Add conversion for SharedArrayBuffer

And remove the `allowShared` option from `conversions.ArrayBuffer`.

Follows whatwg/webidl#1311.

Also fixes a bug in the SharedArrayBuffer conversion.

Author: MattiasBuelens

lib/index.js

@@ -338,9 +338,6 @@ function isArrayBufferDetached(value) {
 
 exports.ArrayBuffer = (value, options = {}) => {
   if (!isNonSharedArrayBuffer(value)) {
-    if (options.allowShared && !isSharedArrayBuffer(value)) {
-      throw makeException(TypeError, "is not an ArrayBuffer or SharedArrayBuffer", options);
-    }
     throw makeException(TypeError, "is not an ArrayBuffer", options);
   }
   if (isArrayBufferDetached(value)) {
@@ -350,6 +347,17 @@ exports.ArrayBuffer = (value, options = {}) => {
   return value;
 };
 
+exports.SharedArrayBuffer = (value, options = {}) => {
+  if (!isSharedArrayBuffer(value)) {
+    throw makeException(TypeError, "is not a SharedArrayBuffer", options);
+  }
+  if (isArrayBufferDetached(value)) {
+    throw makeException(TypeError, "is a detached SharedArrayBuffer", options);
+  }
+
+  return value;
+};
+
 const dvByteLengthGetter =
     Object.getOwnPropertyDescriptor(DataView.prototype, "byteLength").get;
 exports.DataView = (value, options = {}) => {
@@ -358,15 +366,7 @@ exports.DataView = (value, options = {}) => {
   } catch (e) {
     throw makeException(TypeError, "is not a DataView", options);
   }
-
-  if (!options.allowShared && isSharedArrayBuffer(value.buffer)) {
-    throw makeException(TypeError, "is backed by a SharedArrayBuffer, which is not allowed", options);
-  }
-  if (isArrayBufferDetached(value.buffer)) {
-    throw makeException(TypeError, "is backed by a detached ArrayBuffer", options);
-  }
-
-  return value;
+  return exports.ArrayBufferView(value, options);
 };
 
 // Returns the unforgeable `TypedArray` constructor name or `undefined`,
@@ -394,14 +394,7 @@ const typedArrayNameGetter = Object.getOwnPropertyDescriptor(
     if (!ArrayBuffer.isView(value) || typedArrayNameGetter.call(value) !== name) {
       throw makeException(TypeError, `is not ${article} ${name} object`, options);
     }
-    if (!options.allowShared && isSharedArrayBuffer(value.buffer)) {
-      throw makeException(TypeError, "is a view on a SharedArrayBuffer, which is not allowed", options);
-    }
-    if (isArrayBufferDetached(value.buffer)) {
-      throw makeException(TypeError, "is a view on a detached ArrayBuffer", options);
-    }
-
-    return value;
+    return exports.ArrayBufferView(value, options);
   };
 });
 
@@ -424,27 +417,20 @@ exports.ArrayBufferView = (value, options = {}) => {
 
 exports.BufferSource = (value, options = {}) => {
   if (ArrayBuffer.isView(value)) {
-    if (!options.allowShared && isSharedArrayBuffer(value.buffer)) {
-      throw makeException(TypeError, "is a view on a SharedArrayBuffer, which is not allowed", options);
-    }
-
-    if (isArrayBufferDetached(value.buffer)) {
-      throw makeException(TypeError, "is a view on a detached ArrayBuffer", options);
-    }
-    return value;
+    return exports.ArrayBufferView(value, options);
   }
 
-  if (!options.allowShared && !isNonSharedArrayBuffer(value)) {
-    throw makeException(TypeError, "is not an ArrayBuffer or a view on one", options);
+  if (isNonSharedArrayBuffer(value)) {
+    return exports.ArrayBuffer(value, options);
+  } else if (options.allowShared && isSharedArrayBuffer(value)) {
+    return exports.SharedArrayBuffer(value, options);
   }
-  if (options.allowShared && !isSharedArrayBuffer(value) && !isNonSharedArrayBuffer(value)) {
+
+  if (options.allowShared) {
     throw makeException(TypeError, "is not an ArrayBuffer, SharedArrayBuffer, or a view on one", options);
+  } else {
+    throw makeException(TypeError, "is not an ArrayBuffer or a view on one", options);
   }
-  if (isArrayBufferDetached(value)) {
-    throw makeException(TypeError, "is a detached ArrayBuffer", options);
-  }
-
-  return value;
 };
 
 exports.DOMTimeStamp = exports["unsigned long long"];

test/buffer-source.js

@@ -111,6 +111,13 @@ if (typeof SharedArrayBuffer === "function") {
     label: "SharedArrayBuffer same realm",
     creator: () => new SharedArrayBuffer(0)
   });
+  bufferSourceCreators.push({
+    typeName: "SharedArrayBuffer",
+    isShared: true,
+    isDetached: false,
+    label: "SharedArrayBuffer different realm",
+    creator: () => vm.runInContext(`new SharedArrayBuffer(0)`, differentRealm)
+  });
 }
 
 for (const constructor of bufferSourceConstructors) {
@@ -213,6 +220,27 @@ for (const type of bufferSourceConstructors) {
   });
 }
 
+if (typeof SharedArrayBuffer === "function") {
+  const typeName = "SharedArrayBuffer";
+  const sut = conversions[typeName];
+
+  describe(`WebIDL SharedArrayBuffer type`, () => {
+    for (const innerType of bufferSourceCreators) {
+      const testFunction =
+        innerType.typeName === typeName &&
+        innerType.isShared &&
+        !innerType.isDetached &&
+        !innerType.isForged ?
+          testOk :
+          testNotOk;
+
+      testFunction(innerType.label, sut, innerType.creator);
+    }
+
+    commonNotOk(sut);
+  });
+}
+
 describe("WebIDL ArrayBufferView type", () => {
   const sut = conversions.ArrayBufferView;