Changeset a6c3bf3 in mainline for uspace/lib/cpp/include/__bits/thread/future_common.hpp

Timestamp:

2019-07-01T15:33:01Z (5 years ago)

Author:

Jaroslav Jindrak <dzejrou@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

8660ad0

Parents:

a552044

Message:

cpp: remove redundant specializations of shared_future using some metaprogramming tricks

File:

• uspace/lib/cpp/include/__bits/thread/future_common.hpp (modified) (2 diffs)

uspace/lib/cpp/include/__bits/thread/future_common.hpp

@@ -30 +30 @@
 #define LIBCPP_BITS_THREAD_FUTURE_COMMON
 
+#include <__bits/aux.hpp>
 #include <system_error>
 #include <stdexcept>
@@ -82 +83 @@
             error_code code_;
     };
+
+    namespace aux
+    {
+        /**
+         * Auxilliary metafunctions that let us avoid
+         * specializations in some cases. They represent
+         * the inner stored type and the return type of
+         * the get() member function, respectively.
+         */
+
+        template<class T>
+        struct future_inner: aux::type_is<T>
+        { /* DUMMY BODY */ };
+
+        template<class T>
+        struct future_inner<T&>: aux::type_is<T*>
+        { /* DUMMY BODY */ };
+
+        template<class T>
+        using future_inner_t = typename future_inner<T>::type;
+
+        template<class T>
+        struct future_return: aux::type_is<const T&>
+        { /* DUMMY BODY */ };
+
+        template<class T>
+        struct future_return<T&>: aux::type_is<T&>
+        { /* DUMMY BODY */ };
+
+        template<>
+        struct future_return<void>: aux::type_is<void>
+        { /* DUMMY BODY */ };
+
+        template<class T>
+        using future_return_t = typename future_return<T>::type;
+    }
 }