BOOL ForInObjectEnumerator::InitializeCurrentEnumerator(RecyclableObject * object, ForInCache * forInCache)
{
EnumeratorFlags flags = enumerator.GetFlags();
RecyclableObject * prototype = object->GetPrototype();
if (prototype == nullptr || prototype->GetTypeId() == TypeIds_Null)
{
// If this is the last object on the prototype chain, we don't need to get the non-enumerable properties any more to track shadowing
flags &= ~EnumeratorFlags::EnumNonEnumerable;
}
return InitializeCurrentEnumerator(object, flags, GetScriptContext(), forInCache);
}
void ForInObjectEnumerator::Reset()
{
object = baseObject;
if (propertyIds)
{
propertyIds->ClearAll();
}
currentIndex = nullptr;
InitializeCurrentEnumerator();
}
void ForInObjectEnumerator::Initialize(RecyclableObject* currentObject, ScriptContext * scriptContext)
{
Assert(propertyIds == nullptr);
Assert(newPropertyStrings.Empty());
Assert(this->GetScriptContext() == scriptContext);
this->currentIndex = nullptr;
if (currentObject == nullptr)
{
enumerator.Clear();
this->object = nullptr;
this->baseObject = nullptr;
this->baseObjectType = nullptr;
this->firstPrototype = nullptr;
return;
}
Assert(JavascriptOperators::GetTypeId(currentObject) != TypeIds_Null
&& JavascriptOperators::GetTypeId(currentObject) != TypeIds_Undefined);
if (this->object == currentObject &&
this->baseObjectType == currentObject->GetType())
{
// We can re-use the enumerator, only if the 'object' and type from the previous enumeration
// remains the same. If the previous enumeration involved prototype enumeration
// 'object' and 'currentEnumerator' would represent the prototype. Hence,
// we cannot re-use it. Null objects are always equal, therefore, the enumerator cannot
// be re-used.
enumerator.Reset();
}
else
{
this->baseObjectType = currentObject->GetType();
this->object = currentObject;
InitializeCurrentEnumerator();
}
this->baseObject = currentObject;
firstPrototype = GetFirstPrototypeWithEnumerableProperties(object);
if (firstPrototype != nullptr)
{
Recycler *recycler = scriptContext->GetRecycler();
propertyIds = RecyclerNew(recycler, BVSparse<Recycler>, recycler);
}
}
void ForInObjectEnumerator::Initialize(RecyclableObject* initObject, ScriptContext * requestContext, bool enumSymbols, ForInCache * forInCache)
{
this->enumeratingPrototype = false;
if (initObject == nullptr)
{
enumerator.Clear(EnumeratorFlags::None, requestContext);
this->shadowData = nullptr;
this->canUseJitFastPath = false;
return;
}
Assert(JavascriptOperators::GetTypeId(initObject) != TypeIds_Null
&& JavascriptOperators::GetTypeId(initObject) != TypeIds_Undefined);
EnumeratorFlags flags;
RecyclableObject * firstPrototype = nullptr;
RecyclableObject * firstPrototypeWithEnumerableProperties = GetFirstPrototypeWithEnumerableProperties(initObject, &firstPrototype);
if (firstPrototypeWithEnumerableProperties != nullptr)
{
Recycler *recycler = requestContext->GetRecycler();
this->shadowData = RecyclerNew(recycler, ShadowData, initObject, firstPrototype, recycler);
flags = EnumeratorFlags::UseCache | EnumeratorFlags::SnapShotSemantics | EnumeratorFlags::EnumNonEnumerable | (enumSymbols ? EnumeratorFlags::EnumSymbols : EnumeratorFlags::None);
}
// no enumerable properties in the prototype chain, no need to search it
else
{
this->shadowData = nullptr;
flags = EnumeratorFlags::UseCache | EnumeratorFlags::SnapShotSemantics | (enumSymbols ? EnumeratorFlags::EnumSymbols : EnumeratorFlags::None);
}
if (InitializeCurrentEnumerator(initObject, flags, requestContext, forInCache))
{
canUseJitFastPath = this->enumerator.CanUseJITFastPath();
}
else
{
// Nothing to enumerate.
// We keep the shadowData so that it may walk up the prototype chain (e.g. primitive type)
enumerator.Clear(flags, requestContext);
canUseJitFastPath = false;
}
}
JavascriptString * ForInObjectEnumerator::MoveAndGetNext(PropertyId& propertyId)
{
PropertyRecord const * propRecord;
PropertyAttributes attributes = PropertyNone;
while (true)
{
propertyId = Constants::NoProperty;
JavascriptString * currentIndex = enumerator.MoveAndGetNext(propertyId, &attributes);
// The object type may have changed and we may not be able to use Jit fast path anymore.
// canUseJitFastPath is determined in ForInObjectEnumerator::Initialize, once we decide we can't use
// Jit fast path we will never go back to use fast path so && with current value - if it's already
// false we don't call CanUseJITFastPath()
this->canUseJitFastPath = this->canUseJitFastPath && enumerator.CanUseJITFastPath();
if (currentIndex)
{
if (this->shadowData == nullptr)
{
// There are no prototype that has enumerable properties,
// don't need to keep track of the propertyIds we visited.
// We have asked for enumerable properties only, so don't need to check the attribute returned.
Assert(attributes & PropertyEnumerable);
return currentIndex;
}
// Property Id does not exist.
if (propertyId == Constants::NoProperty)
{
if (VirtualTableInfo<Js::PropertyString>::HasVirtualTable(currentIndex))
{
// If we have a property string, it is assumed that the propertyId is being
// kept alive with the object
PropertyString * propertyString = (PropertyString *)currentIndex;
propertyId = propertyString->GetPropertyRecord()->GetPropertyId();
}
else
{
ScriptContext* scriptContext = currentIndex->GetScriptContext();
scriptContext->GetOrAddPropertyRecord(currentIndex->GetString(), currentIndex->GetLength(), &propRecord);
propertyId = propRecord->GetPropertyId();
// We keep the track of what is enumerated using a bit vector of propertyID.
// so the propertyId can't be collected until the end of the for in enumerator
// Keep a list of the property string.
this->shadowData->newPropertyStrings.Prepend(GetScriptContext()->GetRecycler(), propRecord);
}
}
if (TestAndSetEnumerated(propertyId) //checks if the property is already enumerated or not
&& (attributes & PropertyEnumerable))
{
return currentIndex;
}
}
else
{
if (this->shadowData == nullptr)
{
Assert(!this->enumeratingPrototype);
return nullptr;
}
RecyclableObject * object;
if (!this->enumeratingPrototype)
{
this->enumeratingPrototype = true;
object = this->shadowData->firstPrototype;
this->shadowData->currentObject = object;
}
else
{
//walk the prototype chain
object = this->shadowData->currentObject->GetPrototype();
this->shadowData->currentObject = object;
if ((object == nullptr) || (JavascriptOperators::GetTypeId(object) == TypeIds_Null))
{
return nullptr;
}
}
do
{
if (!InitializeCurrentEnumerator(object))
{
return nullptr;
}
if (!enumerator.IsNullEnumerator())
{
break;
}
//walk the prototype chain
object = object->GetPrototype();
this->shadowData->currentObject = object;
if ((object == nullptr) || (JavascriptOperators::GetTypeId(object) == TypeIds_Null))
{
return nullptr;
}
}
while (true);
}
}
}
Var ForInObjectEnumerator::MoveAndGetNext(PropertyId& propertyId)
{
PropertyRecord const * propRecord;
PropertyAttributes attributes = PropertyNone;
while (true)
{
propertyId = Constants::NoProperty;
currentIndex = enumerator.MoveAndGetNext(propertyId, &attributes);
if (currentIndex)
{
if (firstPrototype == nullptr)
{
// We are calculating correct shadowing for non-enumerable properties of the child object, we will receive
// both enumerable and non-enumerable properties from MoveAndGetNext so we need to check before we simply
// return here. If this property is non-enumerable we're going to skip it.
if (!(attributes & PropertyEnumerable))
{
continue;
}
// There are no prototype that has enumerable properties,
// don't need to keep track of the propertyIds we visited.
return currentIndex;
}
// Property Id does not exist.
if (propertyId == Constants::NoProperty)
{
if (!JavascriptString::Is(currentIndex)) //This can be undefined
{
continue;
}
JavascriptString *pString = JavascriptString::FromVar(currentIndex);
if (VirtualTableInfo<Js::PropertyString>::HasVirtualTable(pString))
{
// If we have a property string, it is assumed that the propertyId is being
// kept alive with the object
PropertyString * propertyString = (PropertyString *)pString;
propertyId = propertyString->GetPropertyRecord()->GetPropertyId();
}
else
{
ScriptContext* scriptContext = pString->GetScriptContext();
scriptContext->GetOrAddPropertyRecord(pString->GetString(), pString->GetLength(), &propRecord);
propertyId = propRecord->GetPropertyId();
// We keep the track of what is enumerated using a bit vector of propertyID.
// so the propertyId can't be collected until the end of the for in enumerator
// Keep a list of the property string.
newPropertyStrings.Prepend(GetScriptContext()->GetRecycler(), propRecord);
}
}
//check for shadowed property
if (TestAndSetEnumerated(propertyId) //checks if the property is already enumerated or not
&& (attributes & PropertyEnumerable))
{
return currentIndex;
}
}
else
{
if (object == baseObject)
{
if (firstPrototype == nullptr)
{
return NULL;
}
object = firstPrototype;
}
else
{
//walk the prototype chain
object = object->GetPrototype();
if ((object == NULL) || (JavascriptOperators::GetTypeId(object) == TypeIds_Null))
{
return NULL;
}
}
do
{
if (!InitializeCurrentEnumerator())
{
return nullptr;
}
if (!enumerator.IsNullEnumerator())
{
break;
}
//walk the prototype chain
object = object->GetPrototype();
if ((object == NULL) || (JavascriptOperators::GetTypeId(object) == TypeIds_Null))
{
return NULL;
}
}
while (true);
}
}
}
