2 files changed, 50 insertions, 0 deletions
diff --git a/third_party/rust/uniffi-example-arithmetic/src/arithmetic.udl b/third_party/rust/uniffi-example-arithmetic/src/arithmetic.udl
new file mode 100644
index 0000000000..117df4834a
--- /dev/null
+++ b/third_party/rust/uniffi-example-arithmetic/src/arithmetic.udl
@@ -0,0 +1,16 @@
+[Error]
+enum ArithmeticError {
+  "IntegerOverflow",
+};
+
+namespace arithmetic {
+  [Throws=ArithmeticError]
+  u64 add(u64 a, u64 b);
+
+  [Throws=ArithmeticError]
+  u64 sub(u64 a, u64 b);
+
+  u64 div(u64 dividend, u64 divisor);
+
+  boolean equal(u64 a, u64 b);
+};
diff --git a/third_party/rust/uniffi-example-arithmetic/src/lib.rs b/third_party/rust/uniffi-example-arithmetic/src/lib.rs
new file mode 100644
index 0000000000..92ab8c072b
--- /dev/null
+++ b/third_party/rust/uniffi-example-arithmetic/src/lib.rs
@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#[derive(Debug, thiserror::Error)]
+pub enum ArithmeticError {
+    #[error("Integer overflow on an operation with {a} and {b}")]
+    IntegerOverflow { a: u64, b: u64 },
+}
+
+fn add(a: u64, b: u64) -> Result<u64> {
+    a.checked_add(b)
+        .ok_or(ArithmeticError::IntegerOverflow { a, b })
+}
+
+fn sub(a: u64, b: u64) -> Result<u64> {
+    a.checked_sub(b)
+        .ok_or(ArithmeticError::IntegerOverflow { a, b })
+}
+
+fn div(dividend: u64, divisor: u64) -> u64 {
+    if divisor == 0 {
+        panic!("Can't divide by zero");
+    }
+    dividend / divisor
+}
+
+fn equal(a: u64, b: u64) -> bool {
+    a == b
+}
+
+type Result<T, E = ArithmeticError> = std::result::Result<T, E>;
+
+uniffi::include_scaffolding!("arithmetic");