src/third_party/v8/src/builtins/proxy-get-prototype-of.tq

// Copyright 2019 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/builtins/builtins-proxy-gen.h'

namespace proxy {

// ES #sec-proxy-object-internal-methods-and-internal-slots-isextensible
// https://tc39.github.io/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-isextensible
transitioning builtin
ProxyGetPrototypeOf(implicit context: Context)(proxy: JSProxy): JSAny {
  PerformStackCheck();
  const kTrapName: constexpr string = 'getPrototypeOf';
  try {
    // 1. Let handler be O.[[ProxyHandler]].
    // 2. If handler is null, throw a TypeError exception.
    // 3. Assert: Type(handler) is Object.
    assert(proxy.handler == Null || Is<JSReceiver>(proxy.handler));
    const handler =
        Cast<JSReceiver>(proxy.handler) otherwise ThrowProxyHandlerRevoked;

    // 4. Let target be O.[[ProxyTarget]].
    const target = proxy.target;

    // 5. Let trap be ? GetMethod(handler, "getPrototypeOf").
    // 6. If trap is undefined, then (see 6.a below).
    const trap: Callable = GetMethod(handler, kTrapName)
        otherwise goto TrapUndefined(target);

    // 7. Let handlerProto be ? Call(trap, handler, « target »).
    const handlerProto = Call(context, trap, handler, target);

    // 8. If Type(handlerProto) is neither Object nor Null, throw a TypeError
    // exception.
    if (!Is<JSReceiver>(handlerProto) && handlerProto != Null) {
      goto ThrowProxyGetPrototypeOfInvalid;
    }

    // 9. Let extensibleTarget be ? IsExtensible(target).
    // 10. If extensibleTarget is true, return handlerProto.
    const extensibleTarget: JSAny = object::ObjectIsExtensibleImpl(target);
    assert(extensibleTarget == True || extensibleTarget == False);
    if (extensibleTarget == True) {
      return handlerProto;
    }

    // 11. Let targetProto be ? target.[[GetPrototypeOf]]().
    const targetProto = object::ObjectGetPrototypeOfImpl(target);

    // 12. If SameValue(handlerProto, targetProto) is false, throw a TypeError
    // exception.
    // 13. Return handlerProto.
    if (SameValue(targetProto, handlerProto)) {
      return handlerProto;
    }
    ThrowTypeError(MessageTemplate::kProxyGetPrototypeOfNonExtensible);
  } label TrapUndefined(target: JSAny) {
    // 6.a. Return ? target.[[GetPrototypeOf]]().
    return object::ObjectGetPrototypeOfImpl(target);
  } label ThrowProxyHandlerRevoked deferred {
    ThrowTypeError(MessageTemplate::kProxyRevoked, kTrapName);
  } label ThrowProxyGetPrototypeOfInvalid deferred {
    ThrowTypeError(MessageTemplate::kProxyGetPrototypeOfInvalid);
  }
}
}