feat(neon): Implement TryIntoJs/TryFromJs for either::Either

crates/neon/Cargo.toml

@@ -24,6 +24,7 @@ easy-cast = "0.5.2"  # used for a doc example
 nodejs-sys = "0.15.0"
 
 [dependencies]
+either = "1.13.0"
 getrandom = { version = "0.2.11", optional = true }
 libloading = "0.8.1"
 linkme = "0.3.25"

crates/neon/src/types_impl/extract/either.rs

@@ -0,0 +1,115 @@
+use std::{any, error, fmt};
+
+use either::Either;
+
+use crate::{
+    context::Cx,
+    handle::Handle,
+    object::Object,
+    result::{JsResult, NeonResult},
+    types::{
+        extract::{private, TryFromJs, TryIntoJs},
+        JsError, JsValue,
+    },
+};
+
+impl<'cx, L, R> TryFromJs<'cx> for Either<L, R>
+where
+    L: TryFromJs<'cx>,
+    R: TryFromJs<'cx>,
+{
+    type Error = Error<L::Error, R::Error>;
+
+    fn try_from_js(
+        cx: &mut Cx<'cx>,
+        v: Handle<'cx, JsValue>,
+    ) -> NeonResult<Result<Self, Self::Error>> {
+        let left = match L::try_from_js(cx, v)? {
+            Ok(l) => return Ok(Ok(Either::Left(l))),
+            Err(l) => l,
+        };
+
+        let right = match R::try_from_js(cx, v)? {
+            Ok(r) => return Ok(Ok(Either::Right(r))),
+            Err(r) => r,
+        };
+
+        Ok(Err(Error::new::<L, R>(left, right)))
+    }
+}
+
+impl<'cx, L, R> TryIntoJs<'cx> for Either<L, R>
+where
+    L: TryIntoJs<'cx>,
+    R: TryIntoJs<'cx>,
+{
+    type Value = JsValue;
+
+    fn try_into_js(self, cx: &mut Cx<'cx>) -> JsResult<'cx, Self::Value> {
+        match self {
+            Either::Left(v) => v.try_into_js(cx).map(|v| v.upcast()),
+            Either::Right(v) => v.try_into_js(cx).map(|v| v.upcast()),
+        }
+    }
+}
+
+impl<L, R> private::Sealed for Either<L, R> {}
+
+#[derive(Debug)]
+pub struct Error<L, R> {
+    left: (&'static str, L),
+    right: (&'static str, R),
+}
+
+impl<'cx, L, R> Error<L, R> {
+    fn new<LT, RT>(left: L, right: R) -> Self
+    where
+        LT: TryFromJs<'cx, Error = L>,
+        RT: TryFromJs<'cx, Error = R>,
+    {
+        Self {
+            left: (any::type_name::<LT>(), left),
+            right: (any::type_name::<RT>(), right),
+        }
+    }
+}
+
+impl<L, R> fmt::Display for Error<L, R>
+where
+    L: fmt::Display,
+    R: fmt::Display,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        writeln!(f, "Either::Left: {}", self.left.1)?;
+        write!(f, "Either::Right: {}", self.right.1)
+    }
+}
+
+impl<L, R> error::Error for Error<L, R>
+where
+    L: error::Error,
+    R: error::Error,
+{
+}
+
+impl<'cx, L, R> TryIntoJs<'cx> for Error<L, R>
+where
+    L: TryIntoJs<'cx>,
+    R: TryIntoJs<'cx>,
+{
+    type Value = JsError;
+
+    fn try_into_js(self, cx: &mut Cx<'cx>) -> JsResult<'cx, Self::Value> {
+        let err = JsError::type_error(
+            cx,
+            format!("expected either {} or {}", self.left.0, self.right.0,),
+        )?;
+
+        err.prop(cx, "left").set(self.left.1)?;
+        err.prop(cx, "right").set(self.right.1)?;
+
+        Ok(err)
+    }
+}
+
+impl<L, R> private::Sealed for Error<L, R> {}

crates/neon/src/types_impl/extract/mod.rs

@@ -121,6 +121,7 @@ pub use self::json::Json;
 pub mod json;
 
 mod boxed;
+mod either;
 mod error;
 mod private;
 mod try_from_js;

test/napi/Cargo.toml

@@ -10,6 +10,7 @@ edition = "2021"
 crate-type = ["cdylib"]
 
 [dependencies]
+either = "1.13.0"
 num-bigint-dig = "0.8.4"
 once_cell = "1.18.0"
 tokio = { version = "1.34.0", features = ["rt-multi-thread"] }

test/napi/lib/extract.js

@@ -62,4 +62,20 @@ describe("Extractors", () => {
     assert.strictEqual(addon.extract_json_sum([1, 2, 3, 4]), 10);
     assert.strictEqual(addon.extract_json_sum([8, 16, 18]), 42);
   });
+
+  it("Either", () => {
+    assert.strictEqual(addon.extract_either("hello"), "String: hello");
+    assert.strictEqual(addon.extract_either(42), "Number: 42");
+
+    assert.throws(
+      () => addon.extract_either({}),
+      (err) => {
+        assert.match(err.message, /expected either.*String.*f64/);
+        assert.match(err.left.message, /expected string/);
+        assert.match(err.right.message, /expected number/);
+
+        return true;
+      }
+    );
+  });
 });

test/napi/src/js/extract.rs

@@ -1,3 +1,4 @@
+use either::Either;
 use neon::{prelude::*, types::extract::*};
 
 pub fn extract_values(mut cx: FunctionContext) -> JsResult<JsArray> {
@@ -136,3 +137,11 @@ pub fn extract_single_add_one(mut cx: FunctionContext) -> JsResult<JsNumber> {
 
     Ok(cx.number(n + 1.0))
 }
+
+#[neon::export]
+pub fn extract_either(either: Either<String, f64>) -> String {
+    match either {
+        Either::Left(s) => format!("String: {s}"),
+        Either::Right(n) => format!("Number: {n}"),
+    }
+}