feat(ffi-iterator): Implementation of Iterator in Rust (1/4)

ffi/Cargo.toml

@@ -31,6 +31,7 @@ chrono = "0.4.42"
 oxhttp = "0.3.1"
 # Optional dependencies
 env_logger = { workspace = true, optional = true }
+derive-where = "1.6.0"
 
 [target.'cfg(unix)'.dependencies]
 tikv-jemallocator = "0.6.0"

ffi/src/iterator.rs

@@ -0,0 +1,35 @@
+// Copyright (C) 2025, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE.md for licensing terms.
+
+use std::ops::{Deref, DerefMut};
+
+use derive_where::derive_where;
+use firewood::v2::api::BoxKeyValueIter;
+
+/// An opaque wrapper around a [`BoxKeyValueIter`].
+#[derive_where(Debug)]
+#[derive_where(skip_inner)]
+pub struct IteratorHandle<'view>(BoxKeyValueIter<'view>);
+
+impl<'view> From<BoxKeyValueIter<'view>> for IteratorHandle<'view> {
+    fn from(value: BoxKeyValueIter<'view>) -> Self {
+        IteratorHandle(value)
+    }
+}
+
+impl<'view> Deref for IteratorHandle<'view> {
+    type Target = BoxKeyValueIter<'view>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for IteratorHandle<'_> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+#[derive(Debug)]
+pub struct CreateIteratorResult<'db>(pub IteratorHandle<'db>);