C++ Value::isUndefined方法代码示例

// static
JSObject*
DOMProxyHandler::GetAndClearExpandoObject(JSObject* obj)
{
    MOZ_ASSERT(IsDOMProxy(obj), "expected a DOM proxy object");
    JS::Value v = js::GetProxyExtra(obj, JSPROXYSLOT_EXPANDO);
    if (v.isUndefined()) {
        return nullptr;
    }

    if (v.isObject()) {
        js::SetProxyExtra(obj, JSPROXYSLOT_EXPANDO, UndefinedValue());
        xpc::GetObjectScope(obj)->RemoveDOMExpandoObject(obj);
    } else {
        js::ExpandoAndGeneration* expandoAndGeneration =
            static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
        v = expandoAndGeneration->expando;
        if (v.isUndefined()) {
            return nullptr;
        }
        expandoAndGeneration->expando = UndefinedValue();
    }


    return &v.toObject();
}

js::DOMProxyShadowsResult
DOMProxyShadows(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id)
{
  JS::Rooted<JSObject*> expando(cx, DOMProxyHandler::GetExpandoObject(proxy));
  JS::Value v = js::GetProxyExtra(proxy, JSPROXYSLOT_EXPANDO);
  bool isOverrideBuiltins = !v.isObject() && !v.isUndefined();
  if (expando) {
    bool hasOwn;
    if (!JS_AlreadyHasOwnPropertyById(cx, expando, id, &hasOwn))
      return js::ShadowCheckFailed;

    if (hasOwn) {
      return isOverrideBuiltins ?
        js::ShadowsViaIndirectExpando : js::ShadowsViaDirectExpando;
    }
  }

  if (!isOverrideBuiltins) {
    // Our expando, if any, didn't shadow, so we're not shadowing at all.
    return js::DoesntShadow;
  }

  bool hasOwn;
  if (!GetProxyHandler(proxy)->hasOwn(cx, proxy, id, &hasOwn))
    return js::ShadowCheckFailed;

  return hasOwn ? js::Shadows : js::DoesntShadowUnique;
}

static inline void CheckExpandoAndGeneration(
    JSObject* proxy, js::ExpandoAndGeneration* expandoAndGeneration) {
#ifdef DEBUG
  JS::Value value = expandoAndGeneration->expando;
  if (!value.isUndefined()) CheckExpandoObject(proxy, value);
#endif
}

void ModuleScript::SetParseError(const JS::Value& aError) {
  MOZ_ASSERT(!aError.isUndefined());
  MOZ_ASSERT(!HasParseError());
  MOZ_ASSERT(!HasErrorToRethrow());

  UnlinkModuleRecord();
  mParseError = aError;
  HoldJSObjects(this);
}

//static
JSObject *
DOMProxyHandler::GetExpandoObject(JSObject *obj)
{
  MOZ_ASSERT(IsDOMProxy(obj), "expected a DOM proxy object");
  JS::Value v = js::GetProxyExtra(obj, JSPROXYSLOT_EXPANDO);
  if (v.isObject()) {
    return &v.toObject();
  }

  if (v.isUndefined()) {
    return nullptr;
  }

  js::ExpandoAndGeneration* expandoAndGeneration =
    static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
  v = expandoAndGeneration->expando;
  return v.isUndefined() ? nullptr : &v.toObject();
}

void ModuleScript::SetErrorToRethrow(const JS::Value& aError) {
  MOZ_ASSERT(!aError.isUndefined());

  // This is only called after SetModuleRecord() or SetParseError() so we don't
  // need to call HoldJSObjects() here.
  MOZ_ASSERT(ModuleRecord() || HasParseError());

  mErrorToRethrow = aError;
}

// static
JSObject* DOMProxyHandler::GetExpandoObject(JSObject* obj) {
  CheckDOMProxy(obj);

  JS::Value v = js::GetProxyPrivate(obj);
  if (v.isObject()) {
    CheckExpandoObject(obj, v);
    return &v.toObject();
  }

  if (v.isUndefined()) {
    return nullptr;
  }

  js::ExpandoAndGeneration* expandoAndGeneration =
      static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
  CheckExpandoAndGeneration(obj, expandoAndGeneration);

  v = expandoAndGeneration->expando;
  return v.isUndefined() ? nullptr : &v.toObject();
}

bool CoerceDouble(const JS::Value& v, double* d) {
  if (v.isDouble()) {
    *d = v.toDouble();
  } else if (v.isInt32()) {
    *d = double(v.toInt32());
  } else if (v.isUndefined()) {
    *d = 0.0;
  } else {
    return false;
  }
  return true;
}

/**
 * Extract the FinalizationEvent from an instance of FinalizationWitness
 * and clear the slot containing the FinalizationEvent.
 */
already_AddRefed<FinalizationEvent>
ExtractFinalizationEvent(JSObject *objSelf)
{
  JS::Value slotEvent = JS_GetReservedSlot(objSelf, WITNESS_SLOT_EVENT);
  if (slotEvent.isUndefined()) {
    // Forget() has been called
    return nullptr;
  }

  JS_SetReservedSlot(objSelf, WITNESS_SLOT_EVENT, JS::UndefinedValue());

  return dont_AddRef(static_cast<FinalizationEvent*>(slotEvent.toPrivate()));
}

// static
JSObject*
DOMProxyHandler::GetAndClearExpandoObject(JSObject* obj)
{
  MOZ_ASSERT(IsDOMProxy(obj), "expected a DOM proxy object");
  JS::Value v = js::GetProxyPrivate(obj);
  if (v.isUndefined()) {
    return nullptr;
  }

  if (v.isObject()) {
    js::SetProxyPrivate(obj, UndefinedValue());
  } else {
    js::ExpandoAndGeneration* expandoAndGeneration =
      static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
    v = expandoAndGeneration->expando;
    if (v.isUndefined()) {
      return nullptr;
    }
    // We have to expose v to active JS here.  The reason for that is that we
    // might be in the middle of a GC right now.  If our proxy hasn't been
    // traced yet, when it _does_ get traced it won't trace the expando, since
    // we're breaking that link.  But the Rooted we're presumably being placed
    // into is also not going to trace us, because Rooted marking is done at
    // the very beginning of the GC.  In that situation, we need to manually
    // mark the expando as live here.  JS::ExposeValueToActiveJS will do just
    // that for us.
    //
    // We don't need to do this in the non-expandoAndGeneration case, because
    // in that case our value is stored in a slot and slots will already mark
    // the old thing live when the value in the slot changes.
    JS::ExposeValueToActiveJS(v);
    expandoAndGeneration->expando = UndefinedValue();
  }


  return &v.toObject();
}

// static
JSObject* DOMProxyHandler::GetAndClearExpandoObject(JSObject* obj) {
  CheckDOMProxy(obj);

  JS::Value v = js::GetProxyPrivate(obj);
  if (v.isUndefined()) {
    return nullptr;
  }

  if (v.isObject()) {
    js::SetProxyPrivate(obj, UndefinedValue());
  } else {
    js::ExpandoAndGeneration* expandoAndGeneration =
        static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
    v = expandoAndGeneration->expando;
    if (v.isUndefined()) {
      return nullptr;
    }
    expandoAndGeneration->expando = UndefinedValue();
  }

  CheckExpandoObject(obj, v);

  return &v.toObject();
}

bool
GetSendMmsMessageRequestFromParams(uint32_t aServiceId,
                                   const JS::Value& aParam,
                                   SendMmsMessageRequest& request) {
  if (aParam.isUndefined() || aParam.isNull() || !aParam.isObject()) {
    return false;
  }

  mozilla::AutoJSContext cx;
  JS::Rooted<JS::Value> param(cx, aParam);
  RootedDictionary<MmsParameters> params(cx);
  if (!params.Init(cx, param)) {
    return false;
  }

  // SendMobileMessageRequest.receivers
  if (!params.mReceivers.WasPassed()) {
    return false;
  }
  request.receivers().AppendElements(params.mReceivers.Value());

  // SendMobileMessageRequest.attachments
  mozilla::dom::ContentChild* cc = mozilla::dom::ContentChild::GetSingleton();

  if (!params.mAttachments.WasPassed()) {
    return false;
  }

  for (uint32_t i = 0; i < params.mAttachments.Value().Length(); i++) {
    mozilla::dom::MmsAttachment& attachment = params.mAttachments.Value()[i];
    MmsAttachmentData mmsAttachment;
    mmsAttachment.id().Assign(attachment.mId);
    mmsAttachment.location().Assign(attachment.mLocation);
    mmsAttachment.contentChild() = cc->GetOrCreateActorForBlob(attachment.mContent);
    if (!mmsAttachment.contentChild()) {
      return false;
    }
    request.attachments().AppendElement(mmsAttachment);
  }

  request.smil() = params.mSmil;
  request.subject() = params.mSubject;

  // Set service ID.
  request.serviceId() = aServiceId;

  return true;
}

void ShadowingDOMProxyHandler::trace(JSTracer* trc, JSObject* proxy) const {
  DOMProxyHandler::trace(trc, proxy);

  MOZ_ASSERT(IsDOMProxy(proxy), "expected a DOM proxy object");
  JS::Value v = js::GetProxyPrivate(proxy);
  MOZ_ASSERT(!v.isObject(), "Should not have expando object directly!");

  // The proxy's private slot is set when we allocate the proxy,
  // so it cannot be |undefined|.
  MOZ_ASSERT(!v.isUndefined());

  js::ExpandoAndGeneration* expandoAndGeneration =
      static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
  JS::TraceEdge(trc, &expandoAndGeneration->expando,
                "Shadowing DOM proxy expando");
}

// static
JSObject*
DOMProxyHandler::EnsureExpandoObject(JSContext* cx, JS::Handle<JSObject*> obj)
{
    NS_ASSERTION(IsDOMProxy(obj), "expected a DOM proxy object");
    JS::Value v = js::GetProxyExtra(obj, JSPROXYSLOT_EXPANDO);
    if (v.isObject()) {
        return &v.toObject();
    }

    js::ExpandoAndGeneration* expandoAndGeneration;
    if (!v.isUndefined()) {
        expandoAndGeneration = static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
        if (expandoAndGeneration->expando.isObject()) {
            return &expandoAndGeneration->expando.toObject();
        }
    } else {
        expandoAndGeneration = nullptr;
    }

    JS::Rooted<JSObject*> expando(cx,
                                  JS_NewObjectWithGivenProto(cx, nullptr, nullptr, js::GetObjectParent(obj)));
    if (!expando) {
        return nullptr;
    }

    nsISupports* native = UnwrapDOMObject<nsISupports>(obj);
    nsWrapperCache* cache;
    CallQueryInterface(native, &cache);
    if (expandoAndGeneration) {
        cache->PreserveWrapper(native);
        expandoAndGeneration->expando.setObject(*expando);

        return expando;
    }

    XPCWrappedNativeScope* scope = xpc::GetObjectScope(obj);
    if (!scope->RegisterDOMExpandoObject(obj)) {
        return nullptr;
    }

    cache->SetPreservingWrapper(true);
    js::SetProxyExtra(obj, JSPROXYSLOT_EXPANDO, ObjectValue(*expando));

    return expando;
}

/**
 * Get a field of an object as an object.
 *
 * If the field does not exist, create it. If it exists but is not an
 * object, throw a JS error.
 */
JSObject *GetOrCreateObjectProperty(JSContext *cx, JSObject *aObject,
                                    const char *aProperty)
{
  JS::Value val;
  if (!JS_GetProperty(cx, aObject, aProperty, &val)) {
    return NULL;
  }
  if (!val.isUndefined()) {
    if (val.isObject()) {
      return &val.toObject();
    }

    JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
      JSMSG_UNEXPECTED_TYPE, aProperty, "not an object");
    return NULL;
  }
  return JS_DefineObject(cx, aObject, aProperty, NULL, NULL, JSPROP_ENUMERATE);
}