Implement ECMA262's normative PR 2600 (#3633)

core/engine/src/builtins/iterable/async_from_sync_iterator.rs

@@ -10,7 +10,7 @@ use crate::{
     object::{FunctionObjectBuilder, JsObject},
     realm::Realm,
     string::utf16,
-    Context, JsArgs, JsData, JsResult, JsValue,
+    Context, JsArgs, JsData, JsError, JsNativeError, JsResult, JsValue,
 };
 use boa_gc::{Finalize, Trace};
 use boa_profiler::Profiler;
@@ -129,8 +129,14 @@ impl AsyncFromSyncIterator {
         // 7. IfAbruptRejectPromise(result, promiseCapability).
         let result = if_abrupt_reject_promise!(result, promise_capability, context);
 
-        // 8. Return AsyncFromSyncIteratorContinuation(result, promiseCapability).
+        // 8. Return AsyncFromSyncIteratorContinuation(result, promiseCapability, syncIteratorRecord, true).
-        Self::continuation(&result, &promise_capability, context)
+        Self::continuation(
+            &result,
+            &promise_capability,
+            sync_iterator_record,
+            true,
+            context,
+        )
     }
 
     /// `%AsyncFromSyncIteratorPrototype%.return ( [ value ] )`
@@ -142,14 +148,15 @@ impl AsyncFromSyncIterator {
     fn r#return(this: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
         // 1. Let O be the this value.
         // 2. Assert: O is an Object that has a [[SyncIteratorRecord]] internal slot.
-        // 4. Let syncIterator be O.[[SyncIteratorRecord]].[[Iterator]].
+        // 4. Let syncIteratorRecord be O.[[SyncIteratorRecord]].
-        let sync_iterator = this
+        let sync_iterator_record = this
             .as_object()
             .and_then(JsObject::downcast_ref::<Self>)
             .expect("async from sync iterator prototype must be object")
             .sync_iterator_record
-            .iterator()
             .clone();
+        // 5. Let syncIterator be syncIteratorRecord.[[Iterator]].
+        let sync_iterator = sync_iterator_record.iterator().clone();
 
         // 3. Let promiseCapability be ! NewPromiseCapability(%Promise%).
         let promise_capability = PromiseCapability::new(
@@ -158,14 +165,14 @@ impl AsyncFromSyncIterator {
         )
         .expect("cannot fail with promise constructor");
 
-        // 5. Let return be Completion(GetMethod(syncIterator, "return")).
+        // 6. Let return be Completion(GetMethod(syncIterator, "return")).
         let r#return = sync_iterator.get_method(utf16!("return"), context);
 
-        // 6. IfAbruptRejectPromise(return, promiseCapability).
+        // 7. IfAbruptRejectPromise(return, promiseCapability).
         let r#return = if_abrupt_reject_promise!(r#return, promise_capability, context);
 
         let result = match (r#return, args.first()) {
-            // 7. If return is undefined, then
+            // 8. If return is undefined, then
             (None, _) => {
                 // a. Let iterResult be CreateIterResultObject(value, true).
                 let iter_result =
@@ -180,27 +187,33 @@ impl AsyncFromSyncIterator {
                 // c. Return promiseCapability.[[Promise]].
                 return Ok(promise_capability.promise().clone().into());
             }
-            // 8. If value is present, then
+            // 9. If value is present, then
             (Some(r#return), Some(value)) => {
                 // a. Let result be Completion(Call(return, syncIterator, « value »)).
                 r#return.call(&sync_iterator.clone().into(), &[value.clone()], context)
             }
-            // 9. Else,
+            // 10. Else,
             (Some(r#return), None) => {
                 // a. Let result be Completion(Call(return, syncIterator)).
                 r#return.call(&sync_iterator.clone().into(), &[], context)
             }
         };
 
-        // 11. If Type(result) is not Object, then
+        // 12. If Type(result) is not Object, then
         //     a. Perform ! Call(promiseCapability.[[Reject]], undefined, « a newly created TypeError object »).
         let result = result.and_then(IteratorResult::from_value);
 
-        // 10. IfAbruptRejectPromise(result, promiseCapability).
+        // 11. IfAbruptRejectPromise(result, promiseCapability).
         let result = if_abrupt_reject_promise!(result, promise_capability, context);
 
-        // 12. Return AsyncFromSyncIteratorContinuation(result, promiseCapability).
+        // 13. Return AsyncFromSyncIteratorContinuation(result, promiseCapability, syncIteratorRecord, false).
-        Self::continuation(&result, &promise_capability, context)
+        Self::continuation(
+            &result,
+            &promise_capability,
+            sync_iterator_record,
+            false,
+            context,
+        )
     }
 
     /// `%AsyncFromSyncIteratorPrototype%.throw ( [ value ] )`
@@ -212,14 +225,15 @@ impl AsyncFromSyncIterator {
     fn throw(this: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
         // 1. Let O be the this value.
         // 2. Assert: O is an Object that has a [[SyncIteratorRecord]] internal slot.
-        // 4. Let syncIterator be O.[[SyncIteratorRecord]].[[Iterator]].
+        // 4. Let syncIteratorRecord be O.[[SyncIteratorRecord]].
-        let sync_iterator = this
+        let sync_iterator_record = this
             .as_object()
             .and_then(JsObject::downcast_ref::<Self>)
             .expect("async from sync iterator prototype must be object")
             .sync_iterator_record
-            .iterator()
             .clone();
+        // 5. Let syncIterator be syncIteratorRecord.[[Iterator]].
+        let sync_iterator = sync_iterator_record.iterator().clone();
 
         // 3. Let promiseCapability be ! NewPromiseCapability(%Promise%).
         let promise_capability = PromiseCapability::new(
@@ -228,49 +242,67 @@ impl AsyncFromSyncIterator {
         )
         .expect("cannot fail with promise constructor");
 
-        // 5. Let throw be Completion(GetMethod(syncIterator, "throw")).
+        // 6. Let throw be Completion(GetMethod(syncIterator, "throw")).
         let throw = sync_iterator.get_method(utf16!("throw"), context);
 
-        // 6. IfAbruptRejectPromise(throw, promiseCapability).
+        // 7. IfAbruptRejectPromise(throw, promiseCapability).
         let throw = if_abrupt_reject_promise!(throw, promise_capability, context);
 
         let result = match (throw, args.first()) {
-            // 7. If throw is undefined, then
+            // 8. If throw is undefined, then
             (None, _) => {
-                // a. Perform ! Call(promiseCapability.[[Reject]], undefined, « value »).
+                // a. NOTE: If syncIterator does not have a throw method, close it to give it a chance to clean up before we reject the capability.
+                // b. Let closeCompletion be NormalCompletion(empty).
+                // c. Let result be Completion(IteratorClose(syncIteratorRecord, closeCompletion)).
+                let result = sync_iterator_record.close(Ok(JsValue::undefined()), context);
+                // d. IfAbruptRejectPromise(result, promiseCapability).
+                if_abrupt_reject_promise!(result, promise_capability, context);
+
+                // e. NOTE: The next step throws a TypeError to indicate that there was a protocol violation: syncIterator does not have a throw method.
+                // f. NOTE: If closing syncIterator does not throw then the result of that operation is ignored, even if it yields a rejected promise.
+                // g. Perform ! Call(promiseCapability.[[Reject]], undefined, « a newly created TypeError object »).
                 promise_capability
                     .reject()
                     .call(
-                        &JsValue::Undefined,
+                        &JsValue::undefined(),
-                        &[args.get_or_undefined(0).clone()],
+                        &[JsNativeError::typ()
+                            .with_message("sync iterator does not have a throw method")
+                            .to_opaque(context)
+                            .into()],
                         context,
                     )
                     .expect("cannot fail according to spec");
 
-                // b. Return promiseCapability.[[Promise]].
+                // h. Return promiseCapability.[[Promise]].
                 return Ok(promise_capability.promise().clone().into());
             }
-            // 8. If value is present, then
+            // 9. If value is present, then
             (Some(throw), Some(value)) => {
                 // a. Let result be Completion(Call(throw, syncIterator, « value »)).
                 throw.call(&sync_iterator.clone().into(), &[value.clone()], context)
             }
-            // 9. Else,
+            // 10. Else,
             (Some(throw), None) => {
                 // a. Let result be Completion(Call(throw, syncIterator)).
                 throw.call(&sync_iterator.clone().into(), &[], context)
             }
         };
 
-        // 11. If Type(result) is not Object, then
+        // 12. If Type(result) is not Object, then
         // a. Perform ! Call(promiseCapability.[[Reject]], undefined, « a newly created TypeError object »).
         let result = result.and_then(IteratorResult::from_value);
 
-        // 10. IfAbruptRejectPromise(result, promiseCapability).
+        // 11. IfAbruptRejectPromise(result, promiseCapability).
         let result = if_abrupt_reject_promise!(result, promise_capability, context);
 
-        // 12. Return AsyncFromSyncIteratorContinuation(result, promiseCapability).
+        // 13. Return Return AsyncFromSyncIteratorContinuation(result, promiseCapability, syncIteratorRecord, true).
-        Self::continuation(&result, &promise_capability, context)
+        Self::continuation(
+            &result,
+            &promise_capability,
+            sync_iterator_record,
+            true,
+            context,
+        )
     }
 
     /// `AsyncFromSyncIteratorContinuation ( result, promiseCapability )`
@@ -282,6 +314,8 @@ impl AsyncFromSyncIterator {
     fn continuation(
         result: &IteratorResult,
         promise_capability: &PromiseCapability,
+        sync_iterator_record: IteratorRecord,
+        close_on_rejection: bool,
         context: &mut Context,
     ) -> JsResult<JsValue> {
         // 1. NOTE: Because promiseCapability is derived from the intrinsic %Promise%,
@@ -301,18 +335,28 @@ impl AsyncFromSyncIterator {
         let value = if_abrupt_reject_promise!(value, promise_capability, context);
 
         // 6. Let valueWrapper be Completion(PromiseResolve(%Promise%, value)).
-        let value_wrapper = Promise::promise_resolve(
+        let value_wrapper = match Promise::promise_resolve(
             &context.intrinsics().constructors().promise().constructor(),
             value,
             context,
-        );
+        ) {
+            // 7. If valueWrapper is an abrupt completion, done is false, and closeOnRejection is
+            //    true, then
+            Err(e) if !done && close_on_rejection => {
+                // a. Set valueWrapper to Completion(IteratorClose(syncIteratorRecord, valueWrapper)).
+                Err(sync_iterator_record.close(Err(e), context).expect_err(
+                    "closing an iterator with an error must always return an error back",
+                ))
+            }
+            other => other,
+        };
 
-        // 7. IfAbruptRejectPromise(valueWrapper, promiseCapability).
+        // 8. IfAbruptRejectPromise(valueWrapper, promiseCapability).
         let value_wrapper = if_abrupt_reject_promise!(value_wrapper, promise_capability, context);
 
-        // 8. Let unwrap be a new Abstract Closure with parameters (value)
+        // 9. Let unwrap be a new Abstract Closure with parameters (value)
         // that captures done and performs the following steps when called:
-        // 9. Let onFulfilled be CreateBuiltinFunction(unwrap, 1, "", « »).
+        // 10. Let onFulfilled be CreateBuiltinFunction(unwrap, 1, "", « »).
         let on_fulfilled = FunctionObjectBuilder::new(
             context.realm(),
             NativeFunction::from_copy_closure(move |_this, args, context| {
@@ -328,20 +372,51 @@ impl AsyncFromSyncIterator {
         .length(1)
         .build();
 
-        // 10. NOTE: onFulfilled is used when processing the "value" property of an
+        // 11. NOTE: onFulfilled is used when processing the "value" property of an
         // IteratorResult object in order to wait for its value if it is a promise and
         // re-package the result in a new "unwrapped" IteratorResult object.
 
-        // 11. Perform PerformPromiseThen(valueWrapper, onFulfilled, undefined, promiseCapability).
+        // 12. If done is true, or if closeOnRejection is false, then
+        let on_rejected = if done || !close_on_rejection {
+            // a. Let onRejected be undefined.
+            None
+        } else {
+            // 13. Else,
+            //     a. Let closeIterator be a new Abstract Closure with parameters (error) that
+            //        captures syncIteratorRecord and performs the following steps when called:
+            //     b. Let onRejected be CreateBuiltinFunction(closeIterator, 1, "", « »).
+            //     c. NOTE: onRejected is used to close the Iterator when the "value" property of an
+            //        IteratorResult object it yields is a rejected promise.
+            Some(
+                FunctionObjectBuilder::new(
+                    context.realm(),
+                    NativeFunction::from_copy_closure_with_captures(
+                        |_this, args, iter, context| {
+                            // i. Return ? IteratorClose(syncIteratorRecord, ThrowCompletion(error)).
+                            iter.close(
+                                Err(JsError::from_opaque(args.get_or_undefined(0).clone())),
+                                context,
+                            )
+                        },
+                        sync_iterator_record,
+                    ),
+                )
+                .name("")
+                .length(1)
+                .build(),
+            )
+        };
+
+        // 14. Perform PerformPromiseThen(valueWrapper, onFulfilled, undefined, promiseCapability).
         Promise::perform_promise_then(
             &value_wrapper,
             Some(on_fulfilled),
-            None,
+            on_rejected,
             Some(promise_capability.clone()),
             context,
         );
 
-        // 12. Return promiseCapability.[[Promise]].
+        // 15. Return promiseCapability.[[Promise]].
         Ok(promise_capability.promise().clone().into())
     }
 }