src/v8/src/builtins/proxy-delete-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 {

  // ES #sec-proxy-object-internal-methods-and-internal-slots-delete-p
  // https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-delete-p
  transitioning builtin
  ProxyDeleteProperty(implicit context: Context)(
      proxy: JSProxy, name: Name, languageMode: LanguageMode): Object {
    const kTrapName: constexpr string = 'deleteProperty';
    // 1. Assert: IsPropertyKey(P) is true.
    assert(TaggedIsNotSmi(name));
    assert(IsName(name));
    assert(!IsPrivateSymbol(name));

    try {
      // 2. Let handler be O.[[ProxyHandler]].
      // 3. If handler is null, throw a TypeError exception.
      // 4. Assert: Type(handler) is Object.
      assert(proxy.handler == Null || Is<JSReceiver>(proxy.handler));
      const handler =
          Cast<JSReceiver>(proxy.handler) otherwise ThrowProxyHandlerRevoked;

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

      // 6. Let trap be ? GetMethod(handler, "deleteProperty").
      // 7. If trap is undefined, then (see 7.a below).
      const trap: Callable = GetMethod(handler, kTrapName)
          otherwise goto TrapUndefined(target);

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

      // 9. If booleanTrapResult is false, return false.
      if (BranchIfToBooleanIsFalse(trapResult)) {
        if (languageMode == SmiConstant(kStrict)) {
          ThrowTypeError(kProxyTrapReturnedFalsishFor, kTrapName, name);
        }
        return False;
      }

      // 10. Let targetDesc be ? target.[[GetOwnProperty]](P).
      // 11. If targetDesc is undefined, return true.
      // 12. If targetDesc.[[Configurable]] is false, throw a TypeError
      // exception.
      // 13. Let extensibleTarget be ? IsExtensible(target).
      // 14. If extensibleTarget is false, throw a TypeError exception.
      CheckDeleteTrapResult(target, proxy, name);

      // 15. Return true.
      return True;
    }
    label TrapUndefined(target: Object) {
      // 7.a. Return ? target.[[Delete]](P).
      return DeleteProperty(target, name, languageMode);
    }
    label ThrowProxyHandlerRevoked deferred {
      ThrowTypeError(kProxyRevoked, kTrapName);
    }
  }
}