v8::internal::JSObjectWalkVisitor< ContextObject > Class Template Reference

Collaboration diagram for v8::internal::JSObjectWalkVisitor< ContextObject >:

Public Member Functions
	JSObjectWalkVisitor (ContextObject *site_context, bool copying, JSObject::DeepCopyHints hints)
MUST_USE_RESULT MaybeHandle< JSObject >	StructureWalk (Handle< JSObject > object)

Protected Member Functions
MUST_USE_RESULT MaybeHandle< JSObject >	VisitElementOrProperty (Handle< JSObject > object, Handle< JSObject > value)
ContextObject *	site_context ()
Isolate *	isolate ()
bool	copying () const

Private Attributes
ContextObject *	site_context_
const bool	copying_
const JSObject::DeepCopyHints	hints_

Detailed Description

template<class ContextObject>
class v8::internal::JSObjectWalkVisitor< ContextObject >

Definition at line 5372 of file objects.cc.

Constructor & Destructor Documentation

JSObjectWalkVisitor()

template<class ContextObject >

v8::internal::JSObjectWalkVisitor< ContextObject >::JSObjectWalkVisitor ( ContextObject *  site_context, bool  copying, JSObject::DeepCopyHints  hints  )

inline

Definition at line 5374 of file objects.cc.

    : site_context_(site_context),
      copying_(copying),
      hints_(hints) {}

Member Function Documentation

copying()

template<class ContextObject >

bool v8::internal::JSObjectWalkVisitor< ContextObject >::copying ( ) const

inlineprotected

Definition at line 5395 of file objects.cc.

{ return copying_; }

isolate()

template<class ContextObject >

Isolate* v8::internal::JSObjectWalkVisitor< ContextObject >::isolate ( )

inlineprotected

Definition at line 5393 of file objects.cc.

{ return site_context()->isolate(); }

site_context()

template<class ContextObject >

ContextObject* v8::internal::JSObjectWalkVisitor< ContextObject >::site_context ( )

inlineprotected

Definition at line 5392 of file objects.cc.

{ return site_context_; }

StructureWalk()

template<class ContextObject >

MaybeHandle< JSObject > v8::internal::JSObjectWalkVisitor< ContextObject >::StructureWalk

(

Handle< JSObject >

object

)

Definition at line 5405 of file objects.cc.

                             {
  Isolate* isolate = this->isolate();
  bool copying = this->copying();
  bool shallow = hints_ == JSObject::kObjectIsShallow;
 
  if (!shallow) {
    StackLimitCheck check(isolate);
 
    if (check.HasOverflowed()) {
      isolate->StackOverflow();
      return MaybeHandle<JSObject>();
    }
  }
 
  if (object->map()->is_deprecated()) {
    JSObject::MigrateInstance(object);
  }
 
  Handle<JSObject> copy;
  if (copying) {
    Handle<AllocationSite> site_to_pass;
    if (site_context()->ShouldCreateMemento(object)) {
      site_to_pass = site_context()->current();
    }
    copy = isolate->factory()->CopyJSObjectWithAllocationSite(
        object, site_to_pass);
  } else {
    copy = object;
  }
 
  DCHECK(copying || copy.is_identical_to(object));
 
  ElementsKind kind = copy->GetElementsKind();
  if (copying && IsFastSmiOrObjectElementsKind(kind) &&
      FixedArray::cast(copy->elements())->map() ==
        isolate->heap()->fixed_cow_array_map()) {
    isolate->counters()->cow_arrays_created_runtime()->Increment();
  }
 
  if (!shallow) {
    HandleScope scope(isolate);
 
    // Deep copy own properties.
    if (copy->HasFastProperties()) {
      Handle<DescriptorArray> descriptors(copy->map()->instance_descriptors());
      int limit = copy->map()->NumberOfOwnDescriptors();
      for (int i = 0; i < limit; i++) {
        PropertyDetails details = descriptors->GetDetails(i);
        if (details.type() != FIELD) continue;
        FieldIndex index = FieldIndex::ForDescriptor(copy->map(), i);
        Handle<Object> value(object->RawFastPropertyAt(index), isolate);
        if (value->IsJSObject()) {
          ASSIGN_RETURN_ON_EXCEPTION(
              isolate, value,
              VisitElementOrProperty(copy, Handle<JSObject>::cast(value)),
              JSObject);
        } else {
          Representation representation = details.representation();
          value = Object::NewStorageFor(isolate, value, representation);
        }
        if (copying) {
          copy->FastPropertyAtPut(index, *value);
        }
      }
    } else {
      Handle<FixedArray> names =
          isolate->factory()->NewFixedArray(copy->NumberOfOwnProperties());
      copy->GetOwnPropertyNames(*names, 0);
      for (int i = 0; i < names->length(); i++) {
        DCHECK(names->get(i)->IsString());
        Handle<String> key_string(String::cast(names->get(i)));
        Maybe<PropertyAttributes> maybe =
            JSReceiver::GetOwnPropertyAttributes(copy, key_string);
        DCHECK(maybe.has_value);
        PropertyAttributes attributes = maybe.value;
        // Only deep copy fields from the object literal expression.
        // In particular, don't try to copy the length attribute of
        // an array.
        if (attributes != NONE) continue;
        Handle<Object> value =
            Object::GetProperty(copy, key_string).ToHandleChecked();
        if (value->IsJSObject()) {
          Handle<JSObject> result;
          ASSIGN_RETURN_ON_EXCEPTION(
              isolate, result,
              VisitElementOrProperty(copy, Handle<JSObject>::cast(value)),
              JSObject);
          if (copying) {
            // Creating object copy for literals. No strict mode needed.
            JSObject::SetProperty(copy, key_string, result, SLOPPY).Assert();
          }
        }
      }
    }
 
    // Deep copy own elements.
    // Pixel elements cannot be created using an object literal.
    DCHECK(!copy->HasExternalArrayElements());
    switch (kind) {
      case FAST_SMI_ELEMENTS:
      case FAST_ELEMENTS:
      case FAST_HOLEY_SMI_ELEMENTS:
      case FAST_HOLEY_ELEMENTS: {
        Handle<FixedArray> elements(FixedArray::cast(copy->elements()));
        if (elements->map() == isolate->heap()->fixed_cow_array_map()) {
#ifdef DEBUG
          for (int i = 0; i < elements->length(); i++) {
            DCHECK(!elements->get(i)->IsJSObject());
          }
#endif
        } else {
          for (int i = 0; i < elements->length(); i++) {
            Handle<Object> value(elements->get(i), isolate);
            DCHECK(value->IsSmi() ||
                   value->IsTheHole() ||
                   (IsFastObjectElementsKind(copy->GetElementsKind())));
            if (value->IsJSObject()) {
              Handle<JSObject> result;
              ASSIGN_RETURN_ON_EXCEPTION(
                  isolate, result,
                  VisitElementOrProperty(copy, Handle<JSObject>::cast(value)),
                  JSObject);
              if (copying) {
                elements->set(i, *result);
              }
            }
          }
        }
        break;
      }
      case DICTIONARY_ELEMENTS: {
        Handle<SeededNumberDictionary> element_dictionary(
            copy->element_dictionary());
        int capacity = element_dictionary->Capacity();
        for (int i = 0; i < capacity; i++) {
          Object* k = element_dictionary->KeyAt(i);
          if (element_dictionary->IsKey(k)) {
            Handle<Object> value(element_dictionary->ValueAt(i), isolate);
            if (value->IsJSObject()) {
              Handle<JSObject> result;
              ASSIGN_RETURN_ON_EXCEPTION(
                  isolate, result,
                  VisitElementOrProperty(copy, Handle<JSObject>::cast(value)),
                  JSObject);
              if (copying) {
                element_dictionary->ValueAtPut(i, *result);
              }
            }
          }
        }
        break;
      }
      case SLOPPY_ARGUMENTS_ELEMENTS:
        UNIMPLEMENTED();
        break;
 
 
#define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size)                        \
      case EXTERNAL_##TYPE##_ELEMENTS:                                         \
      case TYPE##_ELEMENTS:                                                    \
 
      TYPED_ARRAYS(TYPED_ARRAY_CASE)
#undef TYPED_ARRAY_CASE
 
      case FAST_DOUBLE_ELEMENTS:
      case FAST_HOLEY_DOUBLE_ELEMENTS:
        // No contained objects, nothing to do.
        break;
    }
  }
 
  return copy;
}

References ASSIGN_RETURN_ON_EXCEPTION, v8::internal::Isolate::counters(), DCHECK, v8::internal::DICTIONARY_ELEMENTS, v8::internal::Isolate::factory(), v8::internal::FAST_DOUBLE_ELEMENTS, v8::internal::FAST_ELEMENTS, v8::internal::FAST_HOLEY_DOUBLE_ELEMENTS, v8::internal::FAST_HOLEY_ELEMENTS, v8::internal::FAST_HOLEY_SMI_ELEMENTS, v8::internal::FAST_SMI_ELEMENTS, v8::internal::FIELD, v8::internal::JSReceiver::GetOwnPropertyAttributes(), v8::internal::Object::GetProperty(), v8::internal::Isolate::heap(), v8::internal::IsFastObjectElementsKind(), v8::internal::IsFastSmiOrObjectElementsKind(), v8::internal::JSObject::kObjectIsShallow, v8::maybe(), v8::internal::JSObject::MigrateInstance(), v8::internal::Object::NewStorageFor(), NONE, v8::internal::Object::SetProperty(), v8::internal::SLOPPY, v8::internal::SLOPPY_ARGUMENTS_ELEMENTS, v8::internal::Isolate::StackOverflow(), TYPED_ARRAY_CASE, TYPED_ARRAYS, and UNIMPLEMENTED.

Referenced by v8::internal::JSObject::DeepCopy(), and v8::internal::JSObject::DeepWalk().

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VisitElementOrProperty()

template<class ContextObject >

MUST_USE_RESULT MaybeHandle<JSObject> v8::internal::JSObjectWalkVisitor< ContextObject >::VisitElementOrProperty ( Handle< JSObject >  object, Handle< JSObject >  value  )

inlineprotected

Definition at line 5383 of file objects.cc.

                              {
    Handle<AllocationSite> current_site = site_context()->EnterNewScope();
    MaybeHandle<JSObject> copy_of_value = StructureWalk(value);
    site_context()->ExitScope(current_site, value);
    return copy_of_value;
  }

Member Data Documentation

copying_

template<class ContextObject >

const bool v8::internal::JSObjectWalkVisitor< ContextObject >::copying_

private

Definition at line 5399 of file objects.cc.

hints_

template<class ContextObject >

const JSObject::DeepCopyHints v8::internal::JSObjectWalkVisitor< ContextObject >::hints_

private

Definition at line 5400 of file objects.cc.

site_context_

template<class ContextObject >

ContextObject* v8::internal::JSObjectWalkVisitor< ContextObject >::site_context_

private

Definition at line 5398 of file objects.cc.

---

The documentation for this class was generated from the following file:

• /mnt/V8SourceCode/src/objects.cc