src/v8/src/builtins/proxy-get-property.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 {

  extern transitioning builtin GetPropertyWithReceiver(
      implicit context: Context)(Object, Name, Object, Smi): Object;

  // ES #sec-proxy-object-internal-methods-and-internal-slots-get-p-receiver
  // https://tc39.github.io/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-get-p-receiver
  transitioning builtin
  ProxyGetProperty(implicit context: Context)(
      proxy: JSProxy, name: Name, receiverValue: Object,
      onNonExistent: Smi): Object {
    PerformStackCheck();
    // 1. Assert: IsPropertyKey(P) is true.
    assert(TaggedIsNotSmi(name));
    assert(IsName(name));
    assert(!IsPrivateSymbol(name));

    // 2. Let handler be O.[[ProxyHandler]].
    // 3. If handler is null, throw a TypeError exception.
    // 4. Assert: Type(handler) is Object.
    let handler: JSReceiver;
    typeswitch (proxy.handler) {
      case (Null): {
        ThrowTypeError(kProxyRevoked, 'get');
      }
      case (h: JSReceiver): {
        handler = h;
      }
    }

    // 5. Let target be O.[[ProxyTarget]].
    const target = Cast<JSReceiver>(proxy.target) otherwise unreachable;

    // 6. Let trap be ? GetMethod(handler, "get").
    // 7. If trap is undefined, then (see 7.a below).
    // 7.a. Return ? target.[[Get]](P, Receiver).
    const trap: Callable = GetMethod(handler, 'get')
        otherwise return GetPropertyWithReceiver(
        target, name, receiverValue, onNonExistent);

    // 8. Let trapResult be ? Call(trap, handler, « target, P, Receiver »).
    const trapResult =
        Call(context, trap, handler, target, name, receiverValue);

    // 9. Let targetDesc be ? target.[[GetOwnProperty]](P).
    // 10. If targetDesc is not undefined and targetDesc.[[Configurable]] is
    // false, then
    //    a. If IsDataDescriptor(targetDesc) is true and targetDesc.[[Writable]]
    //    is false, then
    //      i. If SameValue(trapResult, targetDesc.[[Value]]) is false, throw a
    //      TypeError exception.
    //    b. If IsAccessorDescriptor(targetDesc) is true and targetDesc.[[Get]]
    //    is undefined, then
    //      i. If trapResult is not undefined, throw a TypeError exception.
    // 11. Return trapResult.
    CheckGetSetTrapResult(target, proxy, name, trapResult, kProxyGet);
    return trapResult;
  }
}