File indexing completed on 2024-05-19 04:25:08

 /*
  *  SPDX-FileCopyrightText: 2023 Dmitry Kazakov <dimula73@gmail.com>
  *
  *  SPDX-License-Identifier: GPL-2.0-or-later
  */
 #ifndef KISFUTUREUTILS_H
 #define KISFUTUREUTILS_H
 
 namespace kismpl {
 
 /**
  * Create a future whose value has already been evaluated
  *
  * See rejected C++ proposal for details:
  * https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3721.pdf
  */
 template <typename T>
 std::future<std::decay_t<T>> make_ready_future(T &&value) {
     std::promise<T> promise;
     promise.set_value(std::forward<T>(value));
     return promise.get_future();
 }
 
 std::future<void> make_ready_future() {
     std::promise<void> promise;
     promise.set_value();
     return promise.get_future();
 }
 
 /**
  * Execute a given function \p func when the provided
  * future \p future is completed. The future is not
  * deferefenced outside the passed function to avoid
  * spilling the exceptions.
  *
  * See rejected C++ proposal for details:
  * https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3721.pdf
  */
 template<class T, class Function>
 auto then(std::future<T>&& future, Function&& func)
     -> std::future<decltype(func(std::move(future)))>
 {
     return std::async(std::launch::deferred,
         [](std::future<T>&& future, Function&& func)
         {
             future.wait();
             return std::forward<Function>(func)(std::move(future));
         },
         std::move(future),
         std::forward<Function>(func)
         );
 }
 
 }
 
 #endif // KISFUTUREUTILS_H