bool
ForOfIterator::init(HandleValue iterable, NonIterableBehavior nonIterableBehavior)
{
JSContext* cx = cx_;
RootedObject iterableObj(cx, ToObject(cx, iterable));
if (!iterableObj)
return false;
MOZ_ASSERT(index == NOT_ARRAY);
// Check the PIC first for a match.
if (iterableObj->is<ArrayObject>()) {
ForOfPIC::Chain* stubChain = ForOfPIC::getOrCreate(cx);
if (!stubChain)
return false;
bool optimized;
if (!stubChain->tryOptimizeArray(cx, iterableObj.as<ArrayObject>(), &optimized))
return false;
if (optimized) {
// Got optimized stub. Array is optimizable.
index = 0;
iterator = iterableObj;
return true;
}
}
MOZ_ASSERT(index == NOT_ARRAY);
// The iterator is the result of calling obj[@@iterator]().
InvokeArgs args(cx);
if (!args.init(0))
return false;
args.setThis(ObjectValue(*iterableObj));
RootedValue callee(cx);
RootedId iteratorId(cx, SYMBOL_TO_JSID(cx->wellKnownSymbols().iterator));
if (!GetProperty(cx, iterableObj, iterableObj, iteratorId, &callee))
return false;
// If obj[@@iterator] is undefined and we were asked to allow non-iterables,
// bail out now without setting iterator. This will make valueIsIterable(),
// which our caller should check, return false.
if (nonIterableBehavior == AllowNonIterable && callee.isUndefined())
return true;
// Throw if obj[@@iterator] isn't callable.
// js::Invoke is about to check for this kind of error anyway, but it would
// throw an inscrutable error message about |method| rather than this nice
// one about |obj|.
if (!callee.isObject() || !callee.toObject().isCallable()) {
UniquePtr<char[], JS::FreePolicy> bytes = DecompileValueGenerator(cx, JSDVG_SEARCH_STACK,
iterable, nullptr);
if (!bytes)
return false;
JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_NOT_ITERABLE, bytes.get());
return false;
}
args.setCallee(callee);
if (!Invoke(cx, args))
return false;
iterator = ToObject(cx, args.rval());
if (!iterator)
return false;
return true;
}
