+++ /dev/null
-/* Copyright (c) 2015-2021. The SimGrid Team.
- * All rights reserved. */
-
-/* This program is free software; you can redistribute it and/or modify it
- * under the terms of the license (GNU LGPL) which comes with this package. */
-
-#ifndef XBT_FUTURE_HPP
-#define XBT_FUTURE_HPP
-
-#include <cstddef>
-
-#include <boost/variant.hpp>
-#include <exception>
-#include <functional>
-#include <future> // std::future_error
-#include <stdexcept>
-#include <type_traits>
-#include <utility>
-#include <xbt/ex.h>
-
-namespace simgrid {
-namespace xbt {
-
-/** A value or an exception (or nothing)
- *
- * This is similar to `optional<expected<T>>`` but it with a Future/Promise
- * like API.
- *
- * Also the name is not so great.
- **/
-template<class T>
-class Result {
-public:
- bool is_valid() const
- {
- return value_.which() > 0;
- }
- void set_exception(std::exception_ptr e)
- {
- value_ = std::move(e);
- }
- void set_value(T&& value)
- {
- value_ = std::move(value);
- }
- void set_value(T const& value)
- {
- value_ = value;
- }
-
- /** Extract the value from the future
- *
- * After this, the value is invalid.
- **/
- T get()
- {
- switch (value_.which()) {
- case 1: {
- T value = std::move(boost::get<T>(value_));
- value_ = boost::blank();
- return value;
- }
- case 2: {
- std::exception_ptr exception = std::move(boost::get<std::exception_ptr>(value_));
- value_ = boost::blank();
- std::rethrow_exception(std::move(exception));
- break;
- }
- default:
- throw std::future_error(std::future_errc::no_state);
- }
- }
-
-private:
- boost::variant<boost::blank, T, std::exception_ptr> value_;
-};
-
-template<>
-class Result<void> : public Result<std::nullptr_t>
-{
-public:
- void set_value()
- {
- Result<std::nullptr_t>::set_value(nullptr);
- }
- void get()
- {
- Result<std::nullptr_t>::get();
- }
-};
-
-template<class T>
-class Result<T&> : public Result<std::reference_wrapper<T>>
-{
-public:
- void set_value(T& value)
- {
- Result<std::reference_wrapper<T>>::set_value(std::ref(value));
- }
- T& get()
- {
- return Result<std::reference_wrapper<T>>::get();
- }
-};
-
-/** Execute some code and set a promise or result accordingly
- *
- * Roughly this does:
- *
- * <pre>
- * promise.set_value(code());
- * </pre>
- *
- * but it takes care of exceptions and works with `void`.
- *
- * We might need this when working with generic code because
- * the trivial implementation does not work with `void` (before C++1z).
- *
- * @param code What we want to do
- * @param promise Where to want to store the result
- */
-template <class R, class F> auto fulfill_promise(R& promise, F&& code) -> decltype(promise.set_value(code()))
-{
- try {
- promise.set_value(std::forward<F>(code)());
- } catch (...) {
- promise.set_exception(std::current_exception());
- }
-}
-
-template <class R, class F> auto fulfill_promise(R& promise, F&& code) -> decltype(promise.set_value())
-{
- try {
- std::forward<F>(code)();
- promise.set_value();
- } catch (...) {
- promise.set_exception(std::current_exception());
- }
-}
-
-/** Set a promise/result from a future/result
- *
- * Roughly this does:
- *
- * <pre>promise.set_value(future);</pre>
- *
- * but it takes care of exceptions and works with `void`.
- *
- * We might need this when working with generic code because
- * the trivial implementation does not work with `void` (before C++1z).
- *
- * @param promise output (a valid future or a result)
- * @param future input (a ready/waitable future or a valid result)
- */
-template <class P, class F> inline void set_promise(P& promise, F&& future)
-{
- fulfill_promise(promise, [&future] { return std::forward<F>(future).get(); });
-}
-
-}
-}
-
-#endif
