#include <utility>
#include <exception>
+#include <stdexcept>
+
+#include <type_traits>
+
+
namespace simgrid {
namespace xbt {
-/** A value or an exception
+/** A value or an exception (or nothing)
*
- * The API is similar to the one of future and promise.
+ * This is similar to optional<expected<T>> but it with a Future/Promise
+ * like API.
+ *
+ * Also the name it not so great.
**/
template<class T>
class Result {
}
};
-/** Fulfill a promise by executing a given 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 fulfillPromise(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());
}
}
-/** 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())
{
try {
- (code)();
+ std::forward<F>(code)();
promise.set_value();
}
catch(...) {
}
}
+/** Set a promise/result from a future/resul
+ *
+ * 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 setPromise(P& promise, F&& future)
+{
+ fulfillPromise(promise, [&]{ return std::forward<F>(future).get(); });
+}
+
}
}
