Add optional support for borsh serialisation

Cargo.toml

@@ -16,6 +16,8 @@ tinyvec_macros = { version = "0.1", optional = true }
 serde = { version = "1.0", optional = true, default-features = false }
 # Provides derived `Arbitrary` implementations
 arbitrary = { version = "1", optional = true }
+# Provides `BorshSerialize` and `BorshDeserialize implementations
+borsh = { version = "1.2.0", optional = true, default-features = false }
 
 [features]
 default = []
@@ -63,7 +65,7 @@ experimental_write_impl = []
 real_blackbox = ["criterion/real_blackbox"]
 
 [package.metadata.docs.rs]
-features = ["alloc", "std", "grab_spare_slice", "rustc_1_55", "serde"]
+features = ["alloc", "std", "grab_spare_slice", "rustc_1_55", "serde", "borsh"]
 rustdoc-args = ["--cfg","docs_rs"]
 
 [package.metadata.playground]

src/arrayvec.rs

@@ -218,6 +218,53 @@ where
   }
 }
 
+#[cfg(feature = "borsh")]
+#[cfg_attr(docs_rs, doc(cfg(feature = "borsh")))]
+impl<A: Array> borsh::BorshSerialize for ArrayVec<A>
+where
+  <A as Array>::Item: borsh::BorshSerialize,
+{
+  fn serialize<W: borsh::io::Write>(
+    &self, writer: &mut W,
+  ) -> borsh::io::Result<()> {
+    <usize as borsh::BorshSerialize>::serialize(&self.len(), writer)?;
+    for elem in self.iter() {
+      <<A as Array>::Item as borsh::BorshSerialize>::serialize(elem, writer)?;
+    }
+    Ok(())
+  }
+}
+
+#[cfg(feature = "borsh")]
+#[cfg_attr(docs_rs, doc(cfg(feature = "borsh")))]
+impl<A: Array> borsh::BorshDeserialize for ArrayVec<A>
+where
+  <A as Array>::Item: borsh::BorshDeserialize,
+{
+  fn deserialize_reader<R: borsh::io::Read>(
+    reader: &mut R,
+  ) -> borsh::io::Result<Self> {
+    let len = <usize as borsh::BorshDeserialize>::deserialize_reader(reader)?;
+    let mut new_arrayvec = Self::default();
+
+    for idx in 0..len {
+      let value =
+        <<A as Array>::Item as borsh::BorshDeserialize>::deserialize_reader(
+          reader,
+        )?;
+      if idx >= new_arrayvec.capacity() {
+        return Err(borsh::io::Error::new(
+          borsh::io::ErrorKind::InvalidData,
+          "invalid ArrayVec length",
+        ));
+      }
+      new_arrayvec.push(value)
+    }
+
+    Ok(new_arrayvec)
+  }
+}
+
 #[cfg(feature = "arbitrary")]
 #[cfg_attr(docs_rs, doc(cfg(feature = "arbitrary")))]
 impl<'a, A> arbitrary::Arbitrary<'a> for ArrayVec<A>

src/lib.rs

@@ -44,6 +44,9 @@
 //! * `serde` provides a `Serialize` and `Deserialize` implementation for
 //!   [`TinyVec`] and [`ArrayVec`] types, provided the inner item also has an
 //!   implementation.
+//! * `borsh` provides a `BorshSerialize` and `BorshDeserialize` implementation
+//!   for [`TinyVec`] and [`ArrayVec`] types, provided the inner item also has
+//!   an implementation.
 //!
 //! ## API
 //! The general goal of the crate is that, as much as possible, the vecs here

src/tinyvec.rs

@@ -223,6 +223,47 @@ where
   }
 }
 
+#[cfg(feature = "borsh")]
+#[cfg_attr(docs_rs, doc(cfg(feature = "borsh")))]
+impl<A: Array> borsh::BorshSerialize for TinyVec<A>
+where
+  <A as Array>::Item: borsh::BorshSerialize,
+{
+  fn serialize<W: borsh::io::Write>(
+    &self, writer: &mut W,
+  ) -> borsh::io::Result<()> {
+    <usize as borsh::BorshSerialize>::serialize(&self.len(), writer)?;
+    for elem in self.iter() {
+      <<A as Array>::Item as borsh::BorshSerialize>::serialize(elem, writer)?;
+    }
+    Ok(())
+  }
+}
+
+#[cfg(feature = "borsh")]
+#[cfg_attr(docs_rs, doc(cfg(feature = "borsh")))]
+impl<A: Array> borsh::BorshDeserialize for TinyVec<A>
+where
+  <A as Array>::Item: borsh::BorshDeserialize,
+{
+  fn deserialize_reader<R: borsh::io::Read>(
+    reader: &mut R,
+  ) -> borsh::io::Result<Self> {
+    let len = <usize as borsh::BorshDeserialize>::deserialize_reader(reader)?;
+    let mut new_tinyvec = Self::with_capacity(len);
+
+    for _ in 0..len {
+      new_tinyvec.push(
+        <<A as Array>::Item as borsh::BorshDeserialize>::deserialize_reader(
+          reader,
+        )?,
+      )
+    }
+
+    Ok(new_tinyvec)
+  }
+}
+
 #[cfg(feature = "arbitrary")]
 #[cfg_attr(docs_rs, doc(cfg(feature = "arbitrary")))]
 impl<'a, A> arbitrary::Arbitrary<'a> for TinyVec<A>

tests/arrayvec.rs

@@ -446,6 +446,28 @@ fn ArrayVec_ser_de() {
   );
 }
 
+#[cfg(feature = "borsh")]
+#[test]
+fn ArrayVec_borsh_de_empty() {
+  let tv: ArrayVec<[i32; 0]> = Default::default();
+  let buffer = borsh::to_vec(&tv).unwrap();
+  let des: ArrayVec<[i32; 0]> = borsh::from_slice(&buffer).unwrap();
+  assert_eq!(tv, des);
+}
+
+#[cfg(feature = "borsh")]
+#[test]
+fn ArrayVec_borsh_de() {
+  let mut tv: ArrayVec<[i32; 4]> = Default::default();
+  tv.push(1);
+  tv.push(2);
+  tv.push(3);
+  tv.push(4);
+  let buffer = borsh::to_vec(&tv).unwrap();
+  let des: ArrayVec<[i32; 4]> = borsh::from_slice(&buffer).unwrap();
+  assert_eq!(tv, des);
+}
+
 #[test]
 fn ArrayVec_try_from_slice() {
   use std::convert::TryFrom;

tests/tinyvec.rs

@@ -443,6 +443,39 @@ fn TinyVec_ser_de_heap() {
   );
 }
 
+#[cfg(feature = "borsh")]
+#[test]
+fn TinyVec_borsh_de_empty() {
+  let tv: ArrayVec<[i32; 0]> = Default::default();
+  let buffer = borsh::to_vec(&tv).unwrap();
+  let des: ArrayVec<[i32; 0]> = borsh::from_slice(&buffer).unwrap();
+  assert_eq!(tv, des);
+}
+
+#[cfg(feature = "borsh")]
+#[test]
+fn TinyVec_borsh_de() {
+  let mut tv: ArrayVec<[i32; 4]> = Default::default();
+  tv.push(1);
+  tv.push(2);
+  tv.push(3);
+  tv.push(4);
+  let buffer = borsh::to_vec(&tv).unwrap();
+  let des: ArrayVec<[i32; 4]> = borsh::from_slice(&buffer).unwrap();
+  assert_eq!(tv, des);
+}
+
+#[cfg(feature = "borsh")]
+#[test]
+fn TinyVec_borsh_de_heap() {
+  let mut tv: TinyVec<[i32; 4]> = tiny_vec![1, 2, 3, 4];
+  tv.move_to_the_heap();
+
+  let buffer = borsh::to_vec(&tv).unwrap();
+  let des: TinyVec<[i32; 4]> = borsh::from_slice(&buffer).unwrap();
+  assert_eq!(tv, des);
+}
+
 #[test]
 fn TinyVec_pretty_debug() {
   let tv: TinyVec<[i32; 6]> = tiny_vec![1, 2, 3];