(255, 1)).read_exact(&mut buf).unwrap();
+        assert_eq!(&buf, &expected);
+    }
+
     #[test]
     #[cfg(feature = "thread_rng")]
     fn test_random() {