1 files changed, 126 insertions, 0 deletions
diff --git a/ext/webidl/00_webidl.js b/ext/webidl/00_webidl.js
index 1d05aae5f..eb18cbcc3 100644
--- a/ext/webidl/00_webidl.js
+++ b/ext/webidl/00_webidl.js
@@ -26,6 +26,7 @@ const {
   Float32Array,
   Float64Array,
   FunctionPrototypeBind,
+  FunctionPrototypeCall,
   Int16Array,
   Int32Array,
   Int8Array,
@@ -77,6 +78,7 @@ const {
   StringPrototypeToWellFormed,
   Symbol,
   SymbolIterator,
+  SymbolAsyncIterator,
   SymbolToStringTag,
   TypedArrayPrototypeGetBuffer,
   TypedArrayPrototypeGetSymbolToStringTag,
@@ -920,6 +922,127 @@ function createSequenceConverter(converter) {
   };
 }
 
+function isAsyncIterable(obj) {
+  if (obj[SymbolAsyncIterator] === undefined) {
+    if (obj[SymbolIterator] === undefined) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+const AsyncIterable = Symbol("[[asyncIterable]]");
+
+function createAsyncIterableConverter(converter) {
+  return function (
+    V,
+    prefix = undefined,
+    context = undefined,
+    opts = { __proto__: null },
+  ) {
+    if (type(V) !== "Object") {
+      throw makeException(
+        TypeError,
+        "can not be converted to async iterable.",
+        prefix,
+        context,
+      );
+    }
+
+    let isAsync = true;
+    let method = V[SymbolAsyncIterator];
+    if (method === undefined) {
+      method = V[SymbolIterator];
+
+      if (method === undefined) {
+        throw makeException(
+          TypeError,
+          "is not iterable.",
+          prefix,
+          context,
+        );
+      }
+
+      isAsync = false;
+    }
+
+    return {
+      value: V,
+      [AsyncIterable]: AsyncIterable,
+      open(context) {
+        const iter = FunctionPrototypeCall(method, V);
+        if (type(iter) !== "Object") {
+          throw new TypeError(
+            `${context} could not be iterated because iterator method did not return object, but ${
+              type(iter)
+            }.`,
+          );
+        }
+
+        let asyncIterator = iter;
+
+        if (!isAsync) {
+          asyncIterator = {
+            // deno-lint-ignore require-await
+            async next() {
+              // deno-lint-ignore prefer-primordials
+              return iter.next();
+            },
+          };
+        }
+
+        return {
+          async next() {
+            // deno-lint-ignore prefer-primordials
+            const iterResult = await asyncIterator.next();
+            if (type(iterResult) !== "Object") {
+              throw TypeError(
+                `${context} failed to iterate next value because the next() method did not return an object, but ${
+                  type(iterResult)
+                }.`,
+              );
+            }
+
+            if (iterResult.done) {
+              return { done: true };
+            }
+
+            const iterValue = converter(
+              iterResult.value,
+              `${context} failed to iterate next value`,
+              `The value returned from the next() method`,
+              opts,
+            );
+
+            return { done: false, value: iterValue };
+          },
+          async return(reason) {
+            if (asyncIterator.return === undefined) {
+              return undefined;
+            }
+
+            // deno-lint-ignore prefer-primordials
+            const returnPromiseResult = await asyncIterator.return(reason);
+            if (type(returnPromiseResult) !== "Object") {
+              throw TypeError(
+                `${context} failed to close iterator because the return() method did not return an object, but ${
+                  type(returnPromiseResult)
+                }.`,
+              );
+            }
+
+            return undefined;
+          },
+          [SymbolAsyncIterator]() {
+            return this;
+          },
+        };
+      },
+    };
+  };
+}
+
 function createRecordConverter(keyConverter, valueConverter) {
   return (V, prefix, context, opts) => {
     if (type(V) !== "Object") {
@@ -1302,9 +1425,11 @@ function setlike(obj, objPrototype, readonly) {
 
 export {
   assertBranded,
+  AsyncIterable,
   brand,
   configureInterface,
   converters,
+  createAsyncIterableConverter,
   createBranded,
   createDictionaryConverter,
   createEnumConverter,
@@ -1315,6 +1440,7 @@ export {
   createSequenceConverter,
   illegalConstructor,
   invokeCallbackFunction,
+  isAsyncIterable,
   makeException,
   mixinPairIterable,
   requiredArguments,