Add toImplSequence()

third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp b/third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp
index d0bb9de194cf24ec8ad2487adc5c89c2ed997404..e1b506c3bed84c919bf10b19fab437bf7e1f6d70 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8Binding.cpp
@@ -905,6 +905,30 @@ v8::Local<v8::Function> getBoundFunction(v8::Local<v8::Function> function)
     return boundFunction->IsFunction() ? v8::Local<v8::Function>::Cast(boundFunction) : function;
 }
 
+v8::MaybeLocal<v8::Object> getIterator(v8::Local<v8::Object> object, v8::Isolate* isolate, ExceptionState& exceptionState)

[Yuki, 2016/09/08 06:24:21]

Is it worth doing to make this a general utility as "get an accessor property"?

Then, we can say getAccessorProperty(obj, v8::Symbol::GetIterator(isolate)).

[bashi, 2016/09/08 06:30:49]

That's a good idea but the point of this CL is to provide getIterator defined in
https://tc39.github.io/ecma262/#sec-getiterator

We can generalize it later.

[Yuki, 2016/09/08 08:32:21]

Oops, I thought this is an accessor property, but it's not.
I understand.

By the way, I'm a little uneasy with the name |blink::getIterator|.  Does it
sound a bit too general, especially considering that C++ also supports
iterators?  I don't have a good idea, though.  Off the top of my head,
getEsIterator?  esGetIterator?  where es = ECMAScript.

[Yuki, 2016/09/08 08:32:21]

Please make v8::Isolate* as the first argument.

[bashi, 2016/09/09 00:54:22]

Done.

+{
+    v8::Local<v8::Context> context = isolate->GetCurrentContext();
+    v8::Local<v8::Value> iteratorGetter;
+    if (!object->Get(context, v8::Symbol::GetIterator(isolate)).ToLocal(&iteratorGetter)) {
+        return v8::MaybeLocal<v8::Object>();

[haraken, 2016/09/08 09:32:08]

Don't we need to throw an exception here?

[bashi, 2016/09/09 00:54:22]

No. IIRC, !ToLocal() means that v8 already thrown an exception.

+    }
+    if (!iteratorGetter->IsFunction()) {
+        exceptionState.throwTypeError("Iterator getter is not callable.");
+        return v8::MaybeLocal<v8::Object>();
+    }
+
+    v8::Local<v8::Function> getterFunction = iteratorGetter.As<v8::Function>();
+    v8::Local<v8::Value> iterator;
+    if (!getterFunction->Call(context, object, 0, nullptr).ToLocal(&iterator)) {
+        return v8::MaybeLocal<v8::Object>();

[haraken, 2016/09/08 09:32:08]

Ditto.

+    }
+    if (!iterator->IsObject()) {
+        exceptionState.throwTypeError("Iterator is not an object.");
+        return v8::MaybeLocal<v8::Object>();
+    }
+    return v8::MaybeLocal<v8::Object>(iterator.As<v8::Object>());
+}
+
 bool addHiddenValueToArray(v8::Isolate* isolate, v8::Local<v8::Object> object, v8::Local<v8::Value> value, int arrayIndex)
 {
     ASSERT(!value.IsEmpty());