2 * Copyright 2017 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
19 namespace observer_detail {
23 using type = typename std::decay<T>::type;
27 struct NonSharedPtr<std::shared_ptr<T>> {};
30 struct UnwrapSharedPtr {};
33 struct UnwrapSharedPtr<std::shared_ptr<T>> {
34 using type = typename std::decay<T>::type;
39 typename NonSharedPtr<typename std::result_of<F()>::type>::type;
42 using ResultOfUnwrapSharedPtr =
43 typename UnwrapSharedPtr<typename std::result_of<F()>::type>::type;
44 } // namespace observer_detail