From fd7c1313cf9976bd0f28e80f8dc976444fe51f6d Mon Sep 17 00:00:00 2001
From: Paul Dicker <pitdicker@gmail.com>
Date: Sun, 14 Jan 2018 15:53:10 +0100
Subject: [PATCH] Remove Reseeder trait

---
 src/lib.rs       | 16 +++++++--------
 src/reseeding.rs | 51 +++++++++++++-----------------------------------
 2 files changed, 22 insertions(+), 45 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index ce07b88eef9..ece97fac804 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -276,7 +276,7 @@ use prng::Isaac64Rng as IsaacWordRng;
 
 use distributions::{Range, IndependentSample};
 use distributions::range::SampleRange;
-#[cfg(feature="std")]use reseeding::{ReseedingRng, ReseedWithNew};
+#[cfg(feature="std")]use reseeding::{ReseedingRng};
 
 // public modules
 pub mod distributions;
@@ -942,20 +942,20 @@ pub fn weak_rng() -> XorShiftRng {
 #[cfg(feature="std")]
 #[derive(Clone, Debug)]
 pub struct ThreadRng {
-    rng: Rc<RefCell<ReseedingRng<StdRng, ReseedWithNew>>>,
+    rng: Rc<RefCell<ReseedingRng<StdRng, EntropySource>>>,
 }
 
 #[cfg(feature="std")]
 thread_local!(
-    static THREAD_RNG_KEY: Rc<RefCell<ReseedingRng<StdRng, ReseedWithNew>>> = {
+    static THREAD_RNG_KEY: Rc<RefCell<ReseedingRng<StdRng, EntropySource>>> = {
         const THREAD_RNG_RESEED_THRESHOLD: u64 = 32_768;
-        let r = match StdRng::new() {
-            Ok(r) => r,
-            Err(e) => panic!("could not initialize thread_rng: {:?}", e)
-        };
+        let mut entropy_source = EntropySource::new()
+            .expect("could not initialize thread_rng");
+        let r = StdRng::from_rng(&mut entropy_source)
+            .expect("could not initialize thread_rng");
         let rng = ReseedingRng::new(r,
                                     THREAD_RNG_RESEED_THRESHOLD,
-                                    ReseedWithNew);
+                                    entropy_source);
         Rc::new(RefCell::new(rng))
     }
 );
diff --git a/src/reseeding.rs b/src/reseeding.rs
index 1fdb5dc20b8..9af642c42a5 100644
--- a/src/reseeding.rs
+++ b/src/reseeding.rs
@@ -11,9 +11,7 @@
 //! A wrapper around another RNG that reseeds it after it
 //! generates a certain number of random bytes.
 
-use {Rng, Error};
-#[cfg(feature="std")]
-use NewSeeded;
+use {Rng, SeedableRng, Error};
 
 /// A wrapper around any RNG which reseeds the underlying RNG after it
 /// has generated a certain number of random bytes.
@@ -23,10 +21,10 @@ pub struct ReseedingRng<R, Rsdr> {
     generation_threshold: u64,
     bytes_generated: u64,
     /// Controls the behaviour when reseeding the RNG.
-    pub reseeder: Rsdr,
+    reseeder: Rsdr,
 }
 
-impl<R: Rng, Rsdr: Reseeder<R>> ReseedingRng<R, Rsdr> {
+impl<R: Rng+SeedableRng, Rsdr: Rng> ReseedingRng<R, Rsdr> {
     /// Create a new `ReseedingRng` with the given parameters.
     ///
     /// # Arguments
@@ -47,14 +45,14 @@ impl<R: Rng, Rsdr: Reseeder<R>> ReseedingRng<R, Rsdr> {
     /// generated exceed the threshold.
     pub fn reseed_if_necessary(&mut self) {
         if self.bytes_generated >= self.generation_threshold {
-            self.reseeder.reseed(&mut self.rng).unwrap();
+            R::from_rng(&mut self.reseeder).map(|result| self.rng = result).unwrap();
             self.bytes_generated = 0;
         }
     }
 }
 
 
-impl<R: Rng, Rsdr: Reseeder<R>> Rng for ReseedingRng<R, Rsdr> {
+impl<R: Rng+SeedableRng, Rsdr: Rng> Rng for ReseedingRng<R, Rsdr> {
     fn next_u32(&mut self) -> u32 {
         self.reseed_if_necessary();
         self.bytes_generated += 4;
@@ -80,35 +78,11 @@ impl<R: Rng, Rsdr: Reseeder<R>> Rng for ReseedingRng<R, Rsdr> {
     }
 }
 
-/// Something that can be used to reseed an RNG via `ReseedingRng`.
-///
-/// Note that implementations should support `Clone` only if reseeding is
-/// deterministic (no external entropy source). This is so that a `ReseedingRng`
-/// only supports `Clone` if fully deterministic.
-pub trait Reseeder<R: ?Sized> {
-    /// Reseed the given RNG.
-    ///
-    /// On error, this should just forward the source error; errors are handled
-    /// by the caller.
-    fn reseed(&mut self, rng: &mut R) -> Result<(), Error>;
-}
-
-/// Reseed an RNG using `NewSeeded` to replace the current instance.
-#[cfg(feature="std")]
-#[derive(Debug)]
-pub struct ReseedWithNew;
-
-#[cfg(feature="std")]
-impl<R: Rng + NewSeeded> Reseeder<R> for ReseedWithNew {
-    fn reseed(&mut self, rng: &mut R) -> Result<(), Error> {
-        R::new().map(|result| *rng = result)
-    }
-}
 
 #[cfg(test)]
 mod test {
     use {impls, le};
-    use super::{ReseedingRng, Reseeder};
+    use super::{ReseedingRng};
     use {SeedableRng, Rng, Error};
 
     struct Counter {
@@ -139,17 +113,20 @@ mod test {
     }
 
     #[derive(Debug, Clone)]
-    struct ReseedCounter;
-    impl Reseeder<Counter> for ReseedCounter {
-        fn reseed(&mut self, rng: &mut Counter) -> Result<(), Error> {
-            *rng = Counter { i: 0 };
+    struct ResetCounter;
+    impl Rng for ResetCounter {
+        fn next_u32(&mut self) -> u32 { unimplemented!() }
+        fn next_u64(&mut self) -> u64 { unimplemented!() }
+        fn fill_bytes(&mut self, _dest: &mut [u8]) { unimplemented!() }
+        fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
+            for i in dest.iter_mut() { *i = 0; }
             Ok(())
         }
     }
 
     #[test]
     fn test_reseeding() {
-        let mut rs = ReseedingRng::new(Counter {i:0}, 400, ReseedCounter);
+        let mut rs = ReseedingRng::new(Counter {i:0}, 400, ResetCounter);
 
         let mut i = 0;
         for _ in 0..1000 {