Add method fn Generator::drop

Author: dhardy

CHANGELOG.md

@@ -16,6 +16,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Removed optional dependency `serde` ([#28])
 - Add `SeedableRng::fork` methods ([#17])
 - Rename trait `block::BlockRngCore` to `block::Generator` and associated type `Results` to `Output`; remove assoc. `type Item` and remove type bounds ([#26])
+- Add `fn drop` to trait `block::Generator` (#35)
+
 ### Other
 - Changed repository from [rust-random/rand] to [rust-random/core].
 
@@ -29,6 +31,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [#17]: https://github.com/rust-random/rand-core/pull/17
 [#26]: https://github.com/rust-random/rand-core/pull/28
 [#28]: https://github.com/rust-random/rand-core/pull/28
+[#35]: https://github.com/rust-random/rand-core/pull/35
 
 [rust-random/rand]: https://github.com/rust-random/rand
 [rust-random/core]: https://github.com/rust-random/core

src/block.rs

@@ -59,6 +59,15 @@ pub trait Generator {
     ///
     /// This must fill `output` with random data.
     fn generate(&mut self, output: &mut Self::Output);
+
+    /// Destruct the output buffer
+    ///
+    /// This method is called on [`Drop`] of the [`Self::Output`] buffer.
+    /// The default implementation does nothing.
+    #[inline]
+    fn drop(&mut self, output: &mut Self::Output) {
+        let _ = output;
+    }
 }
 
 /// A cryptographically secure generator
@@ -124,6 +133,12 @@ impl<G: Generator + fmt::Debug> fmt::Debug for BlockRng<G> {
     }
 }
 
+impl<G: Generator> Drop for BlockRng<G> {
+    fn drop(&mut self) {
+        self.core.drop(&mut self.results);
+    }
+}
+
 impl<const N: usize, G: Generator<Output = [u32; N]>> BlockRng<G> {
     /// Create a new `BlockRng` from an existing RNG implementing
     /// `Generator`. Results will be generated on first use.