Implement LookupIterator designed to replace LookupResult

src/lookup.cc

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/v8.h"
+
+#include "src/bootstrapper.h"
+#include "src/lookup.h"
+
+namespace v8 {
+namespace internal {
+
+
+void LookupIterator::Next() {
+  has_property_ = false;
+  do {
+    LookupInHolder();
+  } while (!IsFound() && NextHolder());
+}
+
+
+Handle<JSReceiver> LookupIterator::GetOrigin() const {
+  Handle<Object> receiver = GetReceiver();
+  if (receiver->IsJSReceiver()) return Handle<JSReceiver>::cast(receiver);
+  Context* native_context = isolate_->context()->native_context();
+  JSFunction* function;
+  if (receiver->IsNumber()) {
+    function = native_context->number_function();
+  } else if (receiver->IsString()) {
+    function = native_context->string_function();
+  } else if (receiver->IsSymbol()) {
+    function = native_context->symbol_function();
+  } else if (receiver->IsBoolean()) {
+    function = native_context->boolean_function();
+  } else {
+    UNREACHABLE();
+    function = NULL;
+  }
+  return handle(JSReceiver::cast(function->instance_prototype()));
+}
+
+
+Handle<Map> LookupIterator::GetReceiverMap() const {
+  Handle<Object> receiver = GetReceiver();
+  if (receiver->IsNumber()) return isolate_->factory()->heap_number_map();
+  return handle(Handle<HeapObject>::cast(receiver)->map());
+}
+
+
+bool LookupIterator::NextHolder() {
+  if (holder_map_->prototype()->IsNull()) return false;
+
+  Handle<JSReceiver> next(JSReceiver::cast(holder_map_->prototype()));
+
+  if (!check_derived() &&
+      // TODO(verwaest): Check if this is actually necessary currently. If it
+      // is, this should be handled by setting is_hidden_prototype on the
+      // global object behind the proxy.
+      !holder_map_->IsJSGlobalProxyMap() &&
+      !next->map()->is_hidden_prototype()) {
+    return false;
+  }
+
+  holder_map_ = handle(next->map());
+  maybe_holder_ = next;
+  return true;
+}
+
+
+void LookupIterator::LookupInHolder() {
+  State old_state = state_;
+  state_ = NOT_FOUND;

[rossberg, 2014/06/11 15:37:00]

Might be clearer to not pre-default this. There are only two places it is used
anyway.

[Toon Verwaest, 2014/06/11 17:32:18]

Done.

+  switch (old_state) {
+    case NOT_FOUND:
+      if (holder_map_->IsJSProxyMap()) {
+        state_ = JSPROXY;
+        return;
+      }
+      if (check_access_check() && holder_map_->is_access_check_needed()) {
+        state_ = ACCESS_CHECK;
+        return;
+      }

[rossberg, 2014/06/11 15:37:00]

Put a fall-through comment here and below.

[Toon Verwaest, 2014/06/11 17:32:18]

Done.

+    case ACCESS_CHECK:
+      if (check_interceptor() && holder_map_->has_named_interceptor()) {
+        state_ = INTERCEPTOR;
+        return;
+      }
+    case INTERCEPTOR:
+      if (holder_map_->is_dictionary_map()) {
+        property_encoding_ = DICTIONARY;
+      } else {
+        DescriptorArray* descriptors = holder_map_->instance_descriptors();
+        number_ = descriptors->SearchWithCache(*name_, *holder_map_);
+        if (number_ == DescriptorArray::kNotFound) return;
+        property_encoding_ = DESCRIPTOR;
+      }
+      state_ = PROPERTY;
+    case PROPERTY:
+      return;
+    case JSPROXY:
+      UNREACHABLE();
+  }
+}
+
+
+bool LookupIterator::IsBootstrapping() const {
+  return isolate_->bootstrapper()->IsActive();
+}
+
+
+bool LookupIterator::HasAccess(v8::AccessType access_type) const {
+  ASSERT_EQ(ACCESS_CHECK, state_);
+  ASSERT(is_guaranteed_to_have_holder());
+  return isolate_->MayNamedAccess(GetHolder(), name_, access_type);
+}
+
+
+bool LookupIterator::HasProperty() {
+  ASSERT_EQ(PROPERTY, state_);
+  ASSERT(is_guaranteed_to_have_holder());
+
+  if (property_encoding_ == DICTIONARY) {
+    Handle<JSObject> holder = GetHolder();
+    number_ = holder->property_dictionary()->FindEntry(name_);
+    if (number_ == NameDictionary::kNotFound) return false;
+
+    property_details_ = GetHolder()->property_dictionary()->DetailsAt(number_);
+    // Holes in dictionary cells are absent values unless marked as read-only.
+    if (holder->IsGlobalObject() &&
+        (property_details_.IsDeleted() ||
+         (!property_details_.IsReadOnly() && FetchValue()->IsTheHole()))) {
+      return false;
+    }
+  } else {
+    property_details_ = holder_map_->instance_descriptors()->GetDetails(
+        number_);
+  }
+
+  switch (property_details_.type()) {
+    case v8::internal::FIELD:
+    case v8::internal::NORMAL:
+    case v8::internal::CONSTANT:
+      property_type_ = DATA;
+      break;
+    case v8::internal::CALLBACKS:
+      property_type_ = ACCESSORS;
+      break;
+    case v8::internal::HANDLER:
+    case v8::internal::NONEXISTENT:
+    case v8::internal::INTERCEPTOR:
+      UNREACHABLE();
+  }
+
+  has_property_ = true;
+  return true;
+}
+
+
+Handle<Object> LookupIterator::FetchValue() const {
+  Object* result = NULL;
+  switch (property_encoding_) {
+    case DICTIONARY:
+      result = GetHolder()->property_dictionary()->ValueAt(number_);
+      if (GetHolder()->IsGlobalObject()) {
+        result = PropertyCell::cast(result)->value();
+      }
+      break;
+    case DESCRIPTOR:
+      if (property_details_.type() == v8::internal::FIELD) {
+        FieldIndex field_index = FieldIndex::ForDescriptor(
+            *holder_map_, number_);
+        return JSObject::FastPropertyAt(
+            GetHolder(), property_details_.representation(), field_index);
+      }
+      result = holder_map_->instance_descriptors()->GetValue(number_);
+  }
+  return handle(result, isolate_);
+}
+
+
+Handle<Object> LookupIterator::GetAccessors() const {
+  ASSERT(has_property_);
+  ASSERT_EQ(ACCESSORS, property_type_);
+  return FetchValue();
+}
+
+
+Handle<Object> LookupIterator::GetDataValue() const {
+  ASSERT(has_property_);
+  ASSERT_EQ(DATA, property_type_);
+  Handle<Object> value = FetchValue();
+  if (value->IsTheHole()) {
+    ASSERT_EQ(DICTIONARY, property_encoding_);
+    ASSERT(GetHolder()->IsGlobalObject());
+    ASSERT(property_details_.IsReadOnly());
+    return factory()->undefined_value();
+  }
+  return value;
+}
+
+
+} }  // namespace v8::internal