[runtime] [proxy] Implementing [[Call]]

src/runtime/runtime-proxy.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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
+#include "src/elements.h"
 #include "src/factory.h"
+#include "src/isolate-inl.h"
 #include "src/objects-inl.h"
 
 namespace v8 {
 namespace internal {
 
 
+// 9.5.13 [[Call]] (thisArgument, argumentsList)

[Jakob Kummerow, 2015/12/07 15:55:08]

nit: include "ES6" please

+RUNTIME_FUNCTION(Runtime_JSProxyCall) {

[Camillo Bruni, 2015/12/07 13:26:23]

Would it make sense to create a builtin instead? We well not call this from
JS...

[Jakob Kummerow, 2015/12/07 15:55:08]

A runtime function is fine, I think.

+  HandleScope scope(isolate);
+  int const arguments_length = args.length() - 2;
+  DCHECK_LE(1, args.length());

[Jakob Kummerow, 2015/12/07 15:55:08]

s/1/2/, judging from the "- 2" above.

[Camillo Bruni, 2015/12/07 16:54:10]

this is actually the size of the wrapper arguments array used further down (a
bit confusing).
Moved down to where it's used the first time.

+  // thisArgument == receiver
+  CONVERT_ARG_HANDLE_CHECKED(Object, receiver, 0);
+  CONVERT_ARG_HANDLE_CHECKED(JSProxy, proxy, args.length() - 1);
+  Handle<String> trap_name = isolate->factory()->apply_string();
+  // 1. Let handler be the value of the [[ProxyHandler]] internal slot of O.
+  Handle<Object> handler(proxy->handler(), isolate);
+  // 2. If handler is null, throw a TypeError exception.
+  if (proxy->IsRevoked()) {
+    THROW_NEW_ERROR_RETURN_FAILURE(
+        isolate, NewTypeError(MessageTemplate::kProxyRevoked, trap_name));
+  }
+  // 3. Assert: Type(handler) is Object.
+  DCHECK(handler->IsJSReceiver());
+  // 4. Let target be the value of the [[ProxyTarget]] internal slot of O.
+  Handle<JSReceiver> target(JSReceiver::cast(proxy->target()), isolate);

[Jakob Kummerow, 2015/12/07 15:55:08]

nit: cast is unnecessary, proxy->target() returns a JSReceiver*.

[Camillo Bruni, 2015/12/07 16:54:10]

right.

+  // 5. Let trap be ? GetMethod(handler, "apply").
+  Handle<Object> trap;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, trap,
+      Object::GetMethod(Handle<JSReceiver>::cast(handler), trap_name));
+  // 6. If trap is undefined, then
+  if (trap->IsUndefined()) {
+    // 6.a. Return Call(target, thisArgument, argumentsList).
+    ScopedVector<Handle<Object>> argv(arguments_length);
+    for (int i = 0; i < arguments_length; ++i) {
+      argv[i] = args.at<Object>(i + 1);
+    }
+    Handle<Object> result;
+    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+        isolate, result, Execution::Call(isolate, target, receiver,
+                                         arguments_length, argv.start()));
+    return *result;
+  }
+  // 7. Let argArray be CreateArrayFromList(argumentsList).
+  Handle<JSArray> arg_array = isolate->factory()->NewJSArray(
+      FAST_ELEMENTS, arguments_length, arguments_length);
+  ElementsAccessor* accessor = arg_array->GetElementsAccessor();
+  {
+    DisallowHeapAllocation no_gc;
+    FixedArrayBase* elements = arg_array->elements();
+    for (int i = 0; i < arguments_length; i++) {
+      accessor->Set(elements, i, args[i + 1]);
+    }
+  }
+  // 8. Return Call(trap, handler, «target, thisArgument, argArray»).
+  Handle<Object> trap_result;
+  Handle<Object> trap_args[] = {target, receiver, arg_array};
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, trap_result,
+      Execution::Call(isolate, trap, handler, arraysize(trap_args), trap_args));
+  return *trap_result;
+}
+
 
 RUNTIME_FUNCTION(Runtime_IsJSProxy) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(Object, obj, 0);
   return isolate->heap()->ToBoolean(obj->IsJSProxy());
 }
 
 
 RUNTIME_FUNCTION(Runtime_GetHandler) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(JSProxy, proxy, 0);
   return proxy->handler();
 }
 
 
 RUNTIME_FUNCTION(Runtime_RevokeProxy) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSProxy, proxy, 0);
   JSProxy::Revoke(proxy);
   return isolate->heap()->undefined_value();
 }
 
 }  // namespace internal
 }  // namespace v8