[esnext] implement Object.getOwnPropertyDescriptors() proposal

BUG=v8:4725
LOG=N
R=adamk@chromium.org, cbruni@chromium.org, rossberg@chromium.org

Review URL: https://codereview.chromium.org/1658773003

Cr-Commit-Position: refs/heads/master@{#33752}

src/bootstrapper.cc

@@ -2459,6 +2459,19 @@ void Genesis::InitializeGlobal_harmony_object_values_entries() {
                         Builtins::kObjectValues, 1, false);
 }
 
+void Genesis::InitializeGlobal_harmony_object_own_property_descriptors() {
+  if (!FLAG_harmony_object_own_property_descriptors) return;
+
+  Handle<JSGlobalObject> global(
+      JSGlobalObject::cast(native_context()->global_object()));
+  Isolate* isolate = global->GetIsolate();
+  Factory* factory = isolate->factory();
+
+  Handle<JSFunction> object_function = isolate->object_function();
+  SimpleInstallFunction(object_function,
+                        factory->getOwnPropertyDescriptors_string(),
+                        Builtins::kObjectGetOwnPropertyDescriptors, 1, false);
+}
 
 void Genesis::InstallJSProxyMaps() {
   // Allocate the different maps for all Proxy types.
@@ -2948,6 +2961,8 @@ bool Genesis::InstallExperimentalNatives() {
   static const char* promise_extra_natives[] = {"native promise-extra.js",
                                                 nullptr};
   static const char* harmony_object_values_entries_natives[] = {nullptr};
+  static const char* harmony_object_own_property_descriptors_natives[] = {
+      nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();
        i < ExperimentalNatives::GetBuiltinsCount(); i++) {

src/builtins.cc

@@ -1800,6 +1800,43 @@ BUILTIN(ObjectEntries) {
   return *isolate->factory()->NewJSArrayWithElements(keys);
 }
 
+BUILTIN(ObjectGetOwnPropertyDescriptors) {
+  HandleScope scope(isolate);
+  Handle<Object> object = args.atOrUndefined(isolate, 1);
+  Handle<Object> undefined = isolate->factory()->undefined_value();
+
+  Handle<JSReceiver> receiver;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, receiver,
+                                     Object::ToObject(isolate, object));
+
+  Handle<FixedArray> keys;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, keys, JSReceiver::GetKeys(receiver, OWN_ONLY, ALL_PROPERTIES,
+                                         CONVERT_TO_STRING));
+
+  Handle<Object> descriptors =
+      isolate->factory()->NewJSObject(isolate->object_function());
+
+  for (int i = 0; i < keys->length(); ++i) {
+    Handle<Name> key = Handle<Name>::cast(FixedArray::get(*keys, i, isolate));
+    PropertyDescriptor descriptor;
+    Maybe<bool> did_get_descriptor = JSReceiver::GetOwnPropertyDescriptor(
+        isolate, receiver, key, &descriptor);
+    MAYBE_RETURN(did_get_descriptor, isolate->heap()->exception());
+
+    Handle<Object> from_descriptor = did_get_descriptor.FromJust()
+                                         ? descriptor.ToObject(isolate)
+                                         : undefined;
+
+    LookupIterator it = LookupIterator::PropertyOrElement(
+        isolate, descriptors, key, LookupIterator::OWN);
+    Maybe<bool> success = JSReceiver::CreateDataProperty(&it, from_descriptor,
+                                                         Object::DONT_THROW);
+    CHECK(success.FromJust());
+  }
+
+  return *descriptors;
+}
 
 // ES6 section 19.1.2.15 Object.preventExtensions ( O )
 BUILTIN(ObjectPreventExtensions) {

src/builtins.h

@@ -118,6 +118,7 @@ inline bool operator&(BuiltinExtraArguments lhs, BuiltinExtraArguments rhs) {
   V(ObjectKeys, kNone)                                         \
   V(ObjectValues, kNone)                                       \
   V(ObjectEntries, kNone)                                      \
+  V(ObjectGetOwnPropertyDescriptors, kNone)                    \
   V(ObjectPreventExtensions, kNone)                            \
   V(ObjectSeal, kNone)                                         \
   V(ObjectProtoToString, kNone)                                \

src/flag-definitions.h

@@ -203,16 +203,18 @@ DEFINE_IMPLICATION(es_staging, harmony_regexp_lookbehind)
 DEFINE_IMPLICATION(es_staging, move_object_start)
 
 // Features that are still work in progress (behind individual flags).
-#define HARMONY_INPROGRESS(V)                                 \
-  V(harmony_modules, "harmony modules")                       \
-  V(harmony_function_name, "harmony Function name inference") \
-  V(harmony_function_sent, "harmony function.sent")           \
-  V(harmony_sharedarraybuffer, "harmony sharedarraybuffer")   \
-  V(harmony_simd, "harmony simd")                             \
-  V(harmony_do_expressions, "harmony do-expressions")         \
-  V(harmony_tailcalls, "harmony tail calls")                  \
-  V(harmony_species, "harmony Symbol.species")                \
-  V(harmony_object_values_entries, "harmony Object.values / Object.entries")
+#define HARMONY_INPROGRESS(V)                                                \
+  V(harmony_modules, "harmony modules")                                      \
+  V(harmony_function_name, "harmony Function name inference")                \
+  V(harmony_function_sent, "harmony function.sent")                          \
+  V(harmony_sharedarraybuffer, "harmony sharedarraybuffer")                  \
+  V(harmony_simd, "harmony simd")                                            \
+  V(harmony_do_expressions, "harmony do-expressions")                        \
+  V(harmony_tailcalls, "harmony tail calls")                                 \
+  V(harmony_species, "harmony Symbol.species")                               \
+  V(harmony_object_values_entries, "harmony Object.values / Object.entries") \
+  V(harmony_object_own_property_descriptors,                                 \
+    "harmony Object.getOwnPropertyDescriptors()")
 
 // Features that are complete (but still behind --harmony/es-staging flag).
 #define HARMONY_STAGED(V)                                   \

test/mjsunit/harmony/object-get-own-property-descriptors.js

+// Copyright 2016 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.
+
+// Flags: --harmony-object-own-property-descriptors
+// Flags: --harmony-proxies --harmony-reflect --allow-natives-syntax
+
+function DataDescriptor(value) {
+  return { "enumerable": true, "configurable": true, "writable": true, value };
+}
+
+
+function TestMeta() {
+  assertEquals(1, Object.getOwnPropertyDescriptors.length);
+  assertEquals(Function.prototype,
+               Object.getPrototypeOf(Object.getOwnPropertyDescriptors));
+  assertEquals(
+      'getOwnPropertyDescriptors', Object.getOwnPropertyDescriptors.name);
+  var desc = Reflect.getOwnPropertyDescriptor(
+      Object, 'getOwnPropertyDescriptors');
+  assertFalse(desc.enumerable);
+  assertTrue(desc.writable);
+  assertTrue(desc.configurable);
+}
+TestMeta();
+
+
+function TestToObject() {
+  assertThrows(function() {
+    Object.getOwnPropertyDescriptors(null);
+  }, TypeError);
+
+  assertThrows(function() {
+    Object.getOwnPropertyDescriptors(undefined);
+  }, TypeError);
+
+  assertThrows(function() {
+    Object.getOwnPropertyDescriptors();
+  }, TypeError);
+}
+TestToObject();
+
+
+function TestPrototypeProperties() {
+  function F() {};
+  F.prototype.a = "A";
+  F.prototype.b = "B";
+
+  var F2 = new F();
+  Object.defineProperties(F2, {
+    "b": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "Shadowed 'B'"
+    },
+    "c": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "C"
+    }
+  });
+
+  assertEquals({
+    "b": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "Shadowed 'B'"
+    },
+    "c": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "C"
+    }
+  }, Object.getOwnPropertyDescriptors(F2));
+}
+TestPrototypeProperties();
+
+
+function TestPrototypeProperties() {
+  function F() {};
+  F.prototype.a = "A";
+  F.prototype.b = "B";
+
+  var F2 = new F();
+  Object.defineProperties(F2, {
+    "b": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "Shadowed 'B'"
+    },
+    "c": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "C"
+    }
+  });
+
+  assertEquals({
+    "b": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "Shadowed 'B'"
+    },
+    "c": {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: "C"
+    }
+  }, Object.getOwnPropertyDescriptors(F2));
+}
+TestPrototypeProperties();
+
+
+function TestTypeFilteringAndOrder() {
+  var log = [];
+  var sym = Symbol("foo");
+  var psym = %CreatePrivateSymbol("private");
+  var O = {
+    0: 0,
+    [sym]: 3,
+    "a": 2,
+    [psym]: 4,
+    1: 1,
+  };
+  var P = new Proxy(O, {
+    ownKeys(target) {
+      log.push("ownKeys()");
+      return Reflect.ownKeys(target);
+    },
+    getOwnPropertyDescriptor(target, name) {
+      log.push(`getOwnPropertyDescriptor(${String(name)})`);
+      return Reflect.getOwnPropertyDescriptor(target, name);
+    },
+    get(target, name) { assertUnreachable(); },
+    set(target, name, value) { assertUnreachable(); },
+    deleteProperty(target, name) { assertUnreachable(); },
+    defineProperty(target, name, desc) { assertUnreachable(); }
+  });
+
+  var result1 = Object.getOwnPropertyDescriptors(O);
+  assertEquals({
+    0: DataDescriptor(0),
+    1: DataDescriptor(1),
+    "a": DataDescriptor(2),
+    [sym]: DataDescriptor(3)
+  }, result1);
+
+  var result2 = Object.getOwnPropertyDescriptors(P);
+  assertEquals([
+    "ownKeys()",
+    "getOwnPropertyDescriptor(0)",
+    "getOwnPropertyDescriptor(1)",
+    "getOwnPropertyDescriptor(a)",
+    "getOwnPropertyDescriptor(Symbol(foo))"
+  ], log);
+  assertEquals({
+    0: DataDescriptor(0),
+    1: DataDescriptor(1),
+    "a": DataDescriptor(2),
+    [sym]: DataDescriptor(3)
+  }, result2);
+}
+TestTypeFilteringAndOrder();
+
+
+function TestDuplicateKeys() {
+  var i = 0;
+  var log = [];
+  var P = new Proxy({}, {
+    ownKeys() {
+      log.push(`ownKeys()`);
+      return ["A", "A"];
+    },
+    getOwnPropertyDescriptor(t, name) {
+      log.push(`getOwnPropertyDescriptor(${name})`);
+      if (i++) return;
+      return {
+        configurable: true,
+        writable: false,
+        value: "VALUE"
+      };
+    },
+    get(target, name) { assertUnreachable(); },
+    set(target, name, value) { assertUnreachable(); },
+    deleteProperty(target, name) { assertUnreachable(); },
+    defineProperty(target, name, desc) { assertUnreachable(); }
+  });
+
+  var result = Object.getOwnPropertyDescriptors(P);
+  assertEquals({ "A": undefined }, result);
+  assertTrue(result.hasOwnProperty("A"));
+  assertEquals([
+    "ownKeys()",
+    "getOwnPropertyDescriptor(A)",
+    "getOwnPropertyDescriptor(A)"
+  ], log);
+}
+TestDuplicateKeys();