Implement Proxy object [[getPrototypeOf]] internal method (#3623)

The algorithm is based on ECMA-262 v6, 9.5.1

JerryScript-DCO-1.0-Signed-off-by: Adam Szilagyi aszilagy@inf.u-szeged.hu

jerry-core/ecma/operations/ecma-proxy-object.c

@@ -292,8 +292,92 @@ ecma_value_t
 ecma_proxy_object_get_prototype_of (ecma_object_t *obj_p) /**< proxy object */
 {
   JERRY_ASSERT (ECMA_OBJECT_IS_PROXY (obj_p));
-  JERRY_UNUSED (obj_p);
-  return ecma_raise_type_error (ECMA_ERR_MSG ("UNIMPLEMENTED: Proxy.[[GetPrototypeOf]]"));
+
+  ecma_proxy_object_t *proxy_obj_p = (ecma_proxy_object_t *) obj_p;
+
+  /* 1. */
+  ecma_value_t handler = proxy_obj_p->handler;
+
+  /* 2-5. */
+  ecma_value_t trap = ecma_validate_proxy_object (handler, LIT_MAGIC_STRING_GET_PROTOTYPE_OF_UL);
+
+  /* 6. */
+  if (ECMA_IS_VALUE_ERROR (trap))
+  {
+    return trap;
+  }
+
+  ecma_value_t target = proxy_obj_p->target;
+  ecma_object_t *target_obj_p = ecma_get_object_from_value (target);
+
+  /* 7. */
+  if (ecma_is_value_undefined (trap))
+  {
+    return ecma_builtin_object_object_get_prototype_of (target_obj_p);
+  }
+
+  ecma_object_t *func_obj_p = ecma_get_object_from_value (trap);
+
+  /* 8. */
+  ecma_value_t handler_proto = ecma_op_function_call (func_obj_p, handler, &target, 1);
+
+  ecma_deref_object (func_obj_p);
+
+  /* 9. */
+  if (ECMA_IS_VALUE_ERROR (handler_proto))
+  {
+    return handler_proto;
+  }
+
+  /* 10. */
+  if (!ecma_is_value_object (handler_proto) && !ecma_is_value_null (handler_proto))
+  {
+    ecma_free_value (handler_proto);
+
+    return ecma_raise_type_error (ECMA_ERR_MSG ("Trap returned neither object nor null."));
+  }
+
+  /* 11. */
+  ecma_value_t extensible_target = ecma_builtin_object_object_is_extensible (target_obj_p);
+
+  /* 12. */
+  if (ECMA_IS_VALUE_ERROR (extensible_target))
+  {
+    ecma_free_value (handler_proto);
+
+    return extensible_target;
+  }
+
+  /* 13. */
+  if (ecma_is_value_true (extensible_target))
+  {
+    return handler_proto;
+  }
+
+  /* 14. */
+  ecma_value_t target_proto = ecma_builtin_object_object_get_prototype_of (target_obj_p);
+
+  /* 15. */
+  if (ECMA_IS_VALUE_ERROR (target_proto))
+  {
+    return target_proto;
+  }
+
+  ecma_value_t ret_value = handler_proto;
+
+  /* 16. */
+  if (handler_proto != target_proto)
+  {
+    ecma_free_value (handler_proto);
+
+    ret_value = ecma_raise_type_error (ECMA_ERR_MSG ("Proxy target is non-extensible, but the trap did not "
+                                                     "return its actual prototype."));
+  }
+
+  ecma_free_value (target_proto);
+
+  /* 17. */
+  return ret_value;
 } /* ecma_proxy_object_get_prototype_of */
 
 /**

tests/jerry/es2015/proxy_get_prototoype_of.js

@@ -12,7 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// TODO: Update these tests when the internal routine has been implemented
+// Copyright 2015 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.
 
 var target = {};
 var handler = { getPrototypeOf (target) {
@@ -26,7 +28,7 @@ try {
   Object.getPrototypeOf(proxy);
   assert(false);
 } catch (e) {
-  assert(e instanceof TypeError);
+  assert(e === 42);
 }
 
 try {
@@ -34,7 +36,7 @@ try {
   Object.prototype.isPrototypeOf(proxy);
   assert(false);
 } catch (e) {
-  assert(e instanceof TypeError);
+  assert(e === 42);
 }
 
 (function () {
@@ -49,7 +51,7 @@ try {
     g instanceof f;
     assert(false);
   } catch (e) {
-    assert(e instanceof TypeError);
+    assert(e === 42);
   }
 
   // ecma_op_implicit_class_constructor_has_instance [[GetPrototypeOf]]
@@ -57,7 +59,7 @@ try {
     g instanceof e;
     assert(false);
   } catch (e) {
-    assert(e instanceof TypeError);
+    assert(e === 42);
   }
 })();
 
@@ -68,3 +70,99 @@ try {
 } catch (e) {
   assert(e instanceof TypeError);
 }
+
+// test basic functionality
+var target = {};
+var handler = {
+  getPrototypeOf(target) {
+    return Array.prototype;
+  }
+}
+var proxy = new Proxy(target, handler);
+
+assert(Object.getPrototypeOf(proxy) === Array.prototype);
+assert(Reflect.getPrototypeOf(proxy) === Array.prototype);
+assert(Array.prototype.isPrototypeOf(proxy));
+assert(proxy instanceof Array);
+
+var obj = Object.preventExtensions({});
+assert(Object.getPrototypeOf(obj) === Object.prototype);
+
+var handler = {
+  getPrototypeOf(target) {
+    return Object.prototype;
+  }
+}
+var proxy = new Proxy(target, handler);
+assert(Object.getPrototypeOf(proxy) === Object.prototype);
+
+// test with no trap
+var target = {};
+var handler = {};
+var proxy = new Proxy(target, handler);
+
+assert(Object.getPrototypeOf(proxy) === Object.prototype);
+
+// test with "undefined" trap
+var target = {};
+var handler = { getPrototypeOf: null };
+var proxy = new Proxy(target, handler);
+
+assert(Object.getPrototypeOf(proxy) === Object.prototype);
+
+// test with invalid trap
+var target = {};
+var handler = { getPrototypeOf: 42 };
+var proxy = new Proxy(target, handler);
+
+try {
+  Object.getPrototypeOf(proxy)
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+// test when target is proxy
+var target = {};
+var handler = {};
+var proxy = new Proxy(target, handler);
+
+var target_prototype = {};
+handler.getPrototypeOf = function() {
+  return target_prototype ;
+}
+
+var proxy2 = new Proxy(proxy, handler);
+assert(Object.getPrototypeOf(proxy2) === target_prototype);
+
+// test when invariants gets violated
+var target = {};
+var handler = {
+  getPrototypeOf(target) {
+    return 'foo';
+  }
+}
+var proxy = new Proxy(target, handler);
+
+try {
+  Object.getPrototypeOf(proxy);
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+var target = Object.preventExtensions({});
+var handler = {
+  getPrototypeOf(target) {
+    return {};
+  }
+}
+
+var proxy = new Proxy(target, handler);
+
+try {
+  Object.getPrototypeOf(proxy);
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}

tests/unit-core/test-api.c

@@ -697,18 +697,18 @@ main (void)
 
   if (jerry_is_feature_enabled (JERRY_FEATURE_PROXY))
   {
-    /* Note: update this test when the internal method is implemented */
     jerry_value_t target = jerry_create_object ();
     jerry_value_t handler = jerry_create_object ();
     jerry_value_t proxy = jerry_create_proxy (target, handler);
+    jerry_value_t obj_proto = jerry_eval ((jerry_char_t *) "Object.prototype", 16, JERRY_PARSE_NO_OPTS);
 
     jerry_release_value (target);
     jerry_release_value (handler);
     proto_val = jerry_get_prototype (proxy);
-    TEST_ASSERT (jerry_value_is_error (proto_val));
-    error = jerry_get_value_from_error (proto_val, true);
-    TEST_ASSERT (jerry_get_error_type (error) == JERRY_ERROR_TYPE);
-    jerry_release_value (error);
+    TEST_ASSERT (!jerry_value_is_error (proto_val));
+    TEST_ASSERT (proto_val == obj_proto);
+    jerry_release_value (proto_val);
+    jerry_release_value (obj_proto);
     jerry_release_value (proxy);
   }