Add C++ implementation of Object.defineProperties

src/property-descriptor.cc

+// Copyright 2011 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/property-descriptor.h"
+
+#include "src/factory.h"
+#include "src/isolate-inl.h"
+#include "src/lookup.h"
+#include "src/objects-inl.h"
+
+namespace v8 {
+namespace internal {
+
+// Helper function for ToPropertyDescriptor. Comments describe steps for
+// "enumerable", other properties are handled the same way.
+// Returns false if an exception was thrown.
+bool GetPropertyIfPresent(Handle<Object> obj, Handle<String> name,
+                          Handle<Object>* value) {
+  LookupIterator it(obj, name);
+  // 4. Let hasEnumerable be HasProperty(Obj, "enumerable").
+  Maybe<PropertyAttributes> maybe_attr = JSReceiver::GetPropertyAttributes(&it);
+  // 5. ReturnIfAbrupt(hasEnumerable).
+  if (!maybe_attr.IsJust()) return false;
+  // 6. If hasEnumerable is true, then
+  if (maybe_attr.FromJust() != ABSENT) {
+    // 6a. Let enum be ToBoolean(Get(Obj, "enumerable")).
+    // 6b. ReturnIfAbrupt(enum).
+    if (!JSObject::GetProperty(&it).ToHandle(value)) return false;
+  }
+  return true;
+}
+
+
+// Helper function for ToPropertyDescriptor. Handles the case of "simple"
+// objects: nothing on the prototype chain, just own fast data properties.
+// Must not have observable side effects, because the slow path will restart
+// the entire conversion!
+bool ToPropertyDescriptorFastPath(Isolate* isolate, Handle<Object> obj,
+                                  PropertyDescriptor* desc) {
+  if (!obj->IsJSObject()) return false;
+  Map* map = Handle<JSObject>::cast(obj)->map();
+  if (map->instance_type() != JS_OBJECT_TYPE) return false;
+  if (map->is_access_check_needed()) return false;
+  if (map->prototype() != *isolate->initial_object_prototype()) return false;

[Toon Verwaest, 2015/10/13 11:51:26]

The properties below could have been added to Object.prototype and
Object.prototype.__proto__ could have been modified? We probably need something
similar to the array_protector used in builtins.cc.

[Jakob Kummerow, 2015/10/13 12:04:43]

Is the map check on the next line not enough to address that concern?

[Toon Verwaest, 2015/10/13 13:32:14]

Acknowledged.

+  if (JSObject::cast(map->prototype())->map() !=
+      isolate->native_context()->object_function_prototype_map()) {
+    return false;
+  }
+  // TODO(jkummerow): support dictionary properties?
+  if (map->is_dictionary_map()) return false;
+  Handle<DescriptorArray> descs =
+      Handle<DescriptorArray>(map->instance_descriptors());
+  for (int i = 0; i < map->NumberOfOwnDescriptors(); i++) {
+    PropertyDetails details = descs->GetDetails(i);
+    Name* key = descs->GetKey(i);
+    Handle<Object> value;
+    switch (details.type()) {
+      case DATA:
+        value = JSObject::FastPropertyAt(Handle<JSObject>::cast(obj),
+                                         details.representation(),
+                                         FieldIndex::ForDescriptor(map, i));
+        break;
+      case DATA_CONSTANT:
+        value = handle(descs->GetConstant(i), isolate);
+        break;
+      case ACCESSOR:
+      case ACCESSOR_CONSTANT:
+        // Bail out to slow path.
+        return false;
+    }
+    Heap* heap = isolate->heap();
+    if (key == heap->enumerable_string()) {
+      desc->set_enumerable(value->BooleanValue());
+    } else if (key == heap->configurable_string()) {
+      desc->set_configurable(value->BooleanValue());
+    } else if (key == heap->value_string()) {
+      desc->set_value(value);
+    } else if (key == heap->writable_string()) {
+      desc->set_writable(value->BooleanValue());
+    } else if (key == heap->get_string()) {
+      // Bail out to slow path to throw an exception if necessary.
+      if (!value->IsCallable()) return false;
+      desc->set_get(value);
+    } else if (key == heap->set_string()) {
+      // Bail out to slow path to throw an exception if necessary.
+      if (!value->IsCallable()) return false;
+      desc->set_set(value);
+    }
+  }
+  if ((desc->has_get() || desc->has_set()) &&
+      (desc->has_value() || desc->has_writable())) {
+    // Bail out to slow path to throw an exception.
+    return false;
+  }
+  return true;
+}
+
+
+// ES6 6.2.4.5
+// Returns false in case of exception.
+// static
+bool PropertyDescriptor::ToPropertyDescriptor(Isolate* isolate,
+                                              Handle<Object> obj,
+                                              PropertyDescriptor* desc) {
+  // 1. ReturnIfAbrupt(Obj).
+  // 2. If Type(Obj) is not Object, throw a TypeError exception.
+  if (!obj->IsSpecObject()) {
+    isolate->Throw(*isolate->factory()->NewTypeError(
+        MessageTemplate::kPropertyDescObject, obj));
+    return false;
+  }
+  // 3. Let desc be a new Property Descriptor that initially has no fields.
+  DCHECK(desc->is_empty());
+
+  if (ToPropertyDescriptorFastPath(isolate, obj, desc)) {
+    return true;
+  }
+
+  // TODO(jkummerow): Implement JSProxy support.
+  // Specifically, instead of taking the attributes != ABSENT shortcut, we
+  // have to implement proper HasProperty for proxies.
+  if (!obj->IsJSProxy()) {
+    {  // enumerable?
+      Handle<Object> enumerable;
+      // 4 through 6b.
+      if (!GetPropertyIfPresent(obj, isolate->factory()->enumerable_string(),
+                                &enumerable)) {
+        return false;
+      }
+      // 6c. Set the [[Enumerable]] field of desc to enum.
+      if (!enumerable.is_null()) {
+        desc->set_enumerable(enumerable->BooleanValue());
+      }
+    }
+    {  // configurable?
+      Handle<Object> configurable;
+      // 7 through 9b.
+      if (!GetPropertyIfPresent(obj, isolate->factory()->configurable_string(),
+                                &configurable)) {
+        return false;
+      }
+      // 9c. Set the [[Configurable]] field of desc to conf.
+      if (!configurable.is_null()) {
+        desc->set_configurable(configurable->BooleanValue());
+      }
+    }
+    {  // value?
+      Handle<Object> value;
+      // 10 through 12b.
+      if (!GetPropertyIfPresent(obj, isolate->factory()->value_string(),
+                                &value))
+        return false;
+      // 12c. Set the [[Value]] field of desc to value.
+      if (!value.is_null()) desc->set_value(value);
+    }
+    {  // writable?
+      Handle<Object> writable;
+      // 13 through 15b.
+      if (!GetPropertyIfPresent(obj, isolate->factory()->writable_string(),
+                                &writable)) {
+        return false;
+      }
+      // 15c. Set the [[Writable]] field of desc to writable.
+      if (!writable.is_null()) desc->set_writable(writable->BooleanValue());
+    }
+    {  // getter?
+      Handle<Object> getter;
+      // 16 through 18b.
+      if (!GetPropertyIfPresent(obj, isolate->factory()->get_string(), &getter))
+        return false;
+      if (!getter.is_null()) {
+        // 18c. If IsCallable(getter) is false and getter is not undefined,
+        // throw a TypeError exception.
+        if (!getter->IsCallable() && !getter->IsUndefined()) {
+          isolate->Throw(*isolate->factory()->NewTypeError(
+              MessageTemplate::kObjectGetterCallable, getter));
+          return false;
+        }
+        // 18d. Set the [[Get]] field of desc to getter.
+        desc->set_get(getter);
+      }
+      {  // setter?
+        Handle<Object> setter;
+        // 19 through 21b.
+        if (!GetPropertyIfPresent(obj, isolate->factory()->set_string(),
+                                  &setter))
+          return false;
+        if (!setter.is_null()) {
+          // 21c. If IsCallable(setter) is false and setter is not undefined,
+          // throw a TypeError exception.
+          if (!setter->IsCallable() && !setter->IsUndefined()) {
+            isolate->Throw(*isolate->factory()->NewTypeError(
+                MessageTemplate::kObjectSetterCallable, setter));
+            return false;
+          }
+          // 21d. Set the [[Set]] field of desc to setter.
+          desc->set_set(setter);
+        }
+      }
+      // 22. If either desc.[[Get]] or desc.[[Set]] is present, then
+      // 22a. If either desc.[[Value]] or desc.[[Writable]] is present,
+      // throw a TypeError exception.
+      if ((desc->has_get() || desc->has_set()) &&
+          (desc->has_value() || desc->has_writable())) {
+        isolate->Throw(*isolate->factory()->NewTypeError(
+            MessageTemplate::kValueAndAccessor, obj));
+        return false;
+      }
+    }
+  } else {
+    DCHECK(obj->IsJSProxy());
+    UNIMPLEMENTED();
+  }
+  // 23. Return desc.
+  return true;
+}
+
+
+}  // namespace internal
+}  // namespace v8