[es6] Partially implement Reflect.getOwnPropertyDescriptor.

Proxies are not properly supported yet.

R=rossberg, jkummerow@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1408163005

Cr-Commit-Position: refs/heads/master@{#31674}

src/bootstrapper.cc

@@ -2197,6 +2197,8 @@ void Genesis::InitializeGlobal_harmony_reflect() {
                         Builtins::kReflectDeleteProperty, 2, true);
   SimpleInstallFunction(reflect, "get",
                         Builtins::kReflectGet, 3, false);
+  SimpleInstallFunction(reflect, "getOwnPropertyDescriptor",
+                        Builtins::kReflectGetOwnPropertyDescriptor, 2, true);
   SimpleInstallFunction(reflect, "getPrototypeOf",
                         Builtins::kReflectGetPrototypeOf, 1, true);
   SimpleInstallFunction(reflect, "has",

src/builtins.cc

@@ -1533,6 +1533,33 @@ BUILTIN(ReflectGet) {
 }
 
 
+// ES6 section 26.1.7 Reflect.getOwnPropertyDescriptor
+BUILTIN(ReflectGetOwnPropertyDescriptor) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(3, args.length());
+  Handle<Object> target = args.at<Object>(1);
+  Handle<Object> key = args.at<Object>(2);
+
+  if (!target->IsJSReceiver()) {
+    THROW_NEW_ERROR_RETURN_FAILURE(
+        isolate, NewTypeError(MessageTemplate::kCalledOnNonObject,
+                              isolate->factory()->NewStringFromAsciiChecked(
+                                  "Reflect.getOwnPropertyDescriptor")));
+  }
+
+  Handle<Name> name;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, name,
+                                     Object::ToName(isolate, key));
+
+  PropertyDescriptor desc;
+  bool found = JSReceiver::GetOwnPropertyDescriptor(
+      isolate, Handle<JSReceiver>::cast(target), name, &desc);
+  if (isolate->has_pending_exception()) return isolate->heap()->exception();
+  if (!found) return isolate->heap()->undefined_value();
+  return *desc.ToObject(isolate);
+}
+
+
 // ES6 section 26.1.8 Reflect.getPrototypeOf
 BUILTIN(ReflectGetPrototypeOf) {
   HandleScope scope(isolate);

src/builtins.h

@@ -62,6 +62,7 @@ enum BuiltinExtraArguments {
   V(ReflectDefineProperty, NO_EXTRA_ARGUMENTS)               \
   V(ReflectDeleteProperty, NO_EXTRA_ARGUMENTS)               \
   V(ReflectGet, NO_EXTRA_ARGUMENTS)                          \
+  V(ReflectGetOwnPropertyDescriptor, NO_EXTRA_ARGUMENTS)     \
   V(ReflectGetPrototypeOf, NO_EXTRA_ARGUMENTS)               \
   V(ReflectHas, NO_EXTRA_ARGUMENTS)                          \
   V(ReflectIsExtensible, NO_EXTRA_ARGUMENTS)                 \

src/objects.cc

@@ -6608,7 +6608,7 @@ bool JSArray::ArraySetLength(Isolate* isolate, Handle<JSArray> a,
 
 // static
 bool JSReceiver::GetOwnPropertyDescriptor(Isolate* isolate,
-                                          Handle<JSObject> object,
+                                          Handle<JSReceiver> object,
                                           Handle<Object> key,
                                           PropertyDescriptor* desc) {
   bool success = false;
@@ -6672,6 +6672,8 @@ bool JSReceiver::GetOwnPropertyDescriptor(LookupIterator* it,
   // 8. Set D.[[Configurable]] to the value of X's [[Configurable]] attribute.
   desc->set_configurable((attrs & DONT_DELETE) == 0);
   // 9. Return D.
+  DCHECK(PropertyDescriptor::IsAccessorDescriptor(desc) !=
+         PropertyDescriptor::IsDataDescriptor(desc));
   return true;
 }
 

src/objects.h

@@ -1893,7 +1893,7 @@ class JSReceiver: public HeapObject {
                                         ShouldThrow should_throw);
 
   static bool GetOwnPropertyDescriptor(Isolate* isolate,
-                                       Handle<JSObject> object,
+                                       Handle<JSReceiver> object,
                                        Handle<Object> key,
                                        PropertyDescriptor* desc);
   static bool GetOwnPropertyDescriptor(LookupIterator* it,

src/property-descriptor.cc

@@ -101,6 +101,45 @@ bool ToPropertyDescriptorFastPath(Isolate* isolate, Handle<Object> obj,
 }
 
 
+static void CreateDataProperty(Isolate* isolate, Handle<JSObject> object,
+                               Handle<String> name, Handle<Object> value) {
+  LookupIterator it(object, name);
+  Maybe<bool> result = JSObject::CreateDataProperty(&it, value);
+  CHECK(result.IsJust() && result.FromJust());
+}
+
+
+// ES6 6.2.4.4 "FromPropertyDescriptor"
+Handle<Object> PropertyDescriptor::ToObject(Isolate* isolate) {
+  DCHECK(!(PropertyDescriptor::IsAccessorDescriptor(this) &&
+           PropertyDescriptor::IsDataDescriptor(this)));
+  Factory* factory = isolate->factory();
+  Handle<JSObject> result = factory->NewJSObject(isolate->object_function());
+  if (has_value()) {
+    CreateDataProperty(isolate, result, factory->value_string(), value());
+  }
+  if (has_writable()) {
+    CreateDataProperty(isolate, result, factory->writable_string(),
+                       factory->ToBoolean(writable()));
+  }
+  if (has_get()) {
+    CreateDataProperty(isolate, result, factory->get_string(), get());
+  }
+  if (has_set()) {
+    CreateDataProperty(isolate, result, factory->set_string(), set());
+  }
+  if (has_enumerable()) {
+    CreateDataProperty(isolate, result, factory->enumerable_string(),
+                       factory->ToBoolean(enumerable()));
+  }
+  if (has_configurable()) {
+    CreateDataProperty(isolate, result, factory->configurable_string(),
+                       factory->ToBoolean(configurable()));
+  }
+  return result;
+}
+
+
 // ES6 6.2.4.5
 // Returns false in case of exception.
 // static

src/property-descriptor.h

@@ -89,6 +89,8 @@ class PropertyDescriptor {
         (has_writable() && !writable() ? READ_ONLY : NONE));
   }
 
+  Handle<Object> ToObject(Isolate* isolate);
+
   static bool ToPropertyDescriptor(Isolate* isolate, Handle<Object> obj,
                                    PropertyDescriptor* desc);
 

test/mjsunit/harmony/reflect-get-own-property-descriptor.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// This file only tests very simple descriptors that always have
+// configurable, enumerable, and writable set to true.
+
+// This is adapted from mjsunit/get-own-property-descriptor.js.
+
+// Flags: --harmony-reflect
+
+function get() { return x; }
+function set(x) { this.x = x; }
+
+var obj = {x: 1};
+obj.__defineGetter__("accessor", get);
+obj.__defineSetter__("accessor", set);
+var a = new Array();
+a[1] = 42;
+obj[1] = 42;
+
+var descIsData = Reflect.getOwnPropertyDescriptor(obj, 'x');
+assertTrue(descIsData.enumerable);
+assertTrue(descIsData.writable);
+assertTrue(descIsData.configurable);
+
+var descIsAccessor = Reflect.getOwnPropertyDescriptor(obj, 'accessor');
+assertTrue(descIsAccessor.enumerable);
+assertTrue(descIsAccessor.configurable);
+assertTrue(descIsAccessor.get == get);
+assertTrue(descIsAccessor.set == set);
+
+var descIsNotData = Reflect.getOwnPropertyDescriptor(obj, 'not-x');
+assertTrue(descIsNotData == undefined);
+
+var descIsNotAccessor = Reflect.getOwnPropertyDescriptor(obj, 'not-accessor');
+assertTrue(descIsNotAccessor == undefined);
+
+var descArray = Reflect.getOwnPropertyDescriptor(a, '1');
+assertTrue(descArray.enumerable);
+assertTrue(descArray.configurable);
+assertTrue(descArray.writable);
+assertEquals(descArray.value, 42);
+
+var descObjectElement = Reflect.getOwnPropertyDescriptor(obj, '1');
+assertTrue(descObjectElement.enumerable);
+assertTrue(descObjectElement.configurable);
+assertTrue(descObjectElement.writable);
+assertEquals(descObjectElement.value, 42);
+
+// String objects.
+var a = new String('foobar');
+for (var i = 0; i < a.length; i++) {
+  var descStringObject = Reflect.getOwnPropertyDescriptor(a, i);
+  assertTrue(descStringObject.enumerable);
+  assertFalse(descStringObject.configurable);
+  assertFalse(descStringObject.writable);
+  assertEquals(descStringObject.value, a.substring(i, i+1));
+}
+
+// Support for additional attributes on string objects.
+a.x = 42;
+a[10] = 'foo';
+var descStringProperty = Reflect.getOwnPropertyDescriptor(a, 'x');
+assertTrue(descStringProperty.enumerable);
+assertTrue(descStringProperty.configurable);
+assertTrue(descStringProperty.writable);
+assertEquals(descStringProperty.value, 42);
+
+var descStringElement = Reflect.getOwnPropertyDescriptor(a, '10');
+assertTrue(descStringElement.enumerable);
+assertTrue(descStringElement.configurable);
+assertTrue(descStringElement.writable);
+assertEquals(descStringElement.value, 'foo');
+
+// Test that elements in the prototype chain is not returned.
+var proto = {};
+proto[10] = 42;
+
+var objWithProto = new Array();
+objWithProto.prototype = proto;
+objWithProto[0] = 'bar';
+var descWithProto = Reflect.getOwnPropertyDescriptor(objWithProto, '10');
+assertEquals(undefined, descWithProto);
+
+// Test elements on global proxy object.
+var global = (function() { return this; })();
+
+global[42] = 42;
+
+function el_getter() { return 239; };
+function el_setter() {};
+Object.defineProperty(global, '239', {get: el_getter, set: el_setter});
+
+var descRegularElement = Reflect.getOwnPropertyDescriptor(global, '42');
+assertEquals(42, descRegularElement.value);
+
+var descAccessorElement = Reflect.getOwnPropertyDescriptor(global, '239');
+assertEquals(el_getter, descAccessorElement.get);
+assertEquals(el_setter, descAccessorElement.set);