/* static */ bool
ObjectElements::MakeElementsCopyOnWrite(ExclusiveContext *cx, JSObject *obj)
{
// Make sure there is enough room for the owner object pointer at the end
// of the elements.
JS_STATIC_ASSERT(sizeof(HeapSlot) >= sizeof(HeapPtrObject));
if (!obj->ensureElements(cx, obj->getDenseInitializedLength() + 1))
return false;
ObjectElements *header = obj->getElementsHeader();
// Note: this method doesn't update type information to indicate that the
// elements might be copy on write. Handling this is left to the caller.
JS_ASSERT(!header->isCopyOnWrite());
header->flags |= COPY_ON_WRITE;
header->ownerObject().init(obj);
return true;
}
