src/third_party/v8/src/builtins/proxy-is-extensible.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 ProxyIsExtensible(implicit context: Context)(
    proxy: JSProxy): JSAny {
  PerformStackCheck();
  const kTrapName: constexpr string = 'isExtensible';
  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, "isExtensible").
    // 6. If trap is undefined, then (see 6.a below).
    const trap: Callable = GetMethod(handler, kTrapName)
        otherwise goto TrapUndefined(target);

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

    // 8. Let targetResult be ? IsExtensible(target).
    const targetResult: bool =
        ToBoolean(object::ObjectIsExtensibleImpl(target));

    // 9. If SameValue(booleanTrapResult, targetResult) is false, throw a
    // TypeError exception.
    if (trapResult != targetResult) {
      ThrowTypeError(
          MessageTemplate::kProxyIsExtensibleInconsistent,
          SelectBooleanConstant(targetResult));
    }
    // 10. Return booleanTrapResult.
    return SelectBooleanConstant(trapResult);
  } label TrapUndefined(target: JSAny) {
    // 6.a. Return ? IsExtensible(target).
    return object::ObjectIsExtensibleImpl(target);
  } label ThrowProxyHandlerRevoked deferred {
    ThrowTypeError(MessageTemplate::kProxyRevoked, kTrapName);
  }
}
}