From 847c12c9de2213463aaac11ff2a95a133300b04b Mon Sep 17 00:00:00 2001
From: Mateusz Kowalczyk <fuuzetsu@fuuzetsu.co.uk>
Date: Tue, 28 Nov 2023 08:47:36 +0900
Subject: [PATCH] Add optional support for borsh serialisation

Behind a feature flag.
---
 Cargo.toml                             |   3 +-
 src/array_borsh.rs                     | 101 +++++++++++++++++++++++++
 src/lib.rs                             |   2 +
 xtest-serialization/Cargo.toml         |   6 +-
 xtest-serialization/tests/serialize.rs |  70 +++++++++++++++++
 5 files changed, 180 insertions(+), 2 deletions(-)
 create mode 100644 src/array_borsh.rs

diff --git a/Cargo.toml b/Cargo.toml
index a648b09bc..324b93d67 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -43,6 +43,7 @@ libc = { version = "0.2.82", optional = true }
 
 matrixmultiply = { version = "0.3.2", default-features = false, features=["cgemm"] }
 
+borsh = { version = "1.2", optional = true, default-features = false }
 serde = { version = "1.0", optional = true, default-features = false, features = ["alloc"] }
 rawpointer = { version = "0.2" }
 
@@ -66,7 +67,7 @@ serde-1 = ["serde"]
 test = []
 
 # This feature is used for docs
-docs = ["approx", "approx-0_5", "serde", "rayon"]
+docs = ["approx", "approx-0_5", "serde", "borsh", "rayon"]
 
 std = ["num-traits/std", "matrixmultiply/std"]
 rayon = ["rayon_", "std"]
diff --git a/src/array_borsh.rs b/src/array_borsh.rs
new file mode 100644
index 000000000..abe3550de
--- /dev/null
+++ b/src/array_borsh.rs
@@ -0,0 +1,101 @@
+use crate::imp_prelude::*;
+use crate::IntoDimension;
+use alloc::vec::Vec;
+use borsh::{BorshDeserialize, BorshSerialize};
+use core::ops::Deref;
+
+/// **Requires crate feature `"borsh"`**
+impl<I> BorshSerialize for Dim<I>
+where
+    I: BorshSerialize,
+{
+    fn serialize<W: borsh::io::Write>(&self, writer: &mut W) -> borsh::io::Result<()> {
+        <I as BorshSerialize>::serialize(&self.ix(), writer)
+    }
+}
+
+/// **Requires crate feature `"borsh"`**
+impl<I> BorshDeserialize for Dim<I>
+where
+    I: BorshDeserialize,
+{
+    fn deserialize_reader<R: borsh::io::Read>(reader: &mut R) -> borsh::io::Result<Self> {
+        <I as BorshDeserialize>::deserialize_reader(reader).map(Dim::new)
+    }
+}
+
+/// **Requires crate feature `"borsh"`**
+impl BorshSerialize for IxDyn {
+    fn serialize<W: borsh::io::Write>(&self, writer: &mut W) -> borsh::io::Result<()> {
+        let elts = self.ix().deref();
+        // Output length of dimensions.
+        <usize as BorshSerialize>::serialize(&elts.len(), writer)?;
+        // Followed by actual data.
+        for elt in elts {
+            <Ix as BorshSerialize>::serialize(elt, writer)?;
+        }
+        Ok(())
+    }
+}
+
+/// **Requires crate feature `"borsh"`**
+impl BorshDeserialize for IxDyn {
+    fn deserialize_reader<R: borsh::io::Read>(reader: &mut R) -> borsh::io::Result<Self> {
+        // Deserialize the length.
+        let len = <usize as BorshDeserialize>::deserialize_reader(reader)?;
+        // Deserialize the given number of elements. We assume the source is
+        // trusted so we use a capacity hint...
+        let mut elts = Vec::with_capacity(len);
+        for _ix in 0..len {
+            elts.push(<Ix as BorshDeserialize>::deserialize_reader(reader)?);
+        }
+        Ok(elts.into_dimension())
+    }
+}
+
+/// **Requires crate feature `"borsh"`**
+impl<A, D, S> BorshSerialize for ArrayBase<S, D>
+where
+    A: BorshSerialize,
+    D: Dimension + BorshSerialize,
+    S: Data<Elem = A>,
+{
+    fn serialize<W: borsh::io::Write>(&self, writer: &mut W) -> borsh::io::Result<()> {
+        // Dimensions
+        <D as BorshSerialize>::serialize(&self.raw_dim(), writer)?;
+        // Followed by length of data
+        let iter = self.iter();
+        <usize as BorshSerialize>::serialize(&iter.len(), writer)?;
+        // Followed by data itself.
+        for elt in iter {
+            <A as BorshSerialize>::serialize(elt, writer)?;
+        }
+        Ok(())
+    }
+}
+
+/// **Requires crate feature `"borsh"`**
+impl<A, D, S> BorshDeserialize for ArrayBase<S, D>
+where
+    A: BorshDeserialize,
+    D: BorshDeserialize + Dimension,
+    S: DataOwned<Elem = A>,
+{
+    fn deserialize_reader<R: borsh::io::Read>(reader: &mut R) -> borsh::io::Result<Self> {
+        // Dimensions
+        let dim = <D as BorshDeserialize>::deserialize_reader(reader)?;
+        // Followed by length of data
+        let len = <usize as BorshDeserialize>::deserialize_reader(reader)?;
+        // Followed by data itself.
+        let mut data = Vec::with_capacity(len);
+        for _ix in 0..len {
+            data.push(<A as BorshDeserialize>::deserialize_reader(reader)?);
+        }
+        ArrayBase::from_shape_vec(dim, data).map_err(|_shape_err| {
+            borsh::io::Error::new(
+                borsh::io::ErrorKind::InvalidData,
+                "data and dimensions must match in size",
+            )
+        })
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 07e5ed680..b09f526b2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -164,6 +164,8 @@ mod aliases;
 #[macro_use]
 mod itertools;
 mod argument_traits;
+#[cfg(feature = "borsh")]
+mod array_borsh;
 #[cfg(feature = "serde")]
 mod array_serde;
 mod arrayformat;
diff --git a/xtest-serialization/Cargo.toml b/xtest-serialization/Cargo.toml
index 857e31fe6..8754d598e 100644
--- a/xtest-serialization/Cargo.toml
+++ b/xtest-serialization/Cargo.toml
@@ -8,7 +8,7 @@ publish = false
 test = false
 
 [dependencies]
-ndarray = { path = "..", features = ["serde"] }
+ndarray = { path = "..", features = ["serde", "borsh"] }
 
 [features]
 default = ["ron"]
@@ -23,6 +23,10 @@ version = "1.0.40"
 [dev-dependencies.rmp-serde]
 version = "0.14.0"
 
+[dev-dependencies.borsh]
+version = "1.2"
+default-features = false
+
 [dependencies.ron]
 version = "0.5.1"
 optional = true
diff --git a/xtest-serialization/tests/serialize.rs b/xtest-serialization/tests/serialize.rs
index efb3bacd9..6bed21149 100644
--- a/xtest-serialization/tests/serialize.rs
+++ b/xtest-serialization/tests/serialize.rs
@@ -9,6 +9,8 @@ extern crate rmp_serde;
 #[cfg(feature = "ron")]
 extern crate ron;
 
+extern crate borsh;
+
 use ndarray::{arr0, arr1, arr2, s, ArcArray, ArcArray2, ArrayD, IxDyn};
 
 #[test]
@@ -218,3 +220,71 @@ fn serial_many_dim_ron() {
         assert_eq!(a, a_de);
     }
 }
+
+#[test]
+fn serial_ixdyn_borsh() {
+    {
+        let a = arr0::<f32>(2.72).into_dyn();
+        let serial = borsh::to_vec(&a).unwrap();
+        println!("Borsh encode {:?} => {:?}", a, serial);
+        let res = borsh::from_slice::<ArcArray<f32, _>>(&serial);
+        println!("{:?}", res);
+        assert_eq!(a, res.unwrap());
+    }
+
+    {
+        let a = arr1::<f32>(&[2.72, 1., 2.]).into_dyn();
+        let serial = borsh::to_vec(&a).unwrap();
+        println!("Borsh encode {:?} => {:?}", a, serial);
+        let res = borsh::from_slice::<ArrayD<f32>>(&serial);
+        println!("{:?}", res);
+        assert_eq!(a, res.unwrap());
+    }
+
+    {
+        let a = arr2(&[[3., 1., 2.2], [3.1, 4., 7.]])
+            .into_shape(IxDyn(&[3, 1, 1, 1, 2, 1]))
+            .unwrap();
+        let serial = borsh::to_vec(&a).unwrap();
+        println!("Borsh encode {:?} => {:?}", a, serial);
+        let res = borsh::from_slice::<ArrayD<f32>>(&serial);
+        println!("{:?}", res);
+        assert_eq!(a, res.unwrap());
+    }
+}
+
+#[test]
+fn serial_many_dim_borsh() {
+    use borsh::from_slice as borsh_deserialize;
+    use borsh::to_vec as borsh_serialize;
+
+    {
+        let a = arr0::<f32>(2.72);
+        let a_s = borsh_serialize(&a).unwrap();
+        let a_de: ArcArray<f32, _> = borsh_deserialize(&a_s).unwrap();
+        assert_eq!(a, a_de);
+    }
+
+    {
+        let a = arr1::<f32>(&[2.72, 1., 2.]);
+        let a_s = borsh_serialize(&a).unwrap();
+        let a_de: ArcArray<f32, _> = borsh_deserialize(&a_s).unwrap();
+        assert_eq!(a, a_de);
+    }
+
+    {
+        let a = arr2(&[[3., 1., 2.2], [3.1, 4., 7.]]);
+        let a_s = borsh_serialize(&a).unwrap();
+        let a_de: ArcArray<f32, _> = borsh_deserialize(&a_s).unwrap();
+        assert_eq!(a, a_de);
+    }
+
+    {
+        // Test a sliced array.
+        let mut a = ArcArray::linspace(0., 31., 32).reshape((2, 2, 2, 4));
+        a.slice_collapse(s![..;-1, .., .., ..2]);
+        let a_s = borsh_serialize(&a).unwrap();
+        let a_de: ArcArray<f32, _> = borsh_deserialize(&a_s).unwrap();
+        assert_eq!(a, a_de);
+    }
+}

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