-/* Copyright (c) 2015-2016. The SimGrid Team.
+/* Copyright (c) 2015-2018. The SimGrid Team.
* All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
#include <cstddef>
-#include <utility>
#include <exception>
+#include <functional>
+#include <stdexcept>
+#include <type_traits>
+#include <utility>
+#include <xbt/ex.h>
namespace simgrid {
namespace xbt {
-/** A value or an exception
+/** A value or an exception (or nothing)
+ *
+ * This is similar to `optional<expected<T>>`` but it with a Future/Promise
+ * like API.
*
- * The API is similar to the one of future and promise.
+ * Also the name is not so great.
**/
template<class T>
class Result {
exception,
};
public:
- Result() {}
+ Result() { /* Nothing to do */}
~Result() { this->reset(); }
// Copy (if T is copyable) and move:
switch (that.status_) {
case ResultStatus::invalid:
break;
- case ResultStatus::valid:
+ case ResultStatus::value:
new (&value_) T(that.value);
break;
case ResultStatus::exception:
new (&exception_) T(that.exception);
break;
+ default:
+ THROW_IMPOSSIBLE;
}
return *this;
}
switch (that.status_) {
case ResultStatus::invalid:
break;
- case ResultStatus::valid:
+ case ResultStatus::value:
new (&value_) T(std::move(that.value));
that.value.~T();
break;
new (&exception_) T(std::move(that.exception));
that.exception.~exception_ptr();
break;
+ default:
+ THROW_IMPOSSIBLE;
}
that.status_ = ResultStatus::invalid;
return *this;
case ResultStatus::exception:
exception_.~exception_ptr();
break;
+ default:
+ THROW_IMPOSSIBLE;
}
status_ = ResultStatus::invalid;
}
/** Extract the value from the future
*
- * After this the value is invalid.
+ * After this, the value is invalid.
**/
T get()
{
switch (status_) {
- case ResultStatus::invalid:
- default:
- throw std::logic_error("Invalid result");
case ResultStatus::value: {
T value = std::move(value_);
value_.~T();
status_ = ResultStatus::invalid;
- return std::move(value);
+ return value;
}
case ResultStatus::exception: {
std::exception_ptr exception = std::move(exception_);
std::rethrow_exception(std::move(exception));
break;
}
+ default:
+ throw std::logic_error("Invalid result");
}
}
private:
}
};
-/** Fulfill a promise by executing a given code */
-template<class R, class F>
-auto fulfillPromise(R& promise, F&& code)
--> decltype(promise.set_value(code()))
+/** 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(code());
+ promise.set_value(std::forward<F>(code)());
+ } catch (...) {
+ promise.set_exception(std::current_exception());
+ }
+}
+template <class R, class F>
+XBT_ATTRIB_DEPRECATED_v323("Please use xbt::fulfill_promise()") auto fulfillPromise(R& promise, F&& code)
+ -> decltype(promise.set_value(code()))
+{
+ try {
+ promise.set_value(std::forward<F>(code)());
}
catch(...) {
promise.set_exception(std::current_exception());
}
}
-/** Fulfill a promise by executing a given code
- *
- * This is a special version for `std::promise<void>` because the default
- * version does not compile in this case.
- */
-template<class P, class F>
-auto fulfillPromise(P& promise, F&& code)
--> decltype(promise.set_value())
+template <class P, class F> auto fulfill_promise(P& promise, F&& code) -> decltype(promise.set_value())
{
try {
- (code)();
+ std::forward<F>(code)();
+ promise.set_value();
+ } catch (...) {
+ promise.set_exception(std::current_exception());
+ }
+}
+template <class P, class F>
+XBT_ATTRIB_DEPRECATED_v323("Please use xbt::fulfill_promise()") auto fulfillPromise(P& promise, F&& code)
+ -> decltype(promise.set_value())
+{
+ try {
+ std::forward<F>(code)();
promise.set_value();
}
catch(...) {
}
}
+/** 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, [&] { return std::forward<F>(future).get(); });
+}
+template <class P, class F>
+inline XBT_ATTRIB_DEPRECATED_v323("Please use xbt::set_promise()") void setPromise(P& promise, F&& future)
+{
+ fulfill_promise(promise, [&] { return std::forward<F>(future).get(); });
+}
+
}
}
