Add callbacks-example fixture from uniffi-rs

fixtures/callbacks-example/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "uniffi-example-callbacks"
+edition = "2021"
+version = "0.22.0"
+license = "MPL-2.0"
+publish = false
+
+[lib]
+crate-type = ["lib", "cdylib"]
+name = "callbacks"
+
+[dependencies]
+uniffi = { workspace = true }
+thiserror = "1.0"
+
+[build-dependencies]
+uniffi = { workspace = true, features = ["build"] }
+
+[dev-dependencies]
+uniffi = { workspace = true, features = ["bindgen-tests"] }

fixtures/callbacks-example/README.md

@@ -0,0 +1,5 @@
+This is an example of UniFFI "callbacks".
+
+Callbacks are the ability to implement Rust traits in foreign languages. These are defined by
+[normal UniFFI traits](../../docs/manual/src/foreign_traits.md) or via  ["callback" definitions](../../docs/manual/src/udl/callback_interfaces.md).
+

fixtures/callbacks-example/build.rs

@@ -0,0 +1,9 @@
+/*
+ * 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/
+ */
+
+fn main() {
+    uniffi::generate_scaffolding("src/callbacks.udl").unwrap();
+}

fixtures/callbacks-example/src/callbacks.udl

@@ -0,0 +1,28 @@
+namespace callbacks {
+  // `get_sim_cards` is defined via a procmacro.
+};
+
+// This trait is implemented in Rust and in foreign bindings.
+[Trait, WithForeign]
+interface SimCard {
+  string name(); // The name of the carrier/provider.
+};
+
+[Error]
+enum TelephoneError {
+  "Busy",
+  "InternalTelephoneError",
+};
+
+interface Telephone {
+  constructor();
+  [Throws=TelephoneError]
+  string call(SimCard sim, CallAnswerer answerer);
+};
+
+// callback interfaces are discouraged now that foreign code can
+// implement traits, but here's one!
+callback interface CallAnswerer {
+  [Throws=TelephoneError]
+  string answer();
+};

fixtures/callbacks-example/src/lib.rs

@@ -0,0 +1,94 @@
+/*
+ * 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/
+ */
+
+use std::sync::Arc;
+
+#[derive(Debug, thiserror::Error)]
+pub enum TelephoneError {
+    #[error("Busy")]
+    Busy,
+    #[error("InternalTelephoneError")]
+    InternalTelephoneError,
+}
+
+// Need to implement this From<> impl in order to handle unexpected callback errors.  See the
+// Callback Interfaces section of the handbook for more info.
+impl From<uniffi::UnexpectedUniFFICallbackError> for TelephoneError {
+    fn from(_: uniffi::UnexpectedUniFFICallbackError) -> Self {
+        Self::InternalTelephoneError
+    }
+}
+
+// SIM cards.
+pub trait SimCard: Send + Sync {
+    fn name(&self) -> String;
+}
+
+struct RustySim;
+impl SimCard for RustySim {
+    fn name(&self) -> String {
+        "rusty!".to_string()
+    }
+}
+
+// namespace functions.
+#[uniffi::export]
+fn get_sim_cards() -> Vec<Arc<dyn SimCard>> {
+    vec![Arc::new(RustySim {})]
+}
+
+// The call-answer, callback interface.
+pub trait CallAnswerer {
+    fn answer(&self) -> Result<String, TelephoneError>;
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct Telephone;
+impl Telephone {
+    pub fn new() -> Self {
+        Self {}
+    }
+
+    pub fn call(
+        &self,
+        // Traits are Arc<>, callbacks Box<>.
+        sim: Arc<dyn SimCard>,
+        answerer: Box<dyn CallAnswerer>,
+    ) -> Result<String, TelephoneError> {
+        if sim.name() != "rusty!" {
+            Ok(format!("{} est bon marché", sim.name()))
+        } else {
+            answerer.answer()
+        }
+    }
+}
+
+// Some proc-macro definitions of the same thing.
+#[derive(uniffi::Object, Debug, Default, Clone)]
+pub struct FancyTelephone;
+
+#[uniffi::export]
+impl FancyTelephone {
+    #[uniffi::constructor]
+    pub fn new() -> Arc<Self> {
+        Arc::new(Self)
+    }
+
+    // Exact same signature as the UDL version.
+    pub fn call(
+        &self,
+        sim: Arc<dyn SimCard>,
+        answerer: Box<dyn CallAnswerer>,
+    ) -> Result<String, TelephoneError> {
+        if sim.name() != "rusty!" {
+            Ok(format!("{} est bon marché", sim.name()))
+        } else {
+            answerer.answer()
+        }
+    }
+}
+
+uniffi::include_scaffolding!("callbacks");

fixtures/callbacks-example/tests/bindings/test_callbacks_example.ts

@@ -0,0 +1,69 @@
+/*
+ * 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/
+ */
+
+import generated, {
+  CallAnswerer,
+  Telephone,
+  getSimCards,
+  SimCard,
+  TelephoneError,
+} from "../../generated/callbacks";
+import { test } from "@/asserts";
+
+// This is only needed in tests.
+generated.initialize();
+
+class SomeOtherError extends Error {}
+
+// Simple example just to see it work.
+// Pass in a string, get a string back.
+// Pass in nothing, get unit back.
+class CallAnswererImpl implements CallAnswerer {
+  constructor(private mode: string) {}
+  answer(): string {
+    if (this.mode === "normal") {
+      return "Bonjour";
+    } else if (this.mode === "busy") {
+      throw new TelephoneError.Busy("I'm busy");
+    } else {
+      throw new SomeOtherError();
+    }
+  }
+}
+
+test("A Rust sim, with a Typescript call answerer", (t) => {
+  const telephone = new Telephone();
+  const sim = getSimCards()[0];
+  t.assertEqual(telephone.call(sim, new CallAnswererImpl("normal")), "Bonjour");
+  telephone.uniffiDestroy();
+});
+
+// Our own sim.
+class Sim implements SimCard {
+  name(): string {
+    return "typescript";
+  }
+}
+test("A typescript sim with a typescript answerer", (t) => {
+  const telephone = new Telephone();
+  t.assertEqual(
+    telephone.call(new Sim(), new CallAnswererImpl("normal")),
+    "typescript est bon marché",
+  );
+  telephone.uniffiDestroy();
+});
+
+test("Errors are serialized and returned", (t) => {
+  const telephone = new Telephone();
+  const sim = getSimCards()[0];
+  t.assertThrows(TelephoneError.Busy.instanceOf, () =>
+    telephone.call(sim, new CallAnswererImpl("busy")),
+  );
+  t.assertThrows(TelephoneError.InternalTelephoneError.instanceOf, () =>
+    telephone.call(sim, new CallAnswererImpl("something-else")),
+  );
+  telephone.uniffiDestroy();
+});

fixtures/callbacks-example/tests/test_generated_bindings.rs

@@ -0,0 +1,5 @@
+/*
+ * 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/
+ */

fixtures/callbacks-regression/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "uniffi-example-callbacks"
+name = "uniffi-example-callbacks-deadlock-regression"
 edition = "2021"
 version = "0.22.0"
 license = "MPL-2.0"