Implement ArrayBuffer.isView.

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/25700010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17121 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arraybuffer.js

@@ -81,6 +81,10 @@ function ArrayBufferSlice(start, end) {
   return result;
 }
 
+function ArrayBufferIsView(obj) {
+  return %ArrayBufferIsView(obj);
+}
+
 function SetUpArrayBuffer() {
   %CheckIsBootstrapping();
 
@@ -93,6 +97,10 @@ function SetUpArrayBuffer() {
 
   InstallGetter($ArrayBuffer.prototype, "byteLength", ArrayBufferGetByteLength);
 
+  InstallFunctions($ArrayBuffer, DONT_ENUM, $Array(
+      "isView", ArrayBufferIsView
+  ));
+
   InstallFunctions($ArrayBuffer.prototype, DONT_ENUM, $Array(
       "slice", ArrayBufferSlice
   ));

src/runtime.cc

@@ -801,6 +801,16 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_ArrayBufferSliceImpl) {
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_ArrayBufferIsView) {
+  HandleScope scope(isolate);
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_CHECKED(Object, object, 0);
+  return object->IsJSArrayBufferView()
+    ? isolate->heap()->true_value()
+    : isolate->heap()->false_value();
+}
+
+
 enum TypedArrayId {
   // arrayIds below should be synchromized with typedarray.js natives.
   ARRAY_ID_UINT8 = 1,

src/runtime.h

@@ -362,6 +362,7 @@ namespace internal {
   F(ArrayBufferInitialize, 2, 1)\
   F(ArrayBufferGetByteLength, 1, 1)\
   F(ArrayBufferSliceImpl, 3, 1) \
+  F(ArrayBufferIsView, 1, 1) \
   \
   F(TypedArrayInitialize, 5, 1) \
   F(TypedArrayInitializeFromArrayLike, 4, 1) \

test/mjsunit/harmony/typedarrays.js

@@ -123,6 +123,7 @@ function TestTypedArray(constr, elementSize, typicalElement) {
   var ab = new ArrayBuffer(256*elementSize);
 
   var a0 = new constr(30);
+  assertTrue(ArrayBuffer.isView(a0));
   assertSame(elementSize, a0.BYTES_PER_ELEMENT);
   assertSame(30, a0.length);
   assertSame(30*elementSize, a0.byteLength);
@@ -476,6 +477,7 @@ function TestDataViewConstructor() {
   var ab = new ArrayBuffer(256);
 
   var d1 = new DataView(ab, 1, 255);
+  assertTrue(ArrayBuffer.isView(d1));
   assertSame(ab, d1.buffer);
   assertSame(1, d1.byteOffset);
   assertSame(255, d1.byteLength);