From c1906a3d2a4cf8b2a096dc0b280e494b807d545c Mon Sep 17 00:00:00 2001
From: Avi Kivity <avi@cloudius-systems.com>
Date: Fri, 17 Jul 2015 16:08:28 +0300
Subject: [PATCH] future: add futurize::make_exception_future()

Add a way to create an exceptional future of a type that is not directly
known.
---
 core/future.hh | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/core/future.hh b/core/future.hh
index 946d7262e7..d035793c42 100644
--- a/core/future.hh
+++ b/core/future.hh
@@ -509,6 +509,10 @@ struct futurize {
     /// and return the result, as a future (if it wasn't already).
     template<typename Func, typename... FuncArgs>
     static inline type apply(Func&& func, FuncArgs&&... args);
+
+    /// Makes an exceptional future of type \ref type.
+    template <typename Arg>
+    static type make_exception_future(Arg&& arg);
 };
 
 /// \cond internal
@@ -522,6 +526,9 @@ struct futurize<void> {
 
     template<typename Func, typename... FuncArgs>
     static inline type apply(Func&& func, FuncArgs&&... args);
+
+    template <typename Arg>
+    static type make_exception_future(Arg&& arg);
 };
 
 template <typename... Args>
@@ -534,6 +541,9 @@ struct futurize<future<Args...>> {
 
     template<typename Func, typename... FuncArgs>
     static inline type apply(Func&& func, FuncArgs&&... args);
+
+    template <typename Arg>
+    static type make_exception_future(Arg&& arg);
 };
 /// \endcond
 
@@ -967,6 +977,29 @@ typename futurize<future<Args...>>::type futurize<future<Args...>>::apply(Func&&
     return func(std::forward<FuncArgs>(args)...);
 }
 
+template <typename T>
+template <typename Arg>
+inline
+future<T>
+futurize<T>::make_exception_future(Arg&& arg) {
+    return ::make_exception_future<T>(std::forward<Arg>(arg));
+}
+
+template <typename... T>
+template <typename Arg>
+inline
+future<T...>
+futurize<future<T...>>::make_exception_future(Arg&& arg) {
+    return ::make_exception_future<T...>(std::forward<Arg>(arg));
+}
+
+template <typename Arg>
+inline
+future<>
+futurize<void>::make_exception_future(Arg&& arg) {
+    return ::make_exception_future<>(std::forward<Arg>(arg));
+}
+
 /// \endcond
 
 #endif /* FUTURE_HH_ */