From 7cb6623488e8b79f1b703c71fc0ac0c3a12d15e9 Mon Sep 17 00:00:00 2001
From: Ry Dahl <ry@tinyclouds.org>
Date: Mon, 23 Dec 2019 08:16:01 -0500
Subject: [PATCH] Add Isolate::throw_exception (#123)

---
 src/binding.cc    |  5 +++++
 src/isolate.rs    | 18 ++++++++++++++++++
 tests/test_api.rs | 24 ++++++++++++++++++++++++
 3 files changed, 47 insertions(+)

diff --git a/src/binding.cc b/src/binding.cc
index 2d265bcb..8ebe6577 100644
--- a/src/binding.cc
+++ b/src/binding.cc
@@ -88,6 +88,11 @@ bool v8__Isolate__AddMessageListener(v8::Isolate& isolate,
   return isolate.AddMessageListener(callback);
 }
 
+v8::Value* v8__Isolate__ThrowException(v8::Isolate& isolate,
+                                       v8::Value* exception) {
+  return local_to_ptr(isolate.ThrowException(ptr_to_local(exception)));
+}
+
 v8::Isolate::CreateParams* v8__Isolate__CreateParams__NEW() {
   return new v8::Isolate::CreateParams();
 }
diff --git a/src/isolate.rs b/src/isolate.rs
index 82d2b887..4bbd7279 100644
--- a/src/isolate.rs
+++ b/src/isolate.rs
@@ -33,6 +33,10 @@ extern "C" {
     isolate: *mut Isolate,
     callback: PromiseRejectCallback,
   );
+  fn v8__Isolate__ThrowException(
+    isolate: &Isolate,
+    exception: &Value,
+  ) -> *mut Value;
 
   fn v8__Isolate__CreateParams__NEW() -> *mut CreateParams;
   fn v8__Isolate__CreateParams__DELETE(this: &mut CreateParams);
@@ -124,6 +128,20 @@ impl Isolate {
     unsafe { v8__Isolate__SetPromiseRejectCallback(self, callback) }
   }
 
+  /// Schedules an exception to be thrown when returning to JavaScript. When an
+  /// exception has been scheduled it is illegal to invoke any JavaScript
+  /// operation; the caller must return immediately and only after the exception
+  /// has been handled does it become legal to invoke JavaScript operations.
+  pub fn throw_exception<'sc>(
+    &self,
+    exception: Local<'_, Value>,
+  ) -> Local<'sc, Value> {
+    unsafe {
+      let ptr = v8__Isolate__ThrowException(self, &exception);
+      Local::from_raw(ptr).unwrap()
+    }
+  }
+
   /// Disposes the isolate.  The isolate must not be entered by any
   /// thread to be disposable.
   pub unsafe fn dispose(&mut self) {
diff --git a/tests/test_api.rs b/tests/test_api.rs
index 2567d287..3c629308 100644
--- a/tests/test_api.rs
+++ b/tests/test_api.rs
@@ -282,6 +282,30 @@ fn try_catch() {
   });
 }
 
+#[test]
+fn throw_exception() {
+  let _g = setup();
+  let mut params = v8::Isolate::create_params();
+  params.set_array_buffer_allocator(v8::Allocator::new_default_allocator());
+  let isolate = v8::Isolate::new(params);
+  let mut locker = v8::Locker::new(&isolate);
+  v8::HandleScope::enter(&mut locker, |scope| {
+    let mut context = v8::Context::new(scope);
+    context.enter();
+    {
+      let mut try_catch = v8::TryCatch::new(scope);
+      let tc = try_catch.enter();
+      isolate.throw_exception(v8_str(scope, "boom").into());
+      assert!(tc.has_caught());
+      assert!(tc
+        .exception()
+        .unwrap()
+        .strict_equals(v8_str(scope, "boom").into()));
+    };
+    context.exit();
+  });
+}
+
 #[test]
 fn isolate_add_message_listener() {
   let g = setup();